Battery spacer and battery pack

Abstract

Provided are a battery spacer that does not increase the rigidity of a battery frame more than necessary and a battery pack using the battery spacer.　A battery spacer 52 is interposed between adjacent angular cells C1 having a substantially rectangular shape composed of four sides. The battery spacer 52 is divided into at least an outside region part 52out present at a position corresponding to mutually opposed sides 21aS, 21aL of the angular battery cells C1, and an inside region part 52in present on the inside of the outside region part 52out. The outside region part 52out is constituted of a rigid member, and the inside region part 52in is constituted of a flexible member.

Description

Battery spacer and battery pack

[0001] The present invention relates to battery packs used in various industrial equipment, such as electric vehicles and hybrid vehicles, and more particularly to a battery spacer interposed between adjacent battery cells, and a battery pack using this battery spacer.

[0002] In recent years, development of high-energy-density lithium-ion secondary batteries has been progressing as a power source for electric vehicles, hybrid vehicles, and the like. These lithium-ion secondary batteries include, for example, a battery cell consisting of a wound electrode assembly and a battery container that houses the wound electrode assembly. Lithium-ion secondary batteries can expand when charged. This can lead to phenomena such as an increase in the distance between the electrodes of the wound electrode assembly and wrinkles in the wound electrode assembly.

[0003] For this reason, the above-mentioned problems have been addressed by disposing battery spacers between the battery cells to buffer or restrict the expansion of the wound electrode body. For example, Japanese Patent Laid-Open No. 2009-277575 (Patent Document 1) and Japanese Patent Laid-Open No. 2016-72198 (Patent Document 2) are known as prior art documents that dispose battery spacers between adjacent battery cells.

[0004] JP 2009-277575 A JP 2016-072198 A

[0005] As described above, in lithium-ion battery packs, battery spacers are placed between adjacent battery cells. However, when the battery pack is assembled, the structural members have to be highly rigid and complex mechanisms are required, leaving room for improvement in terms of size and weight reduction.

[0006] An object of the present invention is to provide a battery spacer that can be used to accommodate battery expansion and that can be used to reduce the size and weight of assembled batteries, and to provide an assembled battery that uses this battery spacer.

[0007] The present invention is a battery spacer interposed between adjacent rectangular batteries of rectangular battery cells each having a generally rectangular shape with four sides, and is characterized in that the battery spacer is divided into at least an outer region that exists in a position corresponding to the opposing sides of the rectangular battery cells, and an inner region that exists inside the outer region, with the outer region being made of a rigid material and the inner region being made of a flexible material.

[0008] According to the present invention, the movement of the electrode terminals of the battery cells can be suppressed by the rigid outer region, and the expansion of the battery cells can be cushioned by the flexible inner region. This makes it possible to provide a new battery spacer that does not require an excessively high rigidity for the battery frame and does not require a pressure mechanism or a compliance mechanism, and a battery pack that uses this battery spacer.

[0009] FIG. 1 is an external perspective view showing the appearance of a lithium ion secondary battery. FIG. 2 is an exploded perspective view showing the constituent parts of a disassembled lithium ion secondary battery. FIG. 3 is a schematic diagram of a lithium ion battery according to a first embodiment of the present invention. FIG. 4 is an external perspective view showing the configuration of a lithium ion battery according to a first embodiment of the present invention. FIG. 5 is an external perspective view showing the configuration of a lithium ion battery according to a second embodiment of the present invention. FIG. 6 is an external perspective view showing the configuration of a lithium ion battery according to a third embodiment of the present invention. FIG. 7 is an external perspective view showing the configuration of a lithium ion battery according to a fourth embodiment of the present invention. FIG. 8 is an external perspective view showing the configuration of a lithium ion battery according to a fifth embodiment of the present invention. FIG. 9 is a cross-sectional view showing a cross-section of a conventional lithium ion type assembled battery. FIG. 10 is a cross-sectional view showing a cross-section of another conventional lithium ion type assembled battery.

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment, and various modifications and application examples within the technical concept of the present invention are also included within its scope.

[0011] Before describing the embodiments of the present invention, the structure of a conventional battery spacer will be described. The restraining structure of a conventional battery spacer is, for example, as shown in Figures 9 and 10.

[0012] 9 shows a fixed-size structure in which battery spacers 61 are interposed between adjacent battery cells 60, and these are surrounded on all sides by a battery frame 62. Therefore, when a battery cell 60 expands due to charging or the like, the battery frame 62 suppresses the expansion of the battery cell 60. This makes it possible to avoid phenomena such as an increase in the distance between the electrodes of the wound electrode body and the occurrence of wrinkles in the wound electrode body.

[0013] However, this configuration requires the battery frame 62 to be highly rigid, which creates new problems such as increased weight and cost.

[0014] FIG. 10 also shows a constant pressure restraint structure, in which a pressure mechanism such as an elastic body 63 is disposed between the battery frame body 62 and the battery spacer 61 on the end face side of the battery cell 60, and the elastic body 63 cushions the expansion of the battery cell 60.

[0015] Therefore, when the battery cell 60 expands due to charging or the like, the expansion is buffered by the elastic body 63, and when the expansion of the battery cell is subsequently resolved, it returns to its original state. This makes it possible to avoid phenomena such as an increase in the distance between the electrodes of the wound electrode body and the occurrence of wrinkles in the wound electrode body, without increasing the rigidity of the battery frame body 62.

[0016] However, this configuration presents new problems, such as the need for a pressure mechanism such as the elastic body 63, and the need for a tracking mechanism for the conductive terminal connected to the electrode terminal 64 because the electrode terminal 64 of the battery cell 60 moves.

[0017] Next, an embodiment of the present invention that solves these problems will be described with reference to the drawings. In the following embodiment, a lithium-ion battery pack (hereinafter simply referred to as a battery pack) used in hybrid vehicles and electric vehicles will be described as an example of a battery pack. Note that FIG. 1 shows the appearance of the battery cells of the battery pack as viewed obliquely from above. Therefore, the battery pack is configured by stacking a plurality of these battery cells.

