Battery cell and battery pack

Abstract

A battery cell according to one embodiment of the present invention comprises: an electrode assembly; a battery case for accommodating the electrode assembly; and a cap assembly, which is arranged at the upper portion of battery case and includes a top cap, wherein the top cap includes an inwardly-bent portion, which is bent at the edge of the top cap and extends toward the center of the top cap. The battery cell and a battery pack according to the present invention enhance impact resistance against external impact (crushing).

Description

Battery cells and battery packs

[0001] The present invention relates to a battery cell and a battery pack, and more specifically, to a battery cell and a battery pack in which the impact resistance against crushing is enhanced in a cylindrical battery cell.

[0002] Unlike primary batteries, which cannot be recharged, secondary batteries refer to batteries capable of charging and discharging, and are applied not only to portable devices but also to electric vehicles (EVs) and hybrid electric vehicles (HEVs) driven by electric power sources.

[0003] Currently, widely used types of secondary batteries include lithium-ion batteries, lithium-polymer batteries, nickel-cadmium batteries, nickel-hydrogen batteries, and nickel-zinc batteries. The operating voltage of these unit secondary battery cells, or unit battery cells, is approximately 2.5V to 4.6V. Therefore, if a higher output voltage is required, a battery pack is formed by connecting multiple battery cells in series. Additionally, a battery pack is formed by connecting multiple battery cells in parallel depending on the charge / discharge capacity required for the battery pack. Accordingly, the number of battery cells included in the battery pack can be varied depending on the required output voltage or charge / discharge capacity.

[0004] When configuring a battery pack by connecting multiple battery cells in series or parallel, it is common practice to first configure a battery module consisting of at least one battery cell, preferably multiple battery cells, and then use at least one such battery module and add other components to form a battery pack. Here, a battery module refers to a component in which multiple battery cells are connected in series or parallel, and a battery pack may refer to a component in which multiple battery modules are connected in series or parallel to increase capacity and output.

[0005] Battery cells are classified into pouch type, cylindrical type, prismatic type, etc., depending on the shape of the battery case.

[0006] Among these, cylindrical cells offer excellent safety as they primarily utilize a metal case with a cylindrical structure. They also have the advantage of high energy density by housing a jelly-roll type electrode assembly inside the case, and make it easy to configure a large-capacity power storage device by connecting multiple cells in series or parallel.

[0007] The electrode assembly, housed in a cylindrical case, is a rechargeable power generation device composed of a stacked structure of an anode, a separator, and a cathode, and is classified into jellyroll, stack, and stack / folding types. The jellyroll type is formed by winding a separator between long sheet-shaped anodes and cathodes coated with active material; the stack type is formed by sequentially stacking multiple anodes and cathodes of a predetermined size with a separator in between; and the stack / folding type is a composite structure of the jellyroll and stack types. Among these, the jellyroll electrode assembly has the advantages of being easy to manufacture and having a high energy density per unit weight.

[0008] The jelly roll electrode assembly is wound with a separator interposed between an anode and a cathode, each coated with an active material, and an anode tab protruding from the upper part of the electrode assembly is disposed on the anode, and a cathode tab protruding from the lower part of the electrode assembly can be disposed on the cathode.

[0009] The crush evaluation of cylindrical battery cells is a method of compressing the cell by applying a constant force while the cell is laid horizontally, and the pass condition is that no ignition occurs. However, during the process of compressing the cell, the can may not withstand the external force and may become crushed, causing structural deformation of the jellyroll electrode assembly and potentially leading to a short circuit.

[0010] The present invention aims to solve the problems described above by providing a battery cell and a battery pack with enhanced impact resistance against external shocks.

[0011] A battery cell according to one embodiment of the present invention comprises: an electrode assembly; a battery case for accommodating the electrode assembly; and a cap assembly disposed on the upper part of the battery case and including an upper cap, wherein the upper cap includes a return portion that is bent at the edge of the upper cap and extends toward the center of the upper cap.

[0012] In addition, the return portion of the upper cap is formed along the circumferential direction of the upper cap.

[0013] In addition, the above regression part is formed integrally with the above top cap.

[0014] Additionally, the cap assembly further includes a cap plate positioned below the upper cap.

[0015] In addition, the end of the cap plate can wrap around the return portion from the outside.

[0016] In addition, the cap assembly further includes a gasket between the cap plate and the battery case.

