WO2015097875A1 - Assembled battery - Google Patents

Abstract

The assembled battery (200) comprises a plurality of secondary batteries, each comprising a wound flat electrode group (40) housed in a rectangular battery container (2), which are layered in the thickness direction of the electrode group (40), with a spacer (103) intercalated in between. In a direction along the flat face (40f) of the electrode group (40) and intersecting with an axial direction (D), the closer to the apex (40p) of the bulge of the electrode group (40) in the thickness direction, the thinner the thicknesses (Ta, Tb) of the spacer (103) are.

Description

Assembled battery

The present invention relates to an assembled battery used for in-vehicle applications and the like.

Conventionally, in the field of rechargeable secondary batteries, aqueous solution batteries such as lead batteries, nickel-cadmium batteries, nickel-hydrogen batteries and the like have been mainstream. However, as the size and weight of electrical devices are reduced, attention is focused on lithium ion secondary batteries having high energy density, and their research, development, and commercialization are being promoted rapidly. In addition, due to global warming and exhaustion fuel problems, electric vehicles (EVs) and hybrid electric vehicles (HEVs) that assist a part of the drive with electric motors have been developed by each car manufacturer, and high capacity and high output as their power sources. Secondary batteries are now being sought.

High-voltage non-aqueous solution lithium ion secondary batteries are attracting attention as a power source meeting such requirements. In particular, a prismatic lithium ion secondary battery provided with a flat box type battery container is excellent in volumetric efficiency when a plurality of secondary batteries are stacked to form an assembled battery, so 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 enclosed in a flat rectangular case and a side surface of the largest area of the outer surface of the secondary battery (hereinafter referred to as a compressed surface) partially contact A secondary battery assembly comprising: a contact member for moving the secondary battery and a restraint member for binding the secondary battery and the contact member, wherein the contact member partially presses the compressed surface by the restraint of the restraint member. It is known (refer the following patent document 1).

In the secondary battery assembly described in Patent Document 1, the contact member includes a plurality of discretely provided contact portions in contact with the surface to be compressed, and a connection portion connecting the plurality of contact portions to each other. Have. Further, the contact portion is formed to protrude from the connection portion toward the compressed surface, and both offsets corresponding to a portion of the wound electrode body which is deviated from the center in the winding axial direction. In the region, the compressed surface is compressed more strongly, and the compressed surface in the central region between the two offset regions corresponding to the portion near the center in the winding axial direction in the wound electrode body Is of a shape or arrangement that squeezes less strongly, and 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 Document 1, the contact member partially squeezes the compressed surface of the secondary battery, and the compression force on the compressed surface becomes stronger than the central region in the offset region. It is like that. As a result, the internal pressure of the secondary battery can be made uniform, and the contact pressure at the time of restraint can be made uniform in the secondary battery used at a high rate.

Patent No. 5187400 gazette

The secondary battery assembly described in Patent Document 1 can equalize the surface pressure at the time of restraint of the secondary battery in the central region and the offset region in the winding axial direction of the wound electrode body, but There is a possibility that the contact pressure at the time of restraint of the secondary battery may become uneven in directions other than the rotation direction.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a battery pack capable of making contact pressure at the time of restraint of a prismatic secondary battery uniform.

In order to achieve the above object, in the battery pack of the present invention, a plurality of secondary batteries in which wound flat electrode groups are accommodated in a rectangular battery container are stacked in the thickness direction of the electrode groups A spacer interposed between the first and second spacers, wherein the spacer is expanded in the thickness direction in a direction along the flat surface of the electrode group and in a direction intersecting the axial direction. It is characterized in that the thickness is thinner the closer to the top of the.

According to the battery pack 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 By making uniform the deviation of the surface pressure when the spacer abuts on the container, it is possible to make the surface pressure at the time of restraint of the prismatic secondary battery uniform.

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

The perspective view of a square rechargeable battery. The disassembled perspective view of the square secondary battery shown in FIG. The disassembled perspective view of the electrode group shown in FIG. BRIEF DESCRIPTION OF THE DRAWINGS 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 which are shown in FIG. FIG. 6 is an exploded perspective view of the prismatic secondary battery and the intermediate cell holder shown in FIG. 5; The top view of the square secondary battery and spacer which are 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 of a square secondary battery. The graph which shows the change of the thickness in the width direction at the time of expansion of a prismatic rechargeable battery. The graph which shows the change of the thickness in the height direction at the time of expansion of a prismatic rechargeable 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 in alignment with 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. Sectional drawing of the spacer which follows the BB line shown to 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 taken 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 battery pack of the present invention will be described in detail with reference to the drawings.

