Patent Application
20250210799
Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57.
The present disclosure relates to a lithium secondary battery. More particularly, the present disclosure relates to a lithium secondary battery having a structure in which an electrode assembly is received in a battery can.
Recently, with the development of electric vehicle technology, the demand for high capacity batteries is increasing, and there is a need for development of large cylindrical batteries having high volume. In the case of commonly used small cylindrical batteries, i.e., cylindrical batteries having 1865 or 2170 form factor, due to low capacity, resistance or heat generation does not have a great influence on battery performance. However, when the specification of small cylindrical batteries is applied to large cylindrical batteries, serious problems with battery safety may occur.
As the size of batteries increases, the amount of heat and gas generated in the batteries increases as well, and due to the heat and gas, temperature and pressure in the batteries rises, causing fire or explosion in the batteries. To prevent this, it is necessary to properly release the heat and gas inside the batteries to the atmosphere, and to this end, the cross-sectional area of the batteries as passages for releasing the heat out of the batteries needs to be increased with increasing volume. However, because the increase in cross-sectional area is generally less than the increase in volume, as the batteries increases in size, the amount of heat generated in the batteries increases and the consequential explosion risk increases, while the output decreases. Additionally, during fast charging at high voltage, a large amount of heat may be generated near electrode tabs in a short time, causing fire in the batteries.
To prevent fire or explosion risks, according to the conventional art, secondary batteries are equipped with safety devices. As an example, cylindrical secondary batteries may generally have vent portions. According to the conventional art, when the internal pressure of the secondary batteries rises, the vent portions move up and their parts are ruptured to form paths for the release of gas, and through the paths, gas inside the secondary batteries is released to the atmosphere, thereby preventing explosion risks.
However, even when the vent portions are open, the side rupture of the battery can may occur. When it is used in a vehicle, the cylindrical lithium secondary battery is applied to the vehicle in the form of a battery pack in which a plurality of cylindrical lithium secondary batteries is coupled to each other, and the side rupture of the battery can lead to continuous flame spread to adjacent other unit cells.
The present disclosure is directed to providing a battery having high volume for high capacity and high safety by reducing or preventing side rupture of a battery can when the internal pressure of the battery can rises in the lithium secondary battery having high volume.
Additionally, by reducing or preventing the side rupture of the battery can, the present disclosure may reduce the influence of any one battery on its adjacent other battery in a battery pack including a plurality of batteries, thereby greatly improving safety of the battery pack and a vehicle including the batteries.
Accordingly, the present disclosure relates to the lithium secondary battery, the battery pack and the vehicle with improved safety.
One aspect of the present disclosure provides a battery comprising a can, a jellyroll electrode assembly, and a cap plate. The can comprises a cylindrical body, a first wall at a first end of the cylindrical body, and a second wall a second end of the cylindrical body. The cylindrical body has a diameter and a length between the first end and the second end along a central axis of the cylindrical body. The jellyroll electrode assembly is housed inside the cylindrical body and comprises an anode, a separator, and a cathode that are rolled together about the central axis. The foregoing battery comprises a rupture notch formed into the first wall or the second wall. The first wall comprises a cap plate air-tightly integrated to the cylindrical body in which an edge portion of the cylindrical body near the first end (hereinafter referred to as a “crimping portion”) is crimped around a perimeter of the cap plate, wherein the crimping portion is configured to uncrimp when the internal pressure reaches an uncrimping pressure. The rupture notice is configured to rupture and create an opening when an internal pressure of the battery reaches a rupture pressure. The rupture pressure is lower than the uncrimping pressure such that the crimping portion does not uncrimp when the internal pressure reaches the rupture pressure. The predetermined rupture pressure is set to be sufficient to create an explosive power to eject a portion of the jellyroll electrode assembly to outside the cylindrical body: such that the ejected portion extends telescopically along the central axis outside the cylindrical body in which an inner portion of the jellyroll electrode assembly ejects prior to an outer portion of the jellyroll electrode assembly that surrounds the inner portion inside the cylindrical body before rupture, such that a leading edge of the ejected portion reaches a distance that is at least ¼ of the length from the first end of the cylindrical body along the central axis, such that the ejected portion to outside the cylinder body is at least 25% of a mass of the jellyroll electrode assembly located inside the can prior to rupturing, and such that, being located outside the cylindrical body, the ejected portion would not cause any further chemical reactions that could lead to thermal runaway inside the cylindrical body.
In some embodiments, the predetermined rupture pressure is about 21 kgf/cm2 or higher. In some embodiments, the predetermined rupture ejection pressure is from about 25 kgf/cm2 to about 29 kgf/cm2. In some embodiments, the battery is a 46110 cell battery, a 4875 cell battery, 48110 cell battery, 4880 cell battery, 4680 cell battery, or a 4695 cell battery. In some embodiments, the battery does not comprise another rupture notch or vent configured for venting gas. In some embodiments, the cylindrical body has a side portion that is ruptured at a side rupture pressure that is higher than the predetermined rupture pressure of the rupture notch. In some embodiments, the ejected portion of the jellyroll electrode assembly has a spiral structure. In some embodiments, a ratio of form factor of the battery is 0.4 or more. In some embodiments, the cylindrical body has a side portion with a thickness of from about 0.1 mm to about 0.4 mm. In some embodiments, the second wall is integrally formed with the cylindrical body. In some embodiments, the second wall is airtightly integrated with the cylindrical body with or without a seam connecting therebetween. In some embodiments, the rupture notch is formed into the cap plate of the first wall. In some embodiments, the rupture notch is formed into the second wall.
Another aspect of the present disclosure provides a battery pack comprising the battery provided herein. Another aspect of the present disclosure provides a vehicle comprising the battery pack provided herein.
An embodiment of the present disclosure provides a lithium secondary battery including a battery can, an electrode assembly and an electrolyte received in the battery can, and a cap plate to seal the battery can, wherein the battery can has a first end portion and a second end portion opposite to each other, and wherein when the electrode assembly is ejected through the first end portion of the battery can by an internal pressure rise of the battery can, a distance from an end portion of the electrode assembly located farthest away from the battery can to the second end portion of the battery can is 1.25 times or more as much as a distance between the first end portion and the second end portion of the battery can.
According to an embodiment, the electrode assembly is a jellyroll-type electrode assembly including a positive electrode plate and a negative electrode plate wound in a direction with a separator interposed between the positive electrode plate and the negative electrode plate, and when the electrode assembly is ejected through the first end portion of the battery can, the electrode assembly has a spiral structure.
According to an embodiment, without or before thermal runaway of the battery can; or without or before side rupture of the battery can, the electrode assembly is ejected through the first end portion of the battery can.
According to an embodiment, the first end portion of the battery can includes a vent portion, or the cap plate is secured to the first end portion of the battery can, and the cap plate includes a vent portion. Here, the electrode assembly may be ejected through the first end portion of the battery can through destruction of a structure for securing the cap plate to the first end portion of the battery can or rupture of the vent portion.
According to an embodiment, the cap plate includes a vent portion, and the internal pressure at which the vent portion is ruptured is 21 kgf/cm2 or more. According to an example, the internal pressure at which the vent portion is ruptured may be more than 25 kgf/cm2 and less than 29 kgf/cm2.
According to an embodiment, a ratio of a maximum width in a cross section of the electrode assembly in a direction perpendicular to a winding axis to a maximum width in a cross section of the battery can in the direction perpendicular to the winding axis is less than 1.
According to an embodiment, a sealing tape including polypropylene is attached to an outermost end portion of the electrode assembly.
According to an embodiment, the lithium secondary battery includes a first current collector plate between the first end portion of the battery can and the electrode assembly.
According to an embodiment, the first current collector plate may have a battery can coupling portion having a tapered structure.
According to an embodiment, a flame release area may range from 30% to 50% based on an open area 100% of the first end portion of the battery can.
According to an embodiment, a ratio of form factor of the lithium secondary battery may be 0.4 or more. For example, the lithium secondary battery may be a 46110 cell, a 4875 cell, a 48110 cell, a 4880 cell, a 4680 cell, or a 4695 cell.
According to an embodiment, the electrode assembly is cylindrical in shape.
According to an embodiment, a thickness of a side of the battery can ranges from 0.1 mm to 0.4 mm.
According to an embodiment, each of the positive electrode plate and the negative electrode plate includes an uncoated portion where an active material layer is not formed, and at least part of the uncoated portion of the positive electrode plate or the negative electrode plate defines an electrode tab to form a tab-less structure.
According to an embodiment, the positive electrode plate uncoated portion and the negative electrode plate uncoated portion are respectively formed at an end portion of the positive electrode plate and the negative electrode plate along the direction in which the electrode assembly is wound, a current collector plate is coupled to each of the positive electrode plate uncoated portion and the negative electrode plate uncoated portion, and the current collector plate is connected to an electrode terminal.
According to an embodiment, each of the positive electrode plate uncoated portion and the negative electrode plate uncoated portion is shaped into a plurality of independently bendable segments, and at least part of the plurality of segments is bent toward a winding center of the electrode assembly.
According to an embodiment, the at least part of the plurality of bent segments is overlapped on top or bottom of the electrode assembly, and the current collector plate is coupled to the plurality of overlapped segments.
An embodiment provides a battery pack including the lithium secondary battery according to the above-described embodiments.
An embodiment provides a vehicle including the battery pack.
