Patent Application
20230110500
This application claims priority from Korean Patent Application No. 10-2021-0127163 filed on Sep. 27, 2021 and from Korean Patent Application No. 10-2022-0114320 filed on Sep. 8, 2022, the entire disclosures of both which are hereby incorporated herein by reference.
The present disclosure relates to an electrode assembly and a battery cell including the same, and more particularly, an electrode assembly that prevents the folding phenomenon of the separator, and a battery cell including the same.
In modern society, as portable devices such as mobile phones, notebook computers, camcorders, and digital cameras have become used daily, the development of technologies in the fields related to such mobile devices has become active. In addition, chargeable/dischargeable secondary batteries are used as a power source for electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (P-HEVs) and the like, in an attempt to solve air pollution and the like caused by existing gasoline vehicles that use fossil fuel. Therefore, there is a growing need for improvements to secondary batteries.
Currently commercialized secondary batteries include nickel cadmium batteries, nickel hydrogen batteries, nickel zinc batteries, and lithium secondary batteries. Among them, lithium secondary batteries have come into the spotlight because they have advantages, for example, hardly exhibiting memory effects compared to nickel-based secondary batteries and thus being freely charged and discharged, and having very low self-discharge rate and high energy density.
Secondary batteries may be classified based on the shape of their battery case into: a cylindrical battery having an electrode assembly mounted in a cylindrical metal can, a prismatic battery having an electrode assembly mounted in a prismatic metal can, and a pouch type battery having an electrode assembly mounted in a pouch-shaped case made of a laminated aluminum sheet.
Further, secondary batteries may be classified based on the structure of their electrode assembly, which has a structure in which a cathode and an anode are stacked with a separator being interposed between the cathode and the anode. Typically, the structural classifications include: a jelly-roll (wound) type structure and a stacked (laminated) type structure, or the like. In a jelly-roll (wound) type structure, a long sheet type cathode and a long sheet type anode are wound with a separator being interposed between the cathode and the anode. In a stacked (laminated) type structure, pluralities of cathodes and anodes cut into predetermined unit sizes are sequentially stacked with separators being interposed between the cathodes and the anodes. In recent years, in order to solve problems caused by the jelly-roll type electrode assembly and the stacked type electrode assembly, there has been developed a stacked/folded type electrode assembly, which is a combination of the jelly-roll type electrode assembly and the stacked type electrode assembly.
Referring to
Meanwhile, since the separator 13 is usually formed larger than the cathode 11 or the anode 12, the end of the separator 13 in the electrode assembly projects outwardly of the cathode and anode, such that the projecting portion of the separator 13 is not adhered to the cathode 11 or the anode 12, which may lead to a problem in which the end of the separator 13 becomes bent or folded by an external force as in a region A of
The present invention provides, among other things, an electrode assembly and a battery cell comprising the electrode assembly. An electrode assembly in accordance with aspects of the invention includes a plurality of electrodes arranged in a stack along a stacking dimension with a respective separator portion positioned between each of the electrodes in the stack, and includes a connection component extending between and connecting a least two adjacent overhanging portions of the separator portions. Each of the electrodes in the stack preferably has an outer perimeter within a plane extending transverse to the stacking dimension. The separator portions may each have a respective overhanging portion protruding outwardly in a lateral dimension beyond the outer perimeters of adjacent electrodes, where such lateral dimension is oriented transverse to the stacking dimension. The connection component preferably comprises a network of strands of material, where some of the strands cross over other strands in the network so as to define respective crossing locations. Desirably, a region of the connection component includes multiple crossing locations spaced apart from one another in the stacking dimension.
In accordance with some aspects of the invention, the strands may have a width in a range from 20 µm to 100 µm.
In accordance with some aspects of the invention, the distance between adjacent strands in the network may be in a range from 100 µm to 800 µm.
In accordance with some aspects of the invention, the stack may have at least one lateral side extending parallel to the stacking dimension, where the connection component extends along that lateral side. In accordance with some of such aspects of the invention, the length dimension may be longer than the width dimension, both of which are orthogonal to the stacking dimension, and the lateral side extends along the length dimension of the stack. In accordance with some other of such aspects of the invention, the electrode assembly may include an electrode tab protruding outwardly from the stack, where the lateral side is oriented along the protruding direction of the electrode tab. In accordance with yet some other of such aspects of the invention, the connection component extends along the lateral side for a distance ranging from 70% to 80% of the length dimension thereof.
