Battery module and manufacturing method thereof

Abstract

The problem to be solved is to provide a battery module and a method for manufacturing the same, which can apply uniform pressure to a battery cell even when the thickness of the battery cell changes greatly due to charging and discharging, and which can be reduced in size. In order to solve the problem, provided is a battery module comprising: a cell laminate in which a plurality of battery cells are laminated; a pair of end plates disposed at both ends of the single laminate in the lamination direction; and a buffer member disposed between the battery cells and / or between the battery cells and the end plate, the buffer member being disposed between the battery cells and / or between the battery cells and the end plate. Furthermore, the cushion material is a first cushion material having an inner elastic container and an outer elastic container that accommodates the inner elastic container, the inside of the inner elastic container is filled with a gas, a space between the inner elastic container and the outer elastic container is filled with a liquid, the outer elastic container is connected to a liquid pipe, and the liquid pipe is connected to the inner elastic container. The liquid pipe is a circulation pipe having an accumulator.

Description

Technical Field

[0001] The present invention relates to a battery module and a method for manufacturing the same. Background Art

[0002] In recent years, research and development of battery modules that contribute to energy efficiency has been underway to ensure more people have access to affordable, reliable, sustainable, and advanced energy. A battery module is a modular assembly of multiple battery cells. Generally, it consists of a cell stack, which is a stack of multiple battery cells, and a pair of end plates, located at either end of the stack. Battery modules are used in applications requiring high current and high voltage, such as driving the motors of electric vehicles and hybrid electric vehicles.

[0003] In battery modules, research is underway to place cushioning materials between battery cells or between a stack of cells and end plates to apply pressure in the stacking direction of the battery cells. Known cushioning materials include cushioning materials (Patent Document 1) and spring elastic bodies such as leaf springs and liquid springs (Patent Documents 2 and 3). The cushioning materials have a deformable cavity and a system for supplying a fluid to deform the cavity.

[0004] [Prior Art Literature]

[0005] (Patent Document)

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-64848

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2021-96974

[0008] Patent Document 3: European Patent Application Publication No. 3886202 Summary of the Invention

[0009] [Problems to be solved by the invention]

[0010] However, the technology related to battery modules faces challenges in increasing and miniaturizing the capacity. To increase the capacity of a battery module, it is effective to apply uniform pressure to the entire battery cell incorporated into the battery module via a buffer material. Because the internal pressure of a fluid buffer filled with fluid is highly uniform, it is possible to apply pressure to the entire battery cell with high uniformity. Furthermore, the second buffer material, which uses a liquid as a fluid, has the effect of regulating the temperature of the battery cell due to its high heat absorption. On the other hand, research is underway as a battery cell using lithium metal batteries that use lithium ions as a charge transfer medium, depositing lithium metal on the negative electrode layer during charging and migrating lithium metal as lithium ions to the positive electrode layer during discharge. The thickness of these lithium metal batteries varies significantly due to charging and discharging. Therefore, in order to apply uniform pressure to the lithium metal battery using a fluid buffer, it is necessary to reduce the amount of fluid inside the battery during charging and increase it during discharge. However, using a fluid tank to adjust the amount of fluid in the fluid buffer makes it difficult to miniaturize the battery module.

[0011] The present invention was developed in light of the above circumstances, and its purpose is to provide a battery module and a method for manufacturing the same that can apply uniform pressure to battery cells even when their thickness varies significantly due to charging and discharging, and that can achieve miniaturization, thereby further contributing to achieving energy efficiency.

[0012] [Technical means to solve the problem]

[0013] The present inventors have discovered that disposing a first buffer material between battery cells or between a battery cell and an end plate, wherein the first buffer material has a double-layer structure comprising an inner elastic container and an outer elastic container, wherein the inner elastic container is filled with gas and the space between the outer surface of the inner elastic container and the inner surface of the outer elastic container is filled with liquid, and the outer elastic container is connected to a circulation pipe having an accumulator, can solve the above-mentioned problems, thereby completing the present invention. Therefore, the present invention provides the following.

