WO2020059299A1

WO2020059299A1 - Battery module

Info

Publication number: WO2020059299A1
Application number: PCT/JP2019/029352
Authority: WO
Inventors: 信雄岩月; 幸司田鍬; 絵里小平
Original assignee: 三洋電機株式会社
Priority date: 2018-09-19
Filing date: 2019-07-26
Publication date: 2020-03-26
Also published as: JP2021193639A

Abstract

In order to bind batteries in a battery module stably and maintain capacity, this battery module 1 is provided with: a battery stack 2 provided with a plurality of stacked batteries 10; a pair of end plates (4) which are formed from a first metal, and which are disposed at both ends of the battery stack (2) in the stacking direction (X) of the batteries (10); a binding member (6) which engages with the pair of end plates (4) and binds the plurality of batteries (10); and buffer members (8) which are disposed between the end plates (4) and the batteries (10), and which are at least partially formed from a second metal having a smaller Young's modulus than the first metal.

Description

Battery module

The present invention relates to a battery module.

電池 A battery module in which a plurality of batteries are electrically connected is known as a power source that requires a high output voltage, such as for a vehicle. Generally, such a battery module is bridged between a battery stack having a plurality of stacked batteries, a pair of end plates arranged at both ends of the battery stack in the battery stacking direction, and a pair of end plates. And a bind bar for restraining the plurality of batteries in the stacking direction.

Batteries may swell with use. When each battery expands, the battery module greatly expands in the battery stacking direction. As a result, a load is applied to the end plate and the bind bar, and the restrained state of the battery may become unstable. On the other hand, Patent Literature 1 discloses a battery module in which a rubber elastic member is provided between a battery located at an end in a stacking direction and an end plate. In this battery module, when the battery expands, the elastic member is compressed and deformed, thereby allowing the battery to expand. Thereby, the load on the end plate and the bind bar can be reduced, and the plurality of batteries can be stably restrained.

JP 2017-50200 A

In recent years, there has been a demand for higher capacity battery modules, and to meet this demand, higher capacity batteries have been developed. As the capacity of the battery increases, the amount of expansion of the battery may increase. In particular, at the end of life of the battery (End of Life: EOL), the amount of expansion of the battery may increase significantly. In the structure in which rubber is interposed between the battery and the end plate as in the above-described battery module, the battery may expand excessively because the rubber allows the battery to expand. When the battery expands, the volume inside the battery naturally increases. When the volume inside the battery increases, the water level of the electrolytic solution decreases, and the contact area between the electrode body and the electrolytic solution may decrease. When the contact area between the electrode body and the electrolytic solution decreases, various problems such as a decrease in battery capacity and an increase in internal resistance may occur. For this reason, if the batteries expand excessively, the capacity of each battery, and thus the capacity of the battery module, may decrease.

The present invention has been made in view of such a situation, and an object of the present invention is to provide a technique for achieving both stable restraint of a battery and maintenance of capacity in a battery module.

ある One embodiment of the present invention relates to a battery module. The battery module includes a battery stack having a plurality of stacked batteries, a pair of end plates formed of a first metal, and disposed at both ends of the battery stack in the battery stacking direction, and a pair of end plates. A restraining member that engages and restrains the plurality of batteries, a buffering member that is interposed between the end plate and the batteries and at least partially includes a second metal having a Young's modulus smaller than the first metal; Is provided.

Note that any combination of the above-described components and any conversion of the expression of the present invention between a method, an apparatus, a system, and the like are also effective as embodiments of the present invention.

According to the present invention, it is possible to achieve both stable restraint of the battery and maintenance of the capacity in the battery module.

