Compression pad, battery cell stack, and battery module including same

Abstract

A battery cell stack according to an embodiment of the present invention includes: a plurality of battery cells which each include an electrode assembly having electrode tabs, and an exterior material accommodating the electrode assembly, and which are arranged in parallel to each other; and compression pads interposed between the plurality of battery cells. The compression pads each include: a main portion; and side portions which are disposed at the end portions of the main portion, have a compression rate lower than that of the main portion, and overlap side portions of the electrode tabs of the battery cells with respect to the thickness direction of the compression pad.

Description

Compression pad, battery cell stack and battery module including the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0190432, filed December 22, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a compression pad interposed between a plurality of battery cells, and a battery cell stack and battery module including the same.

[0005] As technological developments and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing. In particular, secondary batteries are attracting significant attention as an energy source not only for mobile devices such as cell phones, digital cameras, laptops, and wearable devices, but also for powertrains such as electric bicycles, electric cars, and hybrid electric vehicles.

[0006] While small mobile devices typically use one or two or three battery cells per device, medium- to large-sized devices, such as automobiles, require high output and large capacity. Therefore, medium- to large-sized battery modules, which electrically connect multiple battery cells, are used.

[0007] It is desirable for medium- to large-sized battery modules to be manufactured with as small a size and weight as possible, so square batteries and pouch-type batteries that can be stacked with high integration and have a small weight per capacity are mainly used as battery cells for medium- to large-sized battery modules.

[0008] Meanwhile, the battery module may include a module frame that houses the battery cell stack in an internal space to protect the battery cell stack from external shock, heat, or vibration.

[0009] A battery cell stack may include a plurality of battery cells and a compression pad in contact with the battery cells. The compression pad may absorb shock transmitted to adjacent battery cells and may also delay the rate of heat propagation in the event of a battery cell ignition.

[0010] When swelling occurs due to gas generated during the charging and discharging process of a battery cell, the compression pad compresses and applies pressure to the battery cell. However, since the thickness of the battery cell varies from location to location, the pressure applied by the compression pad to the battery cell varies, and the gas can infiltrate areas with low pressure, causing problems such as lithium precipitation and deterioration of the battery cell performance.

[0011] The problem to be solved by the present invention is to provide a compression pad capable of applying uniform pressure to a battery cell, and a battery cell stack and battery module including the same.

[0012] A battery cell stack according to an embodiment of the present invention may include an electrode assembly having electrode tabs, an outer material accommodating the electrode assembly, a plurality of battery cells arranged in parallel with each other, and a compression pad interposed between the plurality of battery cells. The compression pad may include a main portion, and a side portion arranged at an end of the main portion, having a lower compression ratio than the main portion, and overlapping a portion of the electrode tab side of the battery cell in the thickness direction of the compression pad.

[0013] The electrode assembly may include electrodes and separators that are alternately arranged. The electrodes may include an overlapping region in which the electrode tabs are connected and overlap the side portion in the thickness direction of the compression pad.

[0014] The length of the overlapping region in the longitudinal direction of the battery cell may be 5% to 10% of the length of the electrode.

[0015] The side portion may include an inner portion connected to the main portion and having a thickness corresponding to the main portion; and an outer portion located on the outside of the inner portion and having a thickness that increases toward the outside.

[0016] When the compression pad is separated from the plurality of battery cells, the thickness of the inner portion and the thickness of the outer portion may correspond to each other.

[0017] The main part may include a polyurethane material, and the side part may include a silicone material.

[0018] The above side portions may be provided on both sides of the main portion in the longitudinal direction of the battery cell.

[0019] The main portion may correspond to the central portion and the long side edge portion of the battery cell, and the side portion may correspond to the short side edge portion of the battery cell.