The lithium secondary battery according to the embodiments of the present disclosure may prevent rupture of the side portion of the battery can or local occurrence of flames at weak or vulnerable elements in the battery can before the rupture of the battery can due to the internal pressure rise of the battery can. Specifically, it may be possible to prevent rupture of the side portion of the battery can by designing the electrode assembly to be ejected at the strong pressure through one end portion of the battery can without or before the rupture of the side portion of the battery can. Accordingly, it may be possible to reduce the influence of any one battery on its adjacent other battery in the battery pack including the plurality of batteries, thereby preventing the spread of fire through the batteries. Additionally, it may be possible to prevent local occurrence of flames at weak or vulnerable elements in the battery can by designing the electrode assembly to be ejected out of the battery can without or before the occurrence of flames in the battery can.
Accordingly, it may be possible to provide the lithium secondary battery with improved safety and the battery pack and the vehicle including the same. Additionally, from the improved safety of the battery, an additional effect of relaxing the requirements of other elements to be taken into account to improve safety can be expected. For example, cost savings and improved process efficiency can be expected by reducing the thickness of the battery can that has been designed with a large thickness in view of safety.
The accompanying drawings illustrate the exemplary embodiments of the present disclosure and together with the following detailed description, serve to provide a better understanding of the technical aspect of the present disclosure, and thus the present disclosure should not be construed as being limited to the drawings.
Hereinafter, the exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Prior to the description, it should be understood that the terms or words used in the specification and the appended claims should not be construed as being limited to general and dictionary meanings, but rather interpreted based on the meanings and concepts corresponding to the technical aspect of the present disclosure on the basis of the principle that the inventor is allowed to define the terms appropriately for the best explanation. Therefore, the embodiments described herein and the illustrations shown in the drawings are exemplary embodiments of the present disclosure to describe the technical aspect of the present disclosure and are not intended to be limiting, so it should be understood that a variety of other equivalents and modifications could have been made thereto at the time the application was filed.
Additionally, to help the understanding of the present disclosure, the accompanying drawings may illustrate some elements in exaggerated dimensions, not in actual scale. Furthermore, the same element in different embodiments may be given the same reference numeral.
Although the terms “first”, “second” and the like, are used to describe various elements, these elements are not limited by the terms. These terms are used to distinguish one element from another, and unless expressly stated otherwise, a first element may be a second element.
Throughout the specification, each element may be singular or plural unless expressly stated otherwise.
When an element is referred to as being present “on (or below)” another element, it can be placed in contact with an upper surface (or a lower surface) of the other element, or intervening elements may be present.
Additionally, when an element is “connected to”, “coupled to” or “linked to” another element, it should be understood that they can be directly connected or linked to each other, but intervening elements may be present, or each element may be “connected to”, “coupled to” or “linked to” each other through another element.
In the specification, “A and/or B” refers to either A or B or both unless expressly stated otherwise. Additionally, “C to D” refers to C or more and D or less unless expressly stated otherwise.
For convenience of description, in the specification, a direction following a length direction of a winding axis of an electrode assembly wound in a jellyroll style is referred to as an axial direction Y. Additionally, a direction around the winding axis is referred to as a peripheral direction or a circumferential direction X. Additionally, a direction facing toward the winding axis or facing away from the winding axis is referred to as a radial direction. Among them, in particular, the direction facing toward the winding axis is referred to as a centripetal direction, and the direction facing away from the winding axis is referred to as a centrifugal direction.
As used herein, the singular form of a word includes the plural, unless the context clearly dictates otherwise. The plural encompasses the singular and vice versa. Thus, the references “a,” “an” and “the” are generally inclusive of the plurals of the respective terms. For example, while the present disclosure has been described in terms of “a” layer, “a” substrate, “a” cell, and the like, more than one of these and other components, including combinations, can be used.
The term “about” indicates and encompasses an indicated value and a range above and below that value.
The words “comprise,” “comprises,” and “comprising” are to be interpreted inclusively rather than exclusively. Likewise, the terms “include,” “including” and “or” should all be construed to be inclusive, unless such a construction is clearly prohibited from the context. A disclosure of an embodiment defined using the term “comprising” is also a disclosure of embodiments “consisting essentially of” and “consisting of” the disclosed components. The phrase “consisting of” excludes any element, step, or ingredient not specified.
As used herein, the term “combination thereof” included in any Markush-type expression means a combination or mixture of one or more elements selected from the group of elements disclosed in the Markush-type expression, and refers to the presence of one or more elements selected from the group. The term “combinations thereof” includes every possible combination of elements to which the term refers.
As used herein, the expression “between” is inclusive of end points.
Furthermore, all numerical ranges herein should be understood to include all integers, whole or fractions, within the range. Moreover, any numerical range recited herein is intended to include all sub-ranges subsumed therein, and these numerical ranges should be construed as providing support for a claim directed to any number or subset of numbers in that range. For example, a disclosure of from 1 to 10 should be construed as supporting a range of from 1 to 8, from 3 to 7, from 1 to 9, from 3.6 to 4.6, from 3.5 to 9.9, and so forth. When ranges are given, any endpoints of those ranges and/or numbers within those ranges can be combined with the scope of the present disclosure.
As used herein, “including,” “such as,” “for example,” and like terms mean “including/such as/for example but not limited to.”
As used herein, the term “example,” particularly when followed by a listing of terms, is merely illustrative, and should not be deemed to be exclusive or comprehensive. Any embodiment disclosed herein can be combined with any other embodiment disclosed herein unless explicitly indicated otherwise.
As used herein, the terms “vent portion” and “rupture notch” are interchangeable. The word “vent” in the term “vent portion” has the same meaning as the word “rupture” in the term “rupture notch.”
First,
The lithium secondary battery of
At least one of the first end portion E1 or the second end portion E2 includes at least one opening portion. Any one of the first end portion E1 and the second end portion E2 may include the opening portion, and both the first end portion E1 and the second end portion E2 may include the opening portion. The electrode assembly 10 and the electrolyte may be received in the battery can 20 through the opening portion included in at least one of the first end portion E1 or the second end portion E2. After the electrode assembly 10 and the electrolyte are received in the battery can 20, the opening portion of at least one of the first end portion E1 or the second end portion E2 may be closed through the cap plate 40.
Besides, the battery 1 may further include a terminal 50 and/or a sealing gasket G1 and/or an insulation gasket G2 and/or a current collector plate 30, P and/or an insulator S and/or a lead 45.
According to need, the battery can 20 may have a beading portion 21 and a crimping portion 22 at the upper end as a structure for securing the cap plate 40 to the first end portion E1 or the second end portion E2 of the battery can 20. The beading portion 21 may be formed by beading the circumference of the outer peripheral surface of the battery can 20 toward a winding center axis up to the distance of D1. The beading portion 21 may prevent the electrode assembly 10 accommodated in the battery can 20 from slipping out through the opening portion of the battery can 20 during storage or normal charging/discharging of the lithium secondary battery, and act as a support on which the cap plate 40 is mounted.
The crimping portion 22 may be formed on the beading portion 21, and is extended and bent to surround the outer peripheral surface of the cap plate 40 disposed on the beading portion 21 and a part of the upper surface of the cap plate 40.
The cap plate 40 is used to seal the open end portion of the battery can 20, for example, the first end portion E1 or the second end portion E2, and may include a sealing gasket G1 that provides sealability between the cap plate 40 and the battery can 20 and has insulating property. According to need, the cap plate 40 may further include a connection plate 42c electrically and mechanically coupled to the cap plate 40. For example, the cap plate 40 may be compressed onto the beading portion 21 of the battery can 20, and secured by the crimping portion 22. The first gasket G1 may be interposed between the cap plate 40 and the crimping portion 22 to ensure sealability of the battery can 20 and electrical insulation between the battery can 20 and the cap plate 40.
The cap plate 40 may include any material and structure for covering the opening portion of the first end portion E1 or the second end portion E2 of the battery can 20 without limitation.
When the cap plate 40 is made of metal having electrical conductivity, the cap plate 40 may be electrically connected to a positive or negative electrode plate of the electrode assembly 10, and electrically isolated from the battery can 20 through the sealing gasket G1. In this case, the cap plate 40 may act as a positive or negative terminal of the lithium secondary battery. In this case, the cap plate 40 may have a protruding portion 42a protruded upward from the winding center C, and when the protruding portion contacts an external power source, an electric current from the external power source may be applied. The protruding portion may be exposed to the outside of the lithium secondary battery for the contact with the external power source, and the degree of protrusion may be designed according to need. For example, as shown in
However, the cap plate 40 does not necessarily act as a passage of electric current. In other words, the cap plate 40 may be made of an electrically non-conductive material. Accordingly, the application of the above-described sealing gasket G1 is not necessarily essential in the case where the battery can 20 and the cap plate 40 can be firmly secured and sealability of the open portion of the battery can 20 can be ensured through welding or by the application of any other component.
Meanwhile, the battery 1 according to the present disclosure may further include the current collector plate 30, P, according to need. Specifically, the battery 1 may include a first current collector plate between the first end portion E1 of the battery can 20 and the electrode assembly and/or a second current collector plate P between the second end portion E2 of the battery can 20 and the electrode assembly. As shown in
The internal pressure rise of the battery can may occur due to overcharge, defects in at least one of the elements of the battery, abnormal chemical reaction, abnormal physical deformation, internal or external impacts of the battery, abnormal temperature increase and so on. These factors are not always the cause of the internal pressure rise of the battery can, but may increase the likelihood.