(Square secondary battery)
First, a square secondary battery provided in a 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 prismatic 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-shaped battery container 2. The battery case 2 is composed of a battery cover 3 and a battery can 4. The battery can 4 is a bottomed rectangular cylindrical container having an opening 4a and an open upper end, and is manufactured by, for example, deep-drawing a metal material. The battery cover 3 is a rectangular plate-like member in a plan view that closes the opening 4a of the battery can 4, 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, for example, a metal material such as aluminum or an aluminum alloy.

The battery case 2 is formed in a rectangular box shape having a rectangular parallelepiped shape by a rectangular cylindrical bottomed battery can 4 and a rectangular plate-like battery cover 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 with a large area, and a pair of narrow side surfaces 2d with a small area.

In the following description, an XYZ orthogonal coordinate system shown in each drawing may be used as needed. 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 container 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 container 2 perpendicular to the upper end surface 2a or the lower end surface 2b.

An electrode group 40 is accommodated inside the battery container 2 via an insulating sheet (not shown). The electrode group 40 is a flat wound electrode group formed by winding the positive electrode 41 and the negative electrode 42 stacked with the separators 43 and 44 around an axial core (not shown) into a flat shape. The electrode group 40 is disposed inside the battery container 2 such that the axial direction D is parallel to the width direction (X-axis direction) of the battery container 2. That is, the thickness direction of the battery case 2 and the thickness direction of the electrode assembly 40 coincide with each other.

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

The positive electrode 41 is formed by forming a positive electrode mixture layer 41 b on both the front and back sides of a positive electrode metal foil 41 a made of, for example, aluminum foil or the like. 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 at one side edge.

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

The positive electrode 41 can be manufactured, for example, as follows. 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-methyl pyrrolidone (hereinafter referred to as NMP) is added as a dispersion solvent, and the mixture is kneaded to prepare a positive electrode slurry. Next, the positive electrode mixture layer 41 b is formed by applying the positive electrode slurry, for example, on both sides of an aluminum foil having a thickness of 15 μm, leaving the foil exposed portions 41 c. Thereafter, through each process of drying, pressing, and cutting, for example, it is possible to obtain the positive electrode 41 having a thickness of 70 μm (total of both front and back sides) of the positive electrode active material coated portion containing no aluminum foil.

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

The positive electrode active material is a natural graphite capable of inserting and desorbing lithium ions, various artificial graphite materials, carbonaceous materials such as coke, compounds such as Si and Sn (for example, SiO, TiSi ₂ etc.), or The composite material thereof may be used, and the particle shape thereof is not particularly limited, such as scaly, spherical, fibrous, and massive. In addition, the negative electrode active material may be other lithium manganate having a spinel crystal structure, a lithium manganese composite oxide partially substituted or doped with a metal element, lithium cobaltate having a layered crystal structure, lithium titanate, or the like It is also possible to use a lithium-metal composite oxide which is partially substituted or doped with a metal element. Further, 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, acrylic resins and mixtures thereof can be used.

In order to manufacture the electrode group 40, the tip end portions of the separators 43 and 44 are welded to an axial core (not shown), and the positive electrode 41, the separator 43, the negative electrode 42 and the separator 44 are wound in this order so as to overlap. At this time, the winding start end portion of the positive electrode 41 is a negative electrode so that the winding start end portion of the positive electrode 41 is positioned inside the electrode group 40 after winding than the winding start end portion of the negative electrode 42. It arrange | positions and winds to the axial core side rather than the winding start side edge part of the electrode 42. As shown in FIG. As the shaft core, for example, one formed by winding 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 can be used.

Here, a direction parallel to the axial center 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 disposed at the side edges of the electrode group 40 in one axial direction D and the other. That is, the positive electrode 41 and the negative electrode 42 are stacked and wound so that the respective foil exposed portions 41 c and 42 c are located at one end and the other end of the electrode group 40 in the axial direction D.

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

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 divided into two in the thickness direction by flat portions 40b and 40b on both sides of the hollow portion 40a, respectively. It joins to the current collection boards 21 and 31 in the junction parts 40d and 40d which are shown by the hatched area | region.

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

Similarly, the current collecting plate 31 constituting the negative electrode terminal 70 has a flat plate-like main body 32 attached along the lower surface of the battery lid 3 and a pair of support parts bent at right angles on both sides of the main body 32. It has 32a. A flat plate-like bonding piece 33 is formed at the tip of each of the pair of support portions 32a. Each bonding piece 33 is bonded to the bonding portion 40d of the foil exposed portion 42c which is divided into two in the thickness direction of the electrode group 40 and bundled, for example, by ultrasonic welding. The current collector 31 is made of, for example, copper or a copper alloy.