[0018] As shown in Figure 1, a battery cell C1 of a lithium-ion battery pack includes a battery can 1 and a lid member (hereinafter referred to as the battery lid) 6. These are collectively defined as the "battery container." A wound electrode assembly 3 (see Figure 2) serving as a "power generating element" is housed within the battery can 1, and an opening 1a (see Figure 2) of the battery can 1 is sealed by the battery lid 6.

[0019] As can be seen from FIG. 1, the battery can 1 of the battery cell C1 is configured as a square battery cell formed in a substantially rectangular shape, having a rectangular can bottom 22 (see FIG. 2), square cylindrical side wall portions 21 a, 21 b rising from the four sides of this can bottom 22 in the cell height direction, and openings 1 a (see FIG. 2) that open in the cell height direction at the upper ends of the side wall portions 21 a, 21 b.

[0020] The rectangular battery cell C1 (more specifically, the side wall portion 21a, which is the stacking surface of the cell C1) is formed in an approximately rectangular shape consisting of four side edges when viewed in the stacking direction, and has a pair of left and right short edges 21aS that face each other perpendicular to the longitudinal direction, and a pair of upper and lower long edges 21aL that face each other perpendicular to the short direction.

[0021] Therefore, the battery spacer that is the subject of the present invention also has a roughly rectangular shape to match this. However, as will be described in the embodiments below, the battery spacer does not have to have an integrated shape, and may be formed as a separate, separate piece. Anything that functions as a battery spacer falls within the category of a battery spacer, and specific examples of these will be described in detail in the embodiments section.

[0022] 1, an expansion region (EXP) is generated in the side wall portion 21a due to the expansion of the wound electrode body 3 during charging, and measures must be taken to deal with this effect. Measures to deal with this will also be explained in the embodiment section.

[0023] The battery lid 6 is joined to the battery can 1 by laser welding, and the battery can 1 and the battery lid 6 form a sealed battery container. A positive electrode external terminal 8A and a negative electrode external terminal 8B are provided on the battery lid 6. The battery cell C1 charges the wound electrode body 3 via the positive electrode external terminal 8A and the negative electrode external terminal 8B, and also supplies power to an external load.

[0024] A gas exhaust mechanism 10 is integrally provided with the battery lid 6, and if the gas pressure inside the battery container rises to a predetermined pressure for some reason, the gas exhaust valve of the gas exhaust mechanism 10 opens to exhaust gas from the inside. This reduces the gas pressure inside the battery container and ensures the safety of the battery cell C1. The battery lid 6 also has a liquid filling port (see Figure 2) for filling the battery with electrolyte, which is closed by a liquid filling plug 11 after the electrolyte has been injected.

[0025] FIG. 2 shows the appearance of the exploded battery cell C1 of the battery pack shown in FIG. 1, viewed obliquely from above.

[0026] As described above, the battery can 1 of the battery cell C1 of the battery pack is square, and has a rectangular can bottom 22, square cylindrical side walls (sometimes referred to as side peripheral surfaces) 21 rising in the cell height direction (+Y direction) from the four sides of this can bottom 22, and an opening 1a that opens in the cell height direction at the upper end of the side walls 21. The side walls 21 of the battery can 1 have a pair of wide side walls 21a that are spaced apart in the cell thickness direction (+Z direction) and face each other, and a pair of narrow side walls 21b that are spaced apart in the cell width direction (+X direction) and face each other.

[0027] The wound electrode body 3 is housed in the battery can 1 while being wrapped and covered with an insulating protective film 2. The wound electrode body 3 has a flattened shape that is approximately rectangular parallelepiped, and has a pair of flat surfaces and a pair of curved surfaces with an arc-shaped cross section that face each other with the pair of flat surfaces in between. The wound electrode body 3 is inserted into the battery can 1 from the side of one of the curved surfaces, and is housed in the battery can 1 in a horizontal position with the winding axis direction along the cell width direction (+X direction).

[0028] The wound electrode assembly 3 has an electrode body portion 3c at its central portion (for example, between the positive electrode foil connection portion 31d and the negative electrode foil connection portion 32d). The electrode body portion 3c has a positive electrode layer formed on the positive electrode foil. The positive electrode layer faces the negative electrode layer formed on the negative electrode foil.

[0029] The wound electrode body 3 has a positive electrode foil connection portion 31 d and a negative electrode foil connection portion 32 d, which are electrode foil exposed portions, at both ends of the electrode body portion 3 c. At least a portion of the positive electrode foil connection portion 31 d and the negative electrode foil connection portion 32 d are bundled together in the flat thickness direction to form a flat plate, and are joined by ultrasonic welding to a positive electrode side connection end 42A of the positive electrode current collector plate (current collector terminal) 4A and a negative electrode side connection end 42B of the negative electrode current collector plate (current collector terminal) 4B, respectively.

[0030] The base ends of the positive current collector 4A and the negative current collector 4B are connected to a positive external terminal 8A and a negative external terminal 8B, respectively. A gasket 5 and an insulating plate 7 are provided on the battery lid 6, which electrically insulate the positive current collector 4A, the negative current collector 4B, and the positive external terminal 8A and the negative external terminal 8B from the battery lid 6.

[0031] The battery can 1 and the battery lid 6 are made of a metallic material such as aluminum or an aluminum alloy. The positive electrode current collector 4A and the positive electrode external terminal 8A are made of aluminum or an aluminum alloy. The negative electrode current collector 4B and the negative electrode external terminal 8B are made of copper or a copper alloy.

[0032] The positive electrode external terminal 8A and the negative electrode external terminal 8B have welded joints that are welded to a bus bar or the like (not shown). The welded joints have a rectangular parallelepiped block shape that protrudes upward from the battery lid 6, and are arranged so that their lower surfaces face the surface of the battery lid 6 and their upper surfaces are parallel to the battery lid 6 at a predetermined height.