The range of ratios of the distance t1 to the distance t2 represents that the electrode assembly 10 was ejected with a strong force through the first end portion of the battery can 20. Accordingly, when the electrode assembly 10 is ejected, only the first end portion E1 of the battery can 20 or the cap plate 40 coupled to the first end portion E1 gets damaged, and any other part than the first end portion E1 or the cap plate 40 coupled to the first end portion E1, for example, the side portion of the battery can is less likely to get damaged. Accordingly, it may be possible to reduce or prevent the risk of fire spreading through batteries in a battery pack including the batteries.
By the above-described mechanism of action, in the lithium secondary battery according to an embodiment of the present disclosure, without or before thermal runaway of the battery can; or without or before side rupture of the battery can, the electrode assembly may be ejected through the first end portion of the battery can.
The thermal runaway of the battery can refers to a phenomenon in which fire occurs due to internal and/or external thermal factors of the battery, or temperature rise by chemical or physical impacts. The side rupture of the battery can refers to expulsion of the pressure in the battery can through the side of the battery can due to tearing or melting or pin holes in the battery can at the part except the first end portion and the second end portion of the battery can, i.e., the part connecting the first end portion to the second end portion. When the bent part by the crimping portion and the beading portion is included in the side of the battery can, it may be understood that the crimping portion and the beading portion are also included in the side of the battery can.
In the lithium secondary battery according to an embodiment of the present disclosure, when the pressure in the battery can increases, the electrode assembly is ejected with the strong force through the first end portion of the battery can, so the part of the battery can other than the first end portion, i.e., the side of the battery can is not destroyed. Additionally, in the lithium secondary battery according to an embodiment of the present disclosure, because the electrode assembly is ejected out of the battery can in a very short time by the strong pressure, thermal runaway does not occur in the battery can before a predetermined part or more of the electrode assembly slips out of the battery can.
For example, the electrode assembly may be ejected through the first end portion of the battery can by the internal pressure rise of the battery can in the overcharge condition by the repeated charge and discharge of the lithium secondary battery at the rate of from 1.5 C to 2 C, for example, at the rate of 1.7 C.
According to an example, the electrode assembly is a jellyroll-type electrode assembly including the positive electrode plate and the negative electrode plate wound in a direction with a separator interposed between the positive electrode plate and the negative electrode plate.
As shown in
According to an embodiment, the first end portion E1 of the battery can 20 or the cap plate 40 disposed at the first end portion E1 include vent portions 41, 201.
The vent portions 41, 201 correspond to an area that is formed at a part of the cap plate 40 or the battery can 20 and is structurally weaker than the surrounding area so as to be easily ruptured when the internal pressure is applied. The vent portions 41, 201 may be, for example, an area having a smaller thickness than the surrounding area. To realize the smaller thickness, the vent portions 41, 201 may include a notch.
According to an embodiment, the internal pressure at which the vent portion is ruptured may be 21 kgf/cm2 or more, 21.5 kgf/cm2 or more, 22 kgf/cm2 or more, 22.5 kgf/cm2 or more, 23 kgf/cm2 or more, 23.5 kgf/cm2 or more, 24 kgf/cm2 or more, 24.5 kgf/cm2 or more, 25 kgf/cm2 or more, more than 25 kgf/cm2, 25.5 kgf/cm2 or more, 26 kgf/cm2 or more, 26.5 kgf/cm2 or more, or 27 kgf/cm2 or more. According to an example, the internal pressure at which the vent portion is ruptured may be equal to or less than the pressure at which the cap plate is separated from the batteryvent, or lower pressure. For example, when the battery can includes the means for securing the cap plate, for example, the crimping portion, the internal pressure at which the vent portion is ruptured may be equal to or less than the pressure at which the crimping portion is uncrimped, or lower pressure. As another example, when the cap plate is joined to the battery can by welding, the internal pressure at which the vent portion is ruptured may be equal to or less than the pressure at which the cap plate is separated from the battery can due to damage to the joined part by the welding, or lower pressure. The internal pressure at which the vent portion is ruptured may be 29 kgf/cm2 or less, 28.5 kgf/cm2 or less, 28 kgf/cm2 or less, 27.5 kgf/cm2 or less, or 27 kgf/cm2 or less. According to an example, the internal pressure at which the vent portion is ruptured may be 21 kgf/cm2 or more and 29 kgf/cm2 or less, 24 kgf/cm2 or more and 29 kgf/cm2 or less, or more than 25 kgf/cm2 and 29 kgf/cm2 or less. When the internal pressure at which the vent portion is ruptured is designed to be high as described above, the electrode assembly is not ejected out of the battery can, or even if the electrode assembly is ejected, the electrode assembly may not be ejected through only the first end portion of the battery can, causing rupture of the side portion of the battery can. Accordingly, with the internal pressure at which the vent portion is ruptured, as described above, it may be possible to improve the safety of the battery and the battery can. The internal pressure at which the vent portion is ruptured may be differently designed depending on the shape, size, material, or thickness of the vent portion, a thickness difference between the vent portion and the surrounding area and so on.
According to an embodiment, a ratio of the maximum width in the cross section of the electrode assembly in the direction perpendicular to the winding axis to the maximum width in the cross section of the battery can in the direction perpendicular to the winding axis may be less than 1. When the lithium secondary battery is cylindrical in shape, the maximum width in the cross section of the battery can or the electrode assembly in the direction perpendicular to the winding axis may be the diameter of the battery can or the electrode assembly passing through the winding axis (the winding center).
According to an embodiment, a sealing tape including polypropylene or polyimide, for example polypropylene may be attached to the outermost end portion of the electrode assembly. According to
The surface of the sealing tape 80 that contacts the battery can is preferably made of a material that does not react with the electrolyte solution solvent and can maintain the original shape. For example, the surface of the sealing tape 80 that contacts the battery can is preferably made of polypropylene or polyimide. Because the polypropylene or polyimide does not react with the solvent of electrolyte solution and can maintain the original shape, as described above, it is advantageous to cause the electrode assembly 10 to be ejected with the strong force through the first end portion E1 of the battery can. For example, the sealing tape 80 includes a substrate and an adhesive layer, the substrate is made of polypropylene or polyimide, and the adhesive layer is attached to the side of the electrode assembly including the outermost end portion of the electrode assembly 10. Here, the adhesive layer is not limited to a particular type, and may include any known type in the art. For example, the adhesive layer may be made of any material that does not cause chemical reaction to the battery without limitation, and may include, for example, an acrylic adhesive, or an SBR-based adhesive.
The sealing tape 80 may have a width ts that is 0.1 times or more, 0.2 times or more, 0.3 times or more, 0.4 times or more, 0.5 times or more, 0.6 times or more, 0.7 times or more, or 0.8 times or more as much as the distance t2 between the two end portions of the electrode assembly 10 or the length of the battery can (the distance between the first end portion E1 and the second end portion E2) in the axial direction Y of the winding axis of the electrode assembly 10. Additionally, the sealing tape 80 may have the width ts that is 0.95 times or less, 0.9 times or less, 0.8 times or less, 0.7 times or less, 0.6 times or less, or 0.5 times or less as much as the distance t2 between the two end portions of the electrode assembly 10 or the length of the battery can (the distance between the first end portion E1 and the second end portion E2) in the axial direction Y of the winding axis of the electrode assembly 10. The sealing tape 80 may have a length that is 0.1 times or more, 0.2 times or more, 0.3 times or more, 0.4 times or more, 0.45 times or more, 0.5 times or more, 0.6 times or more, 0.7 times or more, 0.8 times or more, 0.9 times or more, or 0.95 times or more as much as the outermost circumference of the electrode assembly 10 in the circumferential direction X of the electrode assembly 10. The sealing tape 80 may have the length that is 1 time or less, or 0.98 times or less as much as the outermost circumference of the electrode assembly 10 in the circumferential direction X of the electrode assembly 10. Because the sealing tape having the above-described width and length is made of polypropylene or polyimide on the surface that contacts the battery can, it may be advantageous to cause the electrode assembly 10 to be ejected with the strong force through the first end portion E1 of the battery can. For example, when the lithium secondary battery is a 4680 cell, the width fs of the sealing tape 80 may range from 30 mm to 65 mm, and the length in the circumferential direction X of the electrode assembly 10 may range from 130 mm to 135 mm.
According to an embodiment, as shown in
Here, the first current collector plate may have a battery can coupling portion having a tapered structure. For example, the tapered structure may be a part that is welded to the battery can. Using the current collector plate having the tapered structure, when the electrode assembly 10 passes through the first end portion E1 of the battery can 20, the first current collector plate may easily break, thereby minimizing the interruption of the first current collector plate to eject the electrode assembly 10.
According to an embodiment, as shown in
According to a further embodiment, the electrode assembly may include the uncoated portion 11 (
The tab coupling portion 32 and/or the battery can coupling portion 33 may be one tab coupling portion 32 and/or one battery can coupling portion 33, respectively, but may include a plurality of tab coupling portions 32 and/or a plurality of battery can coupling portions 33. The at least one tab coupling portion 32 and the at least one battery can coupling portion 33 may be, for example, arranged in an approximately radial or crisscross shape, or a combination thereof on the basis of the central portion of the first current collector plate 30. In another aspect, each of the plurality of battery can coupling portions 33 may be disposed between the adjacent tab coupling portions 32.
The support portion 31 and the plurality of tab coupling portions 32 are disposed on the electrode assembly 10. The tab coupling portion 32 is coupled to the uncoated portion 11 of the electrode assembly 10. The tab coupling portion 32 may be, for example, coupled to the uncoated portion 11 by welding along the radial direction of the electrode assembly 10. The tab coupling portion 32 may be, for example, weld-coupled to the uncoated portion 11 in parallel to the first or second end portion of the battery can 20.