[0020] A battery module according to an embodiment of the present invention may include a module housing; and a battery cell stack accommodated within the module housing. The battery cell stack may include an electrode assembly having electrode tabs, an outer material that accommodates the electrode assembly, a plurality of battery cells arranged in parallel with each other; and a compression pad interposed between the plurality of battery cells. The compression pad may include a main portion; and a side portion that is arranged at an end of the main portion, has a lower compression ratio than the main portion, and overlaps a portion of the electrode tab side of the battery cell in the thickness direction of the compression pad.

[0021] The battery module may further include a busbar frame disposed on the outside of the battery cell stack and having a busbar mounted thereon. The battery cell may further include an electrode lead connected to the electrode tab, protruding outward from the exterior of the outer material, and coupled to the busbar. The side portion may face the busbar frame in the longitudinal direction of the battery cell.

[0022] A compression pad according to an embodiment of the present invention includes an electrode assembly having electrode tabs and an outer material for accommodating the electrode assembly, and can be interposed between a plurality of battery cells arranged in parallel. The compression pad can include a main portion; and a side portion arranged at an end of the main portion, having a lower compression ratio than the main portion, and overlapping a portion of the electrode tab side of the battery cell in the thickness direction of the compression pad.

[0023] According to a preferred embodiment of the present invention, in order to compensate for the thickness difference between the electrode tab side portion and the central side portion of the battery cell during swelling of the battery cell, the side portion of the compression pad may have a lower compression ratio than the main portion. This allows the compression pad to apply uniform pressure to the battery cell, and prevents degradation of the battery cell performance due to lithium precipitation, etc.

[0024] In addition, the configurations according to preferred embodiments of the present invention may include effects that can be easily predicted by those skilled in the art.

[0025] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0026] Figure 1 is a perspective view of a battery module according to one embodiment of the present invention.

[0027] Figure 2 is an exploded perspective view of the battery module illustrated in Figure 1.

[0028] FIG. 3 is a plan view of a battery cell stack according to one embodiment of the present invention.

[0029] FIG. 4 is a drawing for explaining the operation of a compression pad according to one embodiment of the present invention.

[0030] FIG. 5 is a cross-sectional view showing a compression pad according to one embodiment of the present invention together with the interior of a battery cell.

[0031] FIG. 6 is a schematic diagram illustrating a compression pad and a battery cell together according to another embodiment of the present invention.

[0032] Hereinafter, with reference to the attached drawings, preferred embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited or restricted by the following examples.

[0033] In order to clearly explain the present invention, a detailed description of a part that is irrelevant to the description or a related known technology that may unnecessarily obscure the gist of the present invention has been omitted, and when adding reference signs to components of each drawing in this specification, the same or similar reference signs are attached to the same or similar components throughout the specification.

[0034] In addition, terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0035] In the drawing, each component of a secondary battery according to one embodiment of the present invention is schematically illustrated, and the size of the component or the thickness of the line may be expressed somewhat exaggerated for the convenience of understanding.

[0036] FIG. 1 is a perspective view of a battery module according to one embodiment of the present invention, and FIG. 2 is an exploded perspective view of the battery module illustrated in FIG. 1.

[0037] A battery module (10) according to one embodiment of the present invention may include a battery cell stack (100) and a module housing (20).

[0038] A battery cell stack (100) can be accommodated within a module housing (20). The battery cell stack (100) can include a plurality of battery cells (200) and a compression pad (300) interposed between the plurality of battery cells (200).

[0039] A plurality of battery cells (200) may be arranged parallel to each other. The plurality of battery cells (200) may be arranged to face each other in a first direction (for example, a direction parallel to the Y-axis). More specifically, the plurality of battery cells (200) may be stacked on top of each other with respect to the first direction. In addition, each battery cell (200) may be arranged longitudinally in a second direction (for example, a direction parallel to the X-axis) perpendicular to the first direction. The first direction may be a direction parallel to the width direction of the module frame (20), the thickness direction of the battery cell (200), or the thickness direction of the compression pad (300). The second direction may be a direction parallel to the length direction of the module frame (20), the length direction of the battery cell (200), or the length direction of the compression pad (300).

