Power storage module

Abstract

To provide a power storage module with which short-circuiting can be suppressed.SOLUTION: A power storage module 1 comprises: an electrode laminate 10; a sealing body 20 for sealing the electrode laminate 10; and a separator 14 interposed between adjustment electrodes. A spacer 22 of the sealing body 20 includes: a body part 22M formed into a frame shape along an outer shape of a current collector 15 of an electrode; and a continuous hole forming part 22F for forming a continuous hole 30 by cutting away a section from an outer edge 22t to an inner edge 22e of the spacer 22. The separator 14 is interposed between a cathode active material layer 16 and an anode active material layer 17 that are adjacent to each other, and extends in the manner of being sandwiched between a sealing material 21 and the spacer 22 that are adjacent to each other in the sealing body 20. The separator 14 includes a substrate 14a and a ceramic layer 14b formed on the substrate 14a in at least a section overlapping the continuous hole forming part 22F.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a power storage module.

Background Art

[0002] Patent Document 1 describes a bipolar battery. This bipolar battery includes a bipolar electrode having a positive electrode active material layer provided on one surface of a current collector and a negative electrode active material layer provided on the other surface, a gel electrolyte sandwiched between the positive electrode active material layer and the negative electrode active material layer, and a seal layer provided between current collectors surrounding the periphery of a single battery composed of the positive electrode active material layer, the negative electrode active material layer, and the gel electrolyte, and has a structure in which a plurality of the single batteries are stacked.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a power storage module such as the bipolar battery described in Patent Document 1 above, a separator may be interposed between adjacent positive electrode active material layers and negative electrode active material layers. In particular, by extending the separator from between the positive electrode active material layer and the negative electrode active material layer to the seal layer, the internal space formed between adjacent current collectors can be partitioned into a positive electrode region on the positive electrode active material layer side and a negative electrode region on the negative electrode active material layer side. In this case, for example, if a foreign object exists in the negative electrode region and the foreign object penetrates the separator, there is a risk of a short circuit occurring in the uncoated portion where the active material layers of adjacent current collectors are not formed via the separator. Note that various objects are assumed as the foreign object, and as an example, deposits generated by re-precipitation of metal foreign objects dissolved by the electrolytic solution in the positive electrode region in the negative electrode region can be considered.

[0005] An object of the present invention is to provide a power storage module capable of suppressing a short circuit.

Means for Solving the Problems

[0006] The power storage module according to the present invention includes an electrode laminate including a plurality of electrodes laminated along a first direction, a sealing body provided on the electrode laminate for sealing the electrode laminate, and a separator interposed between adjacent electrodes along the first direction. The electrode includes a current collector including a first surface intersecting the first direction and a second surface on the opposite side of the first surface, a first active material layer provided on the first surface, and a second active material layer provided on the second surface and having a polarity different from that of the first active material layer. The sealing body is laminated along the first direction and is formed in a frame shape along the outer shape of the current collector as viewed from the first direction. The sealing body includes a plurality of sealing materials joined to the first surface and the second surface at the peripheral portion of the current collector, a plurality of spacers interposed between adjacent sealing materials along the first direction and forming an internal space for accommodating an electrolytic solution between adjacent current collectors along the first direction together with the adjacent sealing materials along the first direction, and a plurality of communication holes for communicating each of the plurality of internal spaces to the outside. When viewed from the first direction, the outer edge of the second active material layer is located outside the outer edge of the first active material layer. The spacer includes a main body portion formed in a frame shape along the outer shape of the current collector as viewed from the first direction, and a communication hole forming portion that forms a communication hole by being missing from the outer edge to the inner edge of the spacer when viewed from the first direction. When viewed from the first direction, the inner edge of the main body portion is located inside the outer edge of the second active material layer. The separator extends while being interposed between the first active material layer and the second active material layer adjacent to each other along the first direction and being sandwiched between the adjacent sealing material and the spacer along the first direction. The separator includes a base material and a ceramic layer formed on the base material at least at a portion overlapping the communication hole forming portion when viewed from the first direction.

