Patent Application
20250015455
The present disclosure relates to a jelly-roll with an improved electrolyte impregnation property, and a cylindrical battery cell, a battery pack and a vehicle including the same.
The present application claims the benefit of Korean Patent Application No. 10-2021-0153452 filed on Nov. 9, 2021 with the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference in its entirety.
Secondary batteries that have ease of application according to product groups and have electrical characteristics such as high energy density are universally applied not only to portable devices, but also to electric vehicles (EVs) or hybrid electric vehicles (HEVs) driven by an electric drive source. These secondary batteries are attracting attention as a new energy source for improving eco-friendliness and energy efficiency because they not only have the primary advantage of dramatically reducing the use of fossil fuels, but also do not generate any by-products from the use of energy.
Types of secondary batteries currently widely used include lithium-ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel hydrogen batteries, nickel zinc batteries, and the like. Such a unit secondary battery cell, that is, a unit battery cell, has an operating voltage of about 2.5 V to 4.5 V. Therefore, when a higher output voltage is required, a battery pack may be configured by connecting a plurality of battery cells in series. In addition, a plurality of battery cells may be connected in parallel to form a battery pack according to the charge/discharge capacity required for the battery pack. Accordingly, the number of battery cells included in the battery pack may be variously set according to a required output voltage and/or charge/discharge capacity.
On the other hand, in general, in a secondary battery, electrolyte may be impregnated in an electrode assembly, so that lithium ions can smoothly move to generate an electric current. At this time, the electrolyte impregnation property is a very important factor affecting the lifespan and capacity of the battery, and it is more advantageous as the electrolyte impregnation rate is higher.
Meanwhile, as the demand for cylindrical secondary batteries for electric vehicles has recently increased, the importance of developing cylindrical battery cells of middle and large sizes, rather than the existing size, has increased in order to improve energy density. However, as the size of the cylindrical battery cell increases, the electrolyte impregnation property may be deteriorated in the central part of the electrode of the jelly-roll, and thus the performance of the battery may be deteriorated. That is, the structure of the conventional electrode assembly has limitations in improving the electrolyte impregnation properties of cylindrical battery cells of middle and large sizes.
Therefore, it is required to find a way to improve the electrolyte impregnation property of the electrode assembly of the cylindrical battery cell.
The present disclosure is designed to solve the problems of the related art, and therefore the present disclosure is directed to improving an electrolyte impregnation property of a cylindrical battery cell by forming an slit through which electrolyte can pass on an electrode tab of the cylindrical battery cell so that the electrolyte is uniformly impregnated in an entire jelly-roll type electrode assembly accommodated inside the cylindrical battery cell.
In addition, the present disclosure is directed to reducing the internal resistance of the cylindrical battery cell by bending one end of the electrode tab to secure a wide contact area between the electrode tab and a current collecting plate of the jelly-roll type electrode assembly.
Furthermore, the present disclosure is directed to improving the coupling strength between the jelly-roll type electrode assembly and the current collecting plate by securing a wide contact area between the electrode tab and the current collecting plate of the jelly-roll type electrode assembly.
However, the technical object to be solved by the present disclosure is not limited to the above, and other objects not mentioned herein will be clearly understood by those skilled in the art from the following disclosure.
A jelly-roll according to an aspect of the present disclosure to accomplish the above object is a jelly-roll in which a stack, which includes a first electrode having a first electrode tab with a first polarity; a second electrode having a second electrode tab with a second polarity; and a separator interposed between the first electrode and the second electrode, is wound in one direction.
Meanwhile, at least one of the first electrode tab and the second electrode tab may have a plurality of slits formed along a winding direction of the jelly-roll, and a distance between the plurality of slits may gradually increase from a core of the jelly-roll to an outer circumference thereof.
At this time, the plurality of slits may have a shape extending in a direction parallel to the winding direction.
Meanwhile, the plurality of slits may be formed on the same line.
Meanwhile, the plurality of slits may be formed on a straight line parallel to the winding direction of the first electrode or the second electrode.
Meanwhile, lengths of the plurality of slits in the winding direction may gradually increase from the core of the jelly-roll to the outer circumference thereof.
Meanwhile, among the plurality of slits, slits adjacent to each other along a radial direction of the jelly-roll may at least partially overlap each other to form an impregnation path through which electrolyte passes along the radial direction.