FIG. 2 is an exploded perspective view of the battery module according to the embodiment. FIG. 2A is a schematic view of the cushioning member viewed from the stacking direction of the battery. FIG. 2B is a cross-sectional view along the line AA in FIG. FIG. 3A is a schematic view of the end plate viewed from the stacking direction of the battery. FIG. 3B is a cross-sectional view taken along line BB of FIG. 3A. FIG. 4A is a schematic diagram when the end plate, the buffer member, and the battery in a state where they are assembled to each other are viewed from the stacking direction of the batteries. FIG. 4B is a cross-sectional view taken along line CC in FIG. 4A. FIG. 9 is a cross-sectional view schematically illustrating a part of the battery module according to the second embodiment.

Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings. The embodiments are illustrative and do not limit the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and the repeated description will be omitted as appropriate. Further, the scale and shape of each part shown in each figure are set for convenience in order to facilitate the description, and are not to be construed as being limited unless otherwise noted. In addition, when terms such as “first” and “second” are used in the present specification or claims, the terms do not indicate any order or importance unless otherwise specified, and a certain configuration may be used. It is for distinguishing from the other configuration. In each of the drawings, some of the members that are not important for describing the embodiments are omitted.

FIG. 1 is an exploded perspective view of the battery module according to the embodiment. In FIG. 1, the cushioning member 8 is schematically illustrated. The battery module 1 includes a battery stack 2, a pair of end plates 4, a restraining member 6, and a buffer member 8.

The battery stack 2 includes a plurality of batteries 10 and a separator 12. Each battery 10 is a rechargeable secondary battery such as a lithium ion battery, a nickel-hydrogen battery, and a nickel-cadmium battery. The battery 10 is a so-called prismatic battery, and has a flat rectangular parallelepiped outer can 14. A substantially rectangular opening (not shown) is provided on one surface of the outer can 14, and an electrode body, an electrolyte, and the like are stored in the outer can 14 through the opening. At the opening of the outer can 14, a sealing plate 16 for sealing the outer can 14 is provided.

正極 The sealing plate 16 is provided with a positive output terminal 18 near one end in the longitudinal direction and a negative output terminal 18 near the other end. Each of the pair of output terminals 18 is electrically connected to a positive electrode plate and a negative electrode plate constituting an electrode body. Hereinafter, the positive output terminal 18 is referred to as a positive terminal 18a, and the negative output terminal 18 is referred to as a negative terminal 18b. When it is not necessary to distinguish the polarity of the output terminal 18, the positive terminal 18a and the negative terminal 18b are collectively referred to as the output terminal 18. The outer can 14, the sealing plate 16, and the output terminal 18 are conductors, and are made of, for example, metal. The sealing plate 16 and the opening of the outer can 14 are joined by welding or the like. Each output terminal 18 is inserted into a through hole (not shown) formed in the sealing plate 16. An insulating sealing member (not shown) is interposed between each output terminal 18 and each through hole.

In the present embodiment, for convenience of explanation, the surface of the outer can 14 on which the sealing plate 16 is provided is defined as the upper surface of the battery 10, and the surface facing the upper surface of the outer can 14 is defined as the bottom surface of the battery 10. Battery 10 also has two main surfaces connecting the top and bottom surfaces. This main surface is the surface having the largest area among the six surfaces of the battery 10. The main surface is a long side surface connected to the long sides of the top surface and the bottom surface. The remaining two surfaces except the upper surface, the bottom surface, and the two main surfaces are side surfaces of the battery 10. This side is a short side connected to the short sides of the top and bottom surfaces. In the battery stack 2, the upper surface of the battery 10 is the upper surface of the battery stack 2, the bottom surface of the battery 10 is the bottom surface of the battery stack 2, and the short side surface of the battery 10 is the battery The side surface of the laminate 2. In addition, the upper surface of the battery stack 2 is vertically upward, and the bottom surface of the battery stack 2 is vertically lower. These directions and positions are defined for convenience. Therefore, for example, in the present invention, the portion defined as the upper surface does not necessarily mean that it is located above the portion defined as the bottom surface.