In accordance with some aspects of the invention, the separator portions are portions of an elongated separator sheet which is folded between each separator portion such that the elongated separator sheet follows a serpentine path traversing back and forth along the lateral dimension so as to extend between each of the successive electrodes in the stack. In accordance with some of such aspects of the invention, the electrode assembly may further include an outer separator encircling a perimeter of the stack and the connection component.
In accordance with some aspects of the invention, the connection component may be spaced away from contacting the electrodes.
In accordance with some aspects of the invention, the electrodes in the stack include at least one cathode and at least one anode, where the connection component is spaced away from contacting the cathode.
In accordance with some aspects of the invention, the connection component may have a thickness in the lateral dimension in a range from of 100 µm to 600 µm.
In accordance with some aspects of the invention, the connection component may extend between and connects more than two overhanging portions of the separator portions. In accordance with some of such aspects of the invention, the overhanging portions include an upper overhanging portion, a lower overhanging portion, and at least one intermediate overhanging portion therebetween. In accordance with such aspect, the connection component may extend continuously between the upper and lower overhanging portions such that the connection component extends around an outer edge of each of the intermediate overhanging portions, where the outer edge is an outermost extremity of the respective overhanging portion in the lateral dimension.
In accordance with some aspects of the invention, the strands of material of the connection component may comprise an adhesive material.
In accordance with some aspects of the invention, the strands of material comprising the network of strands of the connection component may follow circular arc-shaped paths crossing over one another. In accordance with some of such aspects of the invention, the circular arc-shaped paths may have diameters in a range between one half and one eighth of the height of the stack along the stacking dimension. In accordance with some other of such aspects of the invention, the circular arc-shaped paths may define a plurality of parallel, overlapping spirals. In accordance with such aspect, the overlapping spirals overlap by an amount in a range between one half and one eighth of a diameter of loops comprising the spirals. In accordance with yet some other of such aspects of the invention, the circular arc-shaped paths may define at least one spiral comprised of a plurality of loops, where each successive loop in the spiral overlaps a previous loop in the spiral by an amount in a range between one half and one eighth of a diameter of the loop.
As a result of embodiments according to the present invention, the electrode assembly of the present disclosure (and a battery cell including the same) include connection components extending between and connecting the overhanging portions of the separator portions, so as to improve rigidity of the overhanging portions. The connection components may be applied to opposing lateral sides of the electrode assembly.
The effects of the present disclosure are not limited to the effects mentioned above, and additional other effects not described above will be clearly understood by those skilled in the art from the below description.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can carry them out. The present disclosure can be modified in various different ways, and is not limited to the embodiments set forth herein.
Portions that are irrelevant to the description will be omitted to clearly describe the present disclosure, and like reference numerals designate like elements throughout the description.
Further, in the drawings, the size and thickness of each element is arbitrarily illustrated for convenience of description, and the present disclosure is not necessarily limited to those illustrated in the drawings. In the drawings, the thicknesses of some layers, regions, etc. are exaggerated for clarity and/or convenience of description.
In addition, it will be understood that when an element such as a layer, film, region, or plate is referred to as being “on” or “above” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, it means that other intervening elements are not present. Further, the word “on” or “above” includes disposed on or below a reference portion, and it does not necessarily mean being disposed on the upper end of the reference portion toward the opposite direction of gravity. The above qualifications likewise apply to cases where an element is described as being located “below” or “under” another part.
Further, throughout the description, when a portion is referred to as “including” or “comprising” a certain component, it means that the portion can further include other components, without excluding the other components, unless otherwise stated.
Further, throughout the description, when something is referred to as “cross-sectional” or a “cross section,” it refers to a target portion viewed from the side of a cross section cut vertically.
Hereinafter, a battery assembly according to an embodiment of the present disclosure will be described.
Referring to
Further, the electrode assembly 100 of the present embodiment may include one or more connection components 140 positioned along at least one lateral side of the cell stack, in which the electrodes 110 and 120 and the separator portions 130 are alternately stacked along a stacking dimension. Here, the cell stack refers to a stacked body of the electrodes 110 and 120 and the separator portions 130 in the electrode assembly 100, and may not include the connection components 140. Further, the lateral sides of the cell stack refer to the sides extending parallel to the stacking dimension where the ends of the plurality of electrodes 110 and 120 and/or the separator portions 130 in directions transverse to the stacking dimension are exposed. The at least one lateral side of the cell stack may include a side of the cell stack that extends along a longitudinal dimension of the electrode assembly 100 (i.e., the Z-axis direction of
Further, as discussed below, when the electrode assembly 100 is formed by zigzag stacking, the bent parts of the separator sheet comprising the various separator portions 130 may protrude beyond the ends of the electrodes 110 and 120.