[0017] In addition, the battery case portion surrounding the electrode assembly is formed as a double-wall structure consisting of an outer wall and an inner wall disposed on the inner side of the outer wall.

[0018] In addition, the inner wall is formed by connecting a plurality of arch columns to each other.

[0019] In addition, a plurality of the above-mentioned arch columns are arranged along the circumferential direction of the electrode assembly.

[0020] In addition, the arch column includes a concave portion extending outward from the battery cell.

[0021] In addition, the battery cell of the present embodiment further includes a filler material filled between the inner wall and the outer wall.

[0022] In addition, the above filler may be a foam material.

[0023] In addition, the above filler may be rubber.

[0024] The battery cell may include a plurality of elastic spheres surrounding the electrode assembly on the inside of the battery case.

[0025] A plurality of the above elastic spheres can be stacked in a vertical direction.

[0026] The above elastic sphere can be restored by elasticity.

[0027] The electrode assembly may contact the inner side of the elastic sphere, and the battery case may contact the outer side of the elastic sphere.

[0028] The above elastic sphere may be made of rubber.

[0029] The above elastic sphere may be made of foam material.

[0030] The above battery cell may be a cylindrical battery cell.

[0031] The battery pack of the present invention includes a plurality of battery cells.

[0032] The battery cell and battery pack according to the present invention have the effect of enhancing impact resistance against external impact (crushing).

[0033] FIG. 1 is a drawing illustrating a cylindrical battery cell in one embodiment of the present invention, and

[0034] FIG. 2 is a drawing for explaining the structure of a cylindrical battery cell in an embodiment of the present invention, and

[0035] FIG. 3 is a drawing illustrating an electrode assembly in an embodiment of the present invention, and

[0036] FIG. 4 is a drawing illustrating the appearance of an electrode assembly before it is wound in an embodiment of the present invention, and

[0037] FIG. 5 is a drawing for explaining the wound form of an electrode assembly in one embodiment of the present invention, and

[0038] FIG. 6 is a cross-sectional view of a cylindrical battery cell in the first embodiment of the present invention, and

[0039] FIG. 7 is a detailed view of the part marked with a circle in FIG. 6, and

[0040] FIG. 8 is a cross-sectional view along the line B-B' in FIG. 6, and

[0041] FIG. 9 is a partial detail view of FIG. 8, and

[0042] FIG. 10 is a drawing showing an external force being applied to a cylindrical battery cell in the first embodiment of the present invention, and

[0043] FIG. 11 is a cross-sectional view of a cylindrical battery cell in a second embodiment of the present invention, and

[0044] FIG. 12 is a cross-sectional view along the line B-B' in FIG. 11, and

[0045] FIG. 13 is a partial detail view of FIG. 12, and

[0046] FIG. 14 is a drawing showing an external force being applied to a cylindrical battery cell in a second embodiment of the present invention, and

[0047] FIG. 15 is a drawing illustrating a battery pack according to an embodiment of the present invention, and

[0048] FIG. 16 is a drawing illustrating an electric vehicle equipped with a battery pack in one embodiment of the present invention.

[0049] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Accordingly, in some embodiments, well-known process steps, well-known device structures, and well-known techniques are not specifically described to avoid the present invention being interpreted ambiguously. Throughout the specification, like reference numerals refer to like components.

[0050] In drawings, thicknesses may be enlarged to clearly represent multiple layers and regions. Throughout the specification, the same reference numerals are used for similar parts. When a part such as a layer, film, region, or plate is described as being "above" another part, this includes not only cases where it is "immediately above" another part, but also cases where there is another part in between. Conversely, when a part is described as being "immediately above" another part, it means that there is no other part in between. Furthermore, when a part such as a layer, film, region, or plate is described as being "below" another part, this includes not only cases where it is "immediately below" another part, but also cases where there is another part in between. Conversely, when a part is described as being "immediately below" another part, it means that there is no other part in between.

