Battery cells and battery packs that assemble these battery cells

Abstract

To provide a battery cell with a simple structure that can suppress a decrease in cooling performance, and a battery pack that assembles such battery cells. [Solution] The battery cell 10 comprises a secondary battery ND having an electrode body 2, a rectangular cylindrical extrusion can 11 that houses the electrode body and has both ends 11T in the axial direction (Z direction) open, and a metal battery can 1 that seals the ends of the extrusion can 11. The extrusion can 11 has a pair of long side portions 111 extending in the axial direction (Z direction), and an upper short side portion 112a and a lower short side portion 112b perpendicular to the long side portions, with the plate thickness d2 of the lower short side portion being thicker than the plate thickness d1 of the upper short side portion.

Description

[[Technical Field]]

[0001] The technology of the present disclosure relates to a battery cell constituting a secondary battery used as a driving source for hybrid vehicles, electric vehicles, and the like, and a battery pack in which such battery cells are assembled. [[Background Art]]

[0002] Generally, secondary batteries used as driving sources for hybrid vehicles, electric vehicles, and the like require high voltage and high current, and therefore large battery cells or battery packs obtained by assembling a plurality of battery cells are used. Large battery cells also generate a large amount of heat, so cooling is normally performed by bringing the bottom surface of the battery cell into contact with a cooling plate or the like. Further, in a battery pack, for example, a restraining mechanism is provided that arranges and stacks prismatic battery cells in columns, and pressurizes and restrains the outermost battery cells inward in the stacking direction. This restraining mechanism is provided with a cooling plate or the like that abuts against the bottom surface of the battery cells and cools each battery cell (see, for example, Patent Document 1). [[Prior Art Document]] [[Patent Document]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Application Publication No. 2022-866 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] However, when the pressure inside the case rises along with an increase in the temperature of the battery cell during rapid charging of the battery cell or the like, the bottom surface of the battery cell expands downward in an arc shape, which reduces the contact area between the bottom surface of the battery cell and the cooling plate or the like, resulting in a problem that the cooling performance of the battery cell decreases. Also, when the electrode body volume-expands along with aging degradation of the battery cell, the bottom surface of the battery cell expands downward in an arc shape, which reduces the contact area between the bottom surface of the battery cell and the cooling plate or the like, resulting in a problem that the cooling performance of the battery cell decreases.

[0005] This disclosed technology has been made in view of the aforementioned problems, and aims to provide a battery cell with a simple structure that can suppress a decrease in cooling performance, and a battery pack comprising such battery cells. [Means for solving the problem]

[0006] (1) One aspect of the present invention for solving the above problems is a battery cell comprising a metal battery can having an electrode body, a rectangular cylindrical extrusion can housing the electrode body and having open ends on both sides in the axial direction, and a lid that seals the ends of the extrusion can, wherein the extrusion can has a pair of long side portions extending in the axial direction, and an upper short side portion and a lower short side portion perpendicular to the long side portions, and the plate thickness of the lower short side portion is formed to be thicker than the plate thickness of the upper short side portion.

[0007] (2) In the battery cell described in (1), it is preferable that recessed grooves are formed along the axial direction at both ends in the width direction of the lower short side portion, leaving the lower flange portion intact and recessed inward in the width direction.

[0008] (3) In the battery cell described in (1), it is preferable that flanges projecting outward in the width direction are formed along the axial direction at both ends in the width direction of the lower short side portion.

[0009] (4) In a battery cell described in any one of (1) to (3), the extruder can is preferably provided with a partition wall that extends axially between the lower short side portion and the lower end of the electrode body, connecting the long side portions together or the long side portion and the lower short side portion, and a refrigerant flow path is formed between the partition wall, the long side portion and the lower short side portion.

