All-solid-state battery module

Abstract

To prevent current collector foil inside a battery cell from being torn by friction in an all-solid-state battery module with an elastic body placed on the battery cell.SOLUTION: The all-solid-state battery module includes one battery cell and an elastic body arranged on the battery cell. The battery cell has: an electrode laminate with an outermost current collector foil; an outer casing that houses the electrode laminate; and a friction-reducing material arranged between the outer casing and the outermost current collector foil. The battery cell is pressurized so that it is compressed via the elastic body.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an all-solid-state battery module. [Background technology]

[0002] A known all-solid-state battery module has at least one battery cell and an elastic body disposed on the battery cell.

[0003] For example, Patent Document 1 (JP 2015-53261 A) discloses an all-solid-state battery in which multiple battery units are stacked, the battery units having a predetermined configuration, and a heat dissipation member is interposed between each battery unit, and these heat dissipation members are composed of a base layer having a specific configuration and a pair of thermally conductive elastic layers that sandwich the base layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-53261 A Summary of the Invention [Problem to be solved by the invention]

[0005] In an all-solid-state battery module, the battery cells need to be pressurized to reduce contact resistance. In an all-solid-state battery module in which an elastic body is provided on the battery cells, the battery cells are pressurized via the elastic body. At this time, the elastic body is compressed. The compressed elastic body is distorted. Specifically, the elastic body is distorted so as to expand in a direction perpendicular to the pressure direction (hereinafter sometimes referred to as the planar direction).

[0006] The compression amount of the elastic body may vary. For example, the battery cell may expand and contract as it is charged and discharged. The compression amount of the elastic body may change as the battery cell expands and contracts. As a result, the size of the contact surface of the elastic body with the battery cell also changes.

[0007] The present inventors have been studying an all-solid-state battery module using a battery cell having an electrode laminate and a film-like exterior material that houses the electrode laminate. Furthermore, the inventors have been studying an electrode laminate having a current collector foil provided on the outermost layer. Here, the present inventors have found that when such a configuration is adopted, the current collector foil of the outermost layer may break when the compression amount of the elastic body changes.

[0008] Therefore, an object of the present invention is to provide a technique capable of preventing the current collecting foil in the battery cell from being torn due to friction in an all-solid-state battery module in which an elastic body is disposed on the battery cell. [Means for solving the problem]

[0009] In one embodiment, the all-solid-state battery module according to the present invention includes at least one battery cell and an elastic body arranged on the battery cell. The battery cell includes an electrode laminate having an outermost current collector foil as the outermost layer, an exterior material that houses the electrode laminate, and a friction-reducing material arranged between the elastic body and the electrode laminate, the friction-reducing material being arranged between the exterior material and the electrode laminate. The battery cell is pressurized so as to be compressed via the elastic body. Effect of the Invention

[0010] According to the present invention, a technique is provided that can prevent the current collecting foil in the battery cell from being torn due to friction in an all-solid-state battery module in which an elastic body is disposed on the battery cell. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an all-solid-state battery module according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing a configuration of a portion of the all-solid-state battery module. [Diagram 3] FIG. 3 is a schematic diagram showing a reference example. [Figure 4A] FIG. 4A is a schematic diagram showing a modification of the first embodiment. [Figure 4B] FIG. 4B is a schematic diagram showing a modification of the first embodiment. [Diagram 5] FIG. 5 is a schematic diagram showing a modified example of the first embodiment. [Figure 6] FIG. 6 is a schematic diagram showing a modified example of the first embodiment. [Figure 7] FIG. 7 is a schematic cross-sectional view showing an all-solid-state battery module according to the second embodiment. [Figure 8] FIG. 8 is a schematic cross-sectional view showing an all-solid-state battery module 1 according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an all-solid-state battery module according to an embodiment of the present invention will be described with reference to the drawings.