弁 A valve portion 20 is provided on the sealing plate 16 between the pair of output terminals 18. The valve section 20 is also called a safety valve, and is a mechanism for discharging gas generated inside the battery 10. The valve portion 20 is configured to open when the internal pressure of the outer can 14 rises to a predetermined value or more, and to discharge the gas inside. The valve portion 20 is composed of, for example, a thin portion provided on a part of the sealing plate 16 and having a smaller thickness than other portions, and a linear groove formed on the surface of the thin portion. In this configuration, when the internal pressure of the outer can 14 increases, the thin portion is torn from the groove to open the valve. The valve section 20 of each battery 10 is connected to an exhaust duct (not shown), and gas inside the battery is exhausted from the valve section 20 to an exhaust duct.

(4) The plurality of batteries 10 are stacked at predetermined intervals such that the main surfaces of adjacent batteries 10 face each other. Note that “stacking” means arranging a plurality of members in any one direction. Therefore, stacking the batteries 10 includes arranging a plurality of batteries 10 horizontally. Each battery 10 is arranged so that the output terminals 18 face the same direction. In the present embodiment, for convenience, each battery 10 is arranged such that the output terminal 18 faces upward in the vertical direction. Two adjacent batteries 10 are stacked such that the positive electrode terminal 18a of one battery 10 and the negative electrode terminal 18b of the other battery 10 are adjacent to each other. The positive terminal 18a and the negative terminal 18b are electrically connected via a bus bar (not shown). Note that output terminals 18 of the same polarity in a plurality of adjacent batteries 10 may be connected in parallel with a bus bar to form a battery block, and the battery blocks may be connected in series.

The separator 12 is also called an insulating spacer, and is made of, for example, an insulating resin. Examples of the resin forming the separator 12 include thermoplastic resins such as polypropylene (PP), polybutylene terephthalate (PBT), polycarbonate (PC), and Noryl (registered trademark) resin (modified PPE).

The separator 12 includes a plurality of first insulating members 12a and a pair of second insulating members 12b. Each first insulating member 12a is disposed between two adjacent batteries 10 to electrically insulate the two batteries 10 from each other. Each second insulating member 12b extends in the stacking direction X of the battery 10 and contacts the side surface of each battery 10. Thereby, each battery 10 and the restraint member 6 are electrically insulated. If necessary, a bus bar (not shown) and the restraining member 6 may be electrically insulated from each other by the second insulating member 12b.

面 A plurality of ribs 12c arranged in the stacking direction X of the battery 10 are provided on a surface of the second insulating member 12b facing the battery 10 side. The spacing between adjacent ribs 12c corresponds to the dimension between the main surfaces of battery 10. When the second insulating member 12b is fitted on the side surface of each battery 10, the plurality of ribs 12c press the bottom surface of each battery 10. Thereby, the positioning of each battery 10 in the direction Z is performed.

The battery stack 2 is sandwiched between a pair of end plates 4. The pair of end plates 4 are arranged at both ends of the battery stack 2 in the stacking direction X of the battery 10. The pair of end plates 4 are arranged so as to be adjacent to the batteries 10 located at both ends in the stacking direction X via the first insulating member 12a. Each end plate 4 is made of a metal plate made of a first metal. Examples of the first metal include at least one selected from the group consisting of iron, stainless steel, and aluminum. By arranging the first insulating member 12a between the end plate 4 and the battery 10, both are insulated.

The restraining member 6 is also called a bind bar, and is a long member that is long in the stacking direction X of the battery 10. In the present embodiment, a pair of restraining members 6 are arranged in a direction Y orthogonal to the stacking direction X of the battery 10, that is, a direction in which the positive electrode terminal 18a, the valve portion 20, and the negative electrode terminal 18b are arranged. The battery stack 2 and the pair of end plates 4 are arranged between the pair of restraining members 6. Each restraining member 6 has a rectangular flat portion 6 a parallel to the side surface of the battery 10, and an eave portion 6 b protruding from the upper side and lower side of the flat portion 6 a toward the battery 10.