[0007] In this energy storage module, a sealing body is provided in the electrode laminate, so that an internal space for accommodating an electrolyte is formed between the current collectors of adjacent electrodes. A separator is interposed between the first active material layer and the second active material layer of the adjacent electrodes. More specifically, the separator is interposed between the first active material layer and the second active material layer, and extends so as to be sandwiched between the sealing material constituting the sealing body and the spacer adjacent to the sealing material. This allows the separator to divide the internal space into a first region on the first active material layer side and a second region on the second active material layer side.

[0008] On the other hand, in this energy storage module, the spacer includes a main body portion formed in a frame shape that follows the outer shape of the current collector when viewed from the stacking direction (first direction), and the inner edge of the main body portion is located inside the outer edge of the second active material layer that protrudes outward beyond the first active material layer. In other words, the main body portion of the spacer extends from between adjacent sealing materials so as to overlap the second active material layer. Therefore, in the uncoated portion where the active material layer of the adjacent current collectors is not formed via the separator, the presence of the main body portion of the spacer in addition to the separator in the stacking direction suppresses short circuits caused by foreign matter present in the second region of the internal space, for example.

[0009] Here, in addition to the main body, the spacer includes a communication hole forming portion that is missing from the outer edge to the inner edge of the spacer when viewed from the stacking direction to form a communication hole. The communication hole allows the internal space to communicate with the outside, thereby allowing for the introduction and discharge of fluids such as electrolyte and test gas into the internal space. By providing such a communication hole forming portion in the spacer, a region without the spacer may be generated in the uncoated portion where the active material layer of the adjacent current collectors via the separator is not formed. Therefore, in this region, the spacer is less likely to contribute to suppressing short circuits between the uncoated portions due to foreign matter.

[0010] On the other hand, in this power storage module, the separator includes a base material and a ceramic layer formed on the base material, at least in a portion overlapping the communication hole forming portion (i.e., the missing portion of the spacer) when viewed in the stacking direction, and rigidity is ensured as compared with the case of only the base material. Therefore, even in the region where the spacer is not interposed, penetration of foreign matter through the separator is suppressed, and as a result, short circuit between the non-coated portions of adjacent current collectors is suppressed. As described above, according to this power storage module, short circuit can be suppressed.

[0011] Here, the separator is sandwiched between a sealing material provided on the current collector and a spacer laminated on the sealing material. Therefore, for example, when the sealing material and the spacer are welded, the heat input to the sealing material is less likely to be transmitted to the separator through conduction via the current collector, while the heat input to the spacer is likely to be transmitted to the separator, which may cause deterioration of the separator.

[0012] On the other hand, in the power storage module according to the present invention, the ceramic layer may be formed on the spacer side of the sealing material and the spacer sandwiching the separator in the base material. In this case, in the separator, the ceramic layer is formed on the spacer side of the sealing material and the spacer sandwiching the separator in the base material. Therefore, the heat input to the spacer is less likely to be transmitted to the base material, and deterioration of the separator is suppressed. In this case, for example, even if the separator and the spacer slide when the spacer expands and contracts due to heat generation during charge and discharge, wear (or damage) of the separator is suppressed by the ceramic layer.

[0013] In the power storage module according to the present invention, the thickness of the ceramic layer may be 2 μm or more. In this case, short circuit can be more reliably suppressed.

[0014] In the power storage module according to the present invention, the electrolytic solution may contain LiFSI as an electrolyte salt. Thus, in the electrolytic solution containing LiFSI (lithium bis(fluorosulfonyl)imide), since it is easy to dissolve metal foreign matter on the positive electrode side of the first region and the second region, deposits are likely to occur on the negative electrode side of the first region and the second region. Therefore, it becomes more effective to suppress short circuit as described above.