[0013] The all-solid-state battery module according to the present embodiment is a module formed by combining all-solid-state battery cells (battery cells) with other components. In this specification, the term "all-solid-state battery" refers to a secondary battery in which the positive electrode layer, the negative electrode layer, and the electrolyte layer are substantially made of solids. The "all-solid-state battery" may be any battery in which each layer can be said to be "substantially" solid, and may contain a small amount of liquid material. For example, even if a battery uses a small amount of liquid electrolyte in addition to a solid electrolyte as the electrolyte, it is included in the all-solid-state battery in this specification as long as each layer can be said to be substantially solid.

[0014] (First embodiment) Fig. 1 is a schematic cross-sectional view showing an all-solid-state battery module 1 according to a first embodiment. As shown in Fig. 1, the all-solid-state battery module 1 has a plurality of battery cells 2, a plurality of elastic bodies 3, and a pair of end plates 4. The plurality of battery cells 2 and the plurality of elastic bodies 3 are stacked so as to be alternately arranged in the stacking direction. The plurality of battery cells 2 and the plurality of elastic bodies 3 are sandwiched between the pair of end plates 4 in a compressed state. With this configuration, each battery cell 2 is pressurized so as to be compressed via each elastic body 3.

[0015] Fig. 2 is a diagram showing a partial configuration of the all-solid-state battery module 1, and is an enlarged diagram of region A in Fig. 1. As shown in Fig. 2, the elastic body 3 is disposed on the battery cell 2. The battery cell 2 has an electrode laminate 5, an exterior material 6, and a frictional force reduction material 7.

[0016] The exterior material 6 is a member that houses the electrode stack 5. The exterior material 6 is made of, for example, an aluminum laminate film.

[0017] The electrode laminate 5 is a part that realizes the function of a secondary battery. Although not shown, the electrode laminate 5 has a configuration in which a positive electrode layer, a negative electrode layer, an electrolyte layer, and current collector foils (positive electrode current collector foil and negative electrode current collector foil) are laminated along the lamination direction. The electrode laminate 5 may have a plurality of units, and each unit may include a positive electrode layer, a negative electrode layer, an electrolyte layer, and current collector foils (positive electrode current collector foil and negative electrode current collector foil). However, the outermost layer of the electrode laminate 5 is a current collector foil. Hereinafter, the current collector foil constituting the outermost layer of the electrode laminate 5 is referred to as the outermost layer current collector foil 8.

[0018] The frictional force reduction material 7 is disposed between the elastic body 3 and the electrode laminate 5, and between the exterior material 6 and the electrode laminate 5. In other words, the frictional force reduction material 7 is disposed between the exterior material 6 and the outermost current collecting foil 8.

[0019] According to this embodiment, the frictional force reducing material 7 prevents the outermost current collecting foil 8 from breaking. This point will be described below with reference to a reference example.

[0020] FIG. 3 is a schematic diagram showing a reference example. In the reference example, the frictional force reducing material 7 is not provided. That is, in the battery cell 2, the exterior material 6 and the outermost current collecting foil 8 are in contact with each other (they are slightly separated in FIG. 3 for ease of viewing). As described above, in the all-solid-state battery module 1, the compression amount of the elastic body 3 may change due to various reasons. For example, the thickness of the battery cell 2 (the thickness of the electrode laminate 5) may change with charging and discharging. When the thickness of the battery cell 2 increases, the compression amount of the elastic body 3 in the lamination direction increases. As a result, the elastic body 3 is distorted so as to expand in the planar direction. In FIG. 3, the elastic body 3 when the compression amount is small is shown as the elastic body 3a, and the elastic body 3 when the compression amount is large is shown as the elastic body 3b. When the distortion amount of the elastic body 3 changes, the exterior material 6 is pulled in the planar direction by the elastic body 3. As a result, a frictional force is generated between the exterior material 6 and the outermost current collecting foil 8. This frictional force may cause the outermost current collecting foil 8 to break.

[0021] In contrast, according to this embodiment, as shown in Fig. 2, friction reduction material 7 is disposed, so that the frictional force generated between the exterior material 6 and the outermost-layer current collecting foil 8 is reduced. This prevents the outermost-layer current collecting foil 8 from breaking.

[0022] The above is an outline of the all-solid-state battery module 1 according to the present embodiment.