[0051] A battery cell and a battery pack including the same according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0052] FIG. 1 is a drawing illustrating a cylindrical battery cell in an embodiment of the present invention, FIG. 2 is a drawing for explaining the structure of a cylindrical battery cell in an embodiment of the present invention, FIG. 3 is a drawing illustrating an electrode assembly in an embodiment of the present invention, FIG. 4 is a drawing illustrating the appearance of an electrode assembly before it is wound in an embodiment of the present invention, FIG. 5 is a drawing for explaining the wound form of an electrode assembly in an embodiment of the present invention, FIG. 6 is a longitudinal cross-sectional view of a cylindrical battery cell in a first embodiment of the present invention, FIG. 7 is a detailed view of the part indicated by a circle in FIG. 6, FIG. 8 is a cross-sectional view along the line B-B' in FIG. 6, FIG. 9 is a partial detailed view of FIG. 8, and FIG. 10 is a drawing showing an external force being applied to a cylindrical battery cell in a first embodiment of the present invention.

[0053] In the first embodiment of the present invention, a battery cell (100) is described with reference to FIGS. 1 to 10.

[0054] The battery cell (100) may be a cylindrical battery cell (100) in which an electrode assembly (110) is embedded in a cylindrical can.

[0055] A cylindrical battery cell (100) may include a jelly roll-shaped electrode assembly (110) and a battery case (120) for accommodating the electrode assembly (110), and an upper insulating member (150) may be disposed on the top of the electrode assembly (110), and a lower insulating member (160) may be disposed on the bottom of the electrode assembly (110).

[0056] The electrode assembly (110) has a jelly roll-shaped structure with a first electrode (111), a second electrode (113), and a separator (112) interposed between them, and a center pin (140) can be inserted in the center thereof.

[0057] A cylindrical battery cell (100) can be formed by housing an electrode assembly (110) in a battery case (120), injecting an electrolyte into the battery case (120), and then attaching a cap assembly (130) to the top of the battery case (120). The battery case (120) may be a cylindrical can, and a jelly roll-shaped electrode assembly (110) may be housed in the cylindrical battery case (120) to realize a cylindrical secondary battery.

[0058] The battery case (120) may include a beading portion (122) and a crimping portion (123).

[0059] The above beading portion (122) is for stable coupling of the cap assembly (130) and can be formed along the circumferential direction on the upper outer surface of the battery case (120), or can be formed by being concavely recessed from the outer surface of the battery case (120) toward the center of the electrode assembly (110). The beading portion (122) can prevent movement of the electrode assembly (110).

[0060] The crimping portion (123) may be positioned on the upper part of the beading portion (122) and formed to wrap around the edge portion of the cap assembly (130) along the circumferential direction. The crimping portion (123) can facilitate a stable connection of the cap assembly (130).

[0061] The cap assembly (130) may include an upper cap (131) forming an electrode terminal, a cap plate (132), and a gasket (133) for airtightness.

[0062] The top cap (131) can form a positive terminal.

[0063] The gasket (133) is mounted on the upper inner surface of the crimping portion (123) and the beading portion (122) to increase the sealing force between the cap assembly (130) and the battery case (120).

[0064] The second electrode tab (111c) may extend upward from the electrode assembly (110). Specifically, it may extend from the second electrode (111) of the electrode assembly (110). The second electrode tab (111c) may be an anode tab.

[0065] This second electrode tab (111c) is connected to the cap plate (132), so that the upper cap (131) can function as an electrode terminal (positive terminal). An opening (151) is formed in the upper insulating member (150), and the second electrode tab (111c) can be connected to the cap plate (132) through the opening (151).

[0066] The center pin (140) generally comprises a metal material to provide a certain strength and is formed as a cylindrical structure formed by bending a plate into a round shape. In addition to self-heating, this center pin (140) can function as a passage to fix and support the electrode assembly (110) and to release gas generated by internal reactions during charging, discharging, and operation.

[0067] The electrolyte injected into the battery case (120) may be a lithium salt-containing non-aqueous electrolyte, and the lithium salt-containing non-aqueous electrolyte is composed of a non-aqueous electrolyte and a lithium salt. Non-aqueous organic solvents, organic solid electrolytes, inorganic solid electrolytes, etc. are used as non-aqueous electrolytes, but are not limited to these.

[0068] The battery cell (100) is not necessarily provided as a cylindrical battery cell (100), and may be provided as a battery cell of other shapes, such as a rectangular battery cell.

[0069] FIG. 4 is a drawing showing the appearance of the electrode assembly (110) before it is wound. The electrode assembly (110) can be formed into a jelly roll shape by winding together a long sheet-shaped first electrode (113), a second electrode (111), and a separator (112). The separator (112) can be interposed between the first electrode (113) and the second electrode (111). Additionally, the separator (112) can be additionally placed under the second electrode (111) to prevent the first electrode (113) and the second electrode (111) from coming into contact when wound into a jelly roll shape.