電池 The plurality of batteries 10 are restrained in the stacking direction X by the pair of end plates 4 being engaged with the flat portions 6a of each restraining member 6. A contact plate 22 is fixed to the surface of the flat portion 6a facing each end plate 4 by welding or the like. The contact plate 22 is a member that is long in the direction Z in which the top surface and the bottom surface of the battery 10 are aligned, and has a groove 22 a on a surface facing the end plate 4. In the bottom surface of the groove portion 22a, a through hole 22b is provided to reach the surface of the contact plate 22 that is in contact with the plane portion 6a. In the present embodiment, three through holes 22b are arranged in the groove 22a at predetermined intervals in the direction Z.

貫通 The through-hole 7 is provided in the plane portion 6 a at a position corresponding to the through-hole 22 b of the contact plate 22. The end plate 4 has a protruding portion 4a long in the direction Z on a surface facing the flat portion 6a. The shape of the protrusion 4a corresponds to the shape of the groove 22a. The protrusion 4a is provided with a fastening hole 4b at a position corresponding to the through hole 22b of the contact plate 22.

拘束 The restricting member 6 and the end plate 4 are connected by fitting the convex portion 4a into the groove portion 22a. With the protrusion 4a fitted into the groove 22a, the through hole 7 of the restraining member 6, the through hole 22b of the contact plate 22, and the fastening hole 4b of the end plate 4 overlap. Here, the fastening member 24 such as a screw is inserted, whereby the end plate 4 and the restraining member 6 are fixed.

(4) When the size of the battery stack 2 in the stacking direction X increases due to the expansion of the battery 10, a force in the shearing direction is applied to the protrusion 4a. Further, a force is applied to the restraining member 6 in a direction in which both ends are pulled. Thereby, the increase in the size of the battery stack 2 and the expansion of the battery 10 can be suppressed. In general, metals have higher tensile strength than bending strength.

固定 At both ends of the restraining member 6 in the stacking direction X, the fixing portions 26 are arranged. The battery module 1 is fixed to a fixing target such as a battery pack housing or a vehicle body by a fixing unit 26. The fixing portion 26 has a through hole 26a into which a fastening member (not shown) is inserted. The object to be fixed has a fastening hole (not shown), and the fastening hole and the through-hole 26a are overlapped with each other, and the fastening member is inserted therethrough, whereby the battery module 1 is fixed to the object to be fixed. Note that the fixing portion 26 may be fixed to the fixing target by another method such as welding.

The cushioning member 8 is a member that presses the battery 10 in the stacking direction X while appropriately allowing the battery 10 to expand. Hereinafter, the shape and arrangement of the cushioning member 8 will be described in detail with reference to FIGS. 2 (A) to 4 (B).

FIG. 2A is a schematic view of the cushioning member viewed from the stacking direction of the battery. FIG.
FIG. 3A is a cross-sectional view along the line AA in FIG. FIG. 3A is a schematic view of the end plate viewed from the stacking direction of the battery. FIG. 3B is a cross-sectional view taken along line BB of FIG. 3A. FIG. 4A is a schematic diagram when the end plate, the buffer member, and the battery in a state where they are assembled to each other are viewed from the stacking direction of the batteries. FIG. 4B is a cross-sectional view taken along line CC in FIG. 4A. In FIG. 4A, a state in which the battery 10 is seen through is illustrated, and the illustration of the separator 12 is omitted. 4B, illustration of the internal structure of the battery 10 is omitted.

The buffer member 8 is interposed between the end plate 4 and the battery 10. The buffer member 8 comes into contact with the battery 10 via the first insulating member 12a of the separator 12. The buffer member 8 is at least partially made of a second metal having a Young's modulus smaller than the first metal forming the end plate 4. The Young's modulus of the second metal is naturally larger than the Young's modulus of a resin such as rubber. The type of the second metal is selected so that the force applied by the expansion of the battery 10 does not exceed the proof stress of the second metal. Examples of the second metal include at least one selected from the group consisting of magnesium and a magnesium alloy. As an example, the second metal has a Young's modulus of 40 to 50 GPa and a proof stress of 150 to 300 MPa. The first metal has a Young's modulus of 60 to 220 GPa.

