JPWO2015097875A1 - Assembled battery - Google Patents

Abstract

A plurality of secondary batteries in which the wound flat electrode group (40) is accommodated in a rectangular battery container (2) are stacked in the thickness direction of the electrode group (40), and a spacer (103) is interposed therebetween. It is an assembled battery (200) interposing. The spacer (103) is a top portion of the expansion shape of the electrode group (40) expanding in the thickness direction in a direction along the flat surface (40f) of the electrode group (40) and intersecting the axial direction (D) ( The closer to 40p), the thinner the thickness (Ta, Tb).

Description

  The present invention relates to an assembled battery used for in-vehicle use.

  Conventionally, in the field of rechargeable secondary batteries, aqueous batteries such as lead batteries, nickel-cadmium batteries, and nickel-hydrogen batteries have been mainstream. However, as electric devices become smaller and lighter, lithium ion secondary batteries having a high energy density have attracted attention, and their research, development, and commercialization are rapidly progressing. In addition, electric vehicles (EV) and hybrid electric vehicles (HEV) that assist part of driving with electric motors have been developed by each automobile manufacturer due to global warming and depleted fuel problems. Secondary batteries are being demanded.

  As a power source that meets such requirements, high-voltage non-aqueous lithium ion secondary batteries have attracted attention. In particular, a prismatic lithium ion secondary battery including a flat box type battery container is excellent in volumetric efficiency when an assembled battery is configured by stacking a plurality of secondary batteries. Therefore, HEV, EV, or other Demand is increasing as a power source mounted on equipment.

  For example, a secondary battery in which a wound electrode body is sealed in a flat rectangular case, and a part of the outer surface of the secondary battery that is partially in contact with the side surface of the maximum area (hereinafter referred to as a pressed surface) A secondary battery assembly that includes a contact member that restrains the secondary battery and the contact member, and the contact member partially compresses the pressed surface by the restraint of the restraint member. It is known (see Patent Document 1 below).

  In the secondary battery assembly described in Patent Document 1, the contact member includes a plurality of discrete contact portions that are in contact with the pressed surface, and a connection portion that connects the contact portions to each other. Have. In addition, the contact portion is formed to protrude from the coupling portion toward the pressed surface, and both offsets corresponding to a portion off the center in the winding axis direction of the wound electrode body. The pressed surface is more strongly compressed in a region, and the pressed surface is in a central region between the two offset regions corresponding to a central portion in the winding axis direction of the wound electrode body. The protruding height of the contact portion in the offset region is higher than the protruding height of the contact portion in the central region.

  In the secondary battery assembly described in Patent Literature 1, the pressed surface of the secondary battery is partially pressed by the contact member, and the pressing force on the pressed surface is stronger in the offset region than in the central region. I am doing so. As a result, the internal pressure of the secondary battery can be made uniform, and the surface pressure at the time of restraint can be made uniform in the secondary battery used at a high rate.

Japanese Patent No. 5187400

  The secondary battery assembly described in Patent Document 1 can equalize the surface pressure when the secondary battery is restrained in the central region and the offset region in the winding axis direction of the wound electrode body. There is a possibility that the surface pressure when the secondary battery is restrained becomes non-uniform in directions other than the rotational axis direction.

  This invention is made | formed in view of the said subject, The place made into the objective is providing the assembled battery which can equalize the surface pressure at the time of restraint of a square secondary battery.

  In order to achieve the above object, the assembled battery of the present invention is formed by laminating a plurality of secondary batteries each having a wound flat electrode group housed in a rectangular battery container in the thickness direction of the electrode group. An assembled battery in which a spacer is interposed between the electrodes, and the spacer expands in the thickness direction in the direction along the flat surface of the electrode group and in the direction intersecting the axial direction. It is characterized in that the closer it is to the top, the thinner the thickness.

  According to the assembled battery of the present invention, the battery expanded due to the expansion of the electrode group as compared with the case where the thickness of the spacer is uniform in the direction along the flat surface of the electrode group and in the direction intersecting the axial direction. It is possible to equalize the deviation of the surface pressure when the spacer comes into contact with the container, and to equalize the surface pressure when the prismatic secondary battery is restrained.

  Problems, configurations, and effects other than those described above will become apparent from the following description of embodiments.

The perspective view of a square secondary battery. The disassembled perspective view of the square secondary battery shown in FIG. The disassembled perspective view of the electrode group shown in FIG. The perspective view of the assembled battery which concerns on Embodiment 1 of this invention. The perspective view of the square secondary battery and intermediate cell holder shown in FIG. The disassembled perspective view of the square secondary battery and intermediate cell holder shown in FIG. The top view of the square secondary battery and spacer shown in FIG. Sectional drawing of the spacer which follows the BB line shown to FIG. 7A. Sectional drawing corresponding to FIG. 7B which shows the state at the time of expansion | swelling of a square secondary battery. The graph which shows the change of the thickness in the width direction at the time of expansion | swelling of a square secondary battery. The graph which shows the change of the thickness in the height direction at the time of expansion | swelling of a square secondary battery. The top view which shows the spacer of the assembled battery which concerns on Embodiment 2 of this invention. Sectional drawing of the spacer which follows the BB line shown to FIG. 9A. The top view which shows the spacer of the assembled battery which concerns on Embodiment 3 of this invention. FIG. 10B is a cross-sectional view of the spacer along the line BB shown in FIG. 10A. The top view which shows the spacer of the assembled battery which concerns on Embodiment 4 of this invention. FIG. 11B is a cross-sectional view of the spacer along the line BB shown in FIG. 11A. The top view which shows the spacer of the assembled battery which concerns on Embodiment 5 of this invention. Sectional drawing of the spacer which follows the BB line shown to FIG. 12A. The top view which shows the spacer of the assembled battery which concerns on Embodiment 6 of this invention. Sectional drawing of the spacer which follows the BB line shown to FIG. 13A.

[Embodiment 1]
Hereinafter, Embodiment 1 of the assembled battery of the present invention will be described in detail with reference to the drawings.

(Square secondary battery)
First, a prismatic secondary battery included in the secondary battery module according to the embodiment of the assembled battery of the present invention will be described.

  FIG. 1 is an external perspective view of a square secondary battery 100. FIG. 2 is an exploded perspective view of the power generation element 50 of the prismatic secondary battery 100 shown in FIG. FIG. 3 is an exploded perspective view of the electrode group 40 shown in FIG.

  The prismatic secondary battery 100 includes a flat box type battery container 2. The battery container 2 includes a battery lid 3 and a battery can 4. The battery can 4 is a bottomed rectangular tube-shaped container having an opening 4a and an open upper end, and is manufactured, for example, by deep drawing a metal material. The battery lid 3 is a rectangular plate-like member that covers the opening 4a of the battery can 4 in a plan view, and is joined by, for example, laser welding over the entire circumference of the opening 4a to seal the opening 4a. ing. The battery can 4 and the battery lid 3 are made of a metal material such as aluminum or aluminum alloy, for example.