[0070] The first electrode (113) may include a first electrode current collector (113a) and a first active material layer (113b) on the first electrode current collector (113a). The first active material layer (113b) may be formed by applying an electrode active material to one or both sides of the first electrode current collector (113a). Additionally, a first electrode tab (113c) may be attached to an area of ​​the first electrode current collector (113a) where the electrode active material is not applied.

[0071] As illustrated in the example, the electrode active material may not be applied to the core-side end of the first electrode current collector (113a), and the first electrode tab (113c) may be attached to this area. The first electrode (113) may be a negative electrode, and the first electrode tab (113c) may be a negative electrode tab.

[0072] An exposed portion (113d) in which the electrode active material is not applied may be disposed in the area disposed on the outer edge of the electrode assembly (110) in the first electrode current collector (113a). The exposed portion (113d) may be a negative electrode-free portion.

[0073] The second electrode (111) may include a second electrode current collector (111a) and a second active material layer (111b) on the second electrode current collector (111a). The second active material layer (111b) may be formed by applying an electrode active material to one or both sides of the second electrode current collector (111a). Additionally, a second electrode tab (111c) may be attached to an area of ​​the second electrode current collector (111a) where the electrode active material is not applied. As illustrated in the example, the second electrode tab (111c) may be attached to the center of the second electrode current collector (111a), and the second active material layer (111b) may be disposed on both sides of the second electrode tab (111c) on the second electrode current collector (111a). The second electrode (111) may be a positive electrode, and the second electrode tab (111c) may be a positive electrode tab.

[0074] A sealing tape (170) may be disposed on the outer surface of the electrode assembly (100). In one embodiment of the present invention, the sealing tape (170) may be disposed on the upper and lower portions of the outer surface of the electrode assembly (110), as shown in FIG. 4. That is, the sealing tape (170) may be disposed along the circumferential direction on the outer surface of the electrode assembly (110) in the form of a jelly roll, and may be attached to the outer surface of the electrode assembly (110) by an adhesive layer on the lower surface of the sealing tape (170).

[0075] A sealing tape (170) can be attached to the outer surface of a first electrode (113) (negative electrode) that is positioned on the outer edge of the electrode assembly (110). Additionally, the sealing tape (170) can be positioned across the end (113e) of the first electrode (113).

[0076] A sealing tape (170) can be placed on the exposed portion (113d) of the first electrode (113) (negative electrode) which is placed on the outer edge of the electrode assembly (110).

[0077] A sealing tape (170) is placed on the outer surface of the electrode assembly (110) to prevent the jelly roll-shaped electrode assembly (110) from unraveling.

[0078] In this embodiment, as shown in FIGS. 6 and 7, the top cap (131) in the cap assembly (130) includes a return portion (131a) at the edge. The top cap (131) may be approximately circular.

[0079] The return portion (131a) can be bent at the edge of the top cap (131) and extended toward the center of the top cap (131). The return portion (131a) can be formed by bending it into a 'U' shape at the edge of the top cap (131) and can be formed along the circumferential direction at the edge of the top cap (131). The return portion (131a) of the top cap (131) can be formed integrally with the top cap (131).

[0080] When the edge of the top cap (131) is formed in a straight line, there is a problem in that when an external force is applied to the battery cell (100) or the top cap (131), the edge of the top cap (131) penetrates the cap plate (132) and / or gasket (133) and comes into contact with the outer wall of the can, which is the battery case (120), causing a short circuit.

[0081] However, in this embodiment, since the return portion (131a) is positioned at the edge of the upper cap (131) in this manner, even when an external force is applied to the battery cell (100) or the upper cap (131), the edge of the upper cap cannot penetrate the cap plate (132) and / or gasket (133), so that a short circuit does not occur.

[0082] The end of the cap plate (132) positioned on the lower side of the upper cap (131) can wrap around the return portion (131a) from the outside. The cap plate (132) may be approximately circular.

[0083] The edge of the cap plate (132) may be formed to extend along the return portion (131a) from the outer side of the return portion (131a). Alternatively, the end portion (132a) of the cap plate (132) may be bent at the edge of the cap plate (132) to wrap around the return portion (131a) and extend toward the center of the cap plate (132), and may be formed along the circumferential direction at the edge of the cap plate (132).