[0033] The positive electrode connecting portion 12A and the negative electrode connecting portion 12B have a cylindrical shape that protrudes from the lower surfaces of the positive electrode external terminal 8A and the negative electrode external terminal 8B, respectively, and has a tip that can be inserted into the positive electrode side through-hole 6A and the negative electrode side through-hole 6B of the battery lid 6. The positive electrode connecting portion 12A and the negative electrode connecting portion 12B penetrate the battery lid 6 and protrude further into the battery can 1 than the positive electrode current collector base portion 41A and the negative electrode current collector base portion 41B of the positive electrode current collector 4A and the negative electrode current collector 4B, and their tips are crimped to fix the positive electrode external terminal 8A and the negative electrode external terminal 8B and the positive electrode current collector 4A and the negative electrode current collector 4B integrally to the battery lid 6.

[0034] Gaskets 5 are interposed between the positive external terminal 8A and the battery lid 6, and between the negative external terminal 8B and the battery lid 6, and insulating plates 7 are interposed between the positive current collector plate 4A and the battery lid 6, and between the negative current collector plate 4B and the battery lid 6.

[0035] The positive current collector plate 4A and the negative current collector plate 4B have a rectangular plate-shaped positive current collector base 41A and a negative current collector base 41B that are arranged opposite the underside of the battery lid 6, and a positive electrode side connection end 42A and a negative electrode side connection end 42B that are bent at the side edges of the positive current collector base 41A and the negative current collector base 41B and extend toward the can bottom 22 along the wide side surface of the battery can 1, and are connected in a superimposed state opposite the positive electrode foil connection portion 31 d and the negative electrode foil connection portion 32 d of the wound electrode body 3.

[0036] The positive current collector base 41A and the negative current collector base 41B are respectively formed with a positive electrode side opening hole 43A and a negative electrode side opening hole 43B through which the positive electrode connecting portion 12A and the negative electrode connecting portion 12B are inserted.

[0037] The positive electrode external terminal 8A and positive electrode current collector plate 4A described above constitute a positive electrode side terminal component, and the negative electrode external terminal 8B and negative electrode current collector plate 4B constitute a negative electrode side terminal component. These positive electrode side terminal component and negative electrode side terminal component are integrally assembled to the battery lid 6 via the gasket 5 and insulating plate 7, thereby forming a battery lid assembly. The wound electrode body 3 is then assembled to the battery lid assembly, thereby forming a power generation element assembly.

[0038] The wound electrode body 3 is supported between the positive electrode current collector 4A and the negative electrode current collector 4B of the battery lid assembly, with the winding axis direction extending parallel to the battery lid 6 and the flat surface extending along a direction perpendicular to the underside of the battery lid 6, and a pair of curved surfaces of the wound electrode body 3 being arranged separately on the side of the battery lid 6 and the side of the can bottom 22 of the battery can 1.

[0039] The insulating protective film 2 covers the wound electrode body 3 assembled to the battery lid assembly from the outside, together with the positive electrode current collector plate 4A and the negative electrode current collector plate 4B, and is interposed between the side wall portion 21 and the can bottom 22 inside the battery can 1, respectively.

[0040] The insulating protective film 2 is made of an insulating synthetic resin material, and provides insulation between the battery can 1 and the wound electrode body 3, positive electrode current collector 4A, and negative electrode current collector 4B. In addition, when the battery pack is subjected to external impact or vibration, the insulating protective film 2 protects the wound electrode body 3, positive electrode current collector 4A, and negative electrode current collector 4B so that they do not come into direct contact with the battery can 1.

[0041] The battery can 1 has dimensions and a shape such that when the wound electrode body 3 is inserted into the battery can 1 through the opening 1a with the wound electrode body 3 covered around the periphery with the insulating protective film 2, a pair of flat surfaces of the wound electrode body 3 and the wide side wall portions 21a of the side wall portions 21 of the battery can 1 abut against each other with the insulating protective film 2 sandwiched therebetween, and the wound electrode body 3 can be inserted by pressing with a slight pressure. In addition, a slight gap is formed between the end faces on both sides of the winding axis direction of the wound electrode body 3 and the narrow side wall portions 21b of the side wall portions 21 of the battery can 1.

[0042] As described above, the opening 1a of the battery can 1 is closed by the battery lid 6, and the battery lid 6 is sealed by laser welding to the battery can 1. Then, the battery can 1 is filled with an electrolyte. The electrolyte is injected into the battery can 1 through the filling port 9 of the battery lid 6. After the electrolyte is injected, the filling port 9 is closed by the filling plug 11, and the filling plug 11 is sealed by laser welding to the battery lid 6.

[0043] In battery cells of a battery pack configured as described above, for example, battery cells for electric vehicles have a large battery capacity per cell, which leads to a larger cell size and an increase in the number of components per cell, such as an electrode group, electrolyte, and active material. Therefore, the increase in components tends to increase the amount of expansion of the battery cell during charging.

[0044] As described above, the battery spacer restraint structure for a battery assembly shown in FIG. 9 requires a battery frame with higher rigidity, resulting in issues such as increased weight and cost. Furthermore, the battery spacer restraint structure for a battery assembly shown in FIG. 10 requires a pressure mechanism such as an elastic body, and since the electrode terminals of the battery cells move, a tracking mechanism for the current-carrying terminals connected to the electrode terminals is required. Therefore, a battery assembly having the structure of the present invention does not require the rigidity of the battery frame to be greater than necessary. This meets the demand for a compact and lightweight structure. For example, it is possible to provide a battery spacer that does not require a tracking mechanism such as a pressure mechanism, and a battery assembly using this battery spacer.

[0045] Therefore, the present embodiment proposes the following configuration.

[0046] This embodiment is a battery spacer interposed between adjacent prismatic battery cells each having a generally rectangular shape with four sides, and is characterized in that the battery spacer is divided into at least an outer region that exists at a position corresponding to the opposing sides of the prismatic battery cells and an inner region that exists inside the outer region, with the outer region being made of a rigid material and the inner region being made of a flexible material. Note that in this embodiment, the outer region exists at a position corresponding to the pair of short sides 21aS of the opposing sides of the prismatic battery cell C1 shown in Figure 1.

[0047] This allows the rigid outer region to suppress movement of the battery cell electrode terminals, and the flexible inner region to cushion expansion of the battery cells, making it possible to provide a battery spacer that does not require a pressure mechanism or a compliance mechanism without increasing the rigidity of the battery frame more than necessary, and a battery pack that uses this battery spacer.