Here, the impregnation path may be formed from an outer circumferential surface of the jelly-roll to a predetermined depth along the radial direction.
Meanwhile, at least any one electrode tab of the first electrode tab and the second electrode tab may have a plurality of bent portions formed to be spaced apart from each other along the winding direction of the jelly-roll and partitioned by a plurality of cutting lines formed to a predetermined depth from an end of the electrode tab.
At this time, the plurality of bent portions may be bent in a direction toward a winding axis of the jelly-roll, and the plurality of bent portions may cover at least a part of one surface of the jelly-roll perpendicular to the winding axis.
Alternatively, the plurality of bent portions may be bent in a direction toward a winding axis of the jelly-roll, and the plurality of bent portions may entirely cover one surface of the jelly-roll perpendicular to the winding axis.
Meanwhile, among the plurality of slits, slits adjacent to each other along a radial direction of the jelly-roll may at least partially overlap each other to form an impregnation path through which electrolyte passes along the radial direction, the impregnation path may be formed from an outer circumferential surface of the jelly-roll to a predetermined depth along the radial direction, and the depth of the impregnation path may be greater than or equal to a radial length of an area covered by the bent portion in one surface of the jelly-roll perpendicular to the winding axis.
Meanwhile, the cutting line and the slit may be spaced apart from each other by a predetermined distance.
In addition, a cylindrical battery cell according to an embodiment of the present disclosure comprises the jelly-roll according to the above embodiments.
Meanwhile, a battery pack according to an embodiment of the present disclosure comprises at least one cylindrical battery cell according to an embodiment of the present disclosure.
Meanwhile, a vehicle according to an embodiment of the present disclosure comprises at least one battery pack according to an embodiment of the present disclosure.
According to the present disclosure, it is possible to improve the electrolyte impregnation of the jelly-roll electrode assembly. More specifically, according to the present disclosure, it is possible to shorten the electrolyte impregnation time into the jelly-roll electrode assembly and improve the uniformity of the electrolyte impregnation. Accordingly, the initial efficiency may be increased. In addition, it is possible to form a uniform SEI (Solid Electrolyte Interphase) layer on the interface of the electrode.
In particular, according to the present disclosure, it is possible to improve the electrolyte impregnation property of a cylindrical battery cell by forming a path through which electrolyte can pass on an electrode tab of the cylindrical battery cell so that the electrolyte is uniformly impregnated in the entire jelly-roll electrode assembly accommodated inside the cylindrical battery cell.
In addition, according to the present disclosure, it is possible to reduce the internal resistance of the cylindrical battery cell by securing a wide contact area between the electrode tab and the current collecting plate of the jelly-roll type electrode assembly.
Furthermore, according to the present disclosure, it is possible to improve the coupling strength between the jelly-roll type electrode assembly and the current collecting plate by securing a wide contact area between the electrode tab and the current collecting plate of the jelly-roll type electrode assembly.
In addition, the present disclosure may have various other effects, which will be described in each embodiment, or a corresponding description will be omitted for effects that can be easily inferred by a person skilled in the art.
The accompanying drawings illustrate a preferred embodiment of the present disclosure and together with the foregoing disclosure, serve to provide further understanding of the technical features of the present disclosure, and thus, the present disclosure is not construed as being limited to the drawing.
Hereinafter, preferred 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 used in the specification and the appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation.
Therefore, the embodiments disclosed in this specification and the configuration illustrated in the drawings are only one of the most preferred embodiments of the present disclosure and do not represent all the technical idea of the present disclosure, so it should be understood that other equivalents and modifications could be made thereto without departing from the scope of the disclosure.
In addition, in order to help understanding of the present disclosure, the accompanying drawings are not drawn to scale, but dimensions of some components may be exaggerated.
Referring to
The first electrode includes a first electrode tab with a first polarity, and the second electrode includes a second electrode tab with a second polarity. For example, the first electrode may be a positive electrode or a negative electrode, and the second electrode may be an electrode having a polarity opposite to that of the first electrode.