Meanwhile, not only the tab coupling portion 32 but also the support portion 31 may be coupled to the uncoated portion 11. The tab coupling portion 32 and the uncoated portion 11 may be coupled by welding. In the case of the battery can 20 having the beading portion 21, the support portion 31 and the tab coupling portion 32 are located at the lower position than the beading portion 21 (inside of the battery can).
According to an embodiment, the support portion 31 may have a current collector plate hole H2 at a location corresponding to a winding hole H1 formed at the approximately central portion of the electrode assembly 10. The winding hole H1 and the current collector plate hole H2 in communication with each other may act as a passage for insertion of a welding rod or irradiation of a laser beam for welding between the terminal 50 and/or the second current collector plate P or welding between the terminal 50 and the lead tab (not shown). Here, the second current collector plate P may be disposed between the second end portion E2 of the battery can 20 and the electrode assembly 10.
The current collector plate hole H2 may have a diameter that is substantially equal to or larger than the winding hole H1 of the electrode assembly 10 not to cover the winding hole H1 formed at the core of the electrode assembly 10. In this case, because the winding hole H1 of the electrode assembly is not covered with the current collector plate 30, it may be possible to prevent the decrease in injection performance, and allow for the insertion of the device for welding or a sufficient space for laser irradiation. Additionally, when the electrode assembly is ejected through the first end portion of the battery can by the internal pressure rise of the battery can, it is advantageous to cause the upper surface (adjacent to the first end portion of the battery can) of the electrode assembly 10 to slip out from the separator and the electrode plate located at or near the winding center by the strong pressure in the gas release at the winding center H1, C of the electrode assembly 10.
The plurality of tab coupling portions 32 may be extended toward the sidewall of the battery can 20 approximately radially from the support portion 31 of the first current collector plate 30. Each of the plurality of tab coupling portions 32 may be located apart from each other along the circumference of the support portion 31. Meanwhile, to increase the coupling strength and reduce the electrical resistance through the increased coupling area between the first current collector plate 30 and the electrode assembly 10, not only the tab coupling portion 32 but also the support portion 31 may be coupled to the uncoated portion 11.
At least part of the uncoated portion 11 may be formed in bent shape such that the end portion is approximately parallel to the tab coupling portion 32. In this case, the bending may be, for example, made toward the winding center C of the electrode assembly 10. When the end portion of the uncoated portion 11 is formed and coupled to the tab coupling portion 32 in parallel to the tab coupling portion 32, it may be possible to increase the coupling area, thereby improving the coupling strength and reducing the electrical resistance, and to minimize the height of the electrode assembly 10, thereby improving the energy density. Meanwhile, the bent end portion 11a of the uncoated portion 11 may be overlapped in multilayers. When the uncoated portion 11 is overlapped in multilayers, the tab coupling portion 32 of the first current collector plate 30 may be coupled to a coupling surface formed by bending the uncoated portion 11 and overlapping in multilayers.
The plurality of battery can coupling portions 33 may be extended toward the sidewall of the battery can 20 approximately radially from the support portion 31 of the first current collector plate 30. Each of the plurality of battery can coupling portions 33 may be located apart from each other along the circumference of the support portion 31. The at least one battery can coupling portion 33 may be located between the adjacent tab coupling portions 32. The plurality of battery can coupling portions 33 may be coupled to the inner surface of the battery can 20, for example, the beading portion 21. In particular, the battery can coupling portions 33 may be coupled to the upper surface of the beading portion 21. In the battery 1 of the present disclosure, when this structure is applied, the battery can coupling portion 33 may be naturally mounted on the beading portion 21 through the process of accommodating the electrode assembly 10 coupled with the first current collector plate 30 in the battery can 20. Accordingly, the welding process of the battery can 20 and the first current collector plate 30 may be easily performed. The welding for coupling of the battery can 20 and the first current collector plate 30 may include, for example, laser welding, resistance welding, ultrasonic welding, soldering or spot welding. The battery can coupling portion 33 may be weld-coupled to the beading portion 21 to form multiple current paths to limit the resistance level below approximately 4 milliohms that is suitable for fast charging.
The battery can coupling portion 33 includes a coupling portion 33a coupled to the beading portion 21 on the inner surface of the battery can 20 and the connection portion 33b connecting the support portion 31 to the coupling portion 33a.
The coupling portion 33a is coupled to the inner surface of the battery can 20. When the battery can 20 has the beading portion 21, the coupling portion 33a may be coupled to the beading portion 21 as described above. The coupling portion 33a may have a shape that conforms to the shape of the upper surface of the beading portion 21. According to an example, for stable contact and coupling, both the beading portion 21 and the coupling portion 33a may be extended along a direction approximately parallel to the lower surface of the battery can 20, i.e., a direction approximately perpendicular to the sidewall of the battery can 20. The coupling portion 33a may have a flat surface which is coupled to the upper surface of the beading portion 21 facing the open portion. That is, the coupling portion 33a includes the flat portion approximately parallel to the lower surface of the battery can 20 at least in part. When the battery can coupling portion 33 stably contacts the beading portion 21, welding between the two components may be done well, thereby improving the coupling strength between the two components and minimizing the resistance increase at the coupled part.
The connection portion 33b may be extended in the radial direction and the winding axial direction. The connection portion 33b may have an upwardly convex structure (toward the first end portion E1 of the battery can 20), and may include at least one bending portion. For example, the boundary of the coupling portion 33a and the connection portion 33b may be bent at an obtuse angle. The slope of the connection portion 33b may decrease stepwise or gradually as it goes toward the beading portion.
As shown in
The coupling portion 33a may be weld-coupled to the upper surface of the beading portion 21 (the upper surface of the upper beading portion). Moreover, the coupling portion 33a may be weld-coupled to the flat area on the upper surface of the beading portion 21. The weld area between the coupling portion 33a and the beading portion 21 may be narrower than the flat upper surface of the beading portion 21. When the connection portion 33b has the bending portion, the angle between the coupling portion 33a and the connection portion 33b may be acute due to the bending portion.
According to an embodiment, when the first current collector plate is projected onto the open area of the first end portion of the battery can, on the basis of the open area 100%, the area of the projected part of the first current collector plate may range between 50% and 70%. The open area of the first end portion of the battery can does not include the side thickness of the battery can, and when the width of the battery can is reduced due to the presence of the crimping portion 22 or the beading portion 21 at the first end portion side of the battery can, it refers to the open area of the part having the minimum width of the first end portion of the battery can. The projection of the first current collector plate refers to projection of the first current collector plate onto the open area in a direction parallel to the side of the battery can. The aforementioned area range may represent that a flame release area where the electrode assembly directly faces the opening portion of the first end portion of the battery can without the first current collector plate interposed therebetween ranges approximately from 30% to 50% on the basis of the open area 100% of the first end portion of the battery can. The flame release area may be an area except the projected area of the first current collector plate from the open area of the first end portion of the battery can as shown in section A indicated by hatching in
According to an embodiment, the support portion 31 may include at least one hole H3. As shown in
The size of the hole H3, the area (or the width) of the slit S1, and/or the width of the connection portion 33b of the first current collector plate 30 may be designed in such a range that the area of the projected part of the first current collector plate range between 50% and 70% on the basis of the open area 100% when the first current collector plate is projected onto the open area of the first end portion of the battery can. In other words, the size of the hole H3, the area (or the width) of the slit, and/or the width of the connection portion 33b of the first current collector plate 30 may be designed such that the flame release area where the electrode assembly directly faces the first end portion of the battery can without the first current collector plate interposed therebetween ranges approximately between 30% and 50%, for example, between 34% and 36%, between 38% and 40%, or between 44% and 47% on the basis of the open area 100% of the first end portion of the battery can.
The use of the positive electrode plate 210 and the negative electrode plate 211 including the uncoated portion 222 may realize the battery of a tab-less structure in which an electrode tab is absent, and at least part of the uncoated portion of the positive electrode plate 210 and the negative electrode plate 211 defines the electrode tab. Specifically, the uncoated portion 222 may be formed at one end portion of the current collector 220 and extended along the winding direction X, and the current collector plate may be coupled to each of the positive electrode plate uncoated portion and the negative electrode plate uncoated portion, and connected to the electrode terminal to realize the battery of the tab-less structure. The reference numerals 11 and 12 in
The positive electrode plate uncoated portion and the negative electrode plate uncoated portion may be shaped into a plurality of independently bendable segments, and at least part of the plurality of segments may be bent toward the winding center C of the electrode assembly (
When the uncoated portion of the positive electrode plate and the negative electrode plate is shaped into the plurality of segments, it may be possible to reduce stress applied to the uncoated portion during bending, thereby preventing deformation or destruction of the uncoated portion, and improving welding characteristics with the current collector plate.
The current collector plate and the uncoated portion may be joined by welding, and to improve welding characteristics, it is preferable to apply strong pressure to the weld area of the uncoated portion to make the uncoated portion as flat as possible. However, in the bending process, the uncoated portion may be irregularly distorted and deformed, and the deformed part may contact the electrode of the opposite polarity, causing internal shorts or microcracks in the uncoated portion. However, when the uncoated portion of the positive electrode plate and the negative electrode plate is shaped into the plurality of independently bendable segments, it may be possible to mitigate stress applied to the uncoated portion during bending, thereby minimizing deformation and destruction of the uncoated portion.