[0023] The material of the elastic body 3 is not particularly limited. For example, a resin sheet can be used as the elastic body 3. Examples of the resin sheet include a rubber sheet and a thermoplastic elastomer sheet.

[0024] The configuration of the electrode laminate 5 is not particularly limited. However, the electrode laminate 5 preferably contains lithium metal or a lithium-containing alloy as the negative electrode active material. That is, the negative electrode layer of the electrode laminate 5 preferably contains lithium metal or a lithium-containing alloy as the negative electrode active material. The electrode laminate 5 having such a configuration changes in thickness significantly with charging and discharging. Specifically, the thickness increases in a charged state and decreases in a discharged state. As a result, the compression amount of the elastic body 3 changes significantly with charging and discharging, and a large frictional force is repeatedly generated. Therefore, the breakage of the outermost layer current collector foil 8 is likely to be a problem. Therefore, the value of reducing the frictional force according to this embodiment is great.

[0025] The friction-reducing material 7 is not particularly limited as long as it is a material that can reduce the friction generated between the exterior material 6 and the outermost current collecting foil 8.

[0026] For example, a sheet material can be used as the friction-reducing material 7. In this case, a material that reduces the coefficient of friction between the exterior material 6 and the outermost current collecting foil 8 can be used as the friction-reducing material 7. Specifically, a sheet material that satisfies the following relationship (1) and / or (2) can be used as the friction-reducing material 7.

[0027] (1) "Friction coefficient A between the exterior material 6 and the outermost current collecting foil 8" > "Friction coefficient B between the exterior material 6 and the friction reduction material 7" (2) "Friction coefficient A between the exterior material 6 and the outermost current collecting foil 8" > "Friction coefficient C between the outermost current collecting foil 8 and the friction reduction material 7"

[0028] In the above (1) and (2), the “friction coefficient A between the exterior material 6 and the outermost current collecting foil 8” means the friction coefficient between the exterior material 6 and the outermost current collecting foil 8 when they are in direct contact with each other.

[0029] In this specification, the term "friction coefficient" refers to both the kinetic and static coefficients of friction. For example, the fact that the friction coefficient at boundary A is greater than the friction coefficient at boundary B means that both the kinetic and static coefficients of friction are greater at boundary A than at boundary B.

[0030] Examples of sheet materials used as the frictional force reducing material 7 include resin sheets such as PP (polypropylene) sheets, PE (polypropylene) sheets, PI (polyimide) sheets, PC (polycarbonate) sheets, and PTFE (polytetrafluoroethylene) sheets.

[0031] When the frictional force reduction material 7 is a sheet material, the sheet material is preferably fixed to the exterior material 6 or the outermost current collecting foil 8 to prevent displacement. This point will be described in detail with reference to Figs. 4A and 4B.

[0032] 4A is a schematic diagram showing a modified example of the present embodiment. In this modified example, the frictional force reduction material 7 is adhered to the exterior material 6 via an adhesive layer 9. In other words, the frictional force reduction material 7 is fixed to the exterior material 6. This configuration prevents the frictional force reduction material 7 from shifting out of position.

[0033] 4B is a schematic diagram showing another modified example of this embodiment. In this modified example, the frictional force reduction material 7 is adhered to the outermost current collecting foil 8 via an adhesive layer 9. In other words, the frictional force reduction material 7 is fixed to the outermost current collecting foil 8. This configuration also prevents the frictional force reduction material 7 from shifting out of position.

[0034] The frictional force reduction material 7 does not necessarily have to be a sheet material. For example, the frictional force reduction material 7 can also be realized by a lubricant layer containing a lubricant such as lubricating oil. The lubricant may be applied to the inner surface of the exterior material 6, or may be applied onto the outermost current collecting foil 8. A lubricant is used such that the coefficient of friction between the exterior material 6 and the outermost current collecting foil 8 when the lubricant is provided is smaller than the coefficient of friction between the exterior material 6 and the outermost current collecting foil 8 when no lubricant is provided.