  The battery case 2 is formed in a flat box shape having a rectangular parallelepiped shape by a bottomed rectangular tube-shaped battery can 4 and a rectangular plate-like battery lid 3 in a plan view, and has a rectangular upper end surface 2a and a substantially equal area. It has a lower end surface 2b, a pair of rectangular wide side surfaces 2c having a large area, and a pair of narrow side surfaces 2d having a small area.

  In the following description, an XYZ orthogonal coordinate system shown in each drawing may be used as necessary. The X-axis direction is a direction parallel to the width direction of the battery container 2 along the long side direction of the upper end surface 2a or the lower end surface 2b. The Y-axis direction is a direction parallel to the thickness direction of the battery case 2 along the short side direction of the upper end surface 2a or the lower end surface 2b. The Z-axis direction is a direction parallel to the height direction of the battery case 2 perpendicular to the upper end surface 2a or the lower end surface 2b.

  Inside the battery case 2, an electrode group 40 is accommodated via an insulating sheet (not shown). The electrode group 40 is a flat wound electrode group in which a positive electrode 41 and a negative electrode 42 which are stacked via separators 43 and 44 are wound around a shaft core (not shown) and formed into a flat shape. The electrode group 40 is disposed inside the battery case 2 so that the axial direction D is parallel to the width direction (X-axis direction) of the battery case 2. That is, the thickness direction of the battery container 2 and the thickness direction of the electrode group 40 are the same.

  The electrode group 40 includes a pair of curved portions 40c and a pair of flat portions 40b that face the lower end surface 2b and the upper end surface 2a of the battery case 2, respectively. The flat portion 40 b has a pair of flat surfaces 40 f that face a pair of wide side surfaces 2 c along the width direction of the battery case 2. The positive electrode 41, the negative electrode 42, and the separators 43 and 44 are stacked in a flat state in the flat portion 40b, and are stacked in a semi-cylindrical shape in the bending portion 40c.

  The positive electrode 41 has a positive electrode mixture layer 41b formed on both front and back surfaces of a positive electrode metal foil 41a made of, for example, aluminum foil. The positive electrode mixture layer 41b is coated on the positive electrode metal foil 41a, leaving an exposed portion 41c where the positive electrode metal foil 41a is exposed on one side edge.

  The negative electrode 42 has a negative electrode mixture layer 42b formed on both front and back surfaces of a negative electrode metal foil 42a made of, for example, copper foil. The negative electrode mixture layer 42b is coated on the negative electrode metal foil 42a, leaving an exposed portion 42c where the negative electrode metal foil 42a is exposed on one side edge.

The positive electrode 41 can be manufactured as follows, for example. First, the layered lithium nickel cobalt manganese oxide as a positive electrode active material (chemical formula _{Li (Ni x Co y Mn 1} -xy) O 2) relative to 100 parts by weight of scaly graphite and acetylene black and forming a total of 10 parts by weight as the conductive material 4 parts by weight of polyvinylidene fluoride (hereinafter referred to as PVDF) is added as an adhesive. To this, N-methylpyrrolidone (hereinafter referred to as NMP) is added as a dispersion solvent and kneaded to produce a positive electrode slurry. Next, the positive electrode mixture layer 41b is formed by applying the positive electrode slurry, for example, on both surfaces of an aluminum foil having a thickness of 15 μm, leaving the exposed foil portions 41c. Thereafter, through each step of drying, pressing, and cutting, for example, a positive electrode 41 having a thickness of the positive electrode active material application portion that does not include an aluminum foil (total of both front and back surfaces) of 70 μm can be obtained.

  The negative electrode mixture layer 42b can be manufactured, for example, as follows. First, an aqueous CMC solution is added as a thickener to 100 parts by weight of graphitic carbon powder as a negative electrode active material, and after mixing, 1 part by weight of SBR is added as a binder, and the viscosity is adjusted after kneading. Make a slurry. Next, the negative electrode mixture layer 42b is formed by applying the negative electrode slurry, for example, on both surfaces of a copper foil having a thickness of 10 μm, leaving the foil exposed portions 42c. Thereafter, through each step of drying, pressing, and cutting, for example, the negative electrode 42 having a negative electrode active material application portion that does not include a copper foil (total of both front and back surfaces) of 40 μm can be obtained.

The positive electrode active material is natural graphite capable of inserting and removing lithium ions, various artificial graphite materials, carbonaceous materials such as coke, and compounds such as Si and Sn (for example, SiO, TiSi _2, etc.), or The composite material thereof may be used, and the particle shape is not particularly limited to a scale shape, a spherical shape, a fiber shape, a lump shape, or the like. In addition, the negative electrode active material includes other lithium manganate having a spinel crystal structure, lithium manganese composite oxide partially substituted or doped with a metal element, lithium cobaltate or lithium titanate having a layered crystal structure, and these A lithium-metal composite oxide partially substituted or doped with a metal element may be used. The binder is polytetrafluoroethylene (PTFE), polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, styrene butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethyl cellulose, various latexes, acrylonitrile, vinyl fluoride, fluorine. Polymers such as vinylidene fluoride, propylene fluoride, chloroprene fluoride, and acrylic resins, and mixtures thereof can be used.

  In order to manufacture the electrode group 40, the tip portions of the separators 43 and 44 are welded to a shaft core (not shown) and wound so that the positive electrode 41, the separator 43, the negative electrode 42, and the separator 44 overlap in this order. At this time, the winding start side end portion of the positive electrode 41 is positioned at the inner side of the wound electrode group 40 with respect to the winding start side end portion of the negative electrode 42 than the winding start side end portion of the negative electrode 42. The electrode 42 is wound around the axial center side from the winding start side end. As the shaft core, for example, a structure in which a resin sheet having higher bending rigidity than any of the positive electrode metal foil 41a, the negative electrode metal foil 42a, and the separators 43 and 44 is wound can be used.

  Here, a direction parallel to the axis of the electrode group 40, that is, a direction parallel to the width direction of the positive electrode 41 and the negative electrode 42 is defined as an axial direction D. In this case, the exposed portion 41c of the positive electrode and the exposed portion 42c of the negative electrode are arranged so as to be positioned on the side edges on the one side and the other side in the axial direction D of the electrode group 40. That is, the positive electrode 41 and the negative electrode 42 are wound so that the foil exposed portions 41c and 42c are positioned at one end and the other end in the axial direction D of the electrode group 40, respectively.

  The width of the negative electrode mixture layer 42b, that is, the length in the axial direction D is formed wider than the width of the positive electrode mixture layer 41b. The width of the first separator 43 is such that the exposed portion 41 c of the positive electrode 41 is exposed from the first separator 43 at one side edge of the electrode group 40. The width of the second separator 44 is set such that the exposed portion 42 c of the negative electrode 42 is exposed from the second separator 44 at the other side edge of the electrode group 40.

  A hollow portion 40a is formed on the winding start end portion of the electrode group 40, in other words, on the shaft core side. Further, the winding end end of the electrode group 40 has a separator 44 on the outermost periphery and a negative electrode 42 on the inner side. Accordingly, the positive electrode mixture layer 41b is overlapped with the negative electrode mixture layer 42b through the separators 43 and 44 in the width direction over the entire length from the winding start end portion to the winding end end portion.