[0040] The longitudinal direction of each battery cell (200) may be parallel to the second direction. The width direction of each battery cell (200) may be parallel to a third direction (e.g., a direction parallel to the Z axis) that is perpendicular to the first and second directions.

[0041] Each battery cell (200) may include an electrode assembly (210) having an electrode tab (213) and an outer case (220) that accommodates the electrode assembly (210) (see FIG. 5).

[0042] The electrode assembly (210) may be formed by alternately interposing electrodes (211) and separators (212). That is, the electrode assembly (210) may include a plurality of electrodes (211) and a separator (212) interposed between the plurality of electrodes (211) to mutually insulate the plurality of electrodes (211). The electrode assembly (210) may be provided in various types, such as a stack type, a jelly roll type, a stack and folding type, and the type of the electrode assembly (210) is not limited.

[0043] Each battery cell (200) may be a pouch-type battery cell. Since the number of layers per unit area of ​​a pouch-type battery cell can be maximized, the energy density of the battery module (10) can be increased. For example, the battery cell (200) can be manufactured by housing the electrode assembly (210) in an outer material (220) formed of a laminate sheet and then sealing the outer material (220) by heat-fusing. However, the battery cell (200) does not necessarily have to be provided in a pouch type, and may be provided in a square shape, a cylindrical shape, or other various shapes as long as the storage capacity required by the device to be mounted in the future can be achieved.

[0044] Each battery cell (200) may be provided with an electrode tab (213). The electrode tab (213) may connect the electrode (211) of the electrode assembly (210) and an electrode lead (214) to be described later. The electrode tab (213) may include a positive electrode tab connected to the positive electrode and a negative electrode tab connected to the negative electrode.

[0045] Each battery cell (200) may be provided with an electrode lead (214). The electrode lead (214) may include a positive lead connected to the positive tab, and a negative lead connected to the negative tab. That is, the electrode leads (214) may be provided in a pair that protrude in opposite directions, and may protrude parallel to the longitudinal direction of the battery cell (200). However, the present invention is not limited thereto, and a pair of electrode leads (214) may also protrude parallel to each other in the same direction.

[0046] A compression pad (300) may be interposed between a plurality of battery cells (200). At least one compression pad (300), and preferably a plurality of compression pads (300), may be provided. For example, as illustrated in FIG. 3, a plurality of battery cells (200) and a plurality of compression pads (300) may be arranged alternately.

[0047] Battery cells (200) can be in contact with both sides of each compression pad (300). More specifically, both sides of each compression pad (300) can be in contact with adjacent battery cells (200).

[0048] When the battery cell (200) is swollen, the compression pad (300) can be compressed between the two battery cells (200). The compression pad (300) can suppress swelling of the battery cell (200) by applying pressure to the battery cell (200) and alleviate shock applied to the battery cell (200).

[0049] The compression pad (300) may be arranged parallel to the battery cell (200). More specifically, the longitudinal direction of each compression pad (300) may be parallel to the second direction. The width direction of each compression pad (200) may be parallel to the third direction.

[0050] The detailed configuration of the compression pad (300) will be described in detail later.

[0051] Meanwhile, the module frame (20) can form the exterior of the battery module (10). The module frame (20) can have a metal material having high strength.

[0052] The structure of the module frame (20) may vary. For example, the module frame (20) may be a monoframe. The monoframe may be a metal plate having an upper surface, a lower surface, and both side surfaces integrated therewith. As another example, the module frame (20) may have a structure in which a U-shaped frame and an upper plate (upper surface) are combined. The U-shaped frame may be a metal plate having a lower plate (bottom surface) and side plates (both side surfaces) combined or integrated therewith. In addition, the structure of the module frame (20) may be provided as a structure in which L-shaped frames are combined, and may also be provided in various structures not described in the above-described examples.