[0014] (1) A battery module comprises: a cell stack formed by stacking a plurality of cell cells; a pair of end plates disposed at both ends of the cell stack in a stacking direction; and a first buffer material disposed at least one of between the cell cells and between the cell cells and the end plates; wherein the first buffer material comprises an inner elastic container and an outer elastic container for accommodating the inner elastic container, wherein the interior of the inner elastic container is filled with gas, and the space between the outer surface of the inner elastic container and the inner surface of the outer elastic container is filled with liquid, and the outer elastic container is connected to a liquid piping, wherein the liquid piping is a circulation piping having an accumulator.

[0015] According to the battery module of (1), when the thickness of the battery cell increases due to charging and the first buffer material is squeezed, the hydraulic pressure increase of the liquid filled between the inner elastic container and the outer elastic container can be suppressed by the contraction of the inner elastic container and the accumulation of pressure in the accumulator. Therefore, even when the thickness of the battery cell changes significantly due to charging and discharging, it is possible to apply uniform pressure to the battery cell. In addition, since the accumulator is used as a tank for storing liquid, miniaturization is easy to achieve. Furthermore, since the liquid filled inside the first buffer material circulates in the circulation piping, the liquid temperature becomes uniform, thereby suppressing the temperature increase of the battery cell.

[0016] (2) The battery module according to (1), wherein the volume of the inner elastic container of the first buffer material is within a range of 30 to 70, when the total volume of the inner elastic container and the outer elastic container is 100.

[0017] According to the battery module (2), since the volume of the elastic container inside the first buffer material is within the above-mentioned range, it is possible to achieve a more balanced suppression of the increase in the liquid pressure of the liquid filling the interior of the first buffer material and the suppression of the temperature increase of the battery cells caused by the liquid.

[0018] (3) The battery module according to (1), further comprising a second buffer material disposed at least between the battery cells and between the battery cells and the end plate, the second buffer material being connected to the liquid piping and filled with liquid.

[0019] According to the battery module of (3), since the second buffer material is filled with only liquid and has high heat absorption efficiency, it is possible to more reliably suppress the temperature increase of the battery cells.

[0020] (4) The battery module according to (3), wherein the volume of the inner elastic container of the first buffer material is within a range of 50 to 90, when the total volume of the inner elastic container and the outer elastic container is 100.

[0021] According to the battery module of (4), since the volume of the elastic container inside the first buffer material is within the above range and the volume of the inner elastic container is large, the increase in the hydraulic pressure of the liquid filling the interior of the first buffer material and the second buffer material can be more reliably suppressed.

[0022] (5) The battery module according to (3) or (4), wherein the first buffer material is arranged between one of the pair of end plates and the battery cell, and the second buffer material is arranged between the battery cell and the battery cell.

[0023] According to the battery module of (5), since the second buffer material is arranged between the battery cells, the temperature increase of the battery cells can be further reliably suppressed.

[0024] (6) A method for manufacturing a battery module, comprising the following steps: preparing a plurality of battery cells, a pair of end plates, and a double-layer structure, wherein the double-layer structure has an inner elastic container and an outer elastic container for accommodating the inner elastic container; stacking the plurality of battery cells, disposing a pair of end plates at both ends of the obtained cell stack in the stacking direction, and disposing the double-layer structure at at least one of the positions between the battery cells and between the battery cells and the end plates; filling the inner elastic container with gas; and connecting a circulation piping having an accumulator to the outer elastic container, and filling the space between the inner elastic container and the outer elastic container with liquid.

[0025] According to the battery module of (6), the battery module having the first buffer material can be manufactured industrially advantageously.

[0026] (Effects of the Invention)

[0027] According to the present invention, a battery module and a method for manufacturing the same can be provided, which can apply uniform pressure to battery cells even when the thickness of the battery cells varies significantly due to charge and discharge, and can achieve miniaturization. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram illustrating a battery module according to the first embodiment of the present invention.

[0029] Figure 2 This is a cross-sectional view of a battery cell that can be used in the battery module according to the first embodiment of the present invention.

[0030] Figure 3 It is an explanation Figure 1 Schematic diagram of the charging status of the battery module shown.

[0031] Figure 4 It is a schematic diagram illustrating a battery module according to a second embodiment of the present invention.

[0032] Figure 5 It is an explanation Figure 4 Schematic diagram of the charging status of the battery module shown. DETAILED DESCRIPTION

[0033] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments shown below are for illustrative purposes only and the present invention is not limited to the following.

