Battery module

Abstract

The invention provides a battery module which has high energy density, can suppress bending of a current collecting part of a battery cell, and can suppress deterioration and short circuit caused by bending of the current collecting part of the battery cell. A battery module (1) is provided with: a plurality of battery cells (10) stacked in one direction; a restraining body (20) that restrains the plurality of battery cells (10) in the stacking direction; a bus bar (30) that connects the battery cells (10) to each other; and a bus bar holder (40) that holds the bus bar (30), the bus bar holder (40) having a first stretchable section (41) that follows the displacement of the battery cells (10) in the stacking direction.

Description

Technical Field

[0001] The present invention relates to a battery module. Background Art

[0002] Conventionally, when stacking battery cells that expand and contract (for example, batteries using lithium metal as the negative electrode) to form a battery module, elastic members or springs are placed between adjacent battery cells to absorb the expansion and contraction of the cells in order to secure the tab leads of the battery cells. Furthermore, it is known to use a telescopic busbar connecting adjacent battery cells (for example, see Japanese Patent Application Laid-Open No. 2015-207442). Summary of the Invention

[0003] However, placing elastic members or springs between adjacent battery cells takes up space within the battery module, reducing the overall energy density and increasing the module's mass. Furthermore, even with elastic members or springs placed between adjacent battery cells, the amount of expansion and contraction varies between battery cells. This variation generates stress in the battery cell tab leads, sometimes leading to degradation and short circuits caused by bending of the battery cell's current collectors. Furthermore, because the busbar holders that create the gaps between the busbars are fixed, bending of the battery cell's current collectors cannot be prevented by simply expanding or contracting the busbars.

[0004] The present invention aims to provide a battery module that has high energy density and can suppress bending of the current collector of a battery cell, thereby preventing degradation and short circuits caused by bending of the current collector of the battery cell. This invention contributes to stabilizing battery performance, improving quality management of the manufacturing process, and ultimately, improving energy efficiency.

[0005] The first embodiment of the present invention is a battery module comprising: a plurality of battery cells stacked in one direction; a restraining body that restrains the plurality of battery cells in the stacking direction; a bus bar that connects the battery cells to each other; and a bus bar retaining frame that retains the bus bar, the bus bar retaining frame having a first telescopic portion that follows the displacement of the battery cells in the stacking direction.

[0006] In the battery module of the first aspect of the present invention, the busbar holder includes a first telescopic portion that follows the displacement of the multiple battery cells in the stacking direction. This eliminates the need for components that occupy space within the battery module, thereby maintaining the overall energy density of the battery module and minimizing increases in the module's mass. Furthermore, the first telescopic portion of the busbar holder expands and contracts in response to the expansion and contraction of the battery cells, thereby absorbing the expansion and contraction of the battery cells and minimizing degradation and short circuits caused by bending of the battery cell's current collectors.

[0007] A second aspect is the battery module according to the first aspect, wherein an elastic member may be arranged between the restraining body and the battery cell or between the battery cells.

[0008] In the battery module of the second embodiment of the present invention, an elastic member is arranged between the restraint body and the battery cell or between the battery cells. Therefore, the elastic member can absorb the expansion and contraction of the battery cell and suppress degradation and short circuit caused by bending of the collector of the battery cell.

[0009] A third aspect is the battery module according to the first or second aspect, wherein the bus bar may include a second expandable portion that follows displacement of the battery cells in the stacking direction.

[0010] In the battery module of the third embodiment of the present invention, the second telescopic portion of the busbar expands and contracts as the battery cells expand and contract, following the displacement of the multiple battery cells in the stacking direction. Therefore, the second telescopic portion can absorb the expansion and contraction of the battery cells, and can suppress the degradation and short circuit caused by the bending of the collecting portion of the battery cells.

[0011] A fourth aspect is the battery module according to any one of the first to third aspects, wherein the bus bar holder has a rail that enables the bus bar to move in the stacking direction of the battery cells.

[0012] In the battery module of the fourth embodiment of the present invention, the busbar retainer has a track for allowing the busbar to move in the stacking direction of the battery cells, so that the busbar can move along the track as the battery cells expand and contract, and can suppress degradation and short circuit caused by bending of the collecting part of the battery cells.

[0013] A fifth embodiment is the battery module according to any one of the first to fourth embodiments, wherein the negative electrode constituting the battery cell includes a material containing lithium metal or silicon.