[0053] The module frame (20) may have an internal space, and the internal space may accommodate a battery cell stack (100). More specifically, the module frame (20) may include a top surface, a bottom surface, and both side surfaces. The module frame (20) may have both ends open in the electrical direction and may be covered by an end cap (40) to be described later.

[0054] The battery module (10) may further include a busbar frame (30) that is arranged on the outside of the battery cell stack (100) and on which a busbar (31) is mounted.

[0055] A busbar frame (30) may be placed on both sides of a battery cell stack (100). At least one busbar (31) may be mounted on the busbar frame (30). An electrode lead (214) of a battery cell (200) may be coupled to the busbar (31).

[0056] The battery module (10) may further include an end cap (40).

[0057] The end cap (40) can be placed on the outside of the busbar frame (30). That is, the busbar frame (30) can be placed between the battery cell stack (100) and the end cap (40).

[0058] An end cap (40) can be coupled to the module frame (20). The end cap (40) can cover both open ends of the module frame (20). An opening (40H) is formed in the end cap (40), and an electrical connection of a bus bar (31) can be made through the opening (40H). The bus bar (31) of a battery module (10) can be electrically connected to another battery module (10), a BDU (Battery Disconnect Unit), or an external load through the opening (40H).

[0059] FIG. 3 is a plan view of a battery cell stack according to one embodiment of the present invention, FIG. 4 is a drawing for explaining the operation of a compression pad according to one embodiment of the present invention, and FIG. 5 is a cross-sectional view showing the compression pad according to one embodiment of the present invention together with the interior of a battery cell.

[0060] Conventionally, compression pads having the same compression ratio throughout have been used. Consequently, variations in the pressure applied to the battery cell by the conventional compression pad during swelling of the battery cell have occurred. More specifically, the pressure applied to a portion of the battery cell's electrode tab side is lower than the pressure applied to a portion of the battery cell's central side. This has led to problems such as internal gas infiltration of the battery cell toward the electrode tab, which can cause lithium precipitation and deteriorate the performance of the battery cell.

[0061] To solve this problem, the compression pad (300) according to an embodiment of the present invention may include a main part (310) and a side part (320) having different compression ratios.

[0062] The main part (310) can extend in the length direction of the compression pad (300) and can have a predetermined width.

[0063] The side portion (320) can be placed at the end of the main portion (310). The side portion (320) can form the end of the compression pad (300).

[0064] The side portion (320) may extend from the main portion (310). The length of the side portion (320) may be shorter than the length of the main portion (310). The widths of the side portion (320) and the main portion (310) may correspond to each other. The thicknesses of the side portion (320) and the main portion (310) may correspond to each other. Here, correspondence may mean the same or similar.

[0065] The side portion (320) may have a lower compression ratio than the main portion (310). That is, the side portion (320) may have a higher rigidity than the main portion (310). For example, the main portion (310) may include a urethane material, particularly a polyurethane material, and the side portion (320) may include a silicone material. However, the materials of the main portion (310) and the side portion (320) are not limited thereto.

[0066] The side portion (320) may overlap a portion of the electrode tab (213) side of the battery cell (200) in the thickness direction of the compression pad (300). The electrode tab (213) may connect the electrode (211) of the electrode assembly (210) and the electrode lead (214). That is, the side portion (320) may overlap a portion of the electrode lead (214) side of the battery cell (200) in the thickness direction of the compression pad (300).

[0067] In the present embodiment, the electrode leads (214) may protrude in opposite directions from both sides in the longitudinal direction of the battery cell (200). That is, a part of the electrode tab (213) side of the battery cell (200) may refer to a part of both end sides of the battery cell (200). Accordingly, the side portions (320) may be arranged at both ends of the main portion (310). The side portions (320) may be provided on both sides with the main portion (310) interposed therebetween in the longitudinal direction of the battery cell (200). The side portions (320) may form both ends of the compression pad (300). The side portions (320) may face the bus bar frame (30) (see FIG. 2) in the longitudinal direction of the battery cell (200).