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

The positive electrode terminal 60 is composed of a bolt 61, a connection terminal 62, an external terminal 63, an insulator 64, a gasket and a current collector 21 and these are integrally fixed to the battery cover 3. In this state, current collecting plate 21, connection terminal 62 and external terminal 63 are electrically connected to each other, and insulated from battery cover 3 by insulator 64 and a gasket.

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

As shown in FIG. 2, the battery assembly 3 is provided with the positive electrode terminal 60 and the negative electrode terminal 70, whereby the lid assembly 10 is configured. Further, the foil exposed portions 41c and 42c of the electrode group 40 are divided into two in the thickness direction by flat portions 40b and 40b on both sides of the hollow portion 40a, and the bonding portions 40d and 40d are current collector plates 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 all around. As a result, the electrode group 40 and the current collectors 21 and 31 are accommodated and arranged at predetermined positions inside the battery container 2.

In the battery lid 3, a gas discharge valve 13 is provided between the positive electrode terminal 60 and the negative electrode terminal 70. The gas discharge valve 13 is formed by partially thinning the battery cover 3 by press processing. The gas discharge valve 13 may be provided by joining a thin film metal member to the through hole provided in the battery lid 3 by, for example, laser welding. The gas discharge valve 13 generates heat when heat is generated due to an abnormality such as overcharging of the prismatic secondary battery 100, and when the pressure in the battery container rises and reaches a predetermined pressure, the gas discharge valve 13 is split and gas is generated from the inside. By discharging, the pressure in the battery container is reduced.

Furthermore, a liquid injection hole 3 a for injecting an electrolytic solution into the battery case 2 is formed in the battery lid 3. The injection hole 3a is sealed by the injection valve 11 after the injection of the electrolyte. As a non-aqueous electrolytic solution, for example, lithium hexafluorophosphate (LiPF ₆ ) was dissolved at a concentration of 1 mol / liter in a mixed solution of ethylene carbonate and dimethyl carbonate mixed in a ratio of 1: 2 in volume ratio The thing can be used.

(Assembly battery)
Next, as an embodiment of the battery pack of the present invention, a plurality of prismatic secondary batteries 100 are interposed between spacers in the thickness direction (Y-axis direction) of the battery container 2, that is, the thickness direction of the flat electrode group 40. The stacked secondary battery modules will be described in detail.

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

The module 200 has a plurality of prismatic secondary batteries 100 stacked in the thickness direction (Y direction) and a cell holder 91 that holds the prismatic secondary batteries 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 manufacturing the cell holder 91 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. End cell holders 93 are disposed at both ends in the stacking direction of the plurality of prismatic secondary batteries 100 stacked in the thickness direction via intermediate cell holder 92, and the prismatic secondary battery 100 is placed between the opposing intermediate cell holders 92. Hold. End cell holder 93 has a configuration in which intermediate cell holder 92 is divided in half by a plane parallel to wide side surface 2 c of 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, 111 facing the narrow side surfaces 2d, 2d on both sides in the width direction (X-axis direction) of the battery container 2 of the prismatic secondary battery 100, and the lower end surface 2b of the battery container 2. A bottom plate 112 is provided. As shown in FIG. 4, the intermediate cell holder 92 is disposed between the two prismatic secondary batteries 100, 100, and thus passes through the middle of the two prismatic secondary batteries 100, 100 and the wide side 2 c of the battery container 2. In a plane parallel to the plane. That is, the side plates 111 and the bottom plate 112 of the intermediate cell holder 92 are formed on the narrow sides 2 d and 2 d and the lower end faces 2 b and 2 b of the battery containers 2 and 2 of the two prismatic secondary batteries 100 and 100 arranged on both sides of the intermediate cell holder 92. On the other hand, approximately half each of the battery container 2 in the thickness direction (Y-axis direction) is opposed.

The pair of side plates 111 faces the opposite ends in the width direction of the battery case 2 and extends in the thickness direction of the battery case 2 so as to reach half of the thickness of the battery case 2. The bottom plate 112 has a width that reaches half of the thickness of the battery case 2 at the lower end of the battery case 2 in the direction perpendicular to the lower end surface 2 b, ie, the height direction (Z-axis direction) of the battery case 2. It extends in the width direction and connects the lower ends of the pair of side plates 111, 111. Further, the pair of opposing intermediate cell holders 92, 92 disposed on both sides in the thickness direction of the battery container 2 have their end portions of the side plates 111, 111 and the bottom plates 112, 112 butted or slightly separated from each other By being disposed, a space for holding the prismatic secondary battery 100 is formed between them.