[0010] (5) Another aspect of the disclosed technology for solving the above problems is a battery pack comprising a restraining mechanism that stacks a plurality of battery cells described in any one of (2) to (4) with an intervening material between the long side portions and restrains the outermost battery cell by pressurizing it inward in the stacking direction, wherein the restraining mechanism comprises a cooling portion for cooling the battery cell and a pressing portion for pressing the lower short side portion against the cooling portion via the flange portion. [Brief explanation of the drawing]

[0011] [Figure 1] This is a side view of a battery cell according to one aspect of this embodiment. [Figure 2] Figure 1 shows a schematic cross-sectional view of AA. [Figure 3] Figure 1 is a schematic cross-sectional view of a battery pack composed of multiple battery cells. [Figure 4] This is a schematic cross-sectional view AA of modified battery cell 1 shown in Figure 1. [Figure 5] This is a schematic cross-sectional view AA of modified battery cell 2 shown in Figure 1. [Figure 6] This is a schematic cross-sectional view AA of modified example 3 of the battery cell shown in Figure 1. [Figure 7] This is a schematic cross-sectional view AA of modified battery cell 4 shown in Figure 1. [Figure 8] This is a schematic cross-sectional view AA of modified battery cell 5 shown in Figure 1. [Modes for carrying out the invention]

[0012] <Detailed description of this battery cell> Next, a battery cell according to one embodiment of the disclosed technology described above will be described in detail with reference to the drawings. Figure 1 shows a side view of a battery cell according to one embodiment of this embodiment. Figure 2 shows a schematic cross-sectional view of AA shown in Figure 1. In Figures 1 to 8, the X direction indicates the width direction of the short side portion (upper short side portion, lower short side portion) of the extruder can, the Y direction indicates the width direction of the long side portion of the extruder can, and the Z direction indicates the axial direction of the extruder can. The X direction is also the stacking direction of the battery cells in the battery pack. The Y direction is also the vertical direction of the battery cell. The Z direction is also the longitudinal direction of the electrode body.

[0013] A battery cell 10 according to one embodiment of the disclosed technology, as shown in Figures 1 and 2, is a battery cell 1 comprising a metal battery can 1 having an electrode body 2, a rectangular cylindrical extruded can 11 that houses the electrode body 2 and has both ends 11T in the axial direction (Z direction) open, and a lid 12 that seals both ends 11T of the extruded can 11.

[0014] Here, the electrode body 2 is an electrode body formed by rolling and laminating a strip-shaped positive electrode foil 2a, a strip-shaped negative electrode foil 2b, and a strip-shaped separator 2c sandwiched between the two electrode foils in a flattened shape. However, it is not necessarily limited to this, and for example, an electrode body formed by laminating multiple sheet-shaped positive electrode foils, sheet-shaped negative electrode foils, and sheet-shaped separators sandwiched between the two electrode foils may also be used. An insulating film (not shown) is interposed between the electrode body 2 and the battery can 1 to prevent short circuits between the electrode body 2 and the battery can 1. For example, polypropylene (PP) resin can be used for the insulating film.

[0015] The battery cell 10 that constitutes the secondary battery ND may be, for example, a lithium-ion secondary battery. In this case, the positive electrode foil 2a may be, for example, aluminum foil, and the active material fixed thereto may be, for example, lithium transition metal oxide (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3O₂, LiNiO₂, etc.) can be used. Further, for the negative electrode foil 2b, for example, a copper foil is used, and as the active material fixed thereto, for example, graphite, hard carbon, soft carbon, etc. can be used. Further, as the separator 2c, for example, a porous sheet made of polypropylene, polyethylene or the like can be used.

[0016] Further, the extruded can 11 is a square cylindrical body with a rectangular cross-section having a pair of wide long side portions 111 extending in the axial direction (Z direction) and a pair of narrow short side portions 112 (an upper short side portion 112a and a lower short side portion 112b) orthogonal to the long side portions 111, and is formed, for example, by extrusion molding of an aluminum material (including an aluminum alloy material). The lid 12 is formed of, for example, a plate material of an aluminum material (including an aluminum alloy material). The end portion 11T of the extruded can 11 and the lid 12 are watertightly joined by laser welding or the like. Current collecting terminals 3 (a positive electrode current collecting terminal 3a and a negative electrode current collecting terminal 3b) connected to tab portions 2T formed at both ends in the longitudinal direction (Z direction) of the electrode body 2 are fixed to the left and right lids 12 via an insulating material 4.