Additionally, when the uncoated portion is shaped into the segments as described above, overlap may occur between the plurality of segments during bending, thereby increasing the welding strength with the current collector plate, and preventing ablation of the separator or the active material due to laser penetration into the electrode assembly when the advanced technology such as laser welding is used. Preferably, at least part of the plurality of bent segments may be overlapped on the top and bottom of the electrode assembly, and the current collector plate may be coupled to the plurality of overlapped segments.
For example, the battery of the tab-less structure may be manufactured through the following method. First, the separator, the positive electrode plate, the separator, and the negative electrode plate are stacked in a sequential order such that the uncoated portion 222 of each of the positive electrode plate 210 and the negative electrode plate 211 is disposed in opposite directions and they are wound in a direction to manufacture the electrode assembly. Subsequently, as shown in
The current collector plate includes the first current collector plate 30 and the second current collector plate P as shown in
The current collector plate may be made of a conductive metal such as aluminum, copper, or nickel. The lead may be additionally connected to the first current collector plate and/or the second current collector plate according to need. The lead may play a role in electrically connecting the current collector plate to the cap plate and/or the electrode terminal. The coupling of the lead and the other component may be done through welding. For example, the current collector plate may be integrally formed with the lead. In this case, the lead may have a long plate shape extended outward from the central portion of the current collector plate.
The first current collector plate 30 is coupled between the electrode assembly 10 and the first end portion E1 of the battery can, and the second current collector plate P is coupled between the electrode assembly 10 and the second end portion E2 of the battery can. A surface of the current collector plate P may be coupled to the uncoated portion 11 of the negative electrode plate or the uncoated portion 12 of the positive electrode plate, and the opposite surface may be electrically coupled to of the inner bottom surface the battery can 20 or the cap plate. In this instance, the coupling may be done by laser welding, resistance welding, ultrasonic welding, or soldering.
The battery 1 according to the present disclosure may further include the insulator S, according to need. The insulator S of
For example, the battery can 20 may be a cylindrical container having the opening portion on top (the first end portion or the second end portion), and may be made of a conductive metal such as aluminum or steel. According to an example, the battery can 20 is electrically connected to the uncoated portion 11 of the negative electrode plate, and acts as the negative terminal to transfer the electric current from the external power source to the negative electrode plate when the battery can 20 contacts the external power source.
According to an example, the thickness of the side of the battery can 20 may range between 0.1 mm and 0.4 mm, for example, between 0.13 mm and 0.32 mm. By improving safety of the battery according to the above-described embodiments, it may be possible to ensure safety when the thickness of the battery can lies in the aforementioned range.
The lithium secondary battery according to the present disclosure may be a high capacity secondary battery having the capacity of 25 Ah or more.
The lithium secondary battery according to the present disclosure may be a large battery having a ratio of form factor (defined as a value obtained by dividing the diameter of the cylindrical battery by its height, i.e., a diameter(Φ)-to-height(H) ratio) of 0.4 or more. Here, the form factor refers to a value indicating the diameter (the maximum width) and height of the battery.
The battery according to the present disclosure may be, for example, a 46110 cell (diameter 46 mm, height 110 mm, form factor ratio 0.418), a 4875 cell (diameter 48 mm, height 75 mm, form factor ratio 0.640), a 48110 cell (diameter 48 mm, height 110 mm, form factor ratio 0.436), a 4880 cell (diameter 48 mm, height 80 mm, form factor ratio 0.600), a 4680 cell (diameter 46 mm, height 80 mm, form factor ratio 0.575), or a 4695 cell (diameter 46 mm, height 95 mm, form factor ratio 0.484). In the number indicating the form factor, the first two numbers indicate the diameter of the battery, and the next two or three numbers indicate the height of the battery.
According to the above-described embodiments of the present disclosure, the large battery having the ratio of form factor of 0.4 or more may achieve high safety.
Meanwhile, the lithium secondary battery according to the present disclosure is a battery of a tab-less structure including no electrode tab.
The battery of the tab-less structure may be, for example, a structure in which each of the positive electrode plate and the negative electrode plate includes the uncoated portion where the active material layer is not formed, the positive electrode plate uncoated portion and the negative electrode plate uncoated portion are located at the top and bottom of the electrode assembly, respectively, the current collector plate is coupled to the positive electrode plate uncoated portion and the negative electrode plate uncoated portion, and the current collector plate is connected to the electrode terminal.
The positive electrode plate, the negative electrode plate, the separator and the electrolyte which constitute the electrode assembly included in the lithium secondary battery according to the present disclosure may include those well known or commonly used in the corresponding field without limitation.
In an example, the positive electrode active material may include alkali metal compounds represented by the general chemical formula A[AxMy]O2+z (A includes at least one of Li, Na or K; M includes at least one selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x≥0, 1≤x+y≤2, 0.1≤z≤2; the stoichiometric coefficients x, y and z are selected to keep the compound electrically neutral).
In another example, the positive electrode active material may include alkali metal compounds xLiM1O2(1x)Li2M203 (M1 includes at least one element having the average oxidation state of 3; M2 includes at least one element having the average oxidation state of 4; 0≤x≤1) disclosed in U.S. Pat. Nos. 6,677,082, 6,680,143.
In still another example, the positive electrode active material may include lithium metal phosphate represented by the general chemical formula LiaM1xFe1-xM2yPlyM3zO4z (M1 includes at least one selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg and Al; M2 includes at least one selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, Al, As, Sb, Si, Ge, V and S; M3 includes halogen group elements selectively including F; 0<a≤2, 0≤x≤1, 0≤y≤1, 0≤z<1; the stoichiometric coefficients a, x, y and z are selected to keep the compound electrically neutral), or Li3M2(PO4)3 (M includes at least one selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg and Al).
Preferably, the positive electrode active material may include primary particles and/or secondary particles formed by agglomeration of the primary particles.
In an example, the negative electrode active material may include carbon materials, lithium metal or lithium metal compounds, silicon or silicon compounds, tin or tin compounds. The silicon compounds may include pure silicon, silicon oxide, silicon carbon composites, or silicon metal alloys. The metal oxide having the potential of less than 2 V such as TiO2 or SnO2 may be also used as the negative electrode active material. The carbon materials may include low crystalline carbon, and high crystalline carbon.
The separator may include porous polymer films, for example, porous polymer films made of polyolefin-based polymer such as ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer, ethylene/methacylate copolymer, as used singly or in stack. As another example, the separator may include commonly used porous nonwoven fabrics, for example, nonwoven fabrics made of high melting point glass fibers or polyethyleneterephthalate fibers.
The separator may include a coating layer of inorganic particles on at least one surface. Additionally, the separator itself may be a coating layer of inorganic particles. The particles that constitute the coating layer may have a structure in which the particles are held together with a binder such that interstitial volume exists between the adjacent particles.
The inorganic particles may include inorganic matter having the dielectric constant of 5 or more. Non-limiting examples of the inorganic particles may include at least one material selected from the group consisting of Pb(Zr,Ti)O3 (PZT), Pb1-xLaxZr1yTiyO3 (PLZT), PB(Mg3Nb2/3)O3PbTiO3 (PMNPT), BaTiO3, hafnia (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO and Y2O3.
The electrolyte may be a salt having a structure such as A+B−. Here, A+ includes an alkali metal cation such as Li+, Na+, K+ or a combination thereof. Additionally, B− includes at least one anion selected from the group consisting of F−, Cl−, Br−, I−, NO3−, N(CN)2−, BF4−, ClO4−, AlO4−, AlCl4−, PF6−, SbF6−, AsF6−, BF2C2O4−, BC4O8−, (CF3)2PF4−, (CF3)3PF3−, (CF3)4PF2−, (CF3)5PF−, (CF3)6P−, CF3SO3−, C4F9SO3−, CF3CF2SO3−, (CF3SO2)2N−, (FSO2)2N−, CF3CF2(CF3)2CO−, (CF3SO2)2CH−, (SF5)3C−, (CF3SO2)3C−, CF3(CF2)7SO3−, CF3CO2−, CH3CO2, SCN− and (CF3CF2SO2)2N−.
Additionally, the electrolyte that is dissolved in an organic solvent may be used. The organic solvent may include propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), 7-butyrolactone or a mixture thereof.
Referring to
Referring to
Thermal runaway in batteries is a critical safety concern, particularly in lithium-ion batteries used in consumer electronics, electric vehicles, and renewable energy storage. Thermal runaway is a self-sustaining reaction where an increase in temperature causes further increases in temperature, leading to a rapid and uncontrollable rise in heat. In batteries, this can result in fires or explosions. Managing thermal runaway is essential for the safe operation of battery systems, especially as the demand for high-capacity batteries continues to grow.
Thermal runaway can be caused by different reasons. For example, charging a battery beyond a certain level can cause excessive heat, leading to the decomposition of the electrolyte and the release of flammable gases. Manufacturing defects, mechanical damage, or degradation over time can cause internal short circuits; and these generate significant heat, potentially triggering thermal runaway. High external temperatures can overwhelm a battery's cooling mechanisms, causing an uncontrolled rise in temperature. Physical damage, such as punctures or deformation, can compromise the battery's internal structure, leading to short circuits and heat generation. Operating a battery at high discharge rates generates more heat; and if the heat exceeds the battery's capacity to dissipate it, thermal runaway may occur.