The connection components 140 may be composed of an adhesive material, and the connection components 140 may be formed by applying the adhesive material along portions of at least one lateral side of the cell stack. The adhesive material may include a component that is not readily dissolved in the electrolytic solution. An example of the adhesive material used for the connection components 140 may include one or more of PO, PUR, EVA, and rubber series. Other examples may include curable adhesives capable of natural curing, moisture curing, UV curing, and the like.
The connection components 140 comes into contact with the overhanging portions 138 of adjacent separator portions 130, thereby helping to support the shapes of the separator portions 130. Such support provided by the connection components 140 may include providing rigidity to the overhanging portions 138.
Preferably, the connection components 140 do not come into contact with the cathode 110. This may be because the connection components 140 may disturb the flow of ions moving from the cathode 110 to the anode 120. Additionally, or alternatively, it is preferable that the connection components 140 do not come into contact with the anode 120. However, the anode 120 is not a direct charging region, and therefore any negative influence that may be caused by contact from the connection components 140 may be less with respect to the anode 120 than with respect to the cathode 110.
The connection components 140 may be positioned along all lateral sides of the cell stack of the electrode assembly 100. More preferably, the connection components 140 may be positioned along only some of the lateral sides. In that regard, when the connection components 140 are positioned along all of the lateral sides of the electrode assembly 100, the connection components 140 may impede the gas discharge of the electrode assembly 100 in the electrolytic solution impregnation or activation process of the electrodes 110 and 120.
The connection components 140 may be formed so as to cover the whole of one lateral side of the electrode assembly 100, or may be formed so as to cover an amount in a range from 70% to 80% of the lateral side. Such lateral side of the electrode assembly 100 may have a ‘height’ defined along the stacking dimension and a ‘length’ orthogonal to the height, which length corresponds to the length dimension of the long side or the short side of the electrode assembly 100. Thus, the connection components 140 may be formed so as to cover 70 to 80% of the length of the lateral side. By not covering the entire lateral side of the electrode assembly 100, such configuration of the connection components 140 may thereby avoid impeding the gas discharge of the electrode assembly 100 in the electrolytic solution impregnation or activation process of the electrodes 110 and 120.
The electrode assembly 100 may have a rectangular shape in a plane oriented orthogonal to the stacking dimension. Such rectangular shape may have a longer dimension and a shorter dimension. Preferably, the connection components 140 are positioned along the lateral sides corresponding to the longer dimension of the electrode assembly 100. This may be beneficial as it is believed that the folding phenomenon or the like may occur more frequently on the long side of the separator portions 130 having a relatively longer length than on the short side. However, the connection components 140 can also, or alternatively, be formed along one or more of the lateral sides corresponding to the shorter dimension of the electrode assembly 100.
As shown in
Referring to
Specifically, it was found that when the connection components 140 are positioned along the lateral side of the electrode assembly 100, the folding phenomenon appearing in the region A of
Referring to
The network of strands 144 of the adhesive material may be formed by a patterning method. Here, the patterning method may mean applying an adhesive so that the adhesive 10 applied to the target position has a predetermined pattern.
The adhesive application device 200 based on the patterning method may include a housing 210 and one or more nozzles 220. The adhesive 10 may be supplied from the outside of the device 200 and housed in the housing 210, and the adhesive 10 that has passed through each nozzle 220 can be discharged in the form of a line so as to form a linear strand 144. The applied adhesive 10 may have a specific pattern according to the movement of the nozzle(s) 220. As an example, the housing 210 may move in a spiral pattern while discharging the adhesive 10, thus resulting in a pattern defined by a large number of overlapping circular shapes.
In another example (not shown), the housing 210 may be structured such that each of the nozzles 220 have independently-controllable directionality. As a result, the device 200 may control the application of the strands 144 from each nozzle 220 (e.g., by controlling which strands 144 are deposited below or above others), such that the resulting network of strands is more like a woven pattern.