[0048] The specific configuration of the first embodiment will be described below. Figure 3 is a schematic diagram that clearly illustrates the relationship between the battery cell C1, battery spacer 52, side plate 50, and end plate 51 in Figure 4. A cross section of the battery cell C1 is shown in part. The relative positions of the electrode body 3C, positive electrode foil connection portion 31d, negative electrode foil connection portion 32d, and battery spacer 52 are shown.

[0049] 3, multiple (four in this example) battery cells C1 are stacked from left to right in the drawing, with the sidewalls 21a, which are the stacking surfaces, facing each other. The battery cell group 01, in which these battery cells C1 are stacked, is surrounded by side plates 50 and end plates 51, which provide a fixing mechanism for the battery cell group 01.

[0050] The battery cell group 01 has a pair of end plates 51 at both ends in the stacking direction (Z-axis direction) of the battery cells C1, and side plates 50 connecting these end plates 51. A pair of end plates 51 are fixed to the ends of the side plates 50 in a direction perpendicular to the extension direction of the side plates 50. The side plates 50 and end plates 51 surround the entire periphery of the multiple battery cells C1 from the outside.

[0051] The battery spacers 52 of this embodiment are interposed between the end plates 51 and the battery cells C1, and between adjacent battery cells C1. The battery spacers 52 have two separate regions: an outer region 52out and an inner region 52in.

[0052] During charging, an expansion region (EXP) occurs in the battery cell C1, centered around the center of the side wall 21a of the battery can 1 shown in Fig. 1. On the other hand, no expansion occurs near the outer edges (left and right sides and top and bottom sides) of the side wall 21a of the battery cell C1, or if any expansion occurs, it is small. Therefore, it is sufficient to cushion the expansion of the expansion region (EXP) near the center of the side wall 21a of the battery cell C1.

[0053] For this reason, the battery spacer 52 is arranged as an outer region 52out on the end side of the battery cell C1 (the end side in the direction perpendicular to the stacking direction), and as an inner region 52in near the center of the battery cell C1.

[0054] For example, the outer region 52out is disposed closer to the short side 21aS of the battery cell C1 than the inner region 52in in the direction perpendicular to the stacking direction.

[0055] Furthermore, for example, the inner region 52in is arranged so as to overlap the electrode body 3c of the battery cell C1 when viewed in the stacking direction of the battery cells C1. Alternatively, when viewed in the stacking direction of the battery cells C1, the overlap between the outer region (52out) and the electrode body 3c is smaller than the overlap between the inner region 52in and the electrode body 3c.

[0056] The outer region 52out is made of a hard material with high rigidity to prevent the battery cell C1 from moving, and the inner region 52in is made of a soft material with high flexibility to cushion the expansion of the battery cell 52.

[0057] For example, the outer region 52out can be made of a metal material or a rigid hard plastic material, and the inner region 52in can be made of a soft material such as rubber that has the elasticity to return to its original shape after being deformed (hereinafter referred to as shape reversibility).

[0058] The shape reversibility function is a function that when the battery cell 52 expands, it deforms to absorb this expansion, and when the battery cell C1 contracts and restores to its original shape, it follows this contraction and promotes restoration, thereby allowing the inter-electrode distance of the battery cell C1 to return to its original position.

[0059] In this way, the outer region 52out can be formed to have greater rigidity than the inner region 52in. Alternatively, the inner region 52in can be formed to have greater flexibility than the outer region 52out.

[0060] In this way, the rigid outer region 52out can suppress movement of the electrode terminal of the battery cell C1, and the flexible inner region 52in can cushion expansion of the battery cell C1.

[0061] Next, the configuration of a battery pack using the battery spacer of this embodiment will be described with reference to Fig. 4. Fig. 4 shows an exploded view of the battery pack 02 as seen obliquely from above.

[0062] 4, eight battery cells C1 are stacked, and the stacked battery cells C1 (constituting the battery cell group 01) are surrounded at their four outer corners by a pair of side plates 50 and a pair of end plates 51. The side plates 50 are arranged perpendicular to the extension direction of the side wall portions 21a of the battery cells C1, and the end plates 51 are arranged facing the side wall portions 21a of the battery cells C1. Battery spacers 52 are arranged between the end plates 51 and the battery cells C1, and between adjacent battery cells C1.

[0063] The side plates 50 and end plates 51 constitute a fixing mechanism for the battery cell group 01. A pair of end plates 51 are provided on both ends of the stacking direction (Z-axis direction) of the battery cells C1 of the battery cell group 01, and side plates 50 connect these end plates 51. A pair of end plates 51 are arranged at the ends of the side plates 50, fixed in a direction perpendicular to the extension direction of the side plates 50.

[0064] In this way, the assembled battery comprises a battery cell group formed by stacking rectangular battery cells each having a roughly rectangular shape with four sides, side plates 50 that surround the stacked battery cell group from the outside in the stacking direction, end plates 51 that are perpendicular to the side plates and surround the battery cell group from the outside, and battery spacers 52 for the assembled battery that are interposed between adjacent rectangular batteries.

[0065] The side wall 21a of the battery cell C1 is formed in a substantially rectangular shape (rectangular in this case), and the battery spacer 52 is also formed in a substantially rectangular shape (rectangular in this case) to match this shape. As described above, the side wall 21a is formed in a substantially rectangular shape consisting of four sides, and has left and right short sides 21aS that are perpendicular to the longitudinal direction and face each other, and upper and lower long sides 21aL that are perpendicular to the lateral direction and face each other.

[0066] 3, the battery spacer 52 is divided into three sections, two flat outer regions 52out and one flat inner region 52in. Here, as an example, the overall shape of the battery spacer 52 used is a battery spacer 52 formed in a shape and size that overlaps with the four corners of the side wall 21a of the battery cell C1.

[0067] However, the battery spacer 52 may have a shape and size that does not overlap with the four corners of the side wall portion 21a of the battery cell C1. For example, the outer region 52out may be formed inside some or all of the four corners of the side wall portion 21a. The outer edge of the outer region 52out is located closer to the center of the battery cell C1 than some or all of the four corners of the side wall portion 21a.