[0015] In the power storage module according to the present invention, a reinforcing portion is provided on the current collector of the terminal electrode, which is the electrode located at the outermost part of the electrode laminate in the first direction. The reinforcing portion may be provided at least in a portion between the outer edge of at least the first active material layer and the inner edge of the sealing material in the current collector of the terminal electrode when viewed from the first direction. In this case, the reinforcing portion is formed at least in the non-coated portion of the current collector of the terminal electrode, and rigidity is ensured. As a result, for example, when the internal space is depressurized, it is suppressed that the current collector of the terminal electrode bends inward in the stacking direction and the distance between the current collectors is reduced (that is, the distance between the current collectors is ensured). As a result, short circuit between the current collectors is more reliably suppressed, and a fluid flow path in the internal space is reliably ensured.

Advantages of the Invention

[0016] According to the present invention, it is possible to provide a power storage module capable of suppressing short circuit.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0018] Hereinafter, a power storage module according to an embodiment will be described with reference to the drawings. In the description of each figure, the same or corresponding elements may be denoted by the same reference numerals, and redundant descriptions may be omitted. In addition, in each figure, a rectangular coordinate system that defines an X direction, a Y direction orthogonal to the X direction, and a Z direction orthogonal to both the X direction and the Y direction may be shown.

[0019] FIG. 1 is a schematic cross-section of a power storage module according to the present embodiment. FIG. 2 is a schematic plan view of the power storage module shown in FIG. 1. The power storage module 1 shown in FIGS. 1 and 2 is, for example, a power storage module used for a battery of various vehicles such as a forklift, a hybrid vehicle, and an electric vehicle. The power storage module 1 is, for example, a secondary battery such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery. The power storage module 1 may be an electric double layer capacitor or an all-solid-state battery. Here, a case where the power storage module 1 is a lithium-ion secondary battery will be exemplified.

[0020] The power storage module 1 includes an electrode laminate 10 and a sealing body 20. The electrode laminate 10 includes a plurality of electrodes laminated along the Z direction (first direction). The plurality of electrodes includes a plurality of bipolar electrodes 11, a positive electrode terminal electrode 12, and a negative electrode terminal electrode 13. A separator 14 is interposed between the electrodes adjacent to each other along the Z direction.

[0021] The bipolar electrode 11 has a current collector 15, a positive electrode active material layer 16 (first active material layer), and a negative electrode active material layer 17 (second active material layer). The current collector 15 has, for example, a rectangular sheet shape. The current collector 15 includes a first surface 15a and a second surface 15b. The first surface 15a is a surface intersecting the Z direction, and the second surface 15b is a surface intersecting the Z direction and on the opposite side of the first surface 15a. That is, the first surface 15a is a surface facing one direction of the Z direction (the direction from the positive electrode terminal electrode 12 to the negative electrode terminal electrode 13 in FIG. 1), and the second surface 15b of the current collector 15 is a surface facing the other direction of the Z direction (the direction from the negative electrode terminal electrode 13 to the positive electrode terminal electrode 12 in FIG. 1).

[0022] The positive electrode active material layer 16 is provided on the first surface 15a of the current collector 15. The negative electrode active material layer 17 is provided on the second surface 15b of the current collector 15. The plurality of bipolar electrodes 11 are laminated such that the positive electrode active material layer 16 of one bipolar electrode 11 faces the negative electrode active material layer 17 of another bipolar electrode 11. Grooves may be formed in the positive electrode active material layer 16 and the negative electrode active material layer 17.

[0023] The positive electrode active material layer 16 and the negative electrode active material layer 17 are rectangular when viewed from the Z direction. The negative electrode active material layer 17 is slightly larger than the positive electrode active material layer 16 when viewed from the Z direction. That is, in a plan view when viewed from the Z direction, the entire formation region of the positive electrode active material layer 16 is located within the formation region of the negative electrode active material layer 17. In other words, when viewed from the Z direction, the outer edge 17e of the negative electrode active material layer 17 is located outside the outer edge 16e of the positive electrode active material layer 16.