[0084] A sealing gasket (133) can be placed on the outside of the cap plate (132) between the cap plate (132) and the battery case (120) (crimping part (123)).

[0085] In this embodiment, as shown in FIG. 8, an inner wall (200) may be disposed inside a cylindrical can-shaped battery case (120). The inner wall (200) may be disposed along the circumferential direction of the electrode assembly (110) and may surround the electrode assembly (110). The inner wall (200) may be disposed inside the portion of the battery case (120) surrounding the electrode assembly (110). Accordingly, the portion of the battery case (120) surrounding the electrode assembly (110) may be configured as a double-wall structure consisting of an outer wall (125) and an inner wall (200).

[0086] The inner wall (200) may include a plurality of arch columns (210). In this embodiment, the inner wall (200) may be formed by arranging a plurality of arch columns (210) along the circumferential direction of the electrode assembly (110). Additionally, the inner wall (200) may be formed by arranging a plurality of arch columns (210) along the inner surface of the outer wall (125).

[0087] The inner wall (200) can be formed by connecting multiple arch columns (210) to each other.

[0088] Each arch column (210) can be extended in a vertical direction, and the lower part of each arch column (210) can be placed on the bottom of the battery case (120).

[0089] It may include a concave portion (210a) formed concavely on the outer side of the battery cell (100). The concave portion (210a) may form an arc or a semicircle shape. Both ends of the arch column (210) may be connected to one end of an adjacent arch column (210), and may be bent at one end of the arch column (210) to be connected to one end of an adjacent arch column (210). As shown in FIG. 9, the lowest point (210b) located in the middle of the concave portion (210a) may be positioned to be in contact with the outer wall (125).

[0090] Accordingly, the inner wall (200) may be formed by repeatedly bending a single plate outwardly in a concave manner along the circumferential direction of the electrode assembly (110), and the plurality of arch columns (210) may be formed integrally. The material of the inner wall (200) may be metal, for example, stainless steel (SUS).

[0091] In this embodiment, the battery case (120) surrounding the electrode assembly (110) is formed as a double-wall structure of an inner wall (200) and an outer wall (125) in which arch columns (210) are continuously connected and arranged, so that when an external force is applied to the battery cell (100) as in FIG. 10, the resistance to impact such as a crush is enhanced and the electrode assembly (110) is protected from the external force.

[0092] In this embodiment, the space between the inner wall (200) and the outer wall (125) can be filled with a filler material (300).

[0093] The filler material (300) may be, for example, a foam material. The foam material may be urethane foam, synthetic resin foam, expanded foam, etc.

[0094] In addition, the filler (300) may be an elastic material such as rubber, or silicone or synthetic resin.

[0095] In this embodiment, the space between the inner wall (200) and the outer wall (125) is filled with a filler material (300), so that when an external force such as a crush is applied, the external force or impact received by the wall surface of the battery case (120) can be mitigated.

[0096] Next, a battery cell (100) according to a second embodiment of the present invention will be described. FIG. 11 is a longitudinal cross-sectional view of a cylindrical battery cell in the second embodiment of the present invention, FIG. 12 is a cross-sectional view along the line B-B' in FIG. 11, FIG. 13 is a partial detailed view of FIG. 12, and FIG. 14 is a drawing showing an external force being applied to a cylindrical battery cell in the second embodiment of the present invention.

[0097] The difference between the second embodiment and the first embodiment described above is that a buffer is placed instead of the inner wall (200) in the first embodiment described above.

[0098] In this embodiment, as shown in FIG. 11, a buffer may be disposed inside a cylindrical can-shaped battery case (120). The buffer may include a plurality of elastic spheres (400). The plurality of elastic spheres (400) may be arranged along the circumferential direction of the electrode assembly (110) and may surround the electrode assembly (110). The buffer composed of the plurality of elastic spheres (400) may be disposed inside the side wall of the battery case (120) surrounding the electrode assembly (110).

[0099] The elastic sphere (400) may have elasticity and may be elastically recoverable. In this embodiment, a plurality of elastic spheres (400) may be arranged along the circumferential direction of the electrode assembly (110). Additionally, as shown in FIG. 11, a plurality of elastic spheres (400) may be arranged in a vertical direction from the bottom to the top of the electrode assembly (110) on the outer circumference of the electrode assembly (110).