[0035] As the lubricant, a flame-retardant hydraulic fluid is preferably used, for example, a phosphate-based hydraulic fluid, a fatty acid ester-based hydraulic fluid, a water-glycol-based hydraulic fluid, and an emulsion-based hydraulic fluid.

[0036] Next, the size of the frictional force reducing material 7 will be described.

[0037] Fig. 5 is a schematic diagram showing a modified example of this embodiment. This modified example is a modification regarding the size of the frictional force reduction material 7. In this modified example, the frictional force reduction material 7 is a sheet material. When the battery cell 2 is viewed from the elastic body 3 side (when viewed along the stacking direction), the size of the frictional force reduction material 7 is larger than the size of the outermost current collecting foil 8. Specifically, when viewed along the stacking direction, the outer peripheral end a of the frictional force reduction material 7 is located outside the outer peripheral end b of the outermost current collecting foil 8.

[0038] According to the modified example shown in Fig. 5, damage to the outermost current collecting foil 8 due to frictional force is more reliably prevented. If the outer peripheral end a of the frictional force reduction material 7 is located more inward than the outer peripheral end b of the outermost current collecting foil 8, a large frictional force may be generated in the outermost current collecting foil 8 in the portion outside the frictional force reduction material 7. This may result in damage to the outermost current collecting foil 8. In contrast, according to the modified example shown in Fig. 5, the entire area of ​​the outermost current collecting foil 8 is covered with the frictional force reduction material 7, so damage to the outermost current collecting foil 8 is more reliably prevented.

[0039] Next, another modification regarding the size of the frictional force reduction material 7 will be described. FIG. 6 is a schematic diagram showing another modification of this embodiment. In this modification, the relationship between the size of the frictional force reduction material 7 and the size of the elastic body 3 is specified. Specifically, the frictional force reduction material 7 is sheet-shaped. When the battery cell 2 is viewed from the elastic body 3 side (when viewed along the stacking direction), the outer peripheral end a of the frictional force reduction material 7 is located outside the outer peripheral end c of the elastic body 3. With this configuration, when viewed along the stacking direction, the elastic body 3 is not located outside the frictional force reduction material 7. Therefore, a large frictional force is prevented from being generated in the outermost current collecting foil 8 outside the frictional force reduction material 7, and damage to the outermost current collecting foil 8 is more reliably prevented.

[0040] In FIG. 6, the elastic body 3 when the amount of compression is the smallest is shown as the elastic body 3a, and the elastic body 3 when the amount of compression is the largest is shown as the elastic body 3b. As shown in FIG. 6, when the state (elastic body 3b) in which the elastic body 3 is most compressed can be specified, it is preferable that the outer peripheral end a of the frictional force reducing material 7 is located outside the outer peripheral end c of the elastic body 3b when the elastic body 3 is most compressed. For example, when an electrode laminate 5 containing lithium metal or a lithium-containing alloy is used as the negative electrode active material, the thickness of the battery cell 2 (electrode laminate 5) becomes maximum at the time of full charge, and the amount of compression of the elastic body 3 becomes maximum. In such a case, it is preferable that the outer peripheral end a of the frictional force reducing material 7 is located outside the outer peripheral end c of the elastic body 3b at the time of full charge. By adopting such a configuration, the outer peripheral end a of the frictional force reducing material 7 is always located outside the outer peripheral end c of the elastic body 3. Therefore, it is always possible to prevent a large frictional force from being generated on the outer side of the frictional force reducing material 7 in the outermost current collecting foil 8.

[0041] The first embodiment has been described above.

[0042] In the present embodiment, a case has been described in which a plurality of battery cells 2 and a plurality of elastic bodies 3 are provided. However, a plurality of battery cells 2 and a plurality of elastic bodies 3 are not necessarily provided. That is, it is sufficient that the all-solid-state battery module 1 is provided with at least one battery cell 2 and at least one elastic body 3.

[0043] The use of the all-solid-state battery module 1 according to this embodiment is not particularly limited. For example, the all-solid-state battery module 1 can be used for an electric vehicle (EV).