[0024] The positive terminal electrode 12 (terminal electrode) has a current collector 15 and a positive electrode active material layer 16 provided on the first surface 15a of the current collector 15. The positive terminal electrode 12 does not have the positive electrode active material layer 16 and the negative electrode active material layer 17 on the second surface 15b of the current collector 15. That is, no active material layer is provided on the second surface 15b of the current collector 15 of the positive terminal electrode 12. The positive terminal electrode 12 is located at the outermost part of the electrode laminate 10 in the Z direction and is laminated on the bipolar electrode 11. The positive terminal electrode 12 is laminated on the bipolar electrode 11 such that its positive electrode active material layer 16 faces the negative electrode active material layer 17 of the bipolar electrode 11.

[0025] The negative terminal electrode 13 (terminal electrode) has a current collector 15 and a negative electrode active material layer 17 provided on the second surface 15b of the current collector 15. The negative terminal electrode 13 does not have the positive electrode active material layer 16 and the negative electrode active material layer 17 on the first surface 15a of the current collector 15. That is, no active material layer is provided on the first surface 15a of the current collector 15 of the negative terminal electrode 13. The negative terminal electrode 13 is located at the outermost part in the opposite direction (Z negative direction) of the Z direction of the electrode laminate 10 and is laminated on the bipolar electrode 11. The negative terminal electrode 13 is laminated on the bipolar electrode 11 such that its negative electrode active material layer 17 faces the positive electrode active material layer 16 of the bipolar electrode 11.

[0026] In this embodiment, the current collectors of the bipolar electrode 11, the positive terminal electrode 12, and the negative terminal electrode 13 are denoted by the same reference numeral 15 as the current collector, but the current collectors of the bipolar electrode 11, the positive terminal electrode 12, and the negative terminal electrode 13 may be the same as each other or different from each other. Also, the surfaces of the positive terminal electrode 12 where the positive electrode active material layer 16 is not provided and the surfaces of the negative terminal electrode 13 where the negative electrode active material layer 17 is not provided do not come into contact with the electrolytic solution because they come into contact with, for example, tabs for extracting current.

[0027] The separator 14 is disposed between adjacent bipolar electrodes 11, between the positive electrode terminal electrode 12 and the bipolar electrode 11, and between the negative electrode terminal electrode 13 and the bipolar electrode 11. The separator 14 is interposed between the positive electrode active material layer 16 and the negative electrode active material layer 17 and extends so as to reach the sealing body 20. The separator 14 is a member that allows charge carriers such as lithium ions to pass through, and by isolating the positive electrode active material layer 16 and the negative electrode active material layer 17, it prevents short circuits due to contact between adjacent electrodes.

[0028] The current collector 15 is a chemically inert electrical conductor for continuously passing an electric current through the positive electrode active material layer 16 and the negative electrode active material layer 17 during discharge or charging of the lithium-ion secondary battery. The material of the current collector 15 is, for example, a metal material, a conductive resin material, or a conductive inorganic material, etc. Examples of the conductive resin material include a conductive polymer material or a resin obtained by adding a conductive filler to a non-conductive polymer material as necessary. The current collector 15 may include a plurality of layers. In this case, each layer of the current collector 15 may contain the above-mentioned metal material and / or conductive resin material.

[0029] A coating layer may be formed on the surface of the current collector 15. The coating layer may be formed by a known method such as plating or spray coating. The current collector 15 may be in the form of, for example, a plate, a foil (e.g., a metal foil), a film, or a mesh. Examples of the metal foil include aluminum foil, copper foil, nickel foil, titanium foil, or stainless steel foil. The current collector 15 may be an alloy foil of the above-mentioned metals or a foil formed by integrating a plurality of metal foils. When the current collector 15 is in the form of a foil, the thickness of the current collector 15 may be, for example, 1 μm to 200 μm. In the present embodiment, the current collector 15 is a foil formed by integrating an aluminum foil and a copper foil, or a foil obtained by vapor-depositing copper on an aluminum foil.