[0017] Further, the short side portions 112 include the upper short side portion 112a located at the upper side and the lower short side portion 112b located at the lower side, and a plate thickness d2 of the lower short side portion 112b is formed to be thicker than a plate thickness d1 of the upper short side portion 112a. Therefore, even if the upper short side portion 112a with the thin plate thickness d1 is deformed due to an increase in pressure inside the battery can 1 or an increase in volume of the electrode body 2, the lower short side portion 112b with the thick plate thickness d2 is less likely to deform. Here, on the upper short side portion 112a with the thin plate thickness d1, there are formed a safety valve 113 that cleaves to release gas when the pressure inside the battery can 1 rises to a predetermined value or higher, and an injection port 114 for injecting an electrolyte into the battery can 1.

[0018] Therefore, for example, even when the pressure inside the battery can 1 rises as the temperature of the battery cell 10 increases during rapid charging of the battery cell 10, or when the electrode assembly 2 undergoes volume expansion due to aging deterioration of the battery cell 10, heat can be dissipated to a cooling plate or the like through the lower short side surface portion 112b that is not easily deformed, and the battery cell 10 can be effectively cooled. Accordingly, it is possible to provide the battery cell 10 that can suppress a decrease in cooling performance with a simple structure.

[0019] Further, in the present battery cell 10, it is preferable that recessed groove portions 116 recessed inward in the width direction while leaving the lower flange portion 115 are formed along the axial direction (Z direction) at both ends of the lower short side surface portion 112b in the width direction (X direction). In this case, the area of the outer surface of the lower short side surface portion 112b is increased by the recessed groove portions 116 recessed inward in the width direction. Therefore, the heat dissipation from the lower short side surface portion 112b is further improved. Although the recessed groove portions 116 are formed to have a U-shaped cross section, the configuration is not limited thereto, and for example, they may be formed to have a U-shaped cross section, a V-shaped cross section, or the like.

[0020] Further, since the flange portion 115 is formed below the recessed groove portion 116 in the lower short side surface portion 112b, deformation of the lower short side surface portion 112b can be further suppressed by restraining the lower short side surface portion 112b via the flange portion 115. As a result, even when the pressure inside the battery can 1 rises as the temperature of the battery cell 10 increases during rapid charging of the battery cell 10, or when the electrode assembly 2 undergoes volume expansion due to aging deterioration of the battery cell 10, heat can be dissipated to a cooling plate or the like through the lower short side surface portion 112b that is even less likely to deform, and the battery cell 10 can be cooled more effectively.

[0021] <Detailed Description of the Present Battery Pack> Next, a battery pack according to another embodiment of the disclosed technology will be described in detail with reference to the drawings. FIG. 3 is a schematic cross-sectional view of a battery pack in which a plurality of the battery cells shown in FIG. 1 are assembled.

[0022] As shown in Figure 3, this battery pack 10P is a battery pack 10P that stacks the above-mentioned multiple battery cells 10 between their long side portions 111 with an intervening material 51 in between, and is equipped with a restraining mechanism 5 that pressurizes and restrains the outermost battery cell 10 inward in the stacking direction (X direction).

[0023] The intervening material 51 is an elastically deformable and insulating plate-shaped member that prevents the restraining load P1 from rising excessively when the electrode body 2 expands in volume. For example, ethylene propylene rubber (EPDM) can be used. The restraining mechanism 5 includes a pair of side pressure plates 52 that press the long side portion 111 of the outermost battery cell 10 with the intervening material 51b in between, a base 53 that supports the lower ends of the side pressure plates 52, and a connecting plate (not shown) that connects the left and right side pressure plates 52. Furthermore, the multiple battery cells 10 restrained by the restraining mechanism 5 are electrically connected at their respective current collection terminals 3 (positive electrode current collection terminal 3a, negative electrode current collection terminal 3b) via busbars (not shown).