The separator is interposed between the first electrode and the second electrode. The stack in which the first electrode, the separator, the second electrode, and the separator are sequentially stacked at least once is wound based on a winding center C extending along a width direction of the first electrode and the second electrode, that is, a height direction of the jelly-roll 1 (parallel to the Z-axis) to form the jelly-roll 1. That is, the jelly-roll 1 has a structure in which a stack including a first electrode, a second electrode, and a separator interposed between the first and second electrodes is wound in one direction.
Each of the first electrode and the second electrode includes an electrode tab and a coated portion.
The first electrode includes a first electrode current collector and a first electrode active material coated on one surface or both surfaces of the first electrode current collector. At one end of the first electrode current collector in a width direction (parallel to the Z-axis), there is a non-coated portion on which the first electrode active material is not coated. The non-coated portion functions as a first electrode tab 10 by itself. That is, the first electrode tab 10 is the first non-coated portion. The first electrode tab 10 is provided above the electrode assembly accommodated in a battery can in a height direction (parallel to the Z-axis). At an opposite side of the non-coated portion of the first electrode current collector, there is a coated portion 20 coated with the first electrode active material.
Meanwhile, although not shown in the drawings, the second electrode includes a second electrode current collector and a second electrode active material coated on one surface or both surfaces of the second electrode current collector. At the other end of the second electrode current collector in the width direction, there is a non-coated portion on which the second electrode active material is not coated. The non-coated portion functions as a second electrode tab by itself. That is, the second electrode tab 10 is the second non-coated portion. The second electrode tab is provided under the electrode assembly accommodated in the battery can in the height direction. At an opposite side of the non-coated portion of the second electrode current collector, there is a coated portion coated with the second electrode active material.
Meanwhile, in the present disclosure, the positive active material coated on the positive electrode plate and the negative electrode active material coated on the negative electrode plate may be used without limitation as long as the active material is known in the art.
In one example, the positive electrode active material may include alkali metal compounds represented by a general formula A [AxMy]O2+z (A includes at least one element among Li, Na and K; M includes at least one element 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 modulus of components included in x, y, z and M is selected to remain electrically neutral).
In another example, the positive electrode active material may be an alkali metal compound xLiM1O2-(1−x) Li2M2O3 (M1 comprises at least one element having an average oxidation state 3; M2 comprises at least one element having an average oxidation state 4; 0≤x≤1) disclosed in U.S. Pat. Nos. 6,677,082, 6,680,143, et al.
In another example, the positive electrode active material may be lithium metal phosphate represented by a general formula LiaM1xFe1−xM2yP1−yM3zO4−z (M1 includes at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg and Al; M2 includes at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, Al, As, Sb, Si, Ge, V and S; M3 includes a halogen element optionally including F; 0<a≤2, 0≤x≤1, 0≤y<1, 0<z<1; the stoichiometric modulus of components included in a, x, y, z, M1, M2, and M3 are selected to remain electrically neutral), or Li3M2(PO4)3 [M includes at least one element 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 in which the primary particles are aggregated.
In one example, the negative electrode active material may use a carbon material, lithium metal or lithium metal compound, silicon or silicon compound, tin or tin compound. Metal oxides such as TiO2 and SnO2 with a potential of less than 2 V may also be used as the negative electrode active material. As the carbon material, all of low-crystalline carbon, high-crystalline carbon, and the like may be used.
The separator may use a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer and ethylene/methacrylate copolymer, or laminates thereof. As another example, the separator may use a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high melting point glass fiber, polyethylene terephthalate fiber, or the like.
At least one surface of the separator may include a coating layer of inorganic particles. It is also possible that the separator itself is made of a coating layer of inorganic particles. Particles constituting the coating layer may have a structure coupled with a binder so that interstitial volumes exist between adjacent particles.
The inorganic particles may be formed of an inorganic material having a dielectric constant of 5 or more. As a non-limiting example, the inorganic particles may include at least one material selected from the group consisting of Pb(Zr,Ti) O3 (PZT), Pb1−xLaxZr1−yTiyO3 (PLZT), PB(Mg3Nb2/3) O3—PbTiO3 (PMN-PT), 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+, or K+, or an ion composed of a combination thereof. In addition, 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−.
The electrolyte may also be dissolved in an organic solvent and then used. The organic solvent may use 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), γ-butyrolactone, or a mixture thereof.