[0014] In the battery module of the fifth embodiment of the present invention, even if the negative electrode constituting the battery cell includes a material containing lithium metal or silicon, the first telescopic portion of the busbar retainer expands and contracts as the battery cell expands and contracts, following the displacement in the stacking direction of the plurality of battery cells. Therefore, the first telescopic portion can also absorb the expansion and contraction of the battery cell, and can suppress degradation and short circuit caused by bending of the collecting portion of the battery cell.

[0015] The sixth solution is based on the battery module of any one of the first to fifth solutions, and the battery unit may be a solid-state battery.

[0016] In the battery module according to the sixth aspect of the present invention, even if the battery cells are solid-state batteries, the battery module can be reduced in weight because there is no member occupying space within the battery module.

[0017] According to the aspects of the present invention, it is possible to provide a battery module that has high energy density, can suppress bending of the current collecting portions of the battery cells, and can suppress degradation and short circuits caused by bending of the current collecting portions of the battery cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram showing the structure of a battery module according to the first embodiment of the present invention.

[0019] Figure 2 It is a schematic diagram showing the structure of a battery module according to the first embodiment of the present invention.

[0020] Figure 3 It is a schematic diagram showing the structure of a battery module according to a second embodiment of the present invention.

[0021] Figure 4 It is a schematic diagram showing the structure of a battery module according to a second embodiment of the present invention.

[0022] Figure 5 It is a schematic diagram showing the structure of a battery module according to a third embodiment of the present invention.

[0023] Figure 6 It is a schematic diagram showing the structure of a battery module according to a third embodiment of the present invention.

[0024] Figure 7 It is a schematic diagram showing the structure of a battery module according to a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0025] Hereinafter, a battery module according to an embodiment of the present invention will be described with reference to the drawings.

[0026] [Battery Module]

[0027] (First embodiment)

[0028] Figure 1 and Figure 2 This is a schematic diagram illustrating the structure of a battery module according to the first embodiment of the present invention. It should be noted that in the drawings used in the following description, characteristic portions are sometimes enlarged for ease of understanding, and the dimensional ratios of the various components are not limited by the diagrams.

[0029] like Figure 1 and Figure 2 As shown, the battery module 1 of the present embodiment includes a plurality of battery cells 10 , a restraining body 20 , a bus bar 30 , and a bus bar holder 40 .

[0030] The plurality of battery cells 10 are arranged along a direction ( Figure 1 The constraint body 20 is stacked from both sides of the stacking direction ( Figure 1 The plurality of battery cells 10 are constrained on both lateral sides of the middle portion.

[0031] The busbars 30 connect adjacent battery cells 10 along the stacking direction of the battery cells 10. The busbar holders 40 are provided so as to extend along the stacking direction of the battery cells 10 and hold the busbars 30 from both sides in the longitudinal direction of the busbars 30 (a direction perpendicular to the stacking direction of the battery cells 10).

[0032] The bus bar holder 40 has a first expandable portion 41 that follows the displacement of the battery cells 10 in the stacking direction.

[0033] In the battery module 1 of this embodiment, an elastic member 50 is preferably disposed between the restraining body 20 and the battery cell 10. This allows the elastic member 50 to absorb expansion and contraction of the battery cell 10 and suppress degradation and short circuiting caused by bending of the current collecting portion of the battery cell 10.

[0034] Battery Cell

[0035] The battery cell in this embodiment comprises a positive electrode, a negative electrode, an electrolyte layer, and an outer film. While not particularly limited, the battery cell is preferably a solid-state battery. Even if the battery cell 10 is a solid-state battery, the absence of components occupying space within the battery module 1 allows for weight reduction.

[0036] (positive electrode)

[0037] The positive electrode is formed by laminating a first current collector layer and a first active material layer containing at least a positive electrode active material. In this embodiment, the positive electrode includes a first current collector layer and first active material layers formed on both main surfaces of the first current collector layer.

[0038] The first current collector layer can preferably be composed of at least one substance having high electrical conductivity.

[0039] Examples of highly conductive materials include metals or alloys containing at least one of the following metal elements: silver (Ag), palladium (Pd), gold (Au), platinum (Pt), aluminum (Al), chromium (Cr), and nickel (Ni), or non-metals such as carbon (C). Considering both conductivity and manufacturing cost, aluminum, nickel, or stainless steel are preferred. Furthermore, aluminum is less likely to react with the positive electrode active material and the electrolyte. Therefore, using aluminum in the first current collector layer can reduce the internal resistance of the battery.