[0030] The positive electrode active material layer 16 contains a positive electrode active material capable of occluding and releasing charge carriers such as lithium ions. Examples of the positive electrode active material include lithium composite metal oxides having a layered rock salt structure, metal oxides having a spinel structure, polyanion-based compounds, and the like. The positive electrode active material may be any material that can be used in a lithium ion secondary battery. The positive electrode active material layer 16 may contain a plurality of positive electrode active materials. In the present embodiment, the positive electrode active material layer 16 contains olivine-type lithium iron phosphate (LiFePO 4 ) as a composite oxide.

[0031] The negative electrode active material layer 17 contains a negative electrode active material capable of occluding and releasing charge carriers such as lithium ions. The negative electrode active material may be a single substance, an alloy, or a compound. Examples of the negative electrode active material include Li, carbon, metal compounds, and the like. The negative electrode active material may be an element capable of alloying with lithium or a compound thereof. Examples of carbon include natural graphite, artificial graphite, hard carbon (carbon with low graphitization ability), soft carbon (carbon with high graphitization ability), and the like. Examples of artificial graphite include highly oriented graphite, mesocarbon microbeads, and the like. Examples of elements capable of alloying with lithium include silicon and tin. In the present embodiment, the negative electrode active material layer 17 contains graphite as a carbon-based material.

[0032] Each of the positive electrode active material layer 16 and the negative electrode active material layer 17 (hereinafter, may be simply referred to as the "active material layer") may further contain a conductive assistant, a binder, an electrolyte (polymer matrix, ion conductive polymer, electrolyte solution, etc.), an electrolyte supporting salt (lithium salt, etc.) for enhancing ion conductivity, as necessary. The conductive assistant is added to enhance the conductivity of each electrode (bipolar electrode 11, positive electrode terminal electrode 12, negative electrode terminal electrode 13). Examples of the conductive assistant include acetylene black, carbon nanotube (CNT), carbon black, graphite, and the like.

[0033] Examples of the binder include fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber; thermoplastic resins such as polypropylene and polyethylene; imide resins such as polyimide and polyamideimide; alkoxysilyl group-containing resins; acrylic resins such as acrylic acid or methacrylic acid; styrene-butadiene rubber (SBR); carboxymethyl cellulose; alginates such as sodium alginate and ammonium alginate; water-soluble cellulose ester cross-linked products; starch-acrylic acid graft polymers; and the like. These binders can be used alone or in combination. As the solvent for the binder, for example, water, N-methyl-2-pyrrolidone (NMP), or the like is used.

[0034] The separator 14 may be, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains an electrolyte. Examples of the material of the separator 14 include polypropylene, polyethylene, polyolefin, polyester, and the like. The separator 14 may have a single-layer structure or a multilayer structure. The multilayer structure may have, for example, an adhesive layer or a ceramic layer as a heat-resistant layer. The separator 14 may be impregnated with an electrolyte. The electrolyte impregnated in the separator 14 is a liquid electrolyte (electrolyte solution) containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent.

[0035] As the electrolyte salt of the electrolyte solution, LiClO 4 , LiAsF 6 , LiPF 6 , LiBF 4 , LiCF 3 SO 3 , LiN(FSO 2 ) 2 , LiN(CF 3 SO 2 ) 2 and other known lithium salts may be used. That is, the electrolyte solution may contain LiFSI (lithium bisfluorosulfonylimide) as the electrolyte salt. In this case, an example of the electrolyte solution is as follows.

[0036] [Electrolyte solution] Lithium salt: LiFSI 1.6 (mol / L) Non-aqueous solvent: EC (ethylene carbonate) 15 (vol%) MP (methyl propionate) 85 (vol%)

[0037] Also, as the non-aqueous solvent, known solvents such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, ethers, etc. may be used. Note that two or more of these known solvent materials may be used in combination.