In the jelly-roll 1 of the present disclosure, the first electrode and the second electrode extend in opposite directions along the height direction (parallel to the Z-axis) of the jelly-roll 1. In the following description, the structure of the first electrode will be described in detail. However, this is only an exemplary description, and the structure of the first electrode to be described below may be applied to both the first electrode and the second electrode, or may be applied only to the second electrode.
Referring to
The plurality of slits 10a may be formed by, for example, mold punching or laser notching.
The plurality of slits 10a are formed along a circumferential direction of the jelly-roll 1, that is, a winding direction of the jelly-roll 1. At this time, the plurality of slits 10a may be formed on the same line. For example, the plurality of slits 10a may be formed on a straight line parallel to the winding direction of the first electrode and/or the second electrode. That is, the longitudinal extension lines of the slits 10a adjacent to each other along the winding direction may overlap each other.
Referring to
More specifically, referring to
According to this structure of the present disclosure, since the slits 10a may be provided at points of a specific angle of the jelly-roll 1, the impregnation path IP may be formed effectively. Therefore, the electrolyte impregnation property at the electrode center of the jelly-roll 1 may be improved.
In addition, according to the above structure of the present disclosure, it is not necessary to make the size of the slit 10a excessively large, and even if the size of the slit 10a is relatively small, the impregnation path IP may be reliably formed. Accordingly, it is possible to minimize the weakening of the strength of the first electrode tab 10 and/or the second electrode tab.
That is, with the above structure, in the present disclosure, the strength of the first electrode tab 10 may be secured at a certain level.
For example, if the plurality of slits 10a are not provided in a gradient pattern, but are provided at regular intervals or at random intervals, in order to form an impregnation path IP in the radial direction of the jelly-roll 1, the length of the plurality of slits 10a in the winding direction must be long. This is because the slit 10a provided in the previous layer and the slit 10a provided in the next layer are more likely to face each other when the length of the plurality of slits 10a in the winding direction is long. Such a structure is obtained since the increase in the circumferential length according to the increase in the number of windings is not put into consideration in the design. Therefore, according to this structure, the strength of the first electrode tab 10 at the position where the plurality of slits 10a are formed may become very weak. That is, in the first electrode tab 10, the area of the cross section at the position where the slit 10a is formed, that is, the area of the cross section cut along a direction substantially perpendicular to the winding axis of the jelly-roll 1 (parallel to the X-Y plane) is reduced. Accordingly, the first electrode tab 10 may be damaged due to shock or vibration applied during the use of the cylindrical battery cell, which may cause poor performance of the cylindrical battery cell and/or safety issues such as ignition due to internal short circuit.
On the other hand, according to the present disclosure, since the slit 10a provided in the previous layer and the slit 10a provided in the next layer face each other, even if the length of the slit 10a in the winding direction is relatively small, the impregnation path IP may be reliably formed. According to this structure, the reduction of the area of the cross section of the first electrode tab 10 at the position where the slit 10a is formed, that is, the cross section cut along the direction perpendicular to the winding axis of jelly-roll 1 (parallel to the XY plane) may be minimized. Accordingly, the tensile strength of the first electrode tab 10 in a winding axis direction (parallel to the Z axis) may be improved. Therefore, in this case, even when an external force is applied to the first electrode tab 10, the first electrode tab 10 is not easily broken.
As an embodiment of the present disclosure, referring to
On the other hand, as another embodiment of the present disclosure, referring to
On the other hand, for the same purpose as minimizing the reduction of the area of the cross section at the position where the slit 10a is formed as described above, the slit 10a may be arranged to be spaced apart from the cutting line 10b, which will be described later, by a predetermined distance along an extension direction (parallel to the Z-axis) of the winding axis. Accordingly, the possibility of breakage of the first electrode tab 10 due to an external force such as shock or vibration that may be applied during manufacturing and use of the cylindrical battery cell may be further reduced.
Meanwhile, as described above, in this specification, only the case in which the first electrode is provided with the slit 10a has been described for convenience of description, but the slit 10a may be provided only at the second electrode, or may be provided at both the first electrode and the second electrode.