[0068] The outer region 52out of the battery spacer 52 is disposed in correspondence with the short side 21aS of the side wall 21a of the battery cell C1, and the inner region 52in of the battery spacer 52 is disposed in correspondence with the vicinity of the center of the side wall 21a of the battery cell C1. The vicinity of the center includes the expansion region (EXP) shown in FIG. 1 .

[0069] In other words, the outer region 52out of the battery spacer 52 is a battery spacer that is separated from the vertically elongated inner region 52in on the two short sides 21aS side of the side wall portion 21a of the battery cell C1, and has a predetermined length (Loh) along the long side that is approximately the same as the length (Lov) of the short side.

[0070] In addition, the inner region 52in of the battery spacer 52 is a horizontally elongated battery spacer separated from the outer region 52out, which has a predetermined length (Lih) along the long side and is approximately the same as the length (Liv) of the short side of the side wall portion 21a of the battery cell C1.

[0071] In this way, the above-mentioned battery spacers 52 are arranged between the end plates 51 and the battery cells C1, and between adjacent battery cells C1, so that the rigid outer region 52out can suppress movement of the electrode terminals of the battery cells C1, and the flexible inner region 52in can cushion expansion of the battery cells C1.

[0072] This makes it possible to provide a battery spacer that can fix the battery cell group 01 without increasing the rigidity of the battery frame more than necessary, and a battery pack that uses this battery spacer.

[0073] The overall shape of the battery spacer 52 is not limited to a shape and size that overlaps with the four corners of the side wall 21a of the battery cell C1. The battery spacer 52 may have a shape and size that does not overlap with the four corners of the side wall 21a of the battery cell C1. For example, an outer region 52out is formed inside some or all of the four corners of the side wall 21a. The outer edge of the outer region 52out is located closer to the center of the battery cell C1 than some or all of the four corners of the side wall 21a.

[0074] Next, a second embodiment of the present invention will be described. In the first embodiment, the outer region 52out of the battery spacer 52 has a flat plate shape, but in the second embodiment, the outer region 52out of the battery spacer 52 has a T-shaped cross section, which is different from the first embodiment.

[0075] This embodiment is a battery spacer interposed between adjacent rectangular batteries of rectangular battery cells each having a roughly rectangular shape consisting of four side edges, and is characterized in that the battery spacer is divided into an outer region that exists at least in a position corresponding to the opposing side edges of the rectangular battery cells, and an inner region that exists inside the outer region, the outer region being made of a rigid material and the inner region being made of a flexible material, the outer region having a retaining portion that extends in a direction perpendicular to the flat outer region, and the outer region and retaining portion having a cross section formed in a "T" shape.

[0076] This allows the rigid outer region to suppress movement of the battery cell electrode terminals, and the flexible inner region to cushion expansion of the battery cells. This makes it possible to provide a battery spacer that does not require a pressure mechanism or a compliance mechanism without increasing the rigidity of the battery frame more than necessary, and a battery pack using this battery spacer. Furthermore, the outer region is held by the holding portion, and can be positioned by being in close contact with the longitudinal end face of the battery cell C1 (corresponding to the side wall portion 21b in Figure 1).

[0077] Although the above describes an example of a "T" shape having holding portions extending on both sides in the cell stacking direction, this is not limiting. The outer region may have holding portions extending in a direction perpendicular to the flat outer region, and the outer region and holding portions may have a cross section extending to one side, such as an "L" shape.

[0078] Next, the configuration of an actual battery pack using the battery spacer of this embodiment (second embodiment) will be described with reference to Fig. 5. Fig. 5 shows an exploded view of the battery pack from diagonally above. Note that this embodiment differs from the embodiment shown in Fig. 4 only in the outer region, and the rest of the configuration is the same.

[0079] 5 , eight battery cells C1 are stacked, and the stacked battery cells C1 (forming a battery cell group) are surrounded at their four corners by a pair of side plates 50 and a pair of end plates 51. The side plates 50 are arranged perpendicular to the extension direction of the side wall portions 21a of the battery cells C1, and the end plates 51 are arranged facing the side wall portions 21a of the battery cells C1. Battery spacers 52 are arranged between the end plates 51 and the battery cells C1, and between adjacent battery cells C1. The side wall portions 21a of the battery cells C1 are formed in a substantially rectangular shape (rectangle in this case), and the battery spacers 52 are also formed in a substantially rectangular shape (rectangle in this case) to match this shape.

[0080] As described above, the side wall portion 21a is formed in an approximately rectangular shape consisting of four side sides, and has left and right short sides 21aS that are perpendicular to the longitudinal direction and face each other, and upper and lower long sides 21aL that are perpendicular to the short direction and face each other.

[0081] 3, the battery spacer 52 is divided into three parts, two flat outer regions 52out and one flat inner region 52in. The overall shape and size of the battery spacer 52 is such that it overlaps with the four corners of the sidewall 21a of the battery cell C1.

[0082] The outer region 52out is disposed in correspondence with the short side 21aS of the side wall 21a of the battery cell C1, and the inner region 52in is disposed in correspondence with the vicinity of the center of the side wall 21a of the battery cell C1. The vicinity of the center includes the expansion region (EXP) shown in FIG. 1 .

[0083] That is, the outer region 52out is a vertically elongated battery spacer on the side of the two short sides 21aS of the side wall 21a of the battery cell C1, having a predetermined length (Loh) along the long side that is approximately the same as the length (Lov) of the short side. The inner region 52in is a horizontally elongated battery spacer on the side of the two short sides 21aS of the side wall 21a of the battery cell C1, having a predetermined length (Lih) along the long side that is approximately the same as the length (Liv) of the short side.

[0084] The overall shape of the battery spacer 52 is not limited to the battery spacer 52 formed in a shape that is approximately the same as the short side length (Lov) of the side wall portion 21a of the battery cell C1. The battery spacer 52 may have a shape that is shorter than the short side length (Lov) of the side wall portion 21a of the battery cell C1. For example, the outer region 52out has a shape that is shorter than the short side length (Lov).