[0034] [First embodiment]

[0035] Figure 1 It is a schematic diagram illustrating a battery module according to the first embodiment of the present invention.

[0036] like Figure 1 As shown, the battery module 100 of this embodiment includes a single-cell stack 1, a pair of end plates 2a, 2b, and a first buffer material 3. The single-cell stack 1 is a stack of multiple (in Figure 1 The end plates 2a and 2b are arranged in the stacking direction of the single-cell stack 1 (in the stacking direction of the single-cell stack 1). Figure 1 The first buffer material 3 is disposed between the battery cells 10 and between the battery cells 10 and the end plates 2a and 2b. The end plates 2a and 2b are secured by a restraining tool such as a bind bar.

[0037] The battery cell 10 is a lithium metal battery that uses lithium ions as a charge transfer medium. Figure 2 As shown, the battery cell 10 includes an electrode stack 18, which is a stack of a positive electrode layer 11 and a negative electrode layer 14 with a solid electrolyte layer 17 interposed therebetween; and an exterior body 19, which houses the electrode stack 18. The positive electrode layer 11 includes a positive electrode current collector 12 and a positive electrode active material layer 13. The negative electrode layer 14 includes a negative electrode current collector 15 and a metal layer 16. When the battery cell 10 is charged, lithium ions released from the positive electrode active material layer 13 pass through the solid electrolyte layer 17 and deposit on the surface of the metal layer 16 of the negative electrode layer 14, forming a lithium deposit layer, which increases the thickness of the negative electrode layer 14. The lithium deposit layer functions as a negative electrode active material layer, releasing lithium ions and disappearing during discharge. Therefore, the volume of the battery cell 10 changes with charge and discharge. Consequently, the pressure exerted by the battery cell 10 on the first buffer material 3 changes with charge and discharge. The stacking direction of the electrode stack 18 is the same as that of the cell stack 1. That is, the plurality of battery cells 10 of the cell stack 1 are stacked along the stacking direction of the electrode stack 18. Figure 2 In the illustrated battery cell 10 , a single electrode stack 18 is housed in the exterior body 19 . However, a plurality of electrode stacks 18 may be housed in the exterior body 19 .

[0038] The material and shape of the positive electrode current collector 12 are not particularly limited, as long as it can collect current from the positive electrode layer 11. Examples of materials for the positive electrode current collector 12 include aluminum, aluminum alloys, stainless steel, nickel, iron, and titanium, with aluminum, aluminum alloys, and stainless steel being preferred. Examples of the shape of the positive electrode current collector 12 include foil and plate.

[0039] The positive electrode active material layer 13 contains at least one positive electrode active material. There is no particular limitation on the positive electrode active material, and materials used in the positive electrode layer of a conventional solid secondary battery can be used. As the positive electrode active material, for example, a layered active material containing lithium, a spinel type active material, an olivine type active material, etc. can be used. Specific examples of positive electrode active materials include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), LiNiO2, etc. p Mn q Co r O2(p+q+r=1), LiNi p Al q Co r O2(p+q+r=1), lithium manganate (LiMn2O4), Li 1+x Mn 2-x-y Li-Mn spinel substituted with a heterogeneous element represented by MO4 (x+y=2, M=at least one selected from Al, Mg, Co, Fe, Ni and Zn), lithium titanate (an oxide containing Li and Ti), lithium metal phosphate (LiMPO4, M=at least one selected from Fe, Mn, Co and Ni), etc.

[0040] From the perspective of improving lithium ion conductivity, the positive electrode active material layer 13 may optionally include a solid electrolyte. Furthermore, to improve electrical conductivity, a conductive additive may optionally be included. Furthermore, from the perspective of exhibiting flexibility, a binder may optionally be included. The solid electrolyte, conductive additive, and binder are not particularly limited, and materials commonly used in the positive electrode layer of solid secondary batteries may be used.

[0041] The material of the positive electrode lead 11 a may be the same as or different from the material of the positive electrode current collector 12 . The positive electrode lead 11 a may be integrally connected to the positive electrode current collector 12 .