[0068] A portion of the electrode tab (213) side of the battery cell (200) may have a relatively smaller thickness compared to a portion of the central side of the battery cell (200). That is, a portion of the electrode tab (213) side of the battery cell (200) and a portion of the central side of the battery cell (200) may have a thickness difference. In particular, when the battery cell (200) swells, this thickness difference may become larger. Therefore, when the battery cell (200) swells, the main portion (310), which is a portion pressed by a portion of the central side of the battery cell (200), in the compression pad (300), may be compressed relatively greatly, and the side portion (320), which is a portion pressed by a portion of the electrode tab (213) side of the battery cell (200), may be compressed relatively slightly.

[0069] In this regard, since the side portion (320) has a lower compression ratio and higher rigidity than the main portion (310), a strong restoring force can be generated even if it is compressed only slightly. Accordingly, even if the side portion (320) is compressed only slightly, it can apply sufficient pressure to a portion of the electrode tab (213) side of the battery cell (200). As a result, the compression pad (300) can apply uniform pressure to the battery cell (200) as a whole.

[0070] Meanwhile, the side part (320) may include an inner part (321) that is connected to the main part (310) and has a thickness corresponding to the main part (310), and an outer part (322) that is located on the outside of the inner part (321) and has a thickness that increases toward the outside.

[0071] In more detail, referring to FIG. 4, before the battery cell (200) swells, the main portion (310) and the side portion (320) of the compression pad (300) may have corresponding initial thicknesses (t1). When the battery cell (200) swells, the main portion (310) may have a compression thickness (t2) smaller than the initial thickness (t1), and the side portion (320) may be divided into an inner portion (321) and an outer portion (322).

[0072] The inner portion (321) may have a compression thickness (t2) corresponding to that of the main portion (310). The outer portion (322) may have a thickness greater than the compression thickness (t2), and the thickness may increase toward the outside. However, the maximum thickness of the outer portion (322) may be less than or equal to the initial thickness (t1).

[0073] When the compression pad (300) is separated from between the plurality of battery cells (200), the thickness of the inner portion (321) and the thickness of the outer portion (322) can correspond to each other. That is, the inner portion (321) and the outer portion (322) can be restored to have the initial thickness (t1).

[0074] The main portion (310) may correspond to the central portion and the long side edge portion (201) of the battery cell (200) (see FIG. 2), and the side portion (320) may correspond to the short side edge portion (202) of the battery cell (200) (see FIG. 2). Here, corresponding may mean contacting or adjacent. This prevents excessive pressure from being applied to the long side edge portion (201) of the battery cell (200), and prevents lithium precipitation from the long side portion.

[0075] Meanwhile, referring to FIG. 5, the electrode (211), particularly the positive electrode, of the electrode assembly (210) of the battery cell (200) may include an overlapping area that overlaps with the side portion (320) in the thickness direction of the compression pad (300). An electrode tab (213) may be connected to the overlapping area.

[0076] The length (L1) of the overlapping region in the longitudinal direction of the battery cell (200) may be 5% to 10% of the length of the electrode (211). That is, only a portion of the end side corresponding to 5% to 10% of the length of the electrode (211) may overlap with the side portion (320). As a result, the battery cell (200) may receive uniform pressure by the compression pad (300).

[0077] If the length (L1) of the overlapping region is less than 5% of the length of the electrode (211), it may be difficult to apply sufficient pressure to a portion of the electrode tab (213) side of the battery cell (200). If the length (L1) of the overlapping region is greater than 10% of the length of the electrode (211), excessive pressure may be applied to a portion of the central portion of the battery cell (200). That is, if the length (L1) of the overlapping region is outside the range of 5% to 10% of the length of the electrode (211), it may be difficult to apply uniform pressure to the battery cell (200).

[0078] FIG. 6 is a schematic diagram illustrating a compression pad and a battery cell together according to another embodiment of the present invention.