[0044] Second embodiment Next, a second embodiment will be described. Fig. 7 is a schematic cross-sectional view showing an all-solid-state battery module 1 according to this embodiment. Note that detailed description of the points where the same configuration as in the first embodiment can be adopted will be omitted.

[0045] In this embodiment, the surface state of the outermost current collecting foil 8 is devised. Specifically, the outermost current collecting foil 8 has an outer surface a facing the elastic body 3 (outside), and an inner surface b opposite the outer surface a. Here, the surface state of the inner surface b is different from the surface state of the outer surface a. The surface state of the outer surface a is more slippery than that of the inner surface b. More specifically, the friction coefficient between the outer surface a and the frictional force reduction material 7 is smaller than the friction coefficient between the inner surface b and the frictional force reduction material 7 when the inner surface b and the frictional force reduction material 7 are in contact with each other.

[0046] According to the present invention, the coefficient of friction between the friction-reducing material 7 and the outer surface a is smaller, which reduces the frictional force acting on the outermost-layer current collecting foil 8. This makes it possible to more reliably prevent the outermost-layer current collecting foil 8 from breaking.

[0047] The surface conditions of the inner surface b and the outer surface a of the outermost current collecting foil 8 can be made different, for example, by changing the surface roughness. Preferably, the surface roughness of the outer surface a is smaller than the surface roughness of the inner surface b. With this configuration, the surface condition of the outer surface a can be made more slippery than the inner surface b. As a result, the friction coefficient between the frictional force reduction material 7 and the outer surface a can be made smaller than the friction coefficient when the inner surface b and the frictional force reduction material 7 are in contact with each other.

[0048] (Third embodiment) Next, a third embodiment will be described. Fig. 8 is a schematic cross-sectional view showing an all-solid-state battery module 1 according to this embodiment. Note that detailed description will be omitted for the points where the same configuration as in the above-described embodiments can be adopted.

[0049] In this modification, as shown in Fig. 8, the electrode stack 5 is bonded at its outer periphery (the outer periphery on the top and bottom surfaces in the stacking direction) to the exterior material 6 (see adhesive portion 10 in Fig. 8). With this configuration, the electrode stack 5 is fixed to the exterior material 6. Therefore, the positional deviation of the electrode stack 5 with respect to the exterior material 6 is suppressed.

[0050] The present invention has been described above with reference to the first to third embodiments. Representative configurations of the present invention will be summarized below together with their effects as supplementary notes.

[0051] (Appendix 1) An all-solid-state battery module comprising at least one battery cell 2 and an elastic body 3 arranged on the battery cell 2, the battery cell 2 comprising an electrode laminate 5 having an outermost current collecting foil 8 as its outermost layer, an exterior material 6 housing the electrode laminate 5, and a frictional force reducing material 7 arranged between the elastic body 3 and the electrode laminate 5, the frictional force reducing material 7 being arranged between the exterior material 6 and the outermost current collecting foil 8, the battery cell 2 being pressurized so as to be compressed via the elastic body 3. According to this configuration, the frictional force reducing material 7 reduces the frictional force between the exterior material 6 and the outermost current collecting foil 8, thereby preventing the outermost current collecting foil 8 from breaking.

[0052] (Appendix 2) The all-solid-state battery module according to Supplementary Note 1, wherein the electrode laminate 5 further has a negative electrode layer containing lithium metal or a lithium-containing alloy as a negative electrode active material. With this configuration, the electrode laminate 5 changes in thickness significantly with charging and discharging. Since the deformation amount of the elastic body 3 repeatedly changes significantly, tearing of the outermost current collecting foil 8 is usually likely to be a problem. However, according to the present invention, the frictional force can be reduced by the frictional force reducing material 7.

[0053] (Appendix 3) An all-solid-state battery module according to appendix 1 or 2, wherein the frictional force reduction material 7 is fixed to the exterior material 6 or the outermost current collecting foil 8. According to such a configuration, the frictional force reduction material 7 is prevented from shifting in position.