[0042] The material and shape of the negative electrode current collector 15 are not particularly limited, as long as it can collect current from the negative electrode layer 14. Examples of materials for the negative electrode current collector 15 include nickel, copper, and stainless steel. Examples of the shape of the negative electrode current collector 15 include foil and plate.

[0043] The material and shape of metal layer 16 are not particularly limited, as long as it can densely deposit lithium ions. Metal layer 16 can be a layer of metallic lithium or a layer of a metal that forms an alloy with lithium. Examples of metals that form alloys with lithium include Mg, Si, Au, Ag, In, Ge, Sn, Pb, Al, and Zn. The metal forming metal layer 16 can be in powder or thin film form. By using negative electrode layer 14 having this metal layer 16, a uniform lithium deposition layer can be formed on the surface of metal layer 16.

[0044] The material of the negative electrode lead 14a may be the same as or different from the material of the negative electrode current collector 15. The negative electrode lead 14a may be integrally connected to the negative electrode current collector 15.

[0045] The solid electrolyte layer 17 contains at least one solid electrolyte. There is no particular limitation on the solid electrolyte as long as it has lithium ion conductivity. For example, a sulfide solid electrolyte, an oxide solid electrolyte, a nitride solid electrolyte, a halide solid electrolyte, etc. can be used. Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-P2S5-LiI, etc. The sulfide solid electrolyte may have an argyrodite-type crystal structure. Examples of oxide solid electrolytes include NASICON-type oxides, garnet-type oxides, and perovskite-type oxides. Examples of NASICON-type oxides include oxides containing Li, Al, Ti, P, and O (such as Li 1.5 Al 0.5 Ti 1.5 (PO4)3). Examples of garnet-type oxides include oxides containing Li, La, Zr, and O (e.g., Li7La3Zr2O 12 Examples of perovskite-type oxides include oxides containing Li, La, Ti, and O (eg, LiLaTiO 3 ).

[0046] The outer casing 19 can expand and contract as the volume of the battery cell 10 changes due to charge and discharge. A laminated film can be used as the material for the outer casing 19. A laminated film having a three-layer structure can be used, wherein an inner resin layer, a metal layer, and an outer resin layer are sequentially stacked from the inside. Examples of the outer resin layer include a polyamide (nylon) layer or a polyethylene terephthalate (PET) layer, an aluminum layer, and an inner resin layer include a polyethylene layer or a polypropylene layer.

[0047] End plates 2a and 2b have the function of restraining the cell stack 1 in the stacking direction. The restraining force of end plates 2a and 2b can be used to adjust the surface pressure applied to the cell stack 1 via first cushioning material 3. The material of end plates 2a and 2b is not particularly limited, and various materials used for end plates in battery modules can be used.

[0048] The first buffer material 3 has a function of making the surface pressure applied to the battery cell 10 uniform. The surface pressure applied to the battery cell 10 can be within a range of, for example, 1.0 MPa to 2.5 MPa.

[0049] The first cushioning material 3 is a two-layer structure comprising an inner elastic container 31 and an outer elastic container 33 that houses the inner elastic container 31. The inner elastic container 31 is filled with a gas 32. The gas 32 is sealed. A liquid 34 is filled between the outer surface of the inner elastic container 31 and the inner surface of the outer elastic container 33.

[0050] When the total volume of the inner elastic container 31 and the outer elastic container 33 is set to 100, the volume of the inner elastic container 31 of the first cushioning material can be, for example, within a range of 30 to 70. The volume of the inner elastic container 31 is the volume filled with gas 32. The volume of the outer elastic container 33 is the volume between the outer surface of the inner elastic container 31 and the inner surface of the outer elastic container 33, that is, the volume filled with liquid 34. If the volume of the inner elastic container 31 is 30 or greater, the pressure of the outer elastic container 33 when pressurized can be absorbed by the contraction of the inner elastic container 31, thereby suppressing the increase in the hydraulic pressure of the liquid 34. Furthermore, if the volume of the inner elastic container 31 is 70 or less, the temperature increase of the battery cell 10 caused by the liquid 34 can be suppressed.

[0051] The inner elastic container 31 and the outer elastic container 33 are each formed of a shrinkable elastic body. Examples of materials for the inner elastic container 31 and the outer elastic container 33 include rubber, elastomer, and laminated films. Examples of gas 32 include air and non-flammable gases (such as nitrogen and carbon dioxide). Examples of liquid 34 include mineral hydraulic oil, phosphate ester hydraulic oil, water, and glycol-based solvents.