[0100] The elastic sphere (400) may be formed in the shape of a sphere. The material of the elastic sphere (400) may be an elastic material having elasticity. For example, the elastic sphere (400) may be an elastic material such as rubber, a foam material, expanded foam, urethane foam, a sponge, or a soft synthetic resin. The inner part of the elastic sphere (400) may contact the electrode assembly (110), and the outer part of the elastic sphere (400) may contact the inner surface of the battery case (120).

[0101] In this embodiment, a plurality of elastic spheres (400) are arranged along the circumferential direction of the electrode assembly (110) inside the battery case (120) surrounding the electrode assembly (110). As shown in FIG. 14, when an external force is applied to the battery cell (100), the elastic spheres (400) absorb and mitigate the external force, thereby strengthening the resistance to impacts such as crushing and protecting the electrode assembly (110) from the external force. Additionally, external forces in the vertical direction can also be mitigated by the elastic spheres (400) stacked on the outside of the electrode assembly (110).

[0102] Other components and effects are the same as those in the previous embodiment, so a detailed description thereof is omitted here.

[0103] Meanwhile, a plurality of cylindrical battery cells (100) can be accommodated in a pack case (2100) to form a battery pack (2000) (see FIG. 15).

[0104] The battery pack (2000) may additionally include various control and protection systems such as a Battery Management System (BMS), and the battery pack (2000) may be applied to various devices. Specifically, it may be applied to means of transportation such as electric bicycles, electric vehicles, and hybrid vehicles, or to an Energy Storage System (ESS), but is not limited thereto and can be applied to various devices capable of using secondary batteries.

[0105] FIG. 16 is a drawing illustrating an electric vehicle (V) equipped with a battery pack (2000). In the electric vehicle (V), the wheels are driven by a motor that receives power from the battery pack (2000), allowing the electric vehicle to operate.

[0106] Although the present invention has been described with reference to preferred embodiments as described above, it is not limited to the aforementioned embodiments, and various changes and modifications may be made by those skilled in the art within the scope of the invention without departing from the spirit of the invention.

[0107] The present invention can provide a battery cell and a battery pack with enhanced impact resistance against external impact (crush).

Claims

1. Electrode assembly; A battery case for accommodating the above electrode assembly; and A cap assembly disposed on the upper part of the battery case and including a top cap; Includes, A battery cell comprising a top cap that is bent at the edge of the top cap and includes a return portion extending toward the center of the top cap.

2. In Paragraph 1, The return portion of the upper cap is a battery cell formed along the circumferential direction of the upper cap.

3. In Paragraph 1, The above regression portion is a battery cell formed integrally with the above top cap.

4. In Paragraph 1, The above cap assembly further comprises a battery cell including a cap plate positioned below the upper cap.

5. In Paragraph 4, The end of the above cap plate is a battery cell that surrounds the above return portion from the outside.

6. In Paragraph 4, The above cap assembly is a battery cell that further includes a gasket between the cap plate and the battery case.

7. In Paragraph 1, A battery cell having a double-walled structure comprising an outer wall and an inner wall disposed on the inner side of the outer wall, wherein the battery case portion surrounding the electrode assembly is composed of the outer wall.

8. In Paragraph 7, The above inner wall is a battery cell formed by connecting multiple arch columns.

9. In Paragraph 8, A plurality of the above-mentioned arch columns are arranged along the circumferential direction of the electrode assembly, forming a battery cell.

10. In Paragraph 9, The above arch column is a battery cell including a concave portion on the outer side of the battery cell.

11. In Paragraph 7, A battery cell further comprising a filler material filled between the inner wall and the outer wall.

12. In Paragraph 11, The above filler is a foam material, which is a battery cell.

13. In Paragraph 1, A plurality of elastic spheres surrounding the electrode assembly on the inner side of the battery case; A battery cell containing 14. In Paragraph 13, A plurality of the above elastic spheres are stacked in a vertical direction to form a battery cell.

15. In Paragraph 13, The above elastic sphere is a battery cell that can be restored by elasticity.

16. In Paragraph 13, A battery cell in which the electrode assembly contacts the inner side of the elastic sphere and the battery case contacts the outer side of the elastic sphere.

17. In Paragraph 13, The above elastic sphere is a battery cell made of rubber.

18. In Paragraph 13, The above elastic sphere is a battery cell made of foam material.

19. In Paragraph 1, The above battery cell is a cylindrical battery cell.

20. A battery pack comprising a plurality of battery cells according to paragraph 1.

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