[0085] In this way, the battery spacers 52 are arranged between the end plates 51 and the battery cells C1, and between adjacent battery cells C1, so that the rigid outer region 52out can suppress movement of the electrode terminals of the battery cells C1, and the flexible inner region 52in can cushion expansion of the battery cells C1.

[0086] 5, the flat outer region 52out of the battery spacer 52 has a holding portion 53 that is integrally connected to it so as to be perpendicular to it, and the cross section perpendicular to the longitudinal direction of the outer region 52out is T-shaped. The function of the outer region 52out is the same as that of the embodiment shown in FIG. 4, so a description thereof will be omitted here.

[0087] Meanwhile, the holding portion 53 holds the outer region 52out and faces (for example, in close contact with) the side wall portion 21b on the longitudinal end face of the battery cell C1, thereby positioning the outer region 52out. Similar to the first embodiment shown in Figure 4, the outer region 52out and the holding portion 53 can be made of a metal material or a rigid hard plastic material. Similar to the first embodiment, the inner region 52in can also be made of a shape-reversible soft material such as rubber.

[0088] In this way, because the battery spacers 52 are arranged between the end plates 51 and the battery cells C1, and between adjacent battery cells C1, the rigid outer regions 52out can suppress movement of the electrode terminals of the battery cells C1, and the flexible inner regions 52in can cushion expansion of the battery cells C1. Furthermore, the holding portions 53 can hold the outer regions 52out and also position the outer regions 52out.

[0089] Next, a third embodiment of the present invention will be described. In the first embodiment, the outer region 52out of the battery spacer 52 was formed at a position corresponding to the side edge (short edge) perpendicular to the longitudinal direction of the battery cell C1. However, in this embodiment, the outer region 52out is formed at a position corresponding to the upper and lower side edges (long edges) perpendicular to the lateral direction of the battery cell C1.

[0090] This embodiment is a battery spacer interposed between adjacent rectangular battery cells each having a generally rectangular shape with four sides, and is characterized in that the battery spacer is divided into an outer region that exists at least in positions corresponding to the opposing sides of the rectangular battery cells and an inner region that exists inside the outer region, with the outer region being made of a rigid material and the inner region being made of a flexible material. Note that in this embodiment, the outer region corresponds to the long side 21aL shown in Figure 1.

[0091] This allows the rigid outer region to suppress movement of the battery cell electrode terminals, and the flexible inner region to cushion expansion of the battery cells. This makes it possible to provide a secondary battery spacer that does not require an excessively large rigidity for the battery frame and does not require a pressure mechanism or a compliance mechanism, as well as a battery pack that uses this battery spacer.

[0092] Next, the configuration of an actual battery pack using the battery spacer of this embodiment (third embodiment) will be described with reference to Fig. 6. Fig. 6 shows an exploded view of the battery pack as seen obliquely from above.

[0093] 6 , eight battery cells C1 are stacked, and the stacked battery cells C1 (forming a battery cell group) are surrounded at their four corners by a pair of side plates 50 and a pair of end plates 51. The side plates 50 are arranged perpendicular to the extension direction of the side wall portions 21a of the battery cells C1, and the end plates 51 are arranged facing the side wall portions 21a of the battery cells C1. Battery spacers 52 are arranged between the end plates 51 and the battery cells C1, and between adjacent battery cells C1. The side wall portions 21a of the battery cells C1 are formed in a substantially rectangular shape (rectangle in this case), and the battery spacers 52 are also formed in a substantially rectangular shape (rectangle in this case) to match this shape.

[0094] As described above, the side wall portion 21a is formed in an approximately rectangular shape consisting of four side sides, and has left and right short sides 21aS that are perpendicular to the longitudinal direction and face each other, and upper and lower long sides 21aL that are perpendicular to the short direction and face each other.

[0095] The battery spacer 52 is divided into three sections, similar to the embodiment described above, and is composed of two flat outer regions 52out and one flat inner region 52in. The overall shape and size of the battery spacer 52 is such that it overlaps with the four corners of the side wall 21a of the battery cell C1. The outer regions 52out are located in correspondence with the positions of the upper and lower long sides 21aL of the side wall 21a of the battery cell C1, which are perpendicular to the short direction, and the inner region 52in is located in correspondence with the vicinity of the center of the side wall 21a of the battery cell C1. The vicinity of the center includes the expansion region (EXP) shown in FIG. 1 .

[0096] In other words, the outer region 52out is a battery spacer separated from the horizontally elongated inner region 52in, which has a predetermined length (Lov) along the short side and is approximately the same as the length (Loh) of the long side 21aL on the two upper and lower sides of the side wall 21a of the battery cell C1. The inner region 52in also has a predetermined length (Liv) obtained by subtracting the length of the short side of the outer region 52out from the length of the short side 21aS of the side wall 21a of the battery cell C1, and is separated from the horizontally elongated outer region 52out, which has a predetermined length (Lih) along the long side.

[0097] The overall shape of the battery spacer 52 is not limited to the battery spacer 52 formed in a shape that is approximately the same as the long side length (Loh) of the side wall portion 21a of the battery cell C1. The battery spacer 52 may have a shape that is shorter than the long side length (Loh) of the side wall portion 21a of the battery cell C1. For example, the outer region 52out has a shape that is shorter than the long side length (Loh).

[0098] The outer region 52out can be made of a metal material or a rigid hard plastic material, similar to the first embodiment shown in Fig. 4. The inner region 52in can be made of a shape-reversible soft material, such as rubber, similar to the first embodiment.

[0099] In this way, the battery spacers 52 are arranged between the end plates 51 and the battery cells C1, and between adjacent battery cells C1, so that the rigid outer region 52out can suppress movement of the electrode terminals of the battery cells C1, and the flexible inner region 52in can cushion the expansion of the battery cells C1.

[0100] This makes it possible to provide a battery spacer that does not require an excessively large rigidity for the battery frame and does not require a pressure mechanism or a follow-up mechanism, and a battery pack that uses this battery spacer.