[0040] Examples of the shape of the first current collector layer include foil, plate, mesh, nonwoven fabric, and foam. In order to improve adhesion to the first active material layer, carbon or the like may be disposed on the surface of the first current collector layer, or the surface may be roughened.

[0041] The first active material layer contains a positive electrode active material that accepts lithium ions and electrons. As a positive electrode active material, there is no particular limitation as long as it is a material that can reversibly release / absorb lithium ions and can transport electrons, and a known positive electrode active material that can be applied to the positive electrode of a lithium ion battery can be used. Examples of positive electrode active materials include: lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMn2O4), solid solution oxide (Li2MnO3-LiMO2 (M=Co, Ni, etc.)), lithium-manganese-nickel-cobalt oxide (LiNi x Mn y Co z The positive electrode active material may be composed of one or more of the following materials:

[0042] The first active material layer includes an electrolyte that transfers lithium ions to and from the positive electrode active material. As an electrolyte, there is no particular limitation as long as it has lithium ion conductivity, and materials commonly used in lithium ion batteries can be used. Examples of electrolytes include: sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolytes, inorganic solid electrolytes containing lithium salts, solid electrolytes of polymer systems such as polyethylene oxide, and gel-based solid electrolytes containing lithium salts and lithium ion conductive ionic liquids. Among these, sulfide solid electrolyte materials are preferred from the perspective of high lithium ion conductivity, structural formability based on compression, and good interface bonding.

[0043] The electrolyte may be composed of one of the above materials alone, or may be composed of two or more.

[0044] The electrolyte contained in the first active material layer may be the same material as or different from the electrolyte contained in the second active material layer and the solid electrolyte layer.

[0045] From the viewpoint of improving the conductivity of the positive electrode, the first active material layer may contain a conductive auxiliary agent. As the conductive auxiliary agent, any conductive auxiliary agent commonly used in lithium ion batteries can be used.

[0046] Examples of the conductive additive include carbon black such as acetylene black and Ketjen black, carbon fibers, vapor-grown carbon fibers, graphite powder, and carbon materials such as carbon nanotubes. The conductive additive may be composed of one of the above materials alone or a combination of two or more.

[0047] Furthermore, the first active material layer may contain a binder that has the function of binding the positive electrode active materials to each other and to the first current collector layer.

[0048] The first active material layer may be formed on both principal surfaces of the first current collector layer, or may be formed on only one principal surface of the first current collector layer. Furthermore, when the positive electrode is a single-sided coated electrode, a stacked positive electrode formed by stacking two positive electrodes so that the current collector surfaces face each other may be used as a double-sided coated electrode. Furthermore, when the first current collector layer has a three-dimensional porous structure such as a mesh, non-woven fabric, or foam, the first current collector layer may be provided integrally with the first active material layer.

[0049] The first current collector layer is gathered at one end portion in the width direction of the all-solid-state battery.

[0050] The first active material layer is in contact with the electrolyte layer and therefore may include sulfides contained in the electrolyte layer.

[0051] (negative electrode)

[0052] The negative electrode is formed by laminating a second current collector layer and a second active material layer containing at least a negative electrode active material. In this embodiment, the negative electrode includes a second current collector layer and a second active material layer formed on both main surfaces of the second current collector layer and containing a negative electrode active material and an electrolyte.

[0053] The second current collector layer includes at least copper (Cu). Like the first current collector layer, the second current collector layer may also include substances other than copper with high conductivity. Examples of substances other than copper with high conductivity include metals or alloys containing at least one metal element of silver (Ag), palladium (Pd), gold (Au), platinum (Pt), chromium (Cr) and nickel (Ni), or non-metals such as carbon (C). In addition to the level of conductivity, if the manufacturing cost is also considered, nickel or stainless steel can be preferably used as substances other than copper. In addition, stainless steel does not easily react with the positive electrode active material, the negative electrode active material and the electrolyte. Therefore, if stainless steel is used for the second current collector layer, the manufacturing cost of the battery can be reduced.

[0054] The second current collector layer may be in the form of foil, plate, mesh, nonwoven fabric, foam, etc. In order to improve adhesion with the second active material layer, carbon or the like may be disposed on the surface of the second current collector layer, or the surface may be roughened.