[0024] Furthermore, the restraint mechanism 5 includes a cooling section 54 for cooling the battery cells 10, and pressing sections 55 and 55b that press the lower short side portion 112b against the cooling section 54 via a flange portion 115. The cooling section 54 is fixed to the base 53, and a refrigerant flow path 541 with approximately the same width as the battery cell 10 is formed along the axial direction (Z direction) at a position facing each battery cell 10.

[0025] Between the battery cells 10, a retaining flange 551 is formed in a T-shape, and a pressing part 55 that presses against the flange portion 115 via an elastic body 552 is fixed to the cooling unit 54. Between the outermost battery cell 10 and the side pressure plate 52, a retaining flange 551 is formed in an L-shape, and a pressing part 55b that presses against the flange portion 115 via an elastic body 552 is fixed to the cooling unit 54. Here, the pressing parts 55 and 55b press against the flange portion 115 via the elastic body 552, but they may also press against the flange portion 115 directly. There is a gap between the flange portion 115 and the pressing parts 55 and 55b, which maintains the degree of freedom of the battery cell 10 that is constrained by the restraint mechanism 5.

[0026] In this case, even when the pressure inside the battery can 1 increases due to the temperature rise of the battery cells 10 during rapid charging of the battery pack 10P, or when the electrode body 2 expands in volume due to the aging deterioration of the battery cells 10 constituting the battery pack 10P, the pressing parts 55, 55b can bring the lower short side portion 112b into contact with the cooling part 54 to dissipate heat, thereby cooling the battery cells 10 of the battery pack 10P more effectively.

[0027] <Variation> The embodiments described in detail above are merely illustrative and do not limit the disclosed technology in any way. Therefore, the disclosed technology can be improved and modified in various ways without departing from its essence. Figure 4 shows a schematic cross-sectional view AA of Modification 1 of the battery cell shown in Figure 1. Figure 5 shows a schematic cross-sectional view AA of Modification 2 of the battery cell shown in Figure 1. Figure 6 shows a schematic cross-sectional view AA of Modification 3 of the battery cell shown in Figure 1. Figure 7 shows a schematic cross-sectional view AA of Modification 4 of the battery cell shown in Figure 1. Figure 8 shows a schematic cross-sectional view AA of Modification 5 of the battery cell shown in Figure 1.

[0028] In the battery cell 10 described above, for example, as shown in Figures 4, 5, 7, and 8, the extrusion cans 11B, 11C, 11E, and 11F are provided with partition walls 113B, 113C, 113E, and 113F that extend axially (Z direction) between the lower short side portion 112b and the lower end portion 2K of the electrode body 2, connecting the long side portions 111 to each other, or the long side portion 111 and the lower short side portion 112b. Coolant flow paths 117B, 117C, 117E, and 117F are formed between the partition walls 113B, 113C, 113E, and 113F and the long side portion 111 and the lower short side portion 112b. These battery cells 10B, 10C, 10E, and 10F are also possible in modified examples 1, 2, 4, and 5.

[0029] In this case, the cooling performance of the battery cells 10B, 10C, 10E, and 10F can be further improved by the refrigerant flowing through the refrigerant channels 117B, 117C, 117E, and 117F formed between the partition walls 113B, 113C, 113E, and 113F, and the long side portion 111 and the lower short side portion 112b.

[0030] As a result, when rapidly charging the battery cells 10B, 10C, 10E, and 10F, if the pressure inside the battery cans 1B, 1C, 1E, and 1F increases due to the temperature rise of the battery cells 10B, 10C, 10E, and 10F, or if the electrode body 2 expands in volume due to the aging of the battery cells 10B, 10C, 10E, and 10F, heat can be dissipated to the cooling plate, etc., via the lower short side portion 112b, which is less prone to deformation, and also via the refrigerant flowing through the refrigerant channels 117B, 117C, 117E, and 117F, the battery cells 10B, 10C, 10E, and 10F can be cooled more effectively.