At the initiation stage, external factors like overcharging, overheating, or mechanical damage cause a local rise in temperature within the battery cell. This initial heat can trigger chemical reactions, such as electrolyte decomposition. Then, the heat generated in the initiation stage causes further chemical reactions, producing more heat, and this can lead to a feedback loop where the temperature continues to rise. In battery packs, thermal runaway can spread from one cell to adjacent cells, leading to a large-scale event. This is particularly dangerous in applications like electric vehicles.
Conventional approaches for prevention and mitigation of thermal runaway include using cooling systems, battery management systems, safety mechanisms, and heat-resistant materials and barriers. Effective cooling systems can dissipate heat and prevent temperature build-up. Battery Management Systems can monitor and control the charging and discharging of batteries to prevent conditions that could lead to thermal runaway. Making batteries with materials that can withstand higher temperatures and incorporating physical barriers between cells can reduce the risk of thermal propagation. Incorporating safety features like thermal fuses, pressure relief valves and/or gas vents can help mitigate the effects of thermal runaway. For example, pressure relief valves and gas vents release the generated gas and heat before the battery internal pressure becomes too high. These valves and vents usually open to allow the gas and heat to escape when the battery internal pressure is relatively low. Similarly, a rupture notch may be implemented to rupture the battery can before the internal pressure becomes too high to avoid or minimize the chances of explosion.
Contrary to the conventional thinking of relieving pressure or releasing generated gas and heat using pressure relief valves and/or gas vents which open at relatively low pressure, the present disclosure provides a rupture notch that allows the battery's internal pressure to build up and increase to a certain level to create an explosive power to eject out of the battery body a portion of the jellyroll electrode assembly that is sufficient to surprisingly prevent and/or mitigate and/or stop thermal runaway inside of the battery.
According to some embodiments, the rupture notch 41, 201 may be at the first end portion E1 of the battery can 20, as shown in
As shown in
The predetermined rupture pressure is designed to be sufficient to create an explosive power to eject at least a portion of the jellyroll electrode assembly out of the battery can through the opening to a distance away from the first end portion E1 that is at least ¼ of the length of the cylindrical body of the battery can, such that the ejected portion of the jellyroll electrode assembly has a mass that is at least 25% of the total mass of the jellyroll electrode assembly before the ejection. The predetermined rupture pressure may be determined by the diameter (the maximum width) and/or length of the battery and/or the size of the opening. For example, to create the same explosive force, the bigger the opening, the higher the predetermined rupture pressure needs to be. For batteries with the same diameter, the longer the battery is, the more the mass of jellyroll electrode assembly has; and with openings of the same size when the rupture notch is ruptured, to eject the jellyroll electrode assembly to the same distance, the greater the explosive force needs to be, and thus the higher the predetermined rupture pressure needs to be. The predetermined rupture pressure may be determined in view of the battery's form factor. Here, the form factor refers to a value indicating the diameter and length (or height) of the battery.
In embodiments, the rupture notch may be in the middle of the cap plate or bottom plate of the battery, and thus the opening created by rupturing of the rupture notch is also located in the middle of the cap plate or bottom plate. The uncrimping portion is designed to have an uncrimping pressure that is higher than the predetermined rupture pressure, so that the crimping portion 22 does not uncrimp when the internal pressure reaches the predetermined rupture pressure and ruptures the rupture notch 40, 201. As such, the inner portion of the jellyroll electrode assembly ejects through the opening before the outer portion of the jellyroll electrode assembly surrounding the inner portion prior to the ejection. The crimping portion 22 may be made of a material and/or have a thickness, size, and/or shape to have a relatively higher uncrimping pressure when compared to the predetermined rupture pressure. For example, when the crimping portion is made of a hard material, its uncrimping pressure may be higher than that of a crimping portion made of a soft material when they have similar shape, thickness, and/or size. When other factors, such as hardness of material, shape, and thickness, are similar, a larger crimping portion may have a higher uncrimping pressure than a smaller crimping portion. A crimping portion of a more curved shape may have a higher uncrimping pressure than a less curved crimping portion.
In embodiments, the predetermined rupture pressure may be at or about 0.1 kgf/cm2 or more, such as at or about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 17, 19, 20, 21, 21.1, 21.2, 21.3, 21.4, 21.5, 21.6, 21.7, 21.8, 21.9, 22, 22.1, 22.2, 22.3, 22.4, 22.5, 22.6, 22.7, 22.8, 22.9, 23, 23.1, 23.2, 23.3., 23.4, 23.5, 23.6, 23.7, 23.8, 23.9, 24, 24.1, 24.2, 24.3, 24.4, 24.5, 24.6, 24.7, 24.8, 24.9, 25, 25.1, 25.2, 25.3, 25.4, 25.5, 25.6, 25.7, 25.8, 25.9, 26, 26.1, 26.2, 26.3, 26.4, 26.4, 26.6, 26.7, 26.8, 26.9, 27, 27.1, 27.2, 27.3, 27.4, 27.5, 27.6, 27.7, 27.8, 27.9, 28, 28.1, 28.2, 28.3, 28.4, 28.5, 28.6, 28.7, 28.8, 28.9, 29, 29.1, 29.2, 29.3, 29.4, 29.5, 29.6, 29.7, 29.8, 29.9, 30, 30.1, 30.2, 30.3, 30.4, 30.5, 30.6, 30.7, 30.8, 30.9, 31, 32, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 53, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100 kgf/cm2 or more. In embodiments, the predetermined rupture pressure may be within a range formed by selecting any two numbers listed herein, such as from about 0.2 to about 62 kgf/cm2, from about 0.1 to about 10 kgf/cm2, from about 0.3 to about 25 kgf/cm2, from about 1 to about 21 kgf/cm2, from about 2 to about 42 kgf/cm2, from about 5 to about 55 kgf/cm2, from about 6 to about 6 kgf/cm2, from about 7 to about 35 kgf/cm2, from about 21 to about 29 kgf/cm2, from about 21.5 to about 30.5 kgf/cm2, from about 23.5 to about 27.5 kgf/cm2, from about 23 to about 33 kgf/cm2, from about 24 to about 29 kgf/cm2, from about 24.2 to about 28.9 kgf/cm2, from about 25.1 to about 29 kgf/cm2, from about 25 to about 29 kgf/cm2, from about 26 to about 29 kgf/cm2, from about 27 to about 29 kgf/cm2, from about 25 to about 28 kgf/cm2, from about 24.3 to about 27.8 kgf/cm2, from about 28 to about 38 kgf/cm2, etc.
In embodiments, the uncrimping pressure may be at or about 10 kgf/cm2 or more, such as at or about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21.1, 21.2, 21.3, 21.4, 21.5, 21.6, 21.7, 21.8, 21.9, 22, 22.1, 22.2, 22.3, 22.4, 22.5, 22.6, 22.7, 22.8, 22.9, 23, 23.1, 23.2, 23.3., 23.4, 23.5, 23.6, 23.7, 23.8, 23.9, 24, 24.1, 24.2, 24.3, 24.4, 24.5, 24.6, 24.7, 24.8, 24.9, 25, 25.1, 25.2, 25.3, 25.4, 25.5, 25.6, 25.7, 25.8, 25.9, 26, 26.1, 26.2, 26.3, 26.4, 26.4, 26.6, 26.7, 26.8, 26.9, 27, 27.1, 27.2, 27.3, 27.4, 27.5, 27.6, 27.7, 27.8, 27.9, 28, 28.1, 28.2, 28.3, 28.4, 28.5, 28.6, 28.7, 28.8, 28.9, 29, 29.1, 29.2, 29.3, 29.4, 29.5, 29.6, 29.7, 29.8, 29.9, 30, 30.1, 30.2, 30.3, 30.4, 30.5, 30.6, 30.7, 30.8, 30.9, 31, 32, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 53, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, or 200 kgf/cm2 or more. In embodiments, the uncrimping pressure may be within a range formed by selecting any two numbers listed herein, such as from about 10 to about 20 kgf/cm2, from about 20 to about 50 kgf/cm2, from about 50 to about 100 kgf/cm2, from about 30 to about 60 kgf/cm2, from about 40 to about 80 kgf/cm2, from about 10 to about 15 kgf/cm2, from about 30 to about 40 kgf/cm2, from about 40 to about 50 kgf/cm2, from about 15 to about 20 kgf/cm2, from about 21.1 to about 29.5 kgf/cm2, from about 24 to about 33.1 kgf/cm2, from about 27.4 to about 38 kgf/cm2, from about 29.1 to about 40 kgf/cm2, etc. In embodiments, the uncrimping pressure may be more than any number listed herein, such as more than about 29, 29.1, 29.5, 30, 33, 37, 40, 50, 60, 70, 80, 90, or 100 kgf/cm2. In embodiments, the uncrimping pressure may be more than any number higher than about 200 kgf/cm2, such as 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 350, 400, 500, or 600 kgf/cm2, etc.