[0052] The liquid piping 4 is connected to the opposite side of the outer elastic container 33. The liquid piping 4 is a circulation piping having an accumulator 41 and a pump 42. The accumulator 41 suppresses the increase in the hydraulic pressure of the liquid 34 in the first buffer material 3 by compressing and accumulating the gas inside. When the total volume is set to 100, the volume of the gas in the accumulator 41 can be, for example, within a range of 30 to 70. The pump 42 circulates the liquid 34 within the liquid piping 4 and the first buffer material 3. By circulating the liquid 34, the hydraulic pressure and liquid temperature of the liquid 34 within the liquid piping 4 and the first buffer material 3 can be made uniform. By making the hydraulic pressure uniform, the pressure applied to the battery cells 10 by the first buffer material 3 becomes uniform. By making the water temperature uniform, the temperature of the battery cells 10 becomes uniform.

[0053] Figure 3 Schematic diagram illustrating the charging state of the battery module 100 .

[0054] In the charged battery module 100a, the thickness of the battery cells 10a increases. As the thickness of the battery cells 10a increases, the first buffer material 3a is squeezed, reducing its thickness. As the thickness of the first buffer material 3a decreases, the hydraulic pressure of the liquid 34 within the first buffer material 3a increases. When the hydraulic pressure of the liquid 34 within the first buffer material 3a increases, the inner elastic container 31 is pressurized and contracts, and a portion of the liquid 34 within the first buffer material 3a flows out through the liquid piping 4 into the accumulator 41. The accumulator 41 utilizes the contraction of gas to accumulate the increased hydraulic pressure. Therefore, even if the thickness of the battery cells 10a increases, uniform pressure can be applied to the battery cells 10a without excessively increasing the internal pressure of the first buffer material 3a.

[0055] The inner elastic container 31, together with the accumulator 41, suppresses the increase in the hydraulic pressure of the liquid 34 within the first buffer material 3. To miniaturize the accumulator 41, it is effective to enlarge the inner elastic container 31 and increase the amount of gas within the first buffer material 3. On the other hand, the liquid 34 absorbs heat from the battery cells 10, suppressing the temperature rise of the battery cells 10. To suppress the temperature rise of the battery cells 10, it is effective to increase the amount of liquid within the first buffer material 3 by widening the gap between the inner elastic container 31 and the outer elastic container 33. Therefore, the size of the inner elastic container 31 can be varied depending on the placement of the first buffer material 3. For example, for the first buffer material 3 placed between the battery cells 10, where the temperature rises easily, the inner elastic container 31 can be relatively reduced, thereby widening the gap between the inner elastic container 31 and the outer elastic container 33. Alternatively, for the first buffer material 3 placed between the battery cells 10 and the end plates 2a, 2b, the inner elastic container 31 can be relatively enlarged. In this embodiment, the first buffer material 3 is disposed at two locations: between the battery cells 10 and between the battery cells 10 and the end plates 2a, 2b. However, the locations of the first buffer material 3 are not limited to these locations. The first buffer material 3 only needs to be disposed at at least one of the locations between the battery cells 10 and the end plates 2a, 2b.

[0056] The battery module 100 of this embodiment can be manufactured, for example, as follows.

[0057] First, a plurality of battery cells 10 , a pair of end plates 2 a and 2 b , and a double-layered structure including an inner elastic container 31 and an outer elastic container 33 that accommodates the inner elastic container 31 are prepared.

[0058] Next, multiple battery cells 10 are stacked, and a pair of end plates 2a and 2b are placed at each end of the resulting cell stack 1 in the stacking direction. A double-layer structure is then arranged between the battery cells 10 and between the battery cells 10 and the end plates 2a and 2b. After the arrangement is complete, the end plates 2a and 2b can be secured using a restraining tool such as a tie rod.

[0059] Next, the inner elastic container 31 is filled with gas 32. When filling the inner elastic container 31 with gas 32, the pressure may be within the range of 0.1 MPa to 0.9 MPa. Filling the inner elastic container 31 with gas 32 may be performed, for example, using the following methods (1) to (3).