  In the electrode group 40, the foil exposed portions 41c and 42c at one end and the other end in the axial direction D are bundled in two in the thickness direction at the flat portions 40b and 40b on both sides of the cavity portion 40a, respectively. It joins to the current collecting plates 21 and 31 in the joining parts 40d and 40d shown by the hatched area.

  The current collector plate 21 constituting the positive electrode terminal 60 is formed by, for example, bending a plate-shaped metal plate, and is attached to the flat plate-like main body portion 22 along the lower surface of the battery lid 3. It has a pair of support parts 22a bent at a substantially right angle downward. Flat plate-like joining pieces 23 are formed at the tips of the pair of support portions 22a. Each joining piece 23 is joined to the joining part 40d of the foil exposed part 41c bundled in two in the thickness direction of the electrode group 40 by, for example, ultrasonic welding. The current collecting plate 21 is made of, for example, aluminum or an aluminum alloy.

  Similarly, the current collector plate 31 constituting the negative electrode terminal 70 includes a flat plate-like main body portion 32 attached along the lower surface of the battery lid 3 and a pair of support portions bent at right angles on both sides of the main body portion 32. 32a. Flat plate-like joining pieces 33 are formed at the tips of the pair of support portions 32a. Each joining piece 33 is joined to the joining portion 40d of the foil exposed portion 42c bundled in two in the thickness direction of the electrode group 40 by, for example, ultrasonic welding. The current collector plate 31 is made of, for example, copper or a copper alloy.

  The current collector plates 21, 31 are fixed to the battery lid 3 via a gasket (not shown), and the electrode group 40 is joined to the current collector plates 21, 31, so that the electrode group 40 passes through the current collector plates 21, 31. The battery lid 3 is fixed. The battery lid 3 is provided with a positive electrode terminal 60 including the current collector plate 21 and a negative electrode terminal 70 including the current collector plate 31.

  The positive terminal 60 includes a bolt 61, a connection terminal 62, an external terminal 63, an insulator 64, a gasket, and a current collector plate 21, which are integrally fixed to the battery lid 3. In this state, the current collector plate 21, the connection terminal 62, and the external terminal 63 are electrically connected to each other and insulated from the battery lid 3 by the insulator 64 and the gasket.

  Similarly, the negative terminal 70 includes a bolt 71, a connection terminal 72, an external terminal 73, an insulator 74, a gasket, and a current collector plate 31, which are integrally fixed to the battery lid 3. In this state, the current collector plate 31, the connection terminal 72, and the external terminal 73 are electrically connected to each other and insulated from the battery lid 3 by the insulator 74 and the gasket. The insulators 64 and 74 and the gasket are made of an insulating resin material such as polybutylene terephthalate, polyphenylene sulfide, and perfluoroalkoxy fluororesin.

  As shown in FIG. 2, the lid assembly 10 is configured by providing the battery lid 3 with the positive electrode terminal 60 and the negative electrode terminal 70. Further, the foil exposed portions 41c and 42c of the electrode group 40 are bundled in two in the thickness direction at the flat portions 40b and 40b on both sides of the cavity portion 40a, respectively, and the joint portions 40d and 40d are connected to the current collector plate 21, The power generation element 50 is configured by being joined to 31. The power generation element 50 is inserted into the inside of the battery can 4 from the opening 4a of the battery can 4 shown in FIG. 1, and the battery lid 3 is sealed and welded to the opening 4a of the battery can 4 over the entire circumference. As a result, the electrode group 40 and the current collecting plates 21 and 31 are accommodated and arranged at predetermined positions inside the battery container 2.

  The battery cover 3 is provided with a gas discharge valve 13 between the positive electrode terminal 60 and the negative electrode terminal 70. The gas discharge valve 13 is formed by partially thinning the battery lid 3 by press working. In addition, you may provide the gas exhaust valve 13 by joining a thin-film-like metal member to the through-hole provided in the battery cover 3, for example by laser welding. The gas discharge valve 13 generates heat when the square secondary battery 100 generates heat due to an abnormality such as overcharge, and when the pressure in the battery container rises and reaches a predetermined pressure, the gas discharge valve 13 is opened and gas is discharged from the inside. By discharging, the pressure in the battery container is reduced.

Further, the battery lid 3 is provided with a liquid injection hole 3 a for injecting an electrolyte into the battery container 2. The liquid injection hole 3a is sealed by the liquid injection stopper 11 after the electrolyte solution is injected. As the non-aqueous electrolyte, for example, lithium hexafluorophosphate (LiPF ₆ ) was dissolved at a concentration of 1 mol / liter in a mixed solution in which ethylene carbonate and dimethyl carbonate were mixed at a volume ratio of 1: 2. Things can be used.

(Battery)
Next, as one embodiment of the assembled battery of the present invention, a plurality of prismatic secondary batteries 100 are arranged with spacers in the thickness direction (Y-axis direction) of the battery container 2, that is, in the thickness direction of the flat electrode group 40. The secondary battery modules stacked in this manner will be described in detail.

  FIG. 4 is an external perspective view of the secondary battery module 200 of the present embodiment. FIG. 5 is a perspective view showing a state in which the pair of intermediate cell holders 111, 111 and the square secondary battery 100 sandwiched therebetween are removed from the module 200 shown in FIG. 6 is an exploded perspective view showing a state in which the pair of intermediate cell holders 111, 111 are removed from the rectangular secondary battery 100 shown in FIG.

  The module 200 includes a plurality of rectangular secondary batteries 100 stacked in the thickness direction (Y direction), and a cell holder 91 that holds each rectangular secondary battery 100 in a stacked state. The cell holder 91 can be made of, for example, a resin material such as glass epoxy resin, polypropylene, or polybutylene terephthalate resin, or a metal material such as aluminum, copper, or stainless steel. For example, when the cell holder 91 is manufactured by injection molding using a resin material, various shapes to be described later can be easily manufactured by processing the shape of the mold.

  The cell holder 91 includes a plurality of intermediate cell holders 92 and a pair of end cell holders 93. Intermediate cell holder 92 is interposed between prismatic secondary batteries 100 adjacent to each other. The end cell holders 93 are arranged at both ends in the stacking direction of the plurality of prismatic secondary batteries 100 stacked in the thickness direction via the intermediate cell holder 92, and the prismatic secondary battery 100 is interposed between the opposing intermediate cell holders 92. Hold. The end cell holder 93 has a configuration in which the intermediate cell holder 92 is divided in half by a plane parallel to the wide side surface 2 c of the prismatic secondary battery 100. Therefore, in the following description, the configuration of the intermediate cell holder 92 will be described in detail, and the description of the configuration of the end cell holder 93 will be omitted as appropriate.