[0054] (Appendix 4) An all-solid-state battery module according to any one of Supplementary Notes 1 to 3, wherein the frictional force reduction material 7 is sheet-shaped, and when the battery cell 2 is viewed from the elastic body 3 side, the outer peripheral edge a of the frictional force reduction material 7 is located outside the outer peripheral edge b of the outermost current collecting foil 8. This configuration prevents a large frictional force from being generated on the outside of the frictional force reduction material 7 in the outermost current collecting foil 8. Breaking of the outermost current collecting foil 8 is more reliably prevented.

[0055] (Appendix 5) An all-solid-state battery module according to any one of Supplementary Notes 1 to 4, wherein the frictional force reduction material 7 is sheet-shaped, and when the battery cell 2 is viewed from the elastic body 3 side, the outer peripheral edge of the frictional force reduction material 7 is located outside the outer peripheral edge of the elastic body 3. This configuration prevents a large frictional force from being generated on the outer side of the frictional force reduction material 7 in the outermost current collecting foil 8. Breakage of the outermost current collecting foil 8 is more reliably prevented.

[0056] (Appendix 6) An all-solid-state battery module according to any one of Supplementary Notes 1 to 5, wherein the outermost current collecting foil 8 has an outer surface a facing the elastic body 3 and an inner surface b opposite to the outer surface a, the surface state of the inner surface b is different from the surface state of the outer surface a, and the coefficient of friction between the outer surface a and the frictional force reducing material 7 is smaller than the coefficient of friction between the inner surface b and the frictional force reducing material 7 when the inner surface b is in contact with the frictional force reducing material 7. With this configuration, frictional force is less likely to be generated compared to when the outer surface has the same surface state as the inner surface. Breakage of the outermost current collecting foil 8 is more reliably prevented.

[0057] (Appendix 7) An all-solid-state battery module according to any one of Supplementary Notes 1 to 6, wherein the electrode laminate 5 is bonded at its outer periphery to an exterior material 6. With this configuration, displacement of the electrode laminate 5 is prevented. [Explanation of symbols]

[0058] 1 All-solid-state battery module, 2 Battery cell, 3 Elastic body, 4 End plate, 5 Electrode laminate, 6 Exterior material, 7 Friction reduction material, 8 Outermost current collecting foil, 9 Adhesive layer, 10 Adhesive part

Claims

1. At least one battery cell; An elastic body disposed on the battery cell; Equipped with The battery cell includes: an electrode laminate having an outermost current collecting foil as an outermost layer; An exterior material that houses the electrode stack; a friction-reducing material disposed between the elastic body and the electrode laminate, the friction-reducing material being disposed between the exterior material and the outermost current collecting foil, The battery cell is compressed via the elastic body. All-solid-state battery module.

2. The all-solid-state battery module according to claim 1 , The electrode laminate further has a negative electrode layer containing lithium metal or a lithium-containing alloy as a negative electrode active material. All-solid-state battery module.

3. The all-solid-state battery module according to claim 1 or 2, The frictional force reducing material is fixed to the exterior material or the outermost current collecting foil. All-solid-state battery module.

4. The all-solid-state battery module according to claim 1 or 2, The friction reduction material is in a sheet form, When the battery cell is viewed from the elastic body side, an outer peripheral edge of the frictional force reduction material is located outside an outer peripheral edge of the outermost current collecting foil. All-solid-state battery module.

5. The all-solid-state battery module according to claim 1 or 2, The friction reduction material is in a sheet form, When the battery cell is viewed from the elastic body side, an outer circumferential edge of the frictional force reduction material is located outside an outer circumferential edge of the elastic body. All-solid-state battery module.

6. The all-solid-state battery module according to claim 1 or 2, The outermost current collecting foil is An outer surface facing the elastic body; an inner surface opposite the outer surface; the surface condition of the inner surface is different from the surface condition of the outer surface, a friction coefficient between the outer surface and the friction-reducing material is smaller than a friction coefficient between the inner surface and the friction-reducing material when the inner surface and the friction-reducing material are in contact with each other; All-solid-state battery module.

7. The all-solid-state battery module according to claim 1 or 2, The electrode laminate is bonded to the exterior material at its outer periphery. All-solid-state battery module.

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