[0060] (1) A gas supply pipe is provided in advance on the inner elastic container 31 , and after the inner elastic container 31 is filled with gas 32 through the pipe, a valve / joint with a check valve structure is provided at the front end of the pipe.

[0061] (2) A gas supply pipe is provided in advance in the inner elastic container 31 , and after the gas 32 is filled into the inner elastic container 31 through the pipe, the pipe is sealed by heat or pressure.

[0062] (3) A gas supply pipe is pre-installed on the thermoplastic inner elastic container 31. After the gas 32 is filled into the inner elastic container 31 through the pipe, the area around the pipe of the inner elastic container 31 is heated. The pipe is then removed and the inner elastic container 31 is sealed.

[0063] Next, the circulation pipe having the accumulator 41 is connected to the outer elastic container 33, and the liquid 34 is filled between the inner elastic container 31 and the outer elastic container 33. After the liquid 34 is filled, the internal pressure of the accumulator 41 can be adjusted to a range of 1.0 MPa to 2.5 MPa.

[0064] According to the battery module 100 of this embodiment, constructed as described above, when the thickness of the battery cells 10 increases due to charging and the first buffer material 3 is compressed, the contraction of the inner elastic container 31 and the accumulation of pressure in the accumulator 41 can suppress the increase in internal pressure of the liquid filling the first buffer material 3. Therefore, even when the thickness of the battery cells 10 changes significantly due to charging and discharging, uniform pressure can be applied to the battery cells 10. Furthermore, since the accumulator 41 serves as a tank for storing the liquid 34, miniaturization is easily achieved. Furthermore, since the liquid filling the first buffer material circulates within the circulation piping, the liquid temperature becomes uniform, thereby suppressing the temperature increase of the battery cells.

[0065] In the battery module 100 of this embodiment, when the total volume of the inner elastic container 31 and the volume of the outer elastic container 33 is set to 100, the volume of the inner elastic container 31 is within the above-mentioned range. In this case, the suppression of the increase in the hydraulic pressure of the liquid 34 filling the interior of the first buffer material 31 and the suppression of the temperature increase of the battery cell 10 caused by the liquid 34 can be achieved in a more balanced manner.

[0066] According to the method for manufacturing the battery module 100 of the present embodiment, the battery module 100 can be manufactured industrially advantageously.

[0067] [Second embodiment]

[0068] Figure 4 It is a schematic diagram illustrating a battery module according to a second embodiment of the present invention. Figure 5 It is an explanation Figure 4 Schematic diagram of the charging status of the battery module shown.

[0069] like Figure 4 As shown, the battery module 101 of this embodiment is identical to the battery module 100 of the first embodiment, except that second cushioning materials 5 are disposed between the battery cells 10 and between the cell stack 1 and the end plate 2b. Therefore, components common to the battery module 100 of the first embodiment are denoted by the same reference numerals, and their descriptions are omitted.

[0070] The second cushioning material 5 is a cushioning member filled solely with liquid 34. Liquid piping 4 is disposed on the opposite side of the second cushioning material 5. Liquid piping 4 is connected to the opposite side of the second cushioning material 5 to circulate the liquid 34 within the second cushioning material 5. When the total volume is 100, the gas volume of the accumulator 41 disposed on the liquid piping 4 can be within a range of 50 to 90, respectively.

[0071] In the charged battery module 101a, the thickness of the battery cell 10a increases. This compresses the first and second buffer materials 3a, 5. The thickness of the compressed first buffer material 3a decreases, causing the hydraulic pressure of the liquid 34 within the first buffer material 3a to increase. When the hydraulic pressure of the liquid 34 increases, the inner elastic container 31 is pressurized and contracts, causing the liquid 34 to flow out of the liquid pipe 4 into the accumulator 41. The thickness of the compressed second buffer material 5 decreases, causing the hydraulic pressure of the liquid 34 within the second buffer material 5 to increase, causing the liquid 34 to flow out of the liquid pipe 4 into the accumulator 41. Therefore, even if the thickness of the battery cell 10a increases, uniform pressure can be applied to the battery cell 10a without excessively increasing the internal pressure of the first and second buffer materials 3a, 5.