  The intermediate cell holder 92 is opposed to the pair of side plates 111 and 111 facing the narrow side surfaces 2d and 2d on both sides in the width direction (X-axis direction) of the battery case 2 of the square secondary battery 100, and the lower end surface 2b of the battery case 2. A bottom plate 112 is provided. As shown in FIG. 4, since the intermediate cell holder 92 is disposed between the two rectangular secondary batteries 100, 100, it passes through the middle of the two rectangular secondary batteries 100, 100 and has a wide side 2 c of the battery container 2. Have a plane-symmetric shape on a plane parallel to the surface. That is, the side plate 111 and the bottom plate 112 of the intermediate cell holder 92 are formed on the narrow side surfaces 2d and 2d and the lower end surfaces 2b and 2b of the battery containers 2 and 2 of the two rectangular secondary batteries 100 and 100 disposed on both sides of the intermediate cell holder 92. On the other hand, the battery container 2 faces about half of the thickness direction (Y-axis direction).

  The pair of side plates 111, 111 face each other at both ends in the width direction of the battery container 2, and extend in the thickness direction of the battery container 2 with a width that reaches half of the thickness of the battery container 2. The bottom plate 112 is in a direction perpendicular to the lower end surface 2b of the battery case 2, that is, a lower end portion in the height direction (Z-axis direction) of the battery case 2 and has a width reaching half the thickness of the battery case 2. It extends in the width direction and connects the lower ends of the pair of side plates 111, 111. In addition, the pair of opposed intermediate cell holders 92 and 92 disposed on both sides in the thickness direction of the battery container 2 have the end portions of the side plates 111 and 111 and the bottom plates 112 and 112 abutted or slightly spaced from each other. Thus, a space for holding the prismatic secondary battery 100 is formed between them.

  A pair of side plates 111 and 111 facing in the width direction of the battery case 2 are connected by a plurality of spacers 101, 102, and 103 extending in the width direction of the wide side surface 2c. More specifically, the pair of side plates 111, 111 includes a lower end spacer 101 that connects these lower end portions, an upper end spacer 102 that connects these upper end portions, and a plurality of intermediate portions that connect these intermediate portions. The spacer 103 is connected.

  The lower end spacer 101 is connected to the bottom plate 112 at the lower end. The width in the Z-axis direction of the upper end spacer 102 corresponds to the dimension in the Z-axis direction from the curved portion 40c on the upper end surface 2a side of the electrode group 40 built in the battery case 2 to the lower position of the battery lid 3, The width of the other spacers 101 and 103 is wider. The interval between the lower end spacer 101 and the intermediate spacer 103 and the interval between the upper end spacer 102 and the intermediate spacer 103 are narrower than the interval between the intermediate spacers 103.

  The spacers 101, 102, 103 of the intermediate cell holder 92 are disposed between the wide side surfaces 2 c, 2 c of the battery containers 2, 2 of the two adjacent prismatic secondary batteries 100, 100, and are disposed to face the wide side surfaces 2 c, 2 c. Is done. The spacers 101, 102, 103 of the end cell holder 93 are arranged to face the wide side surface 2c of the battery case 2 of the prismatic secondary battery 100 arranged at both ends in the stacking direction.

  The side plate 111 has a first opening 111a and a second opening 111b. The first opening 111a is located between the lower end spacer 101 and the intermediate spacer 103 in the height direction (Z-axis direction) of the battery case 2 and between the upper end spacer 102 and the intermediate spacer 103. It is formed at the position. The second opening 111b is formed at a position between the intermediate spacers 103 in the Z direction. The first opening 111a and the second opening 111b have the same opening width in the thickness direction (Y-axis direction) of the battery case 2. The opening height in the Z-axis direction of each opening 111a, 111b is larger in the second opening 111b than in the first opening 111a, corresponding to the distance between the spacers 101, 102, 103. Yes.

  The spacers 101, 102, and 103 are arranged at intervals in the height direction (Z-axis direction) of the battery container 2, and thereby a plurality of slits extending in the width direction along the wide side surface 2 c of the battery container 2. 114 and 115 are formed. The width in the Z-axis direction is between the lower end spacer 101 and the intermediate spacer 103 and between the upper end spacer 102 and the intermediate spacer 103 in accordance with the interval between the spacers 101, 102, and 103. A relatively narrow first slit 114 is formed. In addition, a second slit 115 having a relatively wide width in the Z-axis direction is formed between the intermediate spacers 103. The first slit 114 communicates with the first opening 111a of the pair of side plates 111, and the second slit 115 communicates with the second opening 111b of the pair of side plates 111. Thereby, the cooling medium is allowed to pass through the slits 114 and 115 so that the wide side surface 2c of the battery container 2 of the rectangular secondary battery 100 can be cooled.

  By interposing the intermediate cell holder 92 having the above configuration, a plurality of prismatic secondary batteries 100 are stacked in the thickness direction, and the end cell holder 93 is disposed outside the prismatic secondary battery 100 at both ends in the stacking direction. A secondary battery module (assembled battery) 200 is obtained in which a plurality of prismatic secondary batteries 100 are stacked with spacers 101, 102, 103 interposed in the thickness direction.

  Although illustration is omitted, a pair of end plates are disposed outside the pair of end cell holders 93, 93, and the pair of end plates are connected by a metal strip. Accordingly, the plurality of prismatic secondary batteries 100 are held and fixed by the cell holder 91 including the intermediate cell holder 92 and the end cell holder 93. Further, the bolts 61 and 71 of the adjacent rectangular secondary batteries 100 and 100 of the module 200 and the bolts 61 and 71 of the negative terminal 70 are inserted into the through holes of the bus bar and fixed with nuts, so that the rectangular secondary of the module 200 is fixed. The battery 100 can be connected in series. As a result, the module 200 supplies the electric power stored in each rectangular secondary battery 100 to an external device such as a motor, and supplies the electric power supplied from an external power source such as a generator to each rectangular secondary battery 100. Can be stored.

  In the square secondary battery 100, the electrode group 40 expands and contracts due to charging and discharging. When the electrode group 40 expands, when the electrode group 40 comes into contact with the inside of the wide side surface 2c of the battery container 2 via an insulating sheet, the battery container 2 is pushed outward and the battery container 2 is moved to the electrode group 40. In some cases, it expands into a shape corresponding to the expanded shape. In this case, the intermediate spacer 103 that faces the wide side surface 2c of the battery container 2 contacts the wide side surface 2c, and the resistance against the expansion of the electrode group 40 acts on the wide side surface 2c, thereby suppressing the expansion of the battery container 2. Is done. At this time, if the surface pressure of the intermediate spacer 103 in contact with the wide side surface 2c becomes uneven, the performance and life of the prismatic secondary battery 100 may be deteriorated. Therefore, it is required to make the surface pressure of the intermediate spacer 103 in contact with the wide side surface 2c of the battery container 2 uniform.

(Spacer)
Hereinafter, the intermediate spacer 103 included in the secondary battery module of the present embodiment will be described in detail. In the following description, the intermediate spacer 103 may be simply referred to as the spacer 103.