[0055] The second active material layer contains a negative electrode active material that donates and accepts lithium ions and electrons. As the negative electrode active material, there is no particular limitation as long as it is a material that can reversibly release / absorb lithium ions and can transport electrons. A known negative electrode active material that can be applied to the negative electrode of a lithium ion battery can be used. Examples of the negative electrode active material include: carbonaceous materials such as natural graphite, artificial graphite, resin carbon, carbon fiber, activated carbon, hard carbon, and soft carbon; alloy materials based on tin, tin alloys, silicon, silicon alloys, gallium, gallium alloys, indium, indium alloys, aluminum, and aluminum alloys; conductive polymers such as polyacetylene, polyacetylene, and polypyrrole; metallic lithium; lithium-titanium composite oxides (such as Li4Ti5O 12 ) etc. These negative electrode active materials may be composed of one of the above materials alone, or may be composed of two or more.

[0056] The second active material layer contains an electrolyte that transfers lithium ions to and from the negative electrode active material. As for the electrolyte, there is no particular limitation as long as it has lithium ion conductivity, and materials commonly used in lithium ion batteries can be used. Examples of the electrolyte include: sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolytes, inorganic solid electrolytes containing lithium salts, solid electrolytes of polymer systems such as polyethylene oxide, and gel-based solid electrolytes containing lithium salts and lithium ion conductive ionic liquids. The electrolyte can be composed of one of the above materials alone, or it can be composed of two or more.

[0057] The electrolyte contained in the second active material layer may be the same electrolyte as the electrolyte contained in the first active material layer and the solid electrolyte layer, or may be a different electrolyte.

[0058] The second active material layer may also contain a conductive additive, a binder, etc. These materials are not particularly limited, and for example, the same materials as those used in the first active material layer can be used.

[0059] The second active material layer may be formed on both principal surfaces of the second current collector layer, or may be formed on only one principal surface of the second current collector layer. In addition, when the second current collector layer has a three-dimensional porous structure such as a mesh, non-woven fabric, or foam, the second current collector layer may be integrally provided with the second active material layer.

[0060] The negative electrode may include a material containing lithium metal or silicon. Figure 1 and Figure 2 As shown, as the battery cells 10 expand and contract, the first telescopic portion 41 of the busbar retainer 40 expands and contracts following the displacement of the multiple battery cells 10 in the stacking direction. Therefore, the first telescopic portion 41 can absorb the expansion and contraction of the battery cells 10 and can suppress the deterioration and short circuit caused by the bending of the collector portion of the battery cells 10.

[0061] (Electrolyte layer)

[0062] The electrolyte layer is disposed between the first active material layer and the second active material layer.

[0063] As electrolytes, there are no particular restrictions as long as they have lithium ion conductivity and insulation properties, and materials commonly used in lithium ion batteries can be used. For example, sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolytes, inorganic solid electrolytes such as lithium salts, solid electrolytes of polymer systems such as polyethylene oxide, and gel electrolytes containing lithium salts and lithium ion conductive ionic liquids. Among these materials, sulfide solid electrolyte materials are preferred from the perspective of high lithium ion conductivity and good structural formability and interface bonding based on compression.

[0064] The form of the electrolyte material is not particularly limited, and an example thereof is a granular form.

[0065] The electrolyte layer may contain a binder for imparting mechanical strength and flexibility.

[0066] The electrolyte layer may also be in the form of a sheet having a porous substrate and a solid electrolyte retained on the porous substrate. The form of the porous substrate is not particularly limited, and examples thereof include woven fabrics, non-woven fabrics, meshes, porous films, stretched sheets, and punched sheets. Among these forms, non-woven fabrics are preferred from the perspective of further improving the operability of the filling amount of the solid electrolyte.

[0067] The porous substrate may preferably be made of an insulating material. This can improve the insulation properties of the electrolyte layer. Examples of insulating materials include: resin materials such as nylon, polyester, polyethylene, polypropylene, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polyvinylidene chloride, polyvinyl chloride, polyurethane, vinylon, polybenzimidazole, polyimide, polyphenylene sulfide, polyetheretherketone, cellulose, and acrylic resin; natural fibers such as hemp, wood pulp, and cotton linter; and glass.

[0068] (Exterior film)

[0069] The outer film houses the electrode stack including the positive electrode, the negative electrode, and the electrolyte layer. The outer film includes, for example, a sealing resin layer, a metal layer, and an outer resin layer.

[0070] According to the battery module 1 of this embodiment, the busbar holder 40 has the first telescopic portion 41 that follows the displacement of the battery cells 10 in the stacking direction. Therefore, there is no component that occupies space in the battery module 1. Therefore, the energy density of the battery module 1 as a whole is not reduced, and the mass of the battery module 1 can be suppressed. Figure 1 and Figure 2 As shown, as the battery cells 10 expand and contract, the first telescopic portion 41 of the busbar retainer 40 expands and contracts following the displacement of the multiple battery cells 10 in the stacking direction. Therefore, the first telescopic portion 41 can absorb the expansion and contraction of the battery cells 10 and can suppress the degradation and short circuit caused by the bending of the collector portion of the battery cells 10.