A pair of side plates 111, 111 facing each other in the width direction of the battery container 2 are connected by a plurality of spacers 101, 102, 103 extending in the width direction of the wide side surface 2c. More specifically, the pair of side plates 111, 111 is a lower end spacer 101 connecting the lower ends thereof, an upper end spacer 102 connecting the upper ends thereof, and a plurality of intermediate portions connecting intermediate portions of these It is connected by the spacer 103.

The lower end spacer 101 is connected to the bottom plate 112 at its 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 container 2 to the lower position of the battery lid 3 It is wider than the width of the other spacers 101 and 103. The distance between the lower end spacer 101 and the middle spacer 103 and the distance between the upper end spacer 102 and the middle spacer 103 are smaller than the distance between the middle spacers 103.

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

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

The spacers 101, 102, and 103 are spaced apart from each other in the height direction (Z-axis direction) of the battery case 2, whereby a plurality of slits extending in the width direction along the wide side 2c of the battery case 2 114 and 115 are formed. Widths in the Z-axis direction between the lower end spacer 101 and the intermediate spacer 103 and between the upper end spacer 102 and the intermediate spacer 103 correspond to the intervals between the respective spacers 101, 102, and 103. A relatively narrow first slit 114 is formed. In addition, second slits 115 having a relatively wide width in the Z-axis direction are formed between the middle portion spacers 103. The first slits 114 communicate the first openings 111 a of the pair of side plates 111, and the second slits 115 communicate the second openings 111 b of the pair of side plates 111. As a result, the cooling medium is allowed to pass through the slits 114 and 115, and the wide side surface 2c of the battery container 2 of the prismatic secondary battery 100 can be cooled.

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

Although not shown, 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 band. Thereby, 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. In addition, by inserting the bolts 61 and 71 of the positive electrode terminal 60 and the negative electrode terminal 70 of the adjacent square secondary batteries 100 and 100 of the module 200 into the through holes of the bus bars and fixing them with nuts, the square secondary of the module 200 is obtained. The batteries 100 can be connected in series. Thus, the module 200 supplies the power stored in each of the prismatic secondary batteries 100 to an external device such as a motor, and transmits the power supplied from an external power source such as a generator to each prismatic secondary battery 100. It can be stored.

In the prismatic secondary battery 100, the electrode group 40 expands and contracts due to charge and discharge. When the electrode group 40 abuts against the inside of the wide side surface 2 c of the battery case 2 via the insulating sheet when the electrode group 40 expands, the battery case 2 is spread outward, and the battery case 2 is obtained by the electrode group 40. May expand to a shape corresponding to the expanded shape of. In this case, the intermediate portion spacer 103 opposed to the wide side 2c of the battery container 2 abuts on the wide side 2c, and the wide side 2c acts against the expansion of the electrode assembly 40, thereby suppressing the expansion of the battery container 2. Be done. At this time, if the surface pressure of the intermediate portion spacer 103 in contact with the wide side surface 2c becomes uneven, the performance and the life of the prismatic secondary battery 100 may be degraded. Therefore, it is required to make the surface pressure of the intermediate portion spacer 103 in contact with the wide side surface 2 c of the battery container 2 uniform.

(Spacer)
Hereinafter, middle part spacer 103 with which the rechargeable battery module of this embodiment is provided is explained 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 a 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, 92 taken along the line BB in FIG. 7A. FIG. 7C shows the expanded state of the battery case 2 of the prismatic secondary battery 100 in the cross-sectional view shown in FIG. 7B. 7A to 7C, illustration of the side plate 111 and the bottom plate 112 of the cell holder 92 is omitted. Further, in FIGS. 7A to 7C, in order to make the description easy to understand, the expansion amount of the battery container 2, the thickness of the spacer 103, and the like are exaggeratingly shown.

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 container 2. Each of the four spacers 103 includes an abutting portion 103A or 103B. As a result, the plurality of contact portions 103A and 103B of the spacer 103 are spaced from each other in the height direction of the battery case 2 and face the wide side surface 2c of the battery case 2.

The spacers 103 and 103 disposed at positions near the pair of curved portions 40c of the electrode group 40 housed inside the battery container 2, that is, at positions near the upper end surface 2a and the lower end surface 2b of the battery container 2, contact portions The thickness Ta of 103A is relatively thick. On the other hand, in the height direction of the battery case 2 (Z-axis direction), the spacers 103 and 103 disposed in the middle of the flat portion 40b of the electrode assembly 40, ie, in the middle 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 disposed at both ends in the Z-axis direction. The contact portion 103B is disposed. In other words, between the pair of contact portions 103A and 103A, the contact portions 103A and 103B having a smaller thickness Tb than the pair of contact portions 103A and 103A are disposed.