[0031] Furthermore, the battery cells 10B, 10C, 10E, and 10F of the modified examples 1, 2, 4, and 5 can also be used with the battery pack 10P described above, allowing for even more effective cooling of the battery cells 10B, 10C, 10E, and 10F that make up the battery pack 10P.

[0032] Furthermore, in the battery cell 10 described above, as shown in Figures 6, 7, and 8, flange portions 115D, 115E, and 115F that protrude outward in the width direction are formed along the axial direction (Z direction) at both ends of the lower short side portion 112b in the width direction (X direction), and these can also be modified versions 3, 4, and 5 of the battery cells 10D, 10E, and 10F.

[0033] In this case, the flange portions 115D, 115E, and 115F that protrude outward in the width direction increase the surface area of ​​the outer surface of the lower short side portion 112b. As a result, heat dissipation from the lower short side portion 112b is further improved. In addition, the deformation of the lower short side portion 112b can be further suppressed by restraining it via the flange portions 115D, 115E, and 115F.

[0034] As a result, even when the pressure inside the battery cans 1D, 1E, and 1F increases due to the temperature rise of the battery cells 10D, 10E, and 10F during rapid charging, or when the electrode body 2 expands in volume due to the aging of the battery cells 10D, 10E, and 10F, heat can be dissipated to the cooling plate, etc., via the lower short side portion 112b, which is less prone to deformation, thereby allowing the battery cells 10D, 10E, and 10F to be cooled more effectively.

[0035] Furthermore, the battery cells 10D, 10E, and 10F of the modified examples 3, 4, and 5 can also be used with the battery pack 10P described above, allowing for even more effective cooling of the battery cells 10D, 10E, and 10F that make up the battery pack 10P. [Explanation of Symbols]

[0036] 1, 1B, 1C, 1D, 1E, 1F Battery cans 2 Electrode body 2K bottom end 5 Restraint mechanism 10, 10B, 10C, 10D, 10E, 10F battery cells 10-pack battery 11, 11B, 11C, 11D, 11E, 11F Extruder 11T end 12 Lid 51 Inclusions 54 Cooling section 55, 55b Pressing part 111 Long side part 112a Upper short side part 112b Lower short side part 113B, 113C, 113E, 113F Bulkhead 115, 115B, 115C Tsubabe 115D, 115E, 115F Tsuba 116, 116B, 116C Concave groove 117B, 117C, 117E, 117F Refrigerant flow path ND secondary battery

Claims

1. A battery cell comprising a metal battery container having an electrode body, a rectangular cylindrical extrusion container housing the electrode body with both ends open in the axial direction, and a lid that seals the ends of the extrusion container, The extruder comprises a pair of long side portions extending in the axial direction, and an upper short side portion and a lower short side portion perpendicular to the long side portions. The thickness of the lower short side portion is formed to be thicker than the thickness of the upper short side portion. Battery cell.

2. In the battery cell described in claim 1, At both ends of the lower short side portion in the width direction, recessed grooves are formed along the axial direction, leaving the lower flange portion intact and recessed inward in the width direction. Battery cell.

3. In the battery cell described in claim 1, At both ends of the lower short side portion in the width direction, flange portions are formed along the axial direction, projecting outward in the width direction. Battery cell.

4. In the battery cell described in claim 1, The extrusion can is provided with a partition wall that extends axially between the lower short side portion and the lower end of the electrode body, connecting the long side portions together, or the long side portion and the lower short side portion. A refrigerant flow path is formed between the partition wall, the long side surface, and the lower short side surface. Battery cell.

5. A battery pack comprising a restraining mechanism that stacks a plurality of battery cells according to any one of claims 2 to 4 with an intervening material between their long side portions, and restrains the outermost battery cell by pressurizing it inward in the stacking direction, The restraining mechanism includes a cooling section for cooling the battery cell and a pressing section for pressing the lower short side portion against the cooling section via the flange. Battery pack.

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