[0101] Next, a fourth embodiment of the present invention will be described. In the first and third embodiments, the outer region 52out of the battery spacer 52 was formed on the side (short side) perpendicular to the longitudinal direction of the battery cell C1 or on the side (long side) perpendicular to the lateral direction of the battery cell C1. However, in this embodiment, the outer region 52out is formed at positions corresponding to the four longitudinal and lateral sides of the battery cell C1.

[0102] This embodiment is a battery spacer interposed between adjacent rectangular batteries of rectangular battery cells each having a generally rectangular shape with four sides, and is characterized in that the battery spacer is divided into an outer region that exists at least in positions corresponding to the four opposing sides of the rectangular battery cell, and an inner region that exists inside the outer region, with the outer region being made of a rigid material and the inner region being made of a flexible material. Note that in this embodiment, the outer region is in the form of a rectangular, integrated frame.

[0103] This allows the rigid outer region to suppress movement of the battery cell electrode terminals, and the flexible inner region to cushion expansion of the battery cells, making it possible to provide a battery spacer that does not require a pressure mechanism or a compliance mechanism without increasing the rigidity of the battery frame more than necessary, and a battery pack that uses this battery spacer.

[0104] Next, the configuration of an actual battery pack using the battery spacer of this embodiment (fourth embodiment) will be described with reference to Fig. 7. Fig. 7 shows an exploded view of the battery pack as seen obliquely from above.

[0105] 7 , eight battery cells C1 are stacked, and the stacked battery cells C1 (forming a battery cell group) are surrounded at their four corners by a pair of side plates 50 and a pair of end plates 51. The side plates 50 are arranged perpendicular to the extension direction of the side wall portions 21a of the battery cells C1, and the end plates 51 are arranged facing the side wall portions 21a of the battery cells C1. Battery spacers 52 are arranged between the end plates 51 and the battery cells C1, and between adjacent battery cells C1. The side wall portions 21a of the battery cells C1 are formed in a substantially rectangular shape (rectangle in this case), and the battery spacers 52 are also formed in a substantially rectangular shape (rectangle in this case) to match this shape.

[0106] As described above, the side wall portion 21a is formed in an approximately rectangular shape consisting of four side sides, and has left and right short sides 21aS that are perpendicular to the longitudinal direction and face each other, and upper and lower long sides 21aL that are perpendicular to the short direction and face each other.

[0107] The battery spacer 52 is divided into two parts: a flat, rectangular outer region 52out and a flat inner region 52in located within the rectangular frame. The overall shape and size of the battery spacer 52 is such that it overlaps with the four corners of the sidewall 21a of the battery cell C1.

[0108] The outer region 52out is integrally formed in a rectangular frame shape corresponding to the four short and long sides of the sidewall 21a of the battery cell C1. The inner region 52in corresponds to the vicinity of the center of the sidewall 21a of the battery cell C1 and is located inside the rectangular frame. The vicinity of the center includes the expansion region (EXP) shown in FIG. 1.

[0109] The overall shape of the battery spacer 52 may correspond to the four sides of the sidewall 21a of the battery cell C1 and be formed to be substantially the same shape as the four sides. However, this is not limited to this. The battery spacer 52 may also be shaped smaller than the four sides of the sidewall 21a of the battery cell C1. For example, the outer region 52out is shaped like a rectangular frame that is smaller than the four sides.

[0110] The outer region 52out can be made of a metal material or a rigid hard plastic material, similar to the first embodiment shown in Fig. 4. The inner region 52in can be made of a shape-reversible soft material, such as rubber, similar to the first embodiment.

[0111] In this way, the battery spacers 52 are arranged between the end plates 51 and the battery cells C1, and between adjacent battery cells C1, so that the rigid outer region 52out can suppress movement of the electrode terminals of the battery cells C1, and the flexible inner region 52in can cushion the expansion of the battery cells C1.

[0112] This makes it possible to provide a battery spacer that does not require an excessively large rigidity for the battery frame and does not require a pressure mechanism or a follow-up mechanism, and a battery pack that uses this battery spacer.

[0113] Next, a fifth embodiment of the present invention will be described. In the first embodiment, the outer region 52out of the battery spacer 52 was formed separately from the side plate 50. However, in this embodiment, the outer region 52out, which exists in a position corresponding to the side edge perpendicular to the longitudinal direction of the battery cell C1, is formed integrally with the side plate 50.

[0114] This embodiment is a battery spacer interposed between adjacent rectangular batteries of rectangular battery cells each having a roughly rectangular shape with four sides, and is characterized in that the battery spacer is divided into an outer region formed integrally with the side plates and located at least on the opposing sides of the rectangular battery cells, and an inner region located inside the outer region, with the outer region being made of a rigid material and the inner region being made of a flexible material.

[0115] This allows the rigid outer region to suppress movement of the battery cell electrode terminals, and the flexible inner region to cushion expansion of the battery cells, making it possible to provide a battery spacer that does not require a pressure mechanism or a compliance mechanism without increasing the rigidity of the battery frame more than necessary, and a battery pack that uses this battery spacer.

[0116] Next, the configuration of an actual battery pack using the battery spacer of this embodiment will be described with reference to Fig. 8. Fig. 8 shows an exploded view of the battery pack as seen obliquely from above.

[0117] 8 , eight battery cells C1 are stacked, and the stacked battery cells C1 (forming a battery cell group) are surrounded at their four corners by a pair of side plates 50 and a pair of end plates 51. The side plates 50 are arranged perpendicular to the extension direction of the side wall portions 21a of the battery cells C1, and the end plates 51 are arranged facing the side wall portions 21a of the battery cells C1. Battery spacers 52 are arranged between the end plates 51 and the battery cells C1, and between adjacent battery cells C1. The side wall portions 21a of the battery cells C1 are formed in a substantially rectangular shape (rectangle in this case), and the battery spacers 52 are also formed in a substantially rectangular shape (rectangle in this case) to match this shape.

[0118] As described above, the side wall portion 21a is formed in an approximately rectangular shape consisting of four side sides, and has left and right short sides 21aS that are perpendicular to the longitudinal direction and face each other, and upper and lower long sides 21aL that are perpendicular to the short direction and face each other.