Thus, in the height direction (Z-axis direction) of the battery case 2, the spacer 103 overlaps the flat portion 40b in the thickness direction (Y-axis direction) of the battery case 2 at a position close to the pair of curved portions 40c of the electrode assembly 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 distance Gb between the spacers 103 and 103 overlapping in the Y-axis direction with the middle part of the flat portion 40b of the electrode group 40 and the wide side 2c of the battery container 2 is relatively wide.

The contact portions 103A and 103B are contact surfaces 103a and 103b that contact the wide side 2c of the battery case 2 when the battery case 2 of the prismatic secondary battery 100 expands in the thickness direction (Y-axis direction). have. As shown in FIG. 7A, in the width direction (X-axis direction) of the battery container 2, the contact surfaces 103 a and 103 b are such that the distances Ga and Gb with the wide side surface 2 c become wider as they approach the center of the battery container 2. Curved and curved. As a result, in the spacer 103, the thicknesses Ta and Tb of the contact portions 103A and 103B are made thinner toward the center of the battery container 2 in the X-axis direction.

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 103A and 103B are 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 charge and discharge of the prismatic secondary battery 100, and the insulating sheet is placed inside the wide side surface 2c of the battery container 2. When in contact, the battery container 2 may be spread outward, and the battery container 2 may expand to a shape corresponding to the expanded shape of the electrode assembly 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 container 2 at this time.

FIG. 8A is a graph showing a change in thickness of battery container 2 in the width direction (X-axis direction) of battery container 2 at the time of expansion of prismatic secondary battery 100 in a cross section taken along line F8a-F8a shown in FIG. is there. FIG. 8B is a graph showing a change in thickness of battery container 2 in the height direction (Z-axis direction) of battery container 2 at the time of expansion of prismatic secondary battery 100 in the cross section along line F8b-F8b shown in FIG. It is.

As shown in FIG. 8A, the thickness which is the dimension in the Y-axis direction of the battery container 2 is the thickness in the region X2 in the widthwise intermediate portion than the thickness in the regions X1 and X3 on both sides in the width direction (X-axis direction) Is thicker. In the battery case 2, the thickness in the vicinity of the center of the region X <b> 2 in the widthwise intermediate portion is the largest. Further, as shown in FIG. 8B, the thickness of the battery case 2 is the thickness in the region Z2 in the middle in the height direction than the thickness in the regions Z1 and Z3 in the upper and lower directions in the height direction (Z-axis direction). Is thicker. In the battery case 2, the thickness in the vicinity of the center of the region Z <b> 2 in the middle in the height direction is the largest.

In the thickest portion of the battery container 2 shown in FIGS. 8A and 8B, the wide side surface 2c of the battery container 2 is in the thickness direction (Y-axis direction) with the top 40p of the expanded shape of the electrode assembly 40 shown in FIG. It is a position which overlaps with.

In the electrode group 40, the foil exposed portions 41c and 42c are bundled and joined at both end portions in the width direction, and bonding portions 40d and 40d are formed. Therefore, in the electrode group 40, both end portions in the width direction hardly expand, and the central portion of the flat portion 40b separated from the bonding portion 40d is most easily expanded. In the electrode group 40, the upper and lower curved portions 40c and 40c are less likely to expand in the direction along the flat surface 40f and in the direction intersecting the axial direction D, specifically, the height direction of the battery container 2, and the curved portions The central portion of the flat portion 40b farther from 40c, 40c tends to expand. Furthermore, in the battery container 2, the peripheral portion of the wide side surface 2 c is not easily deformed, and the central portion is easily deformed. Due to these combined factors, the top 40 p of the expanded shape of the electrode group 40 is formed at the center of the flat portion 40 b of the electrode group 40.

In the present embodiment, in the height direction (Z-axis direction) of the battery container 2 intersecting the axial direction D in the direction along the flat surface 40f of the electrode group 40, the bonding portions 40d and 40d are foil exposed portions 41c. , 42c in the central portion. In this case, the top 40p of the expanded shape 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 bonding portions 40d and 40d when viewed in the axial direction D, ie, the X-axis direction. .

Therefore, as shown in FIGS. 7A to 7C, the spacers 103 have 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 assembly 40. Is made thinner toward the top 40p of the electrode assembly 40. In the spacer 103, the thicknesses Ta and Tb of the contact portions 103A and 103B in the direction along the flat surface 40f of the electrode group 40 of the electrode group 40 and in the Z-axis direction intersecting the axial direction D The closer to the top 40p of the expanded shape of the light source is thinner. The spacer 103 is the thinnest at the position in the Z-axis direction overlapping the position in the Z-axis direction of the bonding 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.