緩衝 The cushioning member 8 of the present embodiment has a plurality of fragments 28 and a support plate 30. Each fragment 28 has a rectangular parallelepiped shape or a quadrangular prism shape, and is made of a second metal. The support plate 30 is a plate-like member that supports the plurality of fragments 28. The support plate 30 may be made of the same first metal as the end plate 4, or may be made of the same second metal as the fragment 28. Further, the support plate 30 may be made of a metal different from the first metal and the second metal.

断片 The fragments 28 are arranged in a matrix on the main surface of the support plate 30. Each of the fragment portions 28 has one arbitrary surface joined to the main surface of the support plate 30. When the support plate 30 is made of the second metal, the plurality of fragments 28 and the support plate 30 may be integrally formed. It is desirable that the projecting heights of the respective fragments 28 from the main surface of the support plate 30 are uniform.

The support plate 30 is disposed so as to extend in parallel with the main surface 4c of the end plate 4. That is, the support plate 30 extends parallel to the YZ plane orthogonal to the stacking direction X of the battery 10. Therefore, the plurality of fragments 28 are arranged in parallel with the main surface 4c of the end plate 4.

The end plate 4 has a concave portion 32 facing the battery 10 on the main surface 4c facing the battery 10. That is, the end plate 4 is assembled to the battery stack 2 such that the opening of the concave portion 32 faces the battery 10 side. The concave portion 32 is arranged approximately at the center of the main surface 4c when viewed from the stacking direction X of the battery 10. The shape of the opening of the recess 32 is similar to the contour of the support plate 30 as viewed in the stacking direction X. The cushioning member 8 is arranged in the recess 32 such that the support plate 30 faces the bottom side of the recess 32 and the plurality of fragments 28 face the battery 10 side.

深 The depth of the recess 32 is equal to the dimension of the cushioning member 8 in the direction in which the fragment 28 and the support plate 30 are arranged. For this reason, in a state where the cushioning member 8 is disposed in the concave portion 32, the surface of each fragment portion 28 facing the battery 10 and the main surface 4c of the end plate 4 facing the battery 10 are disposed on the same plane. Is done. Therefore, in a state where the end plate 4 is assembled to the battery stack 2, each fragment portion 28 and the main surface 4 c of the end plate 4 are in contact with the battery 10 via the first insulating member 12 a. The depth of the recess 32 is such that the surface of each fragment 28 facing the battery 10 is larger than the main surface 4c of the end plate 4 facing the battery 10 in a state where the cushioning member 8 is disposed in the recess 32. , May be configured to protrude outward. In the case of this configuration, it is preferable that the projecting amount of each fragment portion 28 is designed so that the load applied to each fragment portion 28 does not exceed the proof stress limit of the second metal.

{Circle around (4)} The concave portion 32 of the end plate 4 is disposed so as to overlap the center 10C of the battery 10 when viewed from the stacking direction X of the battery 10. Therefore, the buffer member 8 is arranged so as to overlap the center 10 </ b> C of the battery 10 when viewed from the stacking direction X of the battery 10. The center 10C of the battery 10 is, for example, the geometric center of the contour shape of the battery 10 viewed from the stacking direction X or the geometric center of gravity.

As described above, the battery module 1 according to the present embodiment includes the battery stack 2 having the plurality of stacked batteries 10 and the first metal, and includes the battery stack 2 in the stacking direction X of the battery 10. , A pair of end plates 4 disposed at both ends, a restraining member that engages the pair of end plates 4 and restrains the plurality of batteries 10, and is interposed between the end plates 4 and the batteries 10 and at least partially And a buffer member 8 made of a second metal having a smaller Young's modulus than the first metal.