  FIG. 7A is a plan view of prismatic secondary battery 100 sandwiched between a pair of cell holders 92, 92 shown in FIG. FIG. 7B is a cross-sectional view of the cell holders 92 and 92 taken along line BB in FIG. 7A. FIG. 7C shows a state in which the battery case 2 of the square secondary battery 100 is expanded in the cross-sectional view shown in FIG. 7B. 7A to 7C, the side plate 111 and the bottom plate 112 of the cell holder 92 are not shown. 7A to 7C, the expansion amount of the battery container 2, the thickness of the spacer 103, and the like are exaggerated from the actual values for easy understanding.

  In the module 200 of the present embodiment, four spacers 103 are disposed between the upper end spacer 102 and the lower end spacer 101 in the height direction (Z-axis direction) of the battery case 2. Each of the four spacers 103 includes a contact portion 103A or 103B. Accordingly, the plurality of contact portions 103 </ b> A and 103 </ b> B of the spacer 103 are opposed to the wide side surface 2 c of the battery container 2 with an interval in the height direction of the battery container 2.

  The spacers 103, 103 disposed at positions near the pair of curved portions 40 c of the electrode group 40 housed inside the battery container 2, that is, at positions near the upper end surface 2 a and the lower end surface 2 b of the battery container 2, are contact portions. The thickness Ta of 103A is relatively thick. On the other hand, in the height direction (Z-axis direction) of the battery case 2, the spacers 103, 103 disposed in the middle part of the flat part 40 b of the electrode group 40, that is, in the middle part of the battery case 2, The thickness Tb is relatively thin.

  In short, the plurality of spacers 103 have a plurality of contact portions 103A and 103B in the Z-axis direction, and the thickness Tb is the smallest between the contact portions 103A and 103A arranged at both ends in the Z-axis direction. A contact portion 103B is disposed. In other words, the contact portions 103A and 103B having a thickness Tb thinner than the pair of contact portions 103A and 103A are disposed between the pair of contact portions 103A and 103A.

  Thereby, in the height direction (Z-axis direction) of the battery case 2, the spacer 103 overlaps with the flat portion 40 b and the thickness direction (Y-axis direction) of the battery case 2 at a position close to the pair of curved portions 40 c of the electrode group 40. , 103 and the wide side 2c of the battery case 2 are relatively narrow. On the other hand, in the Z-axis direction, the gap Gb between the intermediate portion of the flat portion 40b of the electrode group 40 and the spacers 103, 103 overlapping in the Y-axis direction and the wide side surface 2c of the battery case 2 is relatively wide.

  The contact portions 103A and 103B are contact surfaces 103a and 103b that contact the wide side surface 2c of the battery container 2 when the battery container 2 of the rectangular secondary battery 100 expands in the thickness direction (Y-axis direction). have. As shown in FIG. 7A, the contact surfaces 103a and 103b are arranged such that, in the width direction (X-axis direction) of the battery case 2, the closer to the center of the battery case 2, the wider the gaps Ga and Gb from the wide side surface 2c. Curved in a curve. Thereby, in the X-axis direction, the thicknesses Ta and Tb of the contact portions 103A and 103B are made thinner as the spacer 103 is closer to the center of the battery case 2.

  In the module 200 of the present embodiment, the thickness of the spacer 103, that is, the thicknesses Ta and Tb of the contact portions 103 </ b> A and 103 </ b> B is determined based on the expanded shape of the battery container 2 of the prismatic secondary battery 100. More specifically, as shown in FIG. 7C, the electrode group 40 inside the battery container 2 expands due to charging / discharging of the square secondary battery 100, and an insulating sheet is interposed inside the wide side surface 2 c of the battery container 2. When contacted, the battery container 2 is pushed outward and the battery container 2 may expand to a shape corresponding to the expansion shape of the electrode group 40. The thicknesses Ta and Tb of the contact portions 103A and 103B of the spacer 103 are determined based on the expanded shape of the electrode group 40 in the battery case 2 at this time.

  8A is a graph showing changes in the thickness of the battery case 2 in the width direction (X-axis direction) of the battery case 2 when the rectangular secondary battery 100 is expanded in the cross section taken along the line F8a-F8a shown in FIG. is there. 8B is a graph showing a change in the thickness of the battery case 2 in the height direction (Z-axis direction) of the battery case 2 when the rectangular secondary battery 100 is expanded in the cross section taken along the line F8b-F8b shown in FIG. It is.

  As shown in FIG. 8A, the thickness that is the dimension in the Y-axis direction of the battery container 2 is greater in the region X2 in the intermediate portion in the width direction than in the regions X1 and X3 on both sides in the width direction (X-axis direction). That is thicker. Further, the battery container 2 has the largest thickness in the vicinity of the center of the region X2 in the intermediate portion in the width direction. Further, as shown in FIG. 8B, the thickness of the battery case 2 is greater in the region Z2 in the middle in the height direction than in the regions Z1 and Z3 above and below in the height direction (Z-axis direction). Is getting thicker. Further, the battery container 2 has the largest thickness in the vicinity of the center of the region Z2 in the middle in the height direction.

  The thickest part of the battery case 2 shown in FIGS. 8A and 8B is such that the wide side surface 2c of the battery case 2 is in the thickness direction (Y-axis direction) with the top 40p of the expanded shape of the electrode group 40 shown in FIG. It is a position that overlaps.

  In the electrode group 40, the foil exposed portions 41c and 42c are bundled and joined at both ends in the width direction to form joined portions 40d and 40d. Therefore, the electrode group 40 is less likely to expand at both ends in the width direction, and the center portion of the flat portion 40b far from the joint portion 40d is most likely to expand. Further, in the electrode group 40, the upper and lower curved portions 40c, 40c are difficult to expand in the direction along the flat surface 40f and intersecting the axial direction D, specifically, the height direction of the battery case 2, and the curved portion The central part of the flat part 40b far from 40c, 40c tends to expand. Further, in the battery case 2, the peripheral portion of the wide side surface 2c is hardly deformed, and the center portion is easily deformed. Due to these complex factors, the expanded top 40p of the electrode group 40 is formed at the center of the flat portion 40b of the electrode group 40.

  In the present embodiment, in the height direction (Z-axis direction) of the battery case 2 that intersects the flat surface 40f of the electrode group 40 and intersects the axial direction D, the joint portions 40d and 40d are the foil exposed portions 41c. , 42c. In this case, the expansion-shaped top portion 40p of the electrode group 40 is formed at a position where the position in the Z-axis direction overlaps the position in the Z-axis direction of the joint portions 40d and 40d when viewed in the axial direction D, that is, the X-axis direction. .

  Therefore, as shown in FIGS. 7A to 7C, the spacer 103 has thicknesses Ta and Tb of the contact portions 103A and 103B in the width direction (X-axis direction) of the battery case 2 along the axial direction D of the electrode group 40. However, the closer to the top 40p of the electrode group 40, the thinner. In the spacer 103, the thicknesses Ta and Tb of the contact portions 103 </ b> A and 103 </ b> B in the direction along the flat surface 40 f of the electrode group 40 of the electrode group 40 and in the Z-axis direction intersecting the axial direction D are It is made thinner as it is closer to the top 40p of the expanded shape. The spacer 103 is thinnest at the position in the Z-axis direction that overlaps the position in the Z-axis direction of the joint portion 40 d of the electrode group 40. That is, the spacer 103 has a three-dimensional shape corresponding to the expanded shape of the electrode group 40.