Thus, the spacer 103 has a three-dimensional shape corresponding to the three-dimensional expanded shape of the electrode group 40, and the battery container 2 is based on the expanded shape of the electrode group 40 in both the X-axis direction and the Z-axis direction. It can be allowed to expand in shape. Therefore, according to module 200 of the present embodiment, battery case 2 is expanded to a shape corresponding to the three-dimensional expansion shape of electrode group 40 along with charge and discharge of prismatic secondary battery 100. Also, 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 2c of the battery container 2 abuts on the wide side 2c and a reaction against expansion of the electrode group 40 acts on the wide side 2c, the expansion of the battery case 2 is suppressed. At this time, the surface pressure of the spacer 103 in contact with the wide side surface 2c is equalized, so that deterioration of the performance and life of the prismatic secondary battery 100 can be prevented.

Further, 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 103A and 103B in which the plurality of spacers 103 abut the wide side 2c of the battery case 2 have. Therefore, the slits 115 can be formed between the contact portions 103A and 103B of the respective spacers 103, and the cooling medium can be circulated to cool the wide side surface 2c of the battery container 2.

In addition, the battery container 2 has an expanded shape of the electrode group 40 by arranging the contact portion 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 in contact with 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 thickness of the spacer 103 is reduced closer to the top 40 P of the expanded shape of the electrode assembly 40, so that the battery container is restrained when the square secondary battery 100 is restrained. The surface pressure acting on the wide side surface 2c of 2 can be made uniform to prevent the deterioration of the performance and the life of the prismatic secondary battery 100.

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

FIG. 9A is a plan view showing a spacer 103 of a 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 taken along the line BB in FIG. 9A.

The secondary battery module of the present embodiment is characterized in that the contact surfaces 103c and 103d of the contact portions 103C and 103D of the spacer 103 are inclined to follow the expanded shape of the electrode assembly 40 in the second embodiment. It differs 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. The other points of the secondary battery module according to the present embodiment are the same as those of the secondary battery module 200 according to the first embodiment, so the same reference numerals are given to the same parts and the description will be omitted.

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

According to the secondary battery module of the present embodiment, not only effects similar to those of the secondary battery module 200 of the first embodiment can be obtained, but 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 on the wide side surface 2c of the battery container 2 can be made more uniform than in the case of being 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.

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

FIG. 10A 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. 10B is a cross-sectional view of the spacer 103 along the line BB in FIG. 10A.

The secondary battery module of the present embodiment is formed at a position closer to the upper end surface 2 a than the lower end surface 2 b of the battery container 2, with the bonding portion 40 d of the electrode group 40 accommodated in the battery container 2 of the square secondary battery 100. The second embodiment differs from the secondary battery module 200 according to the first embodiment in that the thicknesses Te, Tf, Tg, and Th of the contact portions 103E, 103F, 103G, and 103H are different. The other points of the secondary battery module according to the present embodiment are the same as those of the secondary battery module 200 according to the first embodiment, so the same reference numerals are given to the same parts and the description will be omitted.

Since the electrode group 40 is difficult to expand at the bonding portion 40d, when the bonding 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, as shown in FIG. The top 40p of the expanded shape of the electrode assembly 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 top 40p of the expanded shape of the electrode group 40 located closer to the lower end surface 2b of the battery container 2 than the bonding portion 40d is made the smallest. ing.

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

Thus, in the height direction of the battery case 2, the spacer 103 has the thickness Te, Tf, Tg, Th of the battery case 2 in the thickness direction, and the top of the expanded shape of the electrode group 40 in which the thickness expands. It is made thinner as it approaches 40p. Therefore, according to the battery module of the present embodiment, the bonding portion 40 d of the electrode group 40 is formed closer to the upper end surface 2 a than the lower end surface 2 b of the battery container 2, and the top 40 p of the expanded shape of the electrode group 40 is bonded Even in the case of being positioned on the lower end surface 2b side of the battery case 2 than the portion 40d, the same effect as the battery module 200 of the first embodiment can be obtained.

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

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

Fourth Embodiment
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, FIGS. 8A and 8B.

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

The secondary battery module of the present embodiment is formed at a position closer to the lower end surface 2b of the battery container 2 than the upper end surface 2a of the electrode assembly 40 of the electrode assembly 40 housed in the battery container 2 of the prismatic secondary battery 100 The second embodiment differs from the secondary battery module 200 of the first embodiment in that the thickness of the contact portions 103I, 103J, 103K and 103L is different. The other points of the secondary battery module according to the present embodiment are the same as those of the secondary battery module 200 according to the first embodiment, so the same reference numerals are given to the same parts and the description will be omitted.