When the battery 10 expands due to charging or the like, the battery 10 is greatly deformed in the stacking direction X as compared with the directions Y and Z. As a result, a force in the stacking direction X is applied to the end plate 4 and the buffer member 8. When a force is applied to the pair of end plates 4, a force is applied to the restraining member 6 in a direction in which the restraining member 6 is pulled in the stacking direction X. On the other hand, the cushioning member 8 of the present embodiment has, at least in part, a portion made of a second metal having a smaller Young's modulus than the first metal forming the end plate 4. Therefore, when the battery 10 expands, the cushioning member 8 is preferentially elastically deformed. Thereby, the stress generated in the end plate 4 and the restraint member 6 due to the expansion of the battery 10 can be reduced, and the restrained state of the plurality of batteries 10 can be stably maintained.

On the other hand, since the second metal has a higher Young's modulus than a resin such as rubber, the expansion of the battery 10 can be suppressed as compared with the resin. Thereby, the amount of displacement of the battery 10 in the stacking direction X can be reduced. For example, the displacement of the battery 10 is suppressed to 1 mm or less, more preferably 0.4 mm or less. Therefore, a decrease in the water level of the electrolytic solution due to an increase in the battery capacity can be suppressed, and as a result, a decrease in the capacity of each battery 10 can be suppressed. In particular, the buffering member 8 balances the function of allowing the battery 10 to expand by elastic deformation when the battery 10 reaches EOL and the amount of expansion of the battery 10 significantly increases, and the function of suppressing the expansion of each battery 10. Demonstrate well.

Therefore, according to the present embodiment, it is possible to achieve both stable restraint of battery 10 and maintenance of capacity in battery module 1. Further, since the dimensional change of the battery 10 is allowed by the buffer member 8, the rigidity required for the end plate 4 and the restraining member 6 can be reduced. Therefore, it is possible to avoid an increase in the size, weight, and cost of the battery module 1 due to securing the rigidity of the end plate 4 and the restraining member 6.

緩衝 The cushioning member 8 of the present embodiment has a plurality of fragments 28 made of the second metal. The plurality of fragments 28 are arranged in parallel to the main surface 4c of the end plate 4. Therefore, the battery 10 is pressed down by the plurality of fragments 28. As described above, by dividing the portion made of the second metal in the cushioning member 8 into a plurality of pieces, that is, by forming a plurality of pieces 28, the portion can be more easily elastically deformed. Therefore, the load on the end plate 4 and the restraint member 6 due to the expansion of the battery 10 can be reduced more reliably. Further, it is possible to reduce the possibility that the force applied to the buffer member 8 due to the expansion of the battery 10 exceeds the proof stress of the second metal.

緩衝 The buffer member 8 has a support plate 30 that supports the plurality of fragments 28. Accordingly, it is possible to prevent the assembly of the battery module 1 from becoming complicated due to the provision of the plurality of fragments 28. The end plate 4 has a concave portion 32 on the main surface 4c facing the battery 10 side. And the buffer member 8 is arrange | positioned in the recessed part 32. FIG. Thereby, the positioning of the buffer member 8 can be easily performed. Further, the provision of the buffer member 8 can suppress an increase in the size of the battery module 1.

The buffer member 8 is disposed so as to overlap the center 10C of the battery 10 when viewed from the stacking direction X of the battery 10. When the battery 10 expands, the displacement of the center 10C of the battery 10 in the stacking direction X is larger than that of other portions. Therefore, by arranging the buffer member 8 so as to overlap the center 10 </ b> C, the load on the end plate 4 and the restraint member 6 due to the expansion of the battery 10 can be reduced more reliably.