  Thereby, the spacer 103 has a three-dimensional shape corresponding to the three-dimensional expansion shape of the electrode group 40, and the battery container 2 is based on the expansion shape of the electrode group 40 in both the X-axis direction and the Z-axis direction. It can be allowed to expand into shape. Therefore, according to the module 200 of the present embodiment, the battery case 2 expands to a shape corresponding to the three-dimensional expansion shape of the electrode group 40 as the prismatic secondary battery 100 is charged and discharged. In addition, the surface pressure of the spacer 103 in contact with the wide side surface 2c can be made uniform.

  In addition, since the spacer 103 facing the wide side surface 2c of the battery case 2 contacts the wide side surface 2c and a resistance against the expansion of the electrode group 40 acts on the wide side surface 2c, the expansion of the battery case 2 is suppressed. At this time, since the surface pressure of the spacer 103 in contact with the wide side surface 2c is made uniform, deterioration of the performance and life of the prismatic secondary battery 100 can be prevented.

  In addition, a plurality of spacers 103 are arranged at intervals in the height direction (Z-axis direction) of the battery case 2, and a plurality of contact portions 103 </ b> A and 103 </ b> B where the plurality of spacers 103 contact the wide side surface 2 c of the battery case 2. have. Therefore, the slit 115 is formed between the contact portions 103A and 103B of the spacers 103, and the wide side surface 2c of the battery case 2 can be cooled by circulating the cooling medium.

  In addition, the battery container 2 has an expanded shape of the electrode group 40 by disposing the contact portions 103B having a thickness Tb thinner than the contact portions 103A and 103A disposed at both ends in the Z-axis direction. Even in the case of expansion to a corresponding shape, the surface pressure of the spacer 103 contacting the wide side surface 2c in the Z-axis direction can be made uniform.

  As described above, according to the battery module 200 of the present embodiment, the battery container 200 is restrained when the prismatic secondary battery 100 is restrained by reducing the thickness of the spacer 103 as it is closer to the top 40P of the expanded shape of the electrode group 40. The surface pressure acting on the second wide side surface 2c can be made uniform, and the performance and life of the prismatic secondary battery 100 can be prevented from deteriorating.

[Embodiment 2]
Next, Embodiment 2 of the assembled battery of the present invention will be described with reference to FIGS. 9A and 9B with reference to FIGS. 1 to 6 and FIGS. 8A and 8B.

  FIG. 9A is a plan view showing the spacer 103 of the secondary battery module of the present embodiment corresponding to FIG. 7A of the first embodiment. FIG. 9B is a cross-sectional view of the spacer 103 along the line BB in FIG. 9A.

  The secondary battery module of this embodiment is different from that of Embodiment 1 in that the contact surfaces 103c and 103d of the contact portions 103C and 103D of the spacer 103 are inclined so as to follow the expanded shape of the electrode group 40. Different from the secondary battery module 200. The upper end spacer 102 and the lower end spacer 101 are connected to the upper and lower spacers 103. Since the other points of the secondary battery module of the present embodiment are the same as those of the secondary battery module 200 of the first embodiment, the same parts are denoted by the same reference numerals and description thereof is omitted.

  In the present embodiment, the contact surfaces 103c and 103d of the spacer 103 facing the wide side surface 2c of the battery container 2 are formed in the height direction (Z-axis direction) and the width direction (X In the axial direction, the electrode group 40 is inclined so as to follow the expanded shape. More specifically, the contact surfaces 103c and 103d of the contact portions 103C and 103D are inclined at an inclination angle with respect to the X-axis direction and the Z-axis direction of the wide side surface 2c of the battery case 2 expanded according to the expanded shape of the electrode group 40. It is inclined at the corresponding angle. Accordingly, the contact portions 103C and 103D are made thinner in the X-axis direction and the Z-axis direction as the thicknesses Tc and Td become closer to the expanded top portion 40p of the electrode group 40, respectively.

  According to the secondary battery module of this embodiment, not only the same effect as the secondary battery module 200 of Embodiment 1 is obtained, but also the contact surfaces 103c and 103d of the contact portions 103C and 103D of the spacer 103 are X The surface pressure when the spacer 103 abuts against the wide side surface 2c of the battery container 2 can be made more uniform than when parallel to the axial direction or the Z-axis direction. Further, since the upper end spacer 102 and the lower end spacer 101 are connected to the upper and lower spacers 103, the cell holder 92 can be easily manufactured.

[Embodiment 3]
Next, Embodiment 3 of the assembled battery of the present invention will be described with reference to FIGS. 10A and 10B with reference to FIGS. 1 to 6 and FIGS. 8A and 8B.

  10A is a plan view showing the spacer 103 of the secondary battery module of the present embodiment corresponding to FIG. 7A of Embodiment 1. FIG. 10B is a cross-sectional view of the spacer 103 taken along line BB in FIG. 10A.

  In the secondary battery module of the present embodiment, the joint portion 40d of the electrode group 40 housed in the battery container 2 of the rectangular secondary battery 100 is formed at a position closer to the upper end surface 2a than the lower end surface 2b of the battery container 2. The contact portions 103E, 103F, 103G, and 103H are different from the secondary battery module 200 of Embodiment 1 in that the thicknesses Te, Tf, Tg, and Th are different. Since the other points of the secondary battery module of the present embodiment are the same as those of the secondary battery module 200 of the first embodiment, the same parts are denoted by the same reference numerals and description thereof is omitted.

  Since the electrode group 40 hardly expands at the joint 40d, when the joint 40d of the electrode group 40 is formed at a position closer to the upper end surface 2a than the lower end surface 2b of the battery container 2, as shown in FIG. The expanded top 40p of the electrode group 40 is positioned closer to the lower end surface 2b of the battery case 2 than the joint 40d. Therefore, in the present embodiment, the thickness Tg of the contact portion 103G of the spacer 103 closest to the expanded top portion 40p of the electrode group 40 located on the lower end surface 2b side of the battery case 2 relative to the joint portion 40d is made the smallest. ing.

  In addition, the thickness Te of the contact portion 103E of the spacer 103 close to the curved portion 40c on the upper end surface 2a side of the battery case 2 farthest from the expanded top portion 40p of the electrode group 40 is made thickest. The thickness Tf of the contact portion 103F of the spacer 103 closer to the expanded top portion 40p of the electrode group 40 than the spacer 103 is made thinner than the thickness Te of the contact portion 103E on the upper end surface 2a side of the battery container 2. ing. The thickness Th of the contact portion 103H closer to the expanded top portion 40p of the electrode group 40 than the spacer 103 and closer to the curved portion 40c on the lower end surface 2b side of the battery case 2 is equal to the thickness Tf of the contact portion 103F. It is thinner than.