[0079] In the present embodiment, the electrode leads (214) may protrude in the same direction from one side of the length of the battery cell (200'). That is, a part of the electrode tab (213) side of the battery cell (200') may mean a part of one end side of the battery cell (200'). Accordingly, the side portion (320) may be arranged at one end of the main portion (310). That is, the side portion (320) may form one end of the compression pad (300), and the other end of the compression pad (300) may be a part of the main portion (310).

[0080] The above description is merely an example of the technical idea of ​​the present invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present invention.

[0081] Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of ​​the present invention but to explain it, and the scope of the technical idea of ​​the present invention is not limited by these embodiments.

[0082] The scope of protection of the present invention should be interpreted by the claims below, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the rights of the present invention.

[0083] [Explanation of symbols]

[0084] 10: Battery module 20: Module frame

[0085] 30: Busbar frame 40: End cap

[0086] 100: Battery cell stack 200: Battery cell

[0087] 210: Electrode assembly 211: Electrode

[0088] 212: Separator 213: Electrode tab

[0089] 214: Electrode lead 220: Sheath

[0090] 300: Compression pad 310: Main part

[0091] 320: Side part 321: Inner part

[0092] 322: Outer Department

Claims

1. A plurality of battery cells arranged in parallel, including an electrode assembly having an electrode tab and an outer material accommodating the electrode assembly; and Including a compression pad interposed between the plurality of battery cells, The above compression pad, Main section; and A battery cell stack including a side portion disposed at an end of the main portion, having a lower compression ratio than the main portion, and overlapping a portion of the electrode tab side of the battery cell with respect to the thickness direction of the compression pad.

2. In paragraph 1, The above electrode assembly comprises electrodes and separators alternately arranged, The above electrodes are, A battery cell stack comprising an overlapping region in which the electrode tabs are connected and overlap with the side portion in the thickness direction of the compression pad.

3. In paragraph 2, A battery cell stack wherein the length of the overlapping region in the longitudinal direction of the battery cells is 5% to 10% of the length of the electrode.

4. In paragraph 1, The above side part, An inner part connected to the main part and having a thickness corresponding to the main part; and A battery cell stack including an outer portion located on the outside of the inner portion and having an increasing thickness toward the outside.

5. In paragraph 4, A battery cell stack in which the thickness of the inner portion and the thickness of the outer portion correspond to each other when the compression pad is separated from between the plurality of battery cells.

6. In paragraph 1, The above main part comprises a polyurethane material, The above side portion is a battery cell stack including a silicon material.

7. In paragraph 1, The above side section is a battery cell stack provided on both sides with the main section in between, with respect to the longitudinal direction of the battery cell.

8. In paragraph 1, The above main part corresponds to the central part and the long side edge part of the battery cell, The above side portion is a battery cell stack corresponding to the short-side edge portion of the battery cell.

9. Module housing; and comprising a battery cell stack accommodated within the module housing; The above battery cell stack, An electrode assembly having electrode tabs and an outer body housing the electrode assembly, the battery cells being arranged in parallel with each other; and A compression pad is included between the plurality of battery cells, The above compression pad, Main section; and A battery module comprising a side portion disposed at an end of the main portion, having a lower compression ratio than the main portion, and overlapping a portion of the electrode tab side of the battery cell with respect to the thickness direction of the compression pad.

10. In paragraph 9, It further includes a busbar frame disposed on the outside of the above battery cell stack and having a busbar mounted thereon, The above battery cell is, It further includes an electrode lead connected to the above electrode tab, protruding outside the above outer material, and coupled with the above bus bar, The above side portion is a battery module facing the bus bar frame in the longitudinal direction of the battery cell.

11. In a compression pad interposed between a plurality of battery cells arranged in parallel, the compression pad comprises an electrode assembly having an electrode tab and an outer material accommodating the electrode assembly. Main section; and A compression pad disposed at an end of the main portion, having a lower compression ratio than the main portion, and including a side portion that overlaps a portion of the electrode tab side of the battery cell with respect to the thickness direction of the compression pad.

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