The network of strands 144 can be formed in patterns other than spiral patterns, as long as such patterns involve the strands intersecting at multiple nodes. Preferably such patterns involve multiple nodes spaced apart from one another in the stacking dimension of the electrode stack. As an example, such pattern may be or include a diagonal lattice, where a first set of multiple, generally parallel linear strands of adhesive material extend along an oblique angle across a lateral side of the stack, and a second set of generally parallel linear strands of the adhesive material that extend across the lateral side at a different oblique angle, such that multiple nodes are created where the strands of the first set cross over the strands of the second set.
Referring to
The adhesive application device 300 based on such surface application method can apply the adhesive 10 so that the adhesive 10 covers the whole of the target portion as shown in the photograph of
Meanwhile, since the adhesive application device 300 of
On the other hand, since the adhesive application device 200 of
The device 200 of
The thickness of the adhesive member 140 formed on the electrode assembly 100 can be variously set according. For example, considering the size of the space between the electrode assembly 100 and the battery case in the battery cell, the thickness of the adhesive member 140 can be designed to be less than or equal to that size. As a specific example, when the electrode assembly 100 is incorporated in the battery case in a state where the connection components 140 are not formed, the separation distance between the electrode assembly 100 and the battery case may be about 600 µm.In this case, the thickness of the connection components 140 positioned along the electrode assembly 100 may be 600 µmor less, 500 µmor less, 400 µmor less, 300 µmor less, or 200 µmor less. Further, the thickness of the connection components 140 positioned along the electrode assembly 100 may be 100 to 600 µm, 100 to 500 µm, 100 to 400 µm, 100 to 300 µm, or 100 to 200 µm.
The adhesive 10 may be provided through the adhesive application device at a predetermined temperature. For example, the adhesive application device may adjust the temperature of the adhesive 10 so that the adhesive 10 can be easily applied. The operating temperature of the device 200 of
Referring to
Other parameters of the spiral patterning method of
With regard to the linear distance that the pattern advances for each loop of the spiral, in some embodiments the amount of such linear advancement may be related to the diameter of the loops. For example, the pattern may advance linearly no more than one half (½) of the diameter of the loop between successive loops, which may provide a sufficient amount of overlap between loops (and thus a sufficient amount of resulting crossing nodes). In a specific embodiment, the pattern may advance linearly by about one quarter (¼) of the diameter of the loop between successive loops in the pattern, and in another embodiment the pattern may advance linearly by about one eighth (⅛) of the diameter of the loop between successive loops in the pattern. In other embodiments, the pattern may advance linearly by an amount in a range between one half (½) and one eighth (⅛) of the diameter of the loops.
As to the amount of overlap between adjacent, parallel rows of loops defined along the length of the pattern, in some embodiments the amount of such overlap may also be related to the diameters of the loops. For example, in some embodiments, the adjacent, parallel rows of loops may overlap by about one half (½) of the diameter of the loops. In other embodiments, the adjacent, parallel rows of loops may overlap by about one quarter (¼) of the diameter of the loops. In yet other embodiments, the adjacent, parallel rows of loops may overlap by about one eighth (⅛) of the diameter of the loops. In some embodiments, the adjacent parallel rows of loops may overlap by an amount in a range from one half (½) to one eighth (⅛) of the diameter of the loops.
Meanwhile,
Since the connection components 140 are formed on the lateral side of the electrode assembly 100, the connection components 140 could impair the electrolytic solution absorbed through the lateral side of the electrode assembly 100 from coming into contact with the electrodes 110 and 120. Therefore, it is desirable that the connection components 140 be formed to minimize any decrease in absorption of the electrolytic solution.
Referring to
Since the pattern application method of
Next, an electrode assembly according to another embodiment of the present disclosure will be described.