  In this way, the spacer 103 is the top of the expanded shape of the electrode group 40 in which the thickness Te, Tf, Tg, Th in the thickness direction of the battery container 2 expands in the thickness direction in the height direction of the battery container 2. The closer it is to 40p, the thinner it is. Therefore, according to the battery module of the present embodiment, the joint portion 40d of the electrode group 40 is formed at a position closer to the upper end surface 2a than the lower end surface 2b of the battery container 2, and the expanded top portion 40p of the electrode group 40 is joined. Even if it is a case where it is located in the lower end surface 2b side of battery case 2 rather than part 40d, the same effect as battery module 200 of Embodiment 1 can be acquired.

  In addition, the length of the current collector plates 21 and 31 in the height direction of the battery container 2 can be increased by forming the joint 40d of the electrode group 40 at a position closer to the upper end face 2a than to the lower end face 2b of the battery container 2. Can be shortened. Therefore, it is possible not only to improve the performance of the prismatic secondary battery 100 by reducing the electric resistance of the current collector plates 21 and 31, but also to reduce the material cost.

  Further, also in the secondary battery module of the present embodiment, as in the second embodiment, the spacer 103 has contact surfaces 103e, 103f, 103g of the contact portions 103E, 103F, 103G, and 103H facing the battery container 2. 103 h may be inclined with respect to the height direction and the width direction of the battery case 2 so as to follow the expanded shape of the electrode group 40. Thereby, the effect similar to Embodiment 2 can be acquired.

[Embodiment 4]
Next, Embodiment 4 of the assembled battery of the present invention will be described with reference to FIGS. 11A and 11B with reference to FIGS. 1 to 6 and FIGS. 8A and 8B.

  FIG. 11A is a plan view showing the spacer 103 of the assembled battery of the present embodiment corresponding to FIG. 7A of the first embodiment. FIG. 11B is a cross-sectional view of the spacer 103 taken along the line BB in FIG. 11A.

  In the secondary battery module of the present embodiment, the joining portion 40d of the electrode group 40 accommodated in the battery container 2 of the rectangular secondary battery 100 is formed at a position closer to the lower end surface 2b than to the upper end surface 2a of the battery container 2. The contact portions 103I, 103J, 103K and 103L are different from the secondary battery module 200 of the first embodiment in that the thicknesses thereof are different. Since the other points of the secondary battery module of the present embodiment are the same as those of the secondary battery module 200 of the first embodiment, the same parts are denoted by the same reference numerals and description thereof is omitted.

  Since the electrode group 40 is difficult to expand at the joint 40d, when the joint 40d of the electrode group 40 is formed at a position closer to the lower end surface 2b than the upper end surface 2a of the battery container 2, as shown in FIG. The expanded top 40p of the electrode group 40 is positioned closer to the upper end surface 2a of the battery case 2 than the joint 40d. Therefore, in the present embodiment, the thickness Tj of the contact portion 103J of the spacer 103 closest to the expanded top portion 40p of the electrode group 40 located on the upper end surface 2a side of the battery case 2 relative to the joint portion 40d is made the thinnest. ing.

  Further, the thickness Tl of the contact portion 103L of the spacer 103 close to the curved portion 40c on the lower end surface 2b side of the battery case 2 farthest from the expanded top portion 40p of the electrode group 40 is set to be the largest. The thickness Tk of the contact portion 103K of the spacer 103 closer to the expanded top portion 40p of the electrode group 40 than the spacer 103 is made thinner than the thickness Tl of the contact portion 103L on the lower end surface 2b side of the battery container 2. ing. The thickness Ti of the contact portion 103I closer to the expanded top portion 40p of the electrode group 40 than the spacer 103 and closer to the curved portion 40c on the upper end surface 2a side of the battery case 2 is equal to the thickness Tk of the contact portion 103K. It is thinner than.

  As described above, the spacer 103 is the top of the expansion shape of the electrode group 40 in which the thicknesses Ti, Tj, Tk, and Tl in the thickness direction of the battery container 2 expand in the thickness direction in the height direction of the battery container 2. The closer it is to 40p, the thinner it is. Therefore, according to the battery module of this embodiment, the joining portion 40d of the electrode group 40 is formed at a position closer to the lower end surface 2b than the upper end surface 2a of the battery container 2, and the expanded top portion 40p of the electrode group 40 is joined. Even if it is a case where it is located in the upper end surface 2a side of battery case 2 rather than part 40d, the same effect as battery module 200 of Embodiment 1 can be acquired.

  In addition, since the joint portion 40d of the electrode group 40 is formed at a position closer to the lower end surface 2b than to the upper end surface 2a of the battery case 2, the length of the current collecting plates 21 and 31 in the height direction of the battery case 2 is increased. Can be long. Therefore, it is possible to facilitate the bending process at the time of manufacturing the current collector plates 21 and 31, improve the productivity, and reduce the manufacturing cost. Further, when an impact or vibration is applied to the rectangular secondary battery 100, the inertial force acting on the electrode group 40 is relaxed by the current collecting plates 21 and 31 to prevent the positive electrode terminal 60 and the negative electrode terminal 70 from being damaged. it can.

  Further, also in the secondary battery module of the present embodiment, as in the second embodiment, the spacer 103 has the contact surfaces 103i, 103j, 103k, 103k of the contact portions 103I, 103J, 103K, 103L facing the battery container 2. 103 l may be inclined with respect to the height direction and the width direction of the battery case 2 so as to follow the expanded shape of the electrode group 40. Thereby, the effect similar to Embodiment 2 can be acquired.

[Embodiment 5]
Next, Embodiment 5 of the assembled battery of the present invention will be described with reference to FIGS. 12A and 12B with reference to FIGS. 1 to 6 and FIGS. 8A and 8B.

  FIG. 12A is a plan view showing the spacer 104 of the secondary battery module of the present embodiment corresponding to FIG. 7A of the first embodiment. FIG. 11B is a cross-sectional view of the spacer 104 taken along line BB in FIG. 11A.

  In the secondary battery module of this embodiment, the intermediate cell holder 92A and the end cell holder (not shown) do not have the upper end spacer 102, the intermediate spacer 103, and the lower end spacer 101, and the The secondary battery module 200 is different from the secondary battery module 200 of the first embodiment in that the spacers 104 that face most of them are provided. Since the other points of the secondary battery module of the present embodiment are the same as those of the secondary battery module 200 of the first embodiment, the same parts are denoted by the same reference numerals and description thereof is omitted.

  The spacer 104 of the present embodiment is formed in a rectangular plate shape in a side view in the thickness direction (Y-axis direction) of the battery case 2. In the height direction (Z-axis direction) and the width direction (X-axis direction) of the battery case 2, the spacer 104 has a top portion 40p of the expansion shape of the electrode group 40 in which the thickness T in the Y-axis direction expands in the Y-axis direction. The closer it is, the thinner it is. Therefore, similarly to the secondary battery module 200 of the first embodiment, the surface pressure acting on the wide side surface 2c of the battery container 2 when the prismatic secondary battery 100 is restrained is made uniform, and the performance and life of the prismatic secondary battery 100 are reduced. Deterioration can be prevented.