Since the electrode group 40 does not easily expand at the bonding portion 40d, when the bonding 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, as shown in FIG. The top 40p of the expanded shape of the electrode assembly 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 top 40p of the expanded shape of the electrode group 40 located closer to the upper end surface 2a of the battery container 2 than the bonding portion 40d is made the smallest. ing.

Further, the thickness Tl of the contact portion 103L of the spacer 103 closest to the curved portion 40c on the lower end surface 2b side of the battery container 2 farthest from the top 40p of the expanded shape of the electrode group 40 is the thickest. The thickness Tk of the contact portion 103K of the spacer 103 closer to the top 40p of the expanded shape of the electrode group 40 than the spacer 103 is 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 top 40p of the expanded shape of the electrode assembly 40 than the spacer 103 and near the curved portion 40c on the upper end surface 2a side of the battery container 2 is the thickness Tk of the contact portion 103K. It is thinner than.

Thus, in the height direction of the battery case 2, the spacer 103 has the thickness Ti, Tj, Tk, Tl in the thickness direction of the battery case 2 at the top of the expanded shape of the electrode group 40 which expands in the thickness direction. It is made thinner as it approaches 40p. Therefore, according to the battery module of the present embodiment, the bonding portion 40 d of the electrode group 40 is formed closer to the lower end surface 2 b than the upper end surface 2 a of the battery container 2, and the top 40 p of the expanded shape of the electrode group 40 is bonded Even in the case of being positioned on the upper end surface 2a side of the battery container 2 than the portion 40d, the same effect as the battery module 200 of the first embodiment can be obtained.

Further, by forming the joint 40 d of the electrode assembly 40 at a position closer to the lower end surface 2 b than the upper end surface 2 a of the battery container 2, the length of the current collector plates 21, 31 in the height direction of the battery container 2 It can be long. Therefore, the bending process at the time of manufacture of current collection boards 21 and 31 is made easy, productivity can be improved, and manufacturing cost can be reduced. In addition, when impact or vibration is applied to prismatic secondary battery 100, the inertial force acting on electrode group 40 is alleviated by current collecting plates 21 and 31 to prevent positive electrode terminal 60 and negative electrode terminal 70 from being damaged. it can.

Furthermore, also in the secondary battery module of the present embodiment, the spacers 103 are the same as the second embodiment in the contact surfaces 103i, 103j, 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 same effect as that of the second embodiment can be obtained.

Fifth Embodiment
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, FIGS. 8A and 8B.

12A is a plan view showing a spacer 104 of a 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 along the line BB in FIG. 11A.

In the secondary battery module of the present 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 wide side surface 2c of the battery container 2 The secondary battery module 200 is different from the secondary battery module 200 according to the first embodiment in that most of the spacers 104 are opposed to each other. The other points of the secondary battery module according to the present embodiment are the same as those of the secondary battery module 200 according to the first embodiment, so the same reference numerals are given to the same parts and the description will be 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 container 2. In the spacer 104, the thickness T of the Y-axis direction in the height direction (Z-axis direction) and the width direction (X-axis direction) of the battery container 2 is the top 40p of the expanded shape of the electrode group 40 expanded in the Y-axis direction. The closer it is to the Therefore, like the secondary battery module 200 of the first embodiment, the surface pressure acting on the wide side surface 2c of the battery case 2 is equalized when the square secondary battery 100 is restrained, and the performance and the life of the square secondary battery 100 are improved. Deterioration can be prevented.

Also in the secondary battery module of the present embodiment, the spacer 104 has the height of the battery container 2 so that the contact surface 104 a facing the battery container 2 conforms to the expanded shape of the electrode assembly 40 as in the second embodiment. It is inclined to the direction and width direction. Thus, the spacer 104 has a three-dimensional concave surface whose abutment surface 104 a facing the wide side surface 2 c of the battery container 2 corresponds to the three-dimensional expansion shape of the battery container 2 based on the expansion shape of the electrode group 40. It is formed in shape. Therefore, like the secondary battery module of the second embodiment, the surface pressure acting on the wide side surface 2 c of the battery container 2 can be made more uniform when the prismatic secondary battery 100 is restrained.

Sixth Embodiment
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, FIGS. 8A and 8B.

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

The secondary battery module of the present embodiment does not have the upper end spacer 102 and the lower end spacer 101, and the thickness Tm, Tn of the contact portions 103M and 103N of the spacer 103 is the width direction of the battery container 2 (X axis direction And the secondary battery module 200 of the first embodiment in that they are uniform. The other points of the secondary battery module according to the present embodiment are the same as those of the secondary battery module 200 according to the first embodiment, so the same reference numerals are given to the same parts and the description will be omitted.