(Embodiment 2)
The battery module according to the second embodiment has the same configuration as that of the first embodiment except that the installation position of the buffer member is different. Hereinafter, the battery module according to the present embodiment will be described focusing on a configuration different from that of the first embodiment, and a common configuration will be briefly described or description thereof will be omitted. FIG. 5 is a cross-sectional view schematically illustrating a part of the battery module according to the second embodiment. In FIG. 5, illustration of the internal structure of the restraining member 6 and the battery 10 is omitted.

The battery module 1 according to the present embodiment includes the battery stack 2, the pair of end plates 4, the restraining member 6, and the buffer member 8, as in the first embodiment. The buffer member 8 is interposed between the end plate 4 and the battery 10. The buffer member 8 has a plurality of fragment portions 28 and a support plate 30. Each fragment 28 is made of a second metal and is arranged on the main surface of the support plate 30.

In the present embodiment, the support plate 30 is disposed closer to the battery 10 than the plurality of fragments 28 in a state where the cushioning member 8 is assembled to the end plate 4. That is, the support plate 30 is interposed between the plurality of fragments 28 and the battery 10. The tips of the plurality of fragments 28 abut the bottom surface of the recess 32. Therefore, in the first embodiment, the cushioning member 8 contacts the battery 10 at a plurality of points, but in the present embodiment, the cushioning member 8 contacts the battery 10 on the surface. Accordingly, the possibility that the battery 10 is pressed against the cushioning member 8 to cause irregularities in the outer can 14 can be reduced. As a result, a decrease in the power generation performance of the battery 10 can be suppressed.

The embodiments of the present invention have been described above in detail. The above-described embodiments are merely specific examples for implementing the present invention. The contents of the embodiments do not limit the technical scope of the present invention, and many design changes such as component changes, additions, and deletions are made without departing from the spirit of the invention defined in the claims. Is possible. The new embodiment with the design change has the effects of the combined embodiment and modification. In the above-described embodiment, such contents that can be changed in design are emphasized with notations such as “of the present embodiment” and “in the present embodiment”. The design change is allowed even for the contents without the. Any combination of the above components is also effective as an aspect of the present invention. The hatching attached to the cross section of the drawing does not limit the material to which hatching is applied.

The buffer member 8 may be provided only on one end plate 4. The buffer member 8 may be joined to the end plate 4. For example, the buffer member 8 may include only the plurality of fragments 28, and the plurality of fragments 28 may be directly joined to the end plate 4. The portion made of the second metal in the buffer member 8 may be a single flat plate. The buffer member 8 may be entirely made of a second metal. The number of batteries 10 included in the battery stack 2 is not particularly limited. The structure of each part of the battery module 1, including the shape of the separator 12 and the fastening structure between the end plate 4 and the restraining member 6, can be appropriately changed.

{1} battery module, {2} battery stack, {4} end plate, {4c} main surface, {6} restraint member, {8} buffer member, {10} battery, {10C} center, {28} fragment, {30} support plate, {32} recess.

Claims

A battery stack having a plurality of stacked batteries,
A pair of end plates formed of a first metal and disposed at both ends of the battery stack in the stacking direction of the battery;
A restraining member that engages with the pair of end plates and restrains the plurality of batteries;
A battery module, comprising: a buffer member interposed between the end plate and the battery, at least a portion of which is made of a second metal having a lower Young's modulus than the first metal.
The buffer member has a plurality of fragments formed of the second metal,
The battery module according to claim 1, wherein the plurality of fragments are arranged in parallel with a main surface of the end plate.
The battery module according to claim 2, wherein the cushioning member has a support plate that supports the plurality of fragments.
The battery module according to claim 3, wherein the support plate is disposed closer to the battery than the plurality of fragments.
The end plate has a concave portion on a main surface facing the battery side,
The battery module according to claim 1, wherein the buffer member is disposed in the recess.
6. The battery module according to claim 1, wherein the buffer member is disposed so as to overlap a center of the battery when viewed from a direction in which the batteries are stacked. 7.