  Also in the secondary battery module of the present embodiment, as in the second embodiment, the spacer 104 has a height of the battery container 2 such that the contact surface 104a facing the battery container 2 follows the expanded shape of the electrode group 40. It is inclined with respect to the direction and the width direction. Accordingly, the spacer 104 has a three-dimensional concave curved surface in which the contact surface 104a facing the wide side surface 2c of the battery container 2 corresponds to the three-dimensional expanded shape of the battery container 2 based on the expanded shape of the electrode group 40. It is formed into a shape. Therefore, similarly to the secondary battery module of Embodiment 2, the surface pressure acting on the wide side surface 2c of the battery container 2 when the prismatic secondary battery 100 is restrained can be made more uniform.

[Embodiment 6]
Next, Embodiment 6 of the assembled battery of the present invention will be described with reference to FIGS. 13A and 13B with reference to FIGS. 1 to 6 and FIGS. 8A and 8B.

  FIG. 13A is a plan view showing the spacer 103 of the secondary battery module of the present embodiment corresponding to FIG. 7A of the first embodiment. FIG. 13B is a cross-sectional view of the spacer 103 taken along line BB in FIG. 13A.

  The secondary battery module of this embodiment does not have the upper end spacer 102 and the lower end spacer 101, and the thicknesses Tm and Tn of the contact portions 103M and 103N of the spacer 103 are the width direction (X-axis direction) of the battery container 2. ) And the secondary battery module 200 of the first embodiment in that it is uniform. Since the other points of the secondary battery module of the present embodiment are the same as those of the secondary battery module 200 of the first embodiment, the same parts are denoted by the same reference numerals and description thereof is omitted.

  According to the secondary battery module of the present embodiment, in the height direction of the battery container 2, as with the secondary battery module 200 of the first embodiment, the closer to the top 40 </ b> P of the expanded shape of the electrode group 40, the closer to the spacer 103. The thicknesses Tm and Tn of the contact portions 103M and 103N are reduced. Accordingly, in the height direction of the battery case 2, similarly to the secondary battery module 200 of the first embodiment, the surface pressure acting on the wide side surface 2c of the battery case 2 when the prismatic secondary battery 100 is restrained is made uniform. The performance and lifetime of the secondary battery 100 can be prevented from deteriorating.

  In addition, since the thicknesses Tm and Tn of the contact portions 103M and 103N of the spacer 103 are uniform in the width direction of the battery container 2, the cell holder 92 can be easily manufactured and the manufacturing cost can be reduced.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, Various modifications are included. The above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.

  For example, in the above-described embodiment, the spacer 103 having a relatively large thickness and a relatively high rigidity has been described. However, the spacer 103 may be formed in a flexible film shape. In the drawings used in the above-described embodiments, the expansion of the battery container 2 of the rectangular secondary battery 100 is exaggerated for easy understanding, but the actual expansion amount in the thickness direction of the battery container 2 is For example, it is 500 μm or less.

  Therefore, the effect of the battery module described in each of the above embodiments can be obtained by forming the spacer 103 in a flexible film or thin film having a thickness of, for example, 1 mm or more. Further, by forming the spacer 103 in a film shape or a thin film shape, the space between the battery containers 2 of the square secondary battery 100 can be minimized, and the secondary battery module can be reduced in size and weight.

  Further, the number of the spacers 103 when the plurality of spacers 103 are arranged in the height direction of the battery container 2 is not limited to four, and may be one, two, three, or five or more. However, by setting the number of the spacers 103 to three or more, the thickness of the spacers 103 therebetween is made thinner than the spacers 103 at both ends in the height direction of the battery container 2, and the surface of the spacer 103 that contacts the battery container 2. It becomes possible to make the pressure uniform.

2 ... Battery container, 2a ... Upper end surface, 2b ... Lower end surface, 2c ... Wide side surface, 40 ... Winding electrode group, 40c ... Curved part, 40b ... Flat part, 40d ... Joint part, 40f ... Flat plane, 40p ... Expansion Top part of shape, 41c, 42c ... foil exposed part, 100 ... square secondary battery, 103 ... intermediate part spacer (spacer), 103A-103N ... contact part, 103a-103n ... contact surface (surface facing the battery container) ), 200 ... secondary battery module (battery assembly), D ... axial direction, T, Ta-Tn ... spacer thickness

Claims (11)

A battery pack in which a plurality of secondary batteries in which a wound flat electrode group is accommodated in a rectangular battery container is laminated in the thickness direction of the electrode group and a spacer is interposed therebetween,
In the direction along the flat plane of the electrode group and in the direction intersecting the axial direction, the spacer has a thickness that is thinner toward the top of the expansion shape of the electrode group that expands in the thickness direction. Assembled battery.   2. The spacer according to claim 1, wherein the spacer has a three-dimensional shape corresponding to an expanded shape of the electrode group as the thickness is closer to the top of the electrode group in a direction along the axial direction. Battery pack.   The spacer has a plurality of abutting portions that abut against the battery container in a direction intersecting the axial direction of the electrode group, and between the pair of abutting portions than the pair of abutting portions. The assembled battery according to claim 1, wherein the contact portion having a small thickness is disposed. The electrode group includes a pair of curved portions, the axial direction of which is arranged in parallel with the width direction of the battery container, facing the lower end surface and the upper end surface of the battery container, and a pair along the width direction of the battery container. A flat portion having the flat surface opposed to the wide side surface, and a joined portion obtained by bundling and joining the foil exposed portions at both ends in the axial direction in the flat portion,
4. The assembled battery according to claim 3, wherein the spacer is thinner as it is closer to the top formed in the flat portion of the electrode group. 5. The joining portion is formed at a central portion of the foil exposed portion in the height direction of the battery container intersecting the axial direction,
The top portion is formed at a position where the position in the height direction overlaps the position in the height direction of the joint portion when viewed in the axial direction,
The assembled battery according to claim 4, wherein the spacer is thinnest at a position in the height direction that overlaps a position in the height direction of the joint portion.   The assembled battery according to claim 5, wherein a surface of the spacer facing the battery container is inclined at least with respect to the height direction so as to follow the expanded shape of the electrode group. The joining portion is formed at a position closer to the upper end surface than the lower end surface of the battery container,
The top portion is formed on the lower end surface side than the joint portion,
The assembled battery according to claim 4, wherein the spacer is thinnest on the lower end surface side than the joint portion.   The assembled battery according to claim 7, wherein a surface of the spacer facing the battery container is inclined at least with respect to the height direction so as to follow the expanded shape of the electrode group. The joining portion is formed at a position closer to the lower end surface than the upper end surface of the battery container,
The top is located on the upper end surface side of the joint,
The assembled battery according to claim 8, wherein the spacer is thinnest on the upper end surface side than the joint portion.   The assembled battery according to claim 7, wherein a surface of the spacer facing the battery container is inclined at least with respect to the height direction so as to follow the expanded shape of the electrode group.   The assembled battery according to claim 1, wherein the spacer is formed in a film shape having flexibility.

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