[0071] (Second embodiment)

[0072] Figure 3 and Figure 4 Schematic diagram showing the structure of a battery module according to a second embodiment of the present invention. Figure 3 and Figure 4 In the Figure 1 and Figure 2 The same components of the battery modules shown are denoted by the same reference numerals, and description thereof will be omitted.

[0073] like Figure 3 and Figure 4 As shown, the battery module 100 of the present embodiment includes a plurality of battery cells 10 , a restraining body 20 , a bus bar 30 , and a bus bar holder 40 .

[0074] In the battery module 100 of this embodiment, the elastic member 50 is arranged between the restraining body 20 and the battery cell 10, and the elastic member 110 is arranged between the battery cells 10. Figure 3 and Figure 4 As shown, the elastic members 50 and 110 can absorb the expansion and contraction of the battery cell 10 , and can suppress degradation and short circuit caused by bending of the current collecting portion of the battery cell 10 .

[0075] (Third embodiment)

[0076] Figure 5 and Figure 6 Schematic diagram showing the structure of a battery module according to a third embodiment of the present invention. Figure 5 and Figure 6 In the Figure 1 and Figure 2 The same components of the battery modules shown are denoted by the same reference numerals, and description thereof will be omitted.

[0077] like Figure 5 and Figure 6 As shown, the battery module 200 of the present embodiment includes a plurality of battery cells 10 , a restraining body 20 , a bus bar 30 , a bus bar holder 40 , and an elastic member 50 .

[0078] In the battery module 200 of this embodiment, the bus bar holder 40 has a first elastic portion 41 that follows the displacement of the battery cells 10 in the stacking direction, and the bus bar 30 has a second elastic portion 31 that follows the displacement of the battery cells 10 in the stacking direction. Figure 5 and Figure 6 As shown, as the battery cells 10 expand and contract, the first telescopic portion 41 of the busbar holder 40 and the second telescopic portion 31 of the busbar 30 expand and contract following the displacement in the stacking direction of the multiple battery cells 10. Therefore, the first telescopic portion 41 and the second telescopic portion 31 can absorb the expansion and contraction of the battery cells 10, and can suppress the degradation and short circuit caused by the bending of the collecting portion of the battery cells 10.

[0079] (Fourth embodiment)

[0080] Figure 7 Schematic diagram showing the structure of a battery module according to a fourth embodiment of the present invention. Figure 7 In the Figure 1 and Figure 2 The same components of the battery modules shown are denoted by the same reference numerals, and description thereof will be omitted.

[0081] like Figure 7As shown, the battery module 300 of this embodiment includes a plurality of battery cells (not shown), a restraining body (not shown), a bus bar 30 , and a bus bar holder 40 .

[0082] In the battery module 300 of this embodiment, the busbar holder 40 includes rails 42 that enable the busbars 30 to move in the stacking direction of the battery cells 10. This allows the busbars 30 to move along the rails 42 as the battery cells 10 expand and contract, thereby preventing degradation and short circuits caused by bending of the current collecting portions of the battery cells 10.

[0083] As mentioned above, although embodiment of this invention was demonstrated in detail, this invention is not limited to the said embodiment, Various deformation|transformation and change are possible within the range of the summary of this invention described in a claim.

Claims

1. A battery module comprising: A plurality of battery cells stacked in one direction; a constraining body, which constrains the plurality of battery cells in a stacking direction; bus bars connecting the battery cells to each other; and A busbar holder, which holds the busbar, The bus bar holder has a first telescopic portion that follows displacement of the battery cells in the stacking direction.

2. The battery module according to claim 1, wherein: An elastic member is arranged between the restraining body and the battery cell or between the battery cells.

3. The battery module according to claim 1, wherein: The bus bar has a second elastic portion that follows displacement of the battery cells in the stacking direction.

4. The battery module according to claim 1, wherein: The bus bar holder has a rail on which the bus bar can move in the stacking direction of the battery cells.

5. The battery module according to claim 1, wherein: The negative electrode constituting the battery cell includes a material containing lithium metal or silicon. The battery module according to claim 1 , wherein: The battery cell is a solid-state battery.

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