According to the secondary battery module of the present embodiment, similarly to the secondary battery module 200 of the first embodiment in the height direction of the battery container 2, the closer to the top 40 P of the expanded shape of the electrode assembly 40, the closer to the spacer 103. The thicknesses Tm and Tn of the contact portions 103M and 103N are reduced. Therefore, like the secondary battery module 200 of the first embodiment, in the height direction of the battery case 2, the surface pressure acting on the wide side surface 2c of the battery case 2 at the time of restraint of the prismatic secondary battery 100 is equalized. Deterioration of the performance and the life of the secondary battery 100 can be prevented.

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 the preferable embodiment of this invention was described, this invention is not limited to above-mentioned embodiment, A various modified example is included. The above 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, although the relatively thick and relatively rigid spacer 103 is described, the spacer 103 may be formed in a flexible film shape. In the drawings used in the above-described embodiment, the expansion of the battery case 2 of the prismatic secondary battery 100 is exaggeratingly expressed for easy understanding of the description, but the actual expansion amount of the battery case 2 in the thickness direction is For example, it is 500 μm or less.

Therefore, the effect of the battery module described in each of the above-described embodiments can be obtained by forming the spacer 103 in the form of a flexible film or thin film having a thickness of, for example, 1 mm or more. In addition, by forming the spacer 103 in a film shape or a thin film shape, it is possible to minimize the space between the battery containers 2 of the prismatic secondary battery 100 and to reduce the size and weight of the secondary battery module.

Further, the number of the spacers 103 in the case of arranging the plurality of spacers 103 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 spacers 103 to three or more, the thickness of the spacer 103 between the spacers 103 at both ends in the height direction of the battery container 2 is thinner, and the surface of the spacer 103 in contact with the battery container 2 It becomes possible to equalize the pressure.

DESCRIPTION OF SYMBOLS 2 ... battery container, 2a ... upper end surface, 2b ... lower end surface, 2c ... wide side, 40 ... wound electrode group, 40c ... curved part, 40b ... flat part, 40d ... junction part, 40f ... flat surface, 40p ... expansion Top of the shape, 41c, 42c ... foil exposed part, 100 ... prismatic secondary battery, 103 ... middle part spacer (spacer), 103A-103N ... contact part, 103a-103n ... contact surface (surface facing battery container ), 200 ... secondary battery module (group battery), D ... axial direction, T, Ta-Tn ... thickness of spacer

Claims (11)

1. It is a battery assembly in which a plurality of secondary batteries in which wound flat electrode groups are accommodated in a rectangular battery container are stacked in the thickness direction of the electrode groups and a spacer is interposed therebetween.
   The spacer is characterized in that the thickness is thinner toward the top of the expanded shape of the electrode group expanding in the thickness direction in the direction along the flat surface of the electrode group and in the direction intersecting the axial direction. Battery pack.
2. The spacer has a three-dimensional shape which is thinner as the thickness is closer to the top of the electrode group in a direction along the axial direction, and has a three-dimensional shape corresponding to the expanded shape of the electrode group. Battery pack.
3. The spacer has a plurality of contact portions that contact the battery container in a direction intersecting the axial direction of the electrode group, and the space between the pair of contact portions is greater than the pair of contact portions. The assembled battery according to claim 1, wherein the contact portion having the small thickness is disposed.
4. The electrode group is disposed such that the axial direction is parallel to the width direction of the battery case, and a pair of curved portions respectively facing the lower end surface and the upper end surface of the battery case, and a pair along the width direction of the battery case A flat portion having the flat surface opposed to the wide side surface, and a joint portion obtained by bundling and joining foil exposed portions at both ends in the axial direction in the flat portion,
   The assembled battery according to claim 3, wherein the spacer is thinner as it is closer to the top portion formed on the flat portion of the electrode group.
5. The joint portion is formed at a central portion of the foil exposed portion in a 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 overlapping the position in the height direction of the joint.
6. 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.
7. The joint 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 closer to the lower end surface than the joint portion,
   The assembled battery according to claim 4, wherein the spacer is thinnest on the lower end face side than the joint portion.
8. The assembled battery according to claim 7, wherein a surface of the spacer facing the battery case is inclined at least with respect to the height direction so as to follow the expanded shape of the electrode group.
9. The joint portion is formed at a position closer to the lower end surface than the upper end surface of the battery container,
   The top portion is positioned closer to the upper end surface than the joint portion,
   The assembled battery according to claim 8, wherein the spacer is thinnest on the upper end surface side than the joint portion.
10. The assembled battery according to claim 7, wherein a surface of the spacer facing the battery case is inclined at least with respect to the height direction so as to follow the expanded shape of the electrode group.
11. The assembled battery according to claim 1, wherein the spacer is formed in a flexible film shape.

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