The rupture notch is designed such that the predetermined rupture pressure is lower than the uncrimping pressure, so that the crimping portion 22 does not uncrimp when the internal pressure reaches the predetermined rupture pressure and ruptures the rupture notch 40, 201. For example, the predetermined rupture pressure may be from about 21 to about 29 kgf/cm2, such as 21.1, 21.2, 21.3, 21.4, 21.5, 21.6, 21.7, 21.8, 21.9, 22, 22.1, 22.2, 22.3, 22.4, 22.5, 22.6, 22.7, 22.8, 22.9, 23, 23.1, 23.2, 23.3., 23.4, 23.5, 23.6, 23.7, 23.8, 23.9, 24, 24.1, 24.2, 24.3, 24.4, 24.5, 24.6, 24.7, 24.8, 24.9, 25, 25.1, 25.2, 25.3, 25.4, 25.5, 25.6, 25.7, 25.8, 25.9, 26, 26.1, 26.2, 26.3, 26.4, 26.4, 26.6, 26.7, 26.8, 26.9, 27, 27.1, 27.2, 27.3, 27.4, 27.5, 27.6, 27.7, 27.8, 27.9, 28, 28.1, 28.2, 28.3, 28.4, 28.5, 28.6, 28.7, 28.8, 28.9, or 29 kgf/cm2; and the uncrimping pressure may be higher than about 29 kgf/cm2, such as at or about 29.1, 29.2, 29.3, 29.4, 29.5, 29.6, 29.7, 29.8, 29.9, 30, 30.1, 30.2, 30.3, 30.4, 30.5, 30.6, 30.7, 30.8, 30.9, 31, 31.1, 31.2, 31.3, 31.4, 31.5, 31.6, 31.7, 31.8, 31.9, 32, 32.1, 32.2., 32.3, 32.4, 32.5, 32.6, 32.7, 32.8, 32.9, 33, 33.1, 33.2, 33.3, 33.4, 33.5, 33.6, 33.7, 33.8, 33.9, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 kgf/cm2, or any number higher than 50 kgf/cm2. In embodiments, the predetermined rupture pressure may be within a range formed by selecting any two numbers provided herein, such as from about 21.1 to about 29, from about 25 to about 29, from about 25.1 to about 29, from about 21 to about 24, from about 25 to about 28.9, from about 24.9 to about 29, from about 25.5 to about 29, from about 26 to about 29, from about 27 to about 29, from about 28 to about 29, from about 25 to about 28.5, from about 24.9 to about 28.9 kgf/cm2, etc; and the uncrimping pressure may be within a range formed by selecting any two numbers provided herein, such as from about 29.1 to about 30.4, from about 30.1 to about 34, from about 35 to about 40, from about 40 to about 45 kgf/cm2, etc.
As another example, the uncrimping pressure may be higher than about 40 kgf/cm2, such as 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60 kgf/cm2, or any number higher than 60 kgf/cm2; and the predetermined rupture pressure may be from about 21 to about 39 kgf/cm2, such as 21.1, 21.2, 21.3, 21.4, 21.5, 21.6, 21.7, 21.8, 21.9, 22, 22.1, 22.2, 22.3, 22.4, 22.5, 22.6, 22.7, 22.8, 22.9, 23, 23.1, 23.2, 23.3., 23.4, 23.5, 23.6, 23.7, 23.8, 23.9, 24, 24.1, 24.2, 24.3, 24.4, 24.5, 24.6, 24.7, 24.8, 24.9, 25, 25.1, 25.2, 25.3, 25.4, 25.5, 25.6, 25.7, 25.8, 25.9, 26, 26.1, 26.2, 26.3, 26.4, 26.4, 26.6, 26.7, 26.8, 26.9, 27, 27.1, 27.2, 27.3, 27.4, 27.5, 27.6, 27.7, 27.8, 27.9, 28, 28.1, 28.2, 28.3, 28.4, 28.5, 28.6, 28.7, 28.8, 28.9, 29, 29.1, 29.2, 29.3, 29.4, 29.5, 29.6, 29.7, 29.8, 29.9, 30, 30.1, 30.2, 30.3, 30.4, 30.5, 30.6, 30.7, 30.8, 30.9, 31, 31.1, 31.2, 31.3, 31.4, 31.5, 31.6, 31.7, 31.8, 31.9, 32, 32.1, 32.2, 32.3, 32.4, 32.5, 32.6, 32.7, 32.8, 32.9, 33, 33.1, 33.2, 33.3, 33.4, 33.5, 33.6, 33.7, 33.8, 33.9, 34, 34.1, 34.2, 34.3, 34.4, 34.5, 34.6, 34.7, 34.8, 34.9, 35, 35.1, 35.2, 35.3, 35.4, 35.5., 35.6, 35.7, 35.8, 35.9, 36, 37, 38, or 39 kgf/cm2. In embodiments, the predetermined rupture pressure may be within a range formed by selecting any two numbers listed herein, such as from about 21.1 to about 29, from about 25 to about 29, from about 25.1 to about 29, from about 21 to about 24, from about 25 to about 28.9, from about 24.9 to about 29, from about 25.5 to about 29, from about 26 to about 29, from about 27 to about 29, from about 28 to about 29, from about 25 to about 28.5, from about 24.9 to about 28.9, from about 21 to about 35, from about 25 to about 39, from about 24.9 to about 35.3, from about 25.1 to about 38, from about 25.5 to about 30.1, from about 29 to about 39, from about 26 to about 38, from about 27 to about 37 kgf/cm2 etc.
The examples of predetermined rupture pressure and uncrimping pressure above are illustrating and non-limiting. The predetermined rupture pressure and the uncrimping pressure can be any two numbers provided herein as long as the predetermined rupture pressure is lower than the uncrimping pressure. For example, the predetermined rupture pressure may be 10 kgf/cm2, and the uncrimping pressure may be 100 kgf/cm2; the predetermined rupture pressure may be 10 kgf/cm2, and the uncrimping pressure may be 100 kgf/cm2; the predetermined rupture pressure may be 20 kgf/cm2, and the uncrimping pressure may be 50 kgf/cm2; the predetermined rupture pressure may be 30 kgf/cm2, and the uncrimping pressure may be 40 kgf/cm2; the predetermined rupture pressure may be 50 kgf/cm2, and the uncrimping pressure may be 100 kgf/cm2; the predetermined rupture pressure may be 21 kgf/cm2, and the uncrimping pressure may be 30 kgf/cm2; the predetermined rupture pressure may be 25 kgf/cm2, and the uncrimping pressure may be 30 kgf/cm2; the predetermined rupture pressure may be kgf/cm2, and the uncrimping pressure may be 60 kgf/cm2; the predetermined rupture pressure may be 1 kgf/cm2, and the uncrimping pressure may be 10 kgf/cm2; the predetermined rupture pressure may be 15 kgf/cm2, and the uncrimping pressure may be 20 kgf/cm2; the predetermined rupture pressure may be 40 kgf/cm2, and the uncrimping pressure may be 90 kgf/cm2, etc.
The battery provided herein may be a battery having a ratio of form factor (defined as a value obtained by dividing the diameter of the cylindrical battery by its height, i.e., a diameter(Φ)-to-height(H) ratio) of 0.4 or more. For example, the battery provided herein may be, for example, a 46110 cell (diameter 46 mm, height 110 mm, form factor ratio 0.418), a 4875 cell (diameter 48 mm, height 75 mm, form factor ratio 0.640), a 48110 cell (diameter 48 mm, height 110 mm, form factor ratio 0.436), a 4880 cell (diameter 48 mm, height 80 mm, form factor ratio 0.600), a 4680 cell (diameter 46 mm, height 80 mm, form factor ratio 0.575), or a 4695 cell (diameter 46 mm, height 95 mm, form factor ratio 0.484). In the number indicating the form factor, the first two numbers indicate the diameter of the battery, and the next two or three numbers indicate the height of the battery. Batteries with similar ratios of form factor may have similar predetermined rupture pressures. For example, batteries with a ratio of form factor of 0.4 or more, such as the 46110, 4875, 48110, 4880, 4680, or 4695 cell battery, may have a predetermined rupture pressure from about 21 to about 29 kgf/cm2, such as 21.1, 21.2, 21.3, 21.4, 21.5, 21.6, 21.7, 21.8, 21.9, 22, 22.1, 22.2, 22.3, 22.4, 22.5, 22.6, 22.7, 22.8, 22.9, 23, 23.1, 23.2, 23.3., 23.4, 23.5, 23.6, 23.7, 23.8, 23.9, 24, 24.1, 24.2, 24.3, 24.4, 24.5, 24.6, 24.7, 24.8, 24.9, 25, 25.1, 25.2, 25.3, 25.4, 25.5, 25.6, 25.7, 25.8, 25.9, 26, 26.1, 26.2, 26.3, 26.4, 26.4, 26.6, 26.7, 26.8, 26.9, 27, 27.1, 27.2, 27.3, 27.4, 27.5, 27.6, 27.7, 27.8, 27.9, 28, 28.1, 28.2, 28.3, 28.4, 28.5, 28.6, 28.7, 28.8, 28.9, or 29 kgf/cm2; and may have an uncrimping pressure of higher than about 29 kgf/cm2, such as at or about 29.1, 29.2, 29.3, 29.4, 29.5, 29.6, 29.7, 29.8, 29.9, 30, 30.1, 30.2, 30.3, 30.4, 30.5, 30.6, 30.7, 30.8, 30.9, 31, 31.1, 31.2, 31.3, 31.4, 31.5, 31.6, 31.7, 31.8, 31.9, 32, 32.1, 32.2., 32.3, 32.4, 32.5, 32.6, 32.7, 32.8, 32.9, 33, 33.1, 33.2, 33.3, 33.4, 33.5, 33.6, 33.7, 33.8, 33.9, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 kgf/cm2, or any number higher than 50 kgf/cm2. In embodiments, the predetermined rupture pressure may be within a range formed by selecting any two numbers provided herein, such as from about 21.1 to about 29, from about 25 to about 29, from about 25.1 to about 29, from about 21 to about 24, from about 25 to about 28.9, from about 24.9 to about 29, from about 25.5 to about 29, from about 26 to about 29, from about 27 to about 29, from about 28 to about 29, from about 25 to about 28.5, from about 24.9 to about 28.9 kgf/cm2, etc; and the uncrimping pressure may be within a range formed by selecting any two numbers provided herein, such as from about 29.1 to about 30.4, from about 30.1 to about 34, from about 35 to about 40, from about 40 to about 45 kgf/cm2, etc.