[0038] The sealing body 20 is provided on the electrode laminate 10 so as to surround the electrode laminate 10 as viewed from the Z direction, and is formed in a rectangular cylindrical shape at the peripheral edge of the electrode laminate 10. The sealing body 20 can be joined (welded) to each of the first surface 15a and the second surface 15b of the current collector 15 at the peripheral edge 15c of each current collector 15. The sealing body 20 forms an internal space S between the current collectors 15 adjacent in the Z direction, and is for sealing each of the internal spaces S (that is, the electrode laminate 10). An electrolyte (for example, an electrolytic solution) is accommodated in each internal space S. The sealing body 20 can suppress the outflow of the electrolytic solution accommodated in the internal space S to the outside. Also, the sealing body 20 can suppress the intrusion of air, moisture, etc. from the outside of the electrode laminate 10 into the internal space S.

[0039] The sealing body 20 contains an insulating material. Examples of the material of the sealing body 20 include various resin materials such as polypropylene, polyethylene, polystyrene, ABS resin, acid-modified polypropylene, acid-modified polyethylene, acrylonitrile styrene resin, etc.

[0040] The sealing body 20 includes a plurality of resin sealing materials 21 and a plurality of resin spacers 22. The sealing materials 21 are provided on each of the current collectors 15. Therefore, the plurality of sealing materials 21 are laminated along the Z direction. The sealing material 21 has a frame shape (here, a rectangular frame shape) along the outer shape of the current collector 15 as viewed from the Z direction, and is provided at the peripheral edge portion 15c of the current collector 15. The sealing material 21 is provided so as to extend from the first surface 15a of the current collector 15 through the end face to the second surface 15b, covering the peripheral edge portion 15c.

[0041] That is, the sealing material 21 includes, on the first surface 15a and the second surface 15b of the current collector 15, an inner portion 21a that overlaps the current collector 15 as viewed from the Z direction, and an outer portion 21b that is located outside the edge of the current collector 15, respectively. A pair of portions of the sealing material 21 adjacent to each other with the current collector 15 interposed therebetween are connected to each other at the outer portion 21b. The inner portion 21a of the sealing material 21 can be welded to the first surface 15a and the second surface 15b of the current collector 15, respectively. In the present embodiment, the sealing material 21 is welded to both the first surface 15a and the second surface 15b of the current collector 15.

[0042] In the present embodiment, the sealing materials provided on the current collectors 15 of the bipolar electrode 11, the current collectors 15 of the positive terminal electrode 12, and the current collectors 15 of the negative terminal electrode 13 are given the same reference numeral 21 as the sealing material, but the sealing materials provided on the current collectors 15 of the bipolar electrode 11, the sealing materials provided on the current collectors 15 of the positive terminal electrode 12, and the sealing materials provided on the current collectors 15 of the negative terminal electrode 13 may be the same as each other or different from each other.

[0043] The spacer 22 is disposed so as to be interposed between the respective sealing materials 21 adjacent to each other in the Z direction. Thereby, the spacer 22, together with a pair of sealing materials 21 adjacent to each other in the Z direction, holds the interval between the current collectors 15 adjacent to each other in the Z direction. An internal space S is defined by a pair of current collectors 15 adjacent to each other in the Z direction, the spacer 22, and a pair of sealing materials 21 adjacent to the spacer 22. Thus, each of the plurality of spacers 22 forms an internal space S between the current collectors 15 adjacent to each other in the Z direction, together with the sealing materials 21 adjacent to each other along the Z direction.

[0044] The spacer 22 has a frame shape (here, a rectangular frame shape) along the outer shape of the current collector 15 as viewed from the Z direction, and is disposed on the peripheral edge portion 15c of the current collector 15 as viewed from the Z direction. That is, the spacer 22 includes an inner portion 22a that overlaps the current collector 15 and an outer portion 22b that is located outside the outer edge 15e of the current collector 15 as viewed from the Z direction. The spacer 22 does not overlap the current collector 15 in the outer portion 22b as viewed from the Z direction. The inner portion 22a and the outer portion 22b each have a frame shape (here, a rectangular frame shape) as viewed from the Z direction.