Prior to the description, it should be clarified that the electrode assembly of the present embodiment is generally the same as the above-mentioned electrode assemblies, except that the shape of the cell stack is different. Therefore, unless otherwise stated, the electrode assembly according to the present embodiment may be assumed to include all the contents related to the electrode assemblies of
Referring to
Here, the separator portions 130 may be portions of an elongated separator sheet which repeatedly traverses back and forth between successive electrodes (cathode 110 and anode 120) in the stack, the separator sheet wrapping around an edge of each successive electrode at a respective folded part 138 of the separator sheet, so as to follow a zigzag or serpentine path through the cell stack. After such zigzag stacking is completed, the separator sheet can wrap around a perimeter of the cell stack at least once, thereby defining outer separators 132 and 134 that cover the lateral sides of the stack. The positions of the cathode 110 and the anode 120 shown in
The connection components 140 can be formed along a lateral side of the cell stack. In particular, as shown in
The connection components 140 may be positioned along all lateral sides of the cell stack, as described above, but in another configuration they can be positioned on both opposing lateral sides where the folded parts 138 of the separator sheet are located. In another alternative, unlike
After the connection components 140 are positioned on the cell stack, the outer separators 132 and 134 may be positioned along the outside of the connection components 140. That is, the outer separators 132 and 134 may wrap around the lateral sides on which the connection components 140 are formed. The outer separator 132 may be formed by surrounding the outer perimeter of the cell stack once, as shown in
Alternatively, without providing the outer separators 132 and 134 in the electrode assembly 100, the lateral side(s) of the cell stack can be finished by attaching an adhesive means such as heat sealing or adhesive tape, and the finishing method may be implemented in various ways in addition to the above-mentioned embodiments.
Next, a method of manufacturing an electrode assembly according to an embodiment of the present disclosure will be described.
The manufacturing method (S1000) of the electrode assembly of the present embodiment may include a step of forming a cell stack in which the electrodes 110 and 120 and the separator portions 130 are alternately stacked (S1100), then a step of applying the adhesive 10 to a lateral side of the cell stack (S1200), and a step of forming the connection components 140 for providing rigidity to the separator portions 130 (S1300).
With respect to the step of forming the cell stack (S1100), any known method can be used, as long as the electrodes and the separator portions are stacked in the order of: cathode 110, separator portion 130, anode 120, and separator portion 130; or in the order of: anode 120, separator portion 130, cathode 110, and separator portion 130. For example, the cell stack can be manufactured in a stacked type as shown in
With regard to the step of applying the adhesive to the side surface of the cell stack (S1200), the device 200 of
Since the adhesive 10 is applied in a viscous state, it may be desirable to allow the shape of the adhesive 10 to be fixed by removing the solvent or moisture in the adhesive. In such case, the step of forming the connection components 140 (S1300) may include a step of drying the adhesive 10. Additionally or alternatively, depending on the nature of the adhesive 10, the adhesive 10 can be solidified by heat curing or UV curing, and, in such a case, the step of forming the connection components 140 (S1300) may include a step of curing the adhesive 10.
On the other hand, when the present embodiment involves a method of manufacturing the zigzag type electrode assembly 100 shown in
Further, the method of manufacturing the electrode assembly 100 according to the present embodiment may further include, after the application of the outer separators 132 and 134, a step of pressing the outer separators 132 and 134 along a direction (e.g., X-axis direction) inwardly towards the lateral side of the cell stack.
When such steps are added, the outer separators 132 and 134 and the connection components 140 are preferably adhered to each other, so that the overall stiffness of the electrode assembly is improved. In addition, the outer separators 132 and 134 may have the beneficial effect of more strongly winding the electrode assembly. Accordingly, the overall result is desirably to resist bending of the battery cell.
The electrode assembly 100 of the present embodiment described above may be housed in a cell case together with an electrolytic solution in order to produce a battery cell.
A battery cell according to an embodiment of the present invention may include an electrode assembly 100 in which a plurality of electrodes and a plurality of separator portions are alternately stacked, electrode leads connected to electrode tabs extending from a plurality of the electrodes, and a cell case for sealing the electrode assembly in a state where one end of the electrode leads protrude.
The above-mentioned battery cell can be stacked with others along a direction to form a battery cell stack, and the battery cell stack can be integrated together with a battery management system (BMS) and/or a cooling device that is modularized into a battery module and manages the temperature or voltage of the battery. The battery pack can be applied to various devices. For example, a device to which the battery pack may be applied may be a vehicle such as an electric bicycle, an electric vehicle, or a hybrid vehicle, but the present disclosure is not limited thereto. The battery pack according to the present embodiment can be used for various devices in addition to the above examples, which also falls within the scope of the present disclosure.
Although preferred embodiments of the present disclosure have been described in detail above, the scope of the present disclosure is not limited thereto. Within the scope of the present disclosure, various modifications and improvements made by those skilled in the art using the basic concepts of the present disclosure, which are defined in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2021-0127163 | Sep 2021 | KR | national |
| 10-2022-0114320 | Sep 2022 | KR | national |