When the internal pressure reaches the predetermined rupture pressure, the rupture notch 40, 201 is ruptured to create an opening on the cap plate 40 or the bottom plate. The opening is within the area on the cap plate 40 or the bottom plate that was surrounded by the rupture notch 40, 201 before it is ruptured. Because the predetermined rupture pressure is lower than the uncrimping pressure, when the internal pressure reaches the predetermined rupture pressure, the internal pressure is lower than the uncrimping pressure. As such, when the rupture notch 40, 201 has been ruptured, the top plate 40 is not uncrimped and is still crimped to the end portion of battery can 20. In embodiments shown in
The predetermined rupture pressure is designed to be sufficient to create an explosive power. When the internal pressure reaches the predetermined rupture pressure, the internal pressure creates an explosive power to eject at least a portion of the jellyroll electrode assembly 10 through the opening on the cap plate 40 or the bottom plate created by the rupturing of the rupture notch. In some embodiments, the explosive power does not damage any other parts of the battery or create any other opening on the cylindrical body of the battery. As such, in embodiments shown in
As shown in
The ejected portion of the jellyroll electrode assembly has a mass that is at least about 25% of the total mass of the jellyroll electrode assembly inside of the battery can prior to the ejection. For example, the ejected portion may have a mass that is at or about 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95%. In embodiment, the ejected portion may have a mass that is within a range formed by selecting any two numbers listed herein, for example, from about 25 to about 30, from about 25 to about 50, from about 25 to about 90, from about 30 to about 60, from about 40 to about 55, from about 45 to about 75, from about 50 to about 70, from about 55 to about 80, from about 60 to about 90% of the total mass of the electrode assembly before being ejected. Surprisingly, the ejected portion of the electrode assembly that has at least about 25% of the total mass as described herein would not cause any further chemical reactions that could lead to thermal runaway inside the cylindrical body of the battery. With at least 25% of the total mass of the electrode assembly ejected to outside of the battery, the electrode assembly remaining inside of the battery may not be enough for the chemical reaction inside of the battery to continue to cause thermal runaway. Moreover, with the ejection of the jellyroll electrode assembly, the gas and heat generated inside of the battery are also released. As such, the chemical reaction inside of the battery may be slowed down or stopped partially or completely, preventing further heat buildup and/or generation of more flammable gas that would cause more breakdown of the electrolyte and/or trigger more reactions insider of the battery.
Factors affecting the amount of the ejected portion of the jellyroll electrode assembly may include jellyroll outer diameter size, jellyroll winding tension, battery can inner empty space volume, the size of the rupture opening on the rupture notch, easy-to-dissipate collector plate properties, such as number of welding points, collector plate structure, etc.
The battery provided herein may not include another rupture notch or vent for venting gas. This way, the gas would not be able to escape from another rupture notch or vent, and the internal pressure can increase to be sufficient to create the explosive power to eject at least a portion of the jellyroll electrode assembly that is sufficient to surprisingly prevent and/or stop the thermal runaway.
The side portion of the battery can 20 is designed to sustain the predetermined rupture pressure of the rupture notch and may have a predetermined side rupture pressure required to damage the side portion. The side portion may be made of a material and/or have a thickness and/or shape that requires a side rupture pressure that is higher than the predetermined rupture pressure. For example, the side portion may have a thickness in a range of from about 0.1 mm to about 0.4 mm, such as 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 016, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, or 0.4 mm. In embodiments, the thickness of the side portion may be within a range formed by selecting any two numbers listed herein, such as from about 0.1 mm to about 0.3 mm, from 0.15 mm to about 0.35 mm, from about 0.1 mm to about 0.3 mm, from about 0.12 mm to about 0.34 mm, from about 0.16 mm to about 0.36 mm, from about 0.2 mm to about 0.4 mm, from about 0.25 mm to about 0.32 mm, from about 0.2 mm to about 0.4 mm, etc. When the internal pressure reaches the predetermined rupture pressure, even if the battery explodes and a flame is generated, the explosion does not create any hole or tear on the side portion of the battery cell, or rupture of the side portion is at least minimized, and the flame is guided toward only one end of the battery with the ejection of the jellyroll electrode assembly therethrough, so that the flame is not directly transmitted to any adjacent unit cell in the vicinity, for example, in a battery pack comprising a plurality of batteries as provided herein.
The above-described embodiments and drawings and the following examples are presented, but they are provided to describe the present disclosure by way of illustration, and the present disclosure is not limited thereto and a variety of changes and modifications may be made by persons having ordinary skill in the technical field pertaining to the present disclosure within the technical aspect of the present disclosure and the appended claims and their equivalents.
A positive electrode plate and a negative electrode plate were stacked with a separator interposed between them in an order of the separator/the positive electrode plate/the separator/the negative electrode plate and wound together to manufacture a jellyroll-type electrode assembly. The positive electrode plate was obtained by coating a slurry (solvent: NMP) in which an NCMA active material, a CNT conductive material and a PDVF binder are mixed at a weight ratio of 97.6:0.6:1.8 on a current collector. The negative electrode plate was obtained by coating a slurry (solvent: DI-Water) in which an active material including graphite and silicon oxide, a CNT conductive material and a CMC binder are mixed at a weight ratio of 98.05:0.05:1.90 on a current collector. The separator was a ceramic coated PE. As shown in
A sealing tape having a 34 μm thick polyurethane substrate was attached to the outside of the electrode assembly over the area of 35 mm×134 mm.
As shown in
A battery can coupling portion of the first current collector plate between the cap plate and the electrode assembly and having the thickness of 0.3 mm, the shape as shown in
The cylindrical battery can was a 4680 cell having the diameter of 46 mm, and the height of 80 mm (the form factor ratio 0.575).
An overcharge test was performed by repeatedly charging the as-prepared lithium secondary battery at 1.7 C from state of charge (SOC) 0% to SOC 100% and discharging on the contrary. When the vent portion was ruptured and the electrode assembly was ejected through the first end portion of the battery can, evaluation was conducted to determine the ejection distance and whether or not the side rupture of the battery can occurred, and the following TABLE 2 summarizes the results.
Example 2 was carried out in the same way as Example 1 except that the sealing tape attached to the outside of the electrode assembly had a 30 μm thick polypropylene substrate and an area of 63 mm×134 mm.
Example 3 was carried out in the same way as Example 1 except that as the first current collector plate located between the cap plate and the electrode assembly, the first current collector plate having the hole H3 as shown in
Example 4 was carried out in the same way as Example 1 except that as the first current collector plate located between the cap plate and the electrode assembly, the first current collector plate having the hole H3 as shown in
Example 5 was carried out in the same way as Example 1 except that a first current collector plate having the hole H3 as shown in
Example 6 was carried out in the same way as Example 1 except that as the first current collector plate located between the cap plate and the electrode assembly, the first current collector plate having the hole H3 and the slit S1 as shown in
Example 7 was carried out in the same way as Example 1 except that the first current collector plate had a thickness of 0.2 mm, and the flame release area A was 34.8%.
Example 8 was carried out in the same way as Example 1 except that the outer diameter of the manufactured electrode assembly was 44.2 mm.
Example 9 was carried out in the same way as Example 1 except that the outer diameter of the manufactured electrode assembly was 44.7 mm.
Example 10 was carried out in the same way as Example 2 except that the cap plate included the vent portion which is ruptured at the pressure of 27 kgf/cm2 or more.
Example 11 was carried out in the same way as Example 2 except that the cap plate included the vent portion which is ruptured at the pressure of 24 kgf/cm2 or more.
Example 12 was carried out in the same way as Example 2 except that the cap plate included the vent portion which is ruptured at the pressure of 21 kgf/cm2 or more.
Example 13 was carried out in the same way as Example 2 except that the cap plate included the vent portion which is ruptured at the pressure of 20 kgf/cm2 or more.
The following TABLE 1 summarizes the vent pressure, the sealing tape condition, and the current collector plate structure of the batteries manufactured in Examples 1 to 13.
In TABLE 1, “X” means non-existence; and “O” means existence.
The following TABLE 2 summarizes the ejection distance ratio when the electrode was ejected in the overcharge test of repeatedly charging and discharging the batteries of Examples 1 to 13 at the rate of 1.7 C. The ejection distance is an average value of repeated experiments. When the electrode was not ejected, the side rupture of the battery can occurred, and the side rupture of the battery can was marked as Fail.
In TABLE 2, “X” means non-existence; “0” means existence; and “N/A” means not applicable or not available.
As can be seen from the above-described experimental results, in Examples 10 to 12, the vent pressure of the battery was 21 kgf/cm2 or more, and the ejection distance ratio was 1.25 times or more, and compared to the other examples, the degree of side rupture of the battery can was extremely low. In particular, in Example 10 and Example 11, in all five repeated experiments, when the electrode assembly was ejected, the central portion of the electrode assembly bulged, and the electrode assembly was ejected in a spiral structure, and the side rupture of the battery can did not occur in the five repeated experiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0189919 | Dec 2023 | KR | national |
| 10-2024-0169074 | Nov 2024 | KR | national |