[0045] The separator 14 extends while being interposed between the positive electrode active material layer 16 and the negative electrode active material layer 17 adjacent to each other along the Z direction, and is sandwiched between the sealing material 21 and the spacer 22 adjacent to each other along the Z direction. The outer end of the separator 14 may be sandwiched and held between the sealing material 21 and the spacer 22. In the present embodiment, the separator 14 is fixed by being welded to the sealing material 21 at the outer end, and no joining such as welding is formed with the spacer 22.

[0046] A part of the part of the seal materials 21 located outside the outer edge 15e of the current collector 15 (i.e., the end of the outer part 21b) and a part of the spacers 22 located outside the outer edge 15e of the current collector 15 (i.e., the end of the outer part 22b) are welded to each other and integrated to form a welded part 23. That is, the sealing body 20 includes the welded part 23 formed by welding and integrating the outer parts 21b of the seal materials 21 and the outer parts 22b of the spacers 22 to each other. The welded part 23 has a frame shape surrounding the electrode stack 10 when viewed from the Z direction, and forms the outer periphery of the sealing body 20. Therefore, the outer surface of the welded part 23 forms the outer surface of the sealing body 20. That is, in this embodiment, the sealing body 20 has four outer surfaces extending along the Z direction. The spacers 22 may not be welded to the sealing materials 21 at least in the inner parts 21a of the sealing materials 21 adjacent to each other in the Z direction. The corners of the welded portion 23 may include chamfered portions by performing chamfering such as light chamfering, C chamfering, and R chamfering.

[0047] A conductive member (not shown) is laminated on each of the first surface 15a of the current collector 15 of the positive terminal electrode 12 and the second surface 15b of the current collector 15 of the negative terminal electrode 13, which are exposed from the sealing body 20 (i.e., the portions where the sealant 21 is not provided when viewed from the Z direction). The conductive members are electrically connected to the current collector 15 of the positive terminal electrode 12 and the current collector 15 of the negative terminal electrode 13, respectively. The conductive members are interposed between adjacent power storage modules 1, and function as terminals for extracting current from the power storage modules 1. The conductive members can be used to electrically connect multiple power storage modules 1. Multiple power storage modules 1 may be arranged in series via the conductive members.

[0048] Further, the conductive member may also be used as a member for applying a restraining load to the electrode laminate 10. That is, when a restraining member (not shown) for restraining the power storage module 1 from the Z direction is arranged, a restraining load may be applied to the electrode laminate 10 via the conductive member. Further, a cooling flow path may be formed in the conductive member. By flowing a cooling medium through the cooling flow path formed in the conductive member, the power storage module 1 can be cooled. Further, members (not shown) configured integrally or separately with the conductive member may be arranged on both sides of the sealing body 20 in the Z direction, and a restraining load may be applied to the sealing body 20 via the members.

[0049] FIG. 3 is a schematic cross-sectional view showing an enlarged part of the power storage module shown in FIG. 1. In FIGS. 1 and 3, the separator 14 is provided between the surface of the spacer 22 on the negative electrode active material layer 17 side and the sealing material 21 facing the surface.

[0050] As shown in FIGS. 1 to 3, when viewed from the Z direction, the inner edge 22e of the spacer 22 (that is, a part of the inner part 22a) is located between the outer edge 17e of the negative electrode active material layer 17 and the outer edge 16e of the positive electrode active material layer 16. Thereby, the spacer 22 includes an overlapping portion 22r that overlaps the negative electrode active material layer 17 when viewed from the Z direction, and a non-overlapping portion 22p that does not overlap the sealing material 21 and the negative electrode active material layer 17 when viewed from the Z direction.

[0051] Among the plurality of spacers 22, the spacer 22 at the outermost part in the Z direction (here, the most positive electrode terminal electrode 12 side) may be sandwiched via the separator 14 between a pair of adjacent negative electrode active material layers 17 along the Z direction in the overlapping portion 