[0119] The battery spacer 52 is divided into two parts, consisting of two flat outer regions 52out and one flat inner region 52in. The overall shape and size of the battery spacer 52 is such that it overlaps with the four corners of the sidewall 21a of the battery cell C1. The outer region 52out is located on the short side 21aS of the sidewall 21a of the battery cell C1, and the inner region 52in is located near the center of the sidewall 21a of the battery cell C1. The area near the center includes the expansion region (EXP) shown in FIG. 1 .

[0120] The outer region 52out is formed integrally with the side plate 50. Therefore, the battery spacer 52 can be easily formed by storing the battery cell C1 in the space formed by the two outer regions 52out formed on the side plate 50 and inserting the inner region 52in into the space formed by the side wall portions 21a of the adjacent battery cells C1.

[0121] The outer region 52out can be made of a metal material or a rigid hard plastic material, similar to the first embodiment shown in Fig. 4. The inner region 52in can be made of a shape-reversible soft material, such as rubber, similar to the first embodiment.

[0122] In this way, the battery spacers 52 are arranged between the end plates 51 and the battery cells C1, and between adjacent battery cells C1, so that the rigid outer region 52out can suppress movement of the electrode terminals of the battery cells C1, and the flexible inner region 52in can cushion the expansion of the battery cells C1.

[0123] This makes it possible to provide a battery spacer that does not require an excessively large rigidity for the battery frame and does not require a pressure mechanism or a follow-up mechanism, and a battery pack that uses this battery spacer.

[0124] As described above, the present invention is a battery spacer interposed between adjacent rectangular batteries of rectangular battery cells each having a generally rectangular shape with four sides, and is characterized in that the battery spacer is divided into at least an outer region that exists in a position corresponding to the opposing sides of the rectangular battery cells, and an inner region that exists inside the outer region, with the outer region being made of a rigid material and the inner region being made of a flexible material.

[0125] This allows the rigid outer region to suppress movement of the battery cell electrode terminals, and the flexible inner region to cushion expansion of the battery cells, making it possible to provide a new battery spacer that does not require an excessively high rigidity for the battery frame and does not require a pressure mechanism, as well as a battery pack that uses this battery spacer.

[0126] It should be noted that the present invention is not limited to the above-described embodiments and includes various modifications. The above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace other configurations with respect to the configuration of each embodiment.

[0127] C1...battery cell, 01...battery cell group, 02...battery assembly, 1...battery can, 1a...opening, 2...insulating protective film, 3...wound electrode body, 3a...front flat surface, 3a...rear flat surface, 4A...positive electrode current collector plate 1, 4B...negative electrode current collector plate, 5...gasket, 6...battery lid, 6A...positive electrode side through-hole, 6B...negative electrode side through-hole, 7...insulating plate, 8A...positive electrode external terminal, 8B...negative electrode external terminal, 9...filling port, 10...gas discharge mechanism, 11...filling tap, 12A...positive electrode connection portion, 12B...negative electrode connection portion, 21a...side wall portion, 21aS...short side, 21aL...long side, 50...side plate, 51...end plate, 52...battery spacer, 52in...inner region portion, 2out...outer region portion, 53...retaining portion.

Claims

1. A battery spacer interposed between a rectangular battery cell having a generally rectangular shape consisting of four sides and an adjacent rectangular battery cell, the battery spacer having at least an outer region that exists in a position corresponding to the opposing sides of the rectangular battery cell, and an inner region that exists inside the outer region, the outer region being made of a material with greater rigidity than the inner region.

2. A battery spacer as described in claim 1, wherein the rectangular battery cells have side walls that are roughly rectangular in shape and are composed of a pair of long sides and a pair of short sides when viewed in the stacking direction, and the battery spacer has at least a flat outer region that exists in a position corresponding to the opposing short sides of the rectangular battery cells, and an inner region that exists inside the outer region.

3. A battery spacer as described in claim 2, characterized in that the outer region is integrally provided with a retaining portion extending in a direction perpendicular to the flat outer region, and the retaining portion is arranged opposite a side wall of the rectangular battery cell that is different from the side wall that the outer region faces.

4. A battery spacer as described in claim 1, wherein the rectangular battery cells have approximately rectangular side walls consisting of a pair of long sides and a pair of short sides when viewed in the stacking direction, and the battery spacer has a flat outer region that exists at least in a position corresponding to the opposing long sides of the rectangular battery cells, and an inner region that exists inside the outer region.

5. A battery spacer as described in claim 1, wherein the rectangular battery cells have substantially rectangular side walls consisting of a pair of long sides and a pair of short sides when viewed in the stacking direction, and the battery spacer has a flat outer region that exists at a position corresponding to at least the opposing long sides and the opposing short sides of the rectangular battery cells, and an inner region that exists inside the outer region.

6. A battery spacer as described in claim 5, characterized in that the battery spacer has an outer region formed in a flat rectangular frame located at a position corresponding to the long sides and the short sides, and an inner region located inside the outer region.

7. A battery spacer as described in claim 2, characterized in that the battery spacer has an outer region formed integrally with a side plate that surrounds the outer periphery of the stacked rectangular battery cells, and an inner region that exists inside the outer region.

8. An assembled battery comprising: a battery cell group formed by stacking rectangular battery cells each having a roughly rectangular shape with four sides; side plates that surround the stacked battery cell group from the outside in the stacking direction; end plates that intersect perpendicularly to the side plates and surround the battery cell group from the outside; and a battery spacer interposed between adjacent rectangular battery cells, wherein the battery spacer is at least the battery spacer described in any one of claims 1 to 7.

9. The battery pack according to claim 8, wherein the battery spacer is disposed between the end plate and the rectangular battery cell adjacent to the end plate.

10. An assembled battery as claimed in claim 8, wherein the prismatic battery cells have an electrode body portion having a positive electrode active material and a negative electrode active material, and an electrode tab formed closer to the side edge than the electrode body portion and electrically connected to an external terminal of the battery, and are arranged such that, when viewed in the stacking direction of the prismatic battery cells, the overlap between the external region and the electrode body portion is less than the overlap between the internal region and the electrode body portion.

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