Referring to
The plurality of bent portions 10c may be bent, for example in a direction toward the winding axis of the jelly-roll 1 to cover at least a part of one surface of the jelly-roll 1 substantially perpendicular to the winding axis. For example, referring to
In this way, since the bent portion 10c provided at one end of the first electrode tab 10 is bent to cover one surface of the jelly-roll 1 perpendicular to the winding axis, a contact area between a current collecting plate (not shown) to be coupled on one surface of the jelly-roll 1 and the first electrode tab 10 may be secured widely. Accordingly, the internal resistance of the cylindrical battery cell may be reduced. In addition, the coupling strength between the jelly-roll 1 and the current collecting plate may be improved.
On the other hand, after the jelly-roll 1 is received in the battery can, electrolyte may be injected through a top opening of the battery can. At this time, since the plurality of bent portions 10c entirely cover one surface of the jelly-roll 1 perpendicular to the winding axis, the electrolyte may not be smoothly impregnated through the top of the jelly-roll 1. In particular, in the case of a cylindrical battery cell of medium or large size, the electrolyte may not be impregnated to the center of the jelly-roll 1.
Therefore, in the present disclosure, among the plurality of slits 10a, the slits 10a adjacent to each other along the radial direction of the jelly-roll 1 may at least partially overlap each other to form an impregnation path IP through which the electrolyte can pass along the radial direction. At this time, the impregnation path IP may be formed from the outer circumferential surface of the jelly-roll 1 to a predetermined depth along the radial direction.
For example, referring to
Meanwhile, in the present invention, when the bent portion 10c as described above is provided in the first electrode tab 10, the slit 10a may be provided in an area other than the area in which the bent portion 10c is formed. Accordingly, the slit 10a may be provided on the outer peripheral surface of the jelly-roll 1.
Referring to
In this case, the length of the first electrode tab 10 in an area adjacent to the winding center C of the jelly-roll 1 and the length of the first electrode tab 10 in an area adjacent to the outer circumferential surface of the jelly-roll 1 may be different from each other. Specifically, the length of the first electrode tab 10 in the area adjacent to the winding center C of the jelly-roll 1 may be shorter than the length of the first electrode tab 10 in the area adjacent to the outer circumferential surface of the jelly-roll 1. In this case, the cutting line 10b and the bent portion 10c may not be provided to the first electrode tab 10 in the area adjacent to the winding center C of the jelly-roll 1. That is, the plurality of cutting lines 10b and the plurality of bent portions 10c may be provided only to the first electrode tab 10 in the area adjacent to the outer circumferential surface of the jelly-roll 1.
Therefore, according to the above embodiment, in the area adjacent to the winding center C of the jelly-roll 1, the first electrode tab 10 may have a structure that is open upward without being bent. Hereinafter, the area whose upper side is not covered by the bent portion 10c will be referred to as a first area A1. At this time, the radial length of the first area A1 will be referred to as D1.
On the other hand, the plurality of bent portions 10c provided to the first electrode tab 10 in the area adjacent to the outer circumferential surface of the jelly-roll 1 are bent in a direction toward the winding axis to cover only a part of one surface of the jelly-roll 1 perpendicular to the winding axis. Hereinafter, the area whose upper side is covered by the bent portion 10c will be referred to as a second area A2. At this time, the radial length of the second area A2 will be referred to as D2.
According to this structure, since the first area A1 is not covered by the bent portion 10c and has a structure that is open upward, the electrolyte introduced through the top opening of the battery can may smoothly flow into the first area A1. Therefore, the electrolyte impregnation property may be further improved.
However, in this case, the impregnation rate of the second area A2 whose upper side is covered due to bending of the plurality of bent portions 10c provided to the first electrode tab 10 toward the core may be slightly lower than the impregnation rate of the first area A1 whose upper side is not covered. Therefore, it is necessary to improve the impregnation rate of the second area A2. Accordingly, in the present disclosure, the depth P of the impregnation path IP may be greater than or equal to the radial length of the area covered by the bent portion 10c, in one surface of the jelly-roll 1 perpendicular to the winding axis. That is, referring to
According to this structure, the electrolyte may move to at least a boundary point between the second area A2 and the first area A1 through the impregnation path IP. Alternatively, the electrolyte may move beyond the second area A2 to the first area A1. After that, the electrolyte may flow down due to the force of gravity. Therefore, the jelly-roll 1 of the present disclosure may be uniformly impregnated by the electrolyte even to the inside thereof.