[0072] According to the battery module 101 of this embodiment constructed as described above, when the thickness of the battery cells 10 increases due to charging and the first and second buffer materials 3 and 5 are squeezed, the internal pressure of the first and second buffer materials 3 and 5 can be suppressed by the contraction of the elastic container 31 inside the first buffer material 3 and the accumulation of pressure in the accumulator 41. Therefore, even when the thickness of the battery cells 10 changes significantly due to charging and discharging, uniform pressure can be applied to the battery cells 10. In addition, because the accumulator 41 serves as a tank for storing the liquid 34, miniaturization can be achieved. Furthermore, according to the battery module 101 of this embodiment, because the second buffer material 5, which is filled only with liquid 34 and has high heat absorption efficiency, is arranged between the battery cells 10, the temperature rise of the battery cells 10 can be effectively suppressed.

[0073] In the battery module 101 of this embodiment, when the total volume of the inner elastic container 31 and the volume of the outer elastic container 33 is set to 100, the volume of the inner elastic container 31 is within the above-mentioned range. In this case, due to the larger volume of the inner elastic container 31, the increase in the hydraulic pressure of the liquid 34 filling the first and second cushioning materials 3 and 5 can be more reliably suppressed.

[0074] In the above embodiment, the battery cell 10 is described as a solid battery having a solid electrolyte layer 17. However, the battery cell 10 is not limited thereto. The battery cell 10 may be, for example, a non-aqueous battery using an organic electrolyte solution as an electrolyte or a polymer battery using a high molecular gel (polymer).

[0075] Reference numerals

[0076] 1 Monomer laminate

[0077] 2a, 2b end plates

[0078] 3,3a First cushioning material

[0079] 4 liquid piping

[0080] 5. Second cushioning material

[0081] 10,10a battery cells

[0082] 11 positive electrode layer

[0083] 11a positive lead

[0084] 12 positive electrode collector

[0085] 13 Positive electrode active material layer

[0086] 14 negative electrode layer

[0087] 14a negative lead

[0088] 15 negative electrode collector

[0089] 16 metal layers

[0090] 17Solid electrolyte layer

[0091] 18-electrode stack

[0092] 19 outer body

[0093] 31Inner elastic container

[0094] 32 Gas

[0095] 33 outer elastic container

[0096] 34 liquid

[0097] 41 accumulator

[0098] 42 pumps

[0099] 100, 100a, 101, 101a battery modules

Claims

1. A battery module comprising: A monomer stack, formed by stacking multiple battery cells; a pair of end plates disposed at both ends of the aforementioned single-unit stack in the stacking direction; and, The first buffer material is disposed at least one of between the battery cells and between the battery cells and the end plate; and The first cushioning material comprises an inner elastic container and an outer elastic container for accommodating the inner elastic container. The interior of the inner elastic container is filled with gas. The space between the outer surface of the inner elastic container and the inner surface of the outer elastic container is filled with liquid. The outer elastic container is connected to the liquid pipe. The liquid piping is a circulation piping having an accumulator.

2. The battery module according to claim 1, wherein: When the total volume of the inner elastic container and the outer elastic container is 100, the volume of the inner elastic container of the first cushioning material is within a range of 30 to 70.

3. The battery module according to claim 1, wherein: A second buffer material is further arranged at least between the battery cells and between the battery cells and the end plate. The second buffer material is connected to the liquid pipe and is filled with liquid.

4. The battery module according to claim 3, wherein: When the total volume of the inner elastic container and the outer elastic container is 100, the volume of the inner elastic container of the first cushioning material is within a range of 50 to 90.

5. The battery module according to claim 3 or 4, wherein: The first buffer material is disposed between one of the pair of end plates and the battery cell, and the second buffer material is disposed between the battery cell.

6. A method for manufacturing a battery module, comprising the following steps: Preparing a plurality of battery cells, a pair of end plates, and a double-layer structure having an inner elastic container and an outer elastic container for accommodating the inner elastic container; A plurality of the battery cells are stacked, a pair of end plates are disposed at both ends of the resulting cell stack in the stacking direction, and the double-layer structure is disposed at least one of between the battery cells and between the battery cells and the end plates; Filling the inner elastic container with gas; and, A circulation pipe having an accumulator is connected to the outer elastic container, and a liquid is filled between the inner elastic container and the outer elastic container.

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