Meanwhile, as described above, in this specification, only the case in which the cutting line 10b and the bent portion 10c are provided to the first electrode has been described for convenience of description, but the cutting line 10b and the bent portion 10c may also be provided only to the second electrode or to both the first electrode and the second electrode.
The electrolyte impregnation property of the jelly-roll of the present disclosure was evaluated. In addition, a drop test and a vibration test were performed to evaluate the strength of the electrode tab.
A jelly-roll in which slits are formed for electrolyte impregnation is fabricated. Then, after the jelly-roll is received through the top or bottom opening of the battery can, electrolyte is injected into the battery can. After the electrolyte is injected, it is aged for 24 hours, and then the level of impregnation of the electrolyte (checking whether a non-impregnation region exists) is analyzed.
After the jelly-roll and the current collecting plate are welded, this is inserted into the battery can to manufacture a cylindrical battery cell. After that, the cylindrical battery cell fully charged up to 4.2 V freely falls from a height of 1.0 m onto a concrete floor, and then it is checked whether short circuit and/or ignition occurs in the cylindrical battery cell.
After the jelly-roll and the current collecting plate are welded, this is inserted into the battery can to manufacture a cylindrical battery cell. After that, the cylindrical battery cell fully discharged to 2.5 V is vibrated. The vibration method is to change vibration the frequency every 15 minutes as 7 Hz↔200 Hz, which is repeated 12 times in each of X-axis, Y-axis and Z-axis directions. After the vibration test is completed, it is checked whether short circuit and/or ignition occurs in the cylindrical battery cell.
A jelly-roll was manufactured such that a plurality of slits are formed on the same line and the distance between the plurality of slits gradually increases from the core of the jelly-roll toward the outer circumference (gradient pattern type).
Except that the slit was not provided at all, a jelly-roll was manufactured with the other conditions being the same as in Example 1.
Except that a plurality of slits were provided at regular intervals, a jelly-roll was manufactured with the other conditions being the same as in Example 1.
A jelly-roll was manufactured such that among the plurality of slits, slits adjacent to each other along the winding direction were not formed on the same line but were provided at staggered positions (zigzag type).
For each jelly-roll obtained as described above, the results of evaluating the electrolyte impregnation property and the strength of the electrode tab are summarized in Table 1.
From this table, the following points are evident.
In the example 1, there was no non-impregnation area in the jelly-roll since the electrolyte impregnation property was excellent. In addition, the jelly-roll of Example 1 passed the drop test and the vibration test, so it might be confirmed that the electrode tab had excellent strength.
In the comparative example 1, since the slit was not provided, the electrolyte impregnation property was poor, and thus a non-impregnation area existed in the jelly-roll.
In the comparative example 2, the electrolyte impregnation property was satisfactory, but since a plurality of slits elongated in the winding direction were provided on the same line at regular intervals, the strength of the electrode tab was not secured. Specifically, the jelly-roll of the comparative example 2 was damaged in a part of the electrode tab as a result of the drop test and the vibration test. That is, the jelly-roll of the comparative example 2 could not secure the quality and safety of the battery since the strength of the electrode tab was low.
In the comparative example 3, the electrolyte impregnation property was satisfied, but the strength of the electrode tab was not secured because a plurality of slits elongated in the winding direction were provided in a zigzag pattern at alternating positions. Specifically, the jelly-roll of the comparative example 3 was damaged in a part of the electrode tab as a result of the drop test and the vibration test. That is, the jelly-roll of the comparative example 3 could not secure the quality and safety of the battery since the strength of the electrode tab was low.
Referring to
The battery pack 3 may be mounted on the vehicle. The vehicle may be, for example, an electric vehicle, a hybrid electric vehicle, or a plug-in hybrid vehicle. The vehicle includes a four-wheeled vehicle or a two-wheeled vehicle.
Referring to
On the other hand, although terms indicating directions such as up and down are used in this specification, these terms are only for convenience of explanation, and it is obvious to those skilled in the art of the present disclosure that they may vary depending on the location of a target object or the location of an observer.
The present disclosure has been described in detail. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the scope of the disclosure will become apparent to those skilled in the art from this detailed description.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2021-0153452 | Nov 2021 | KR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2022/016735 | 10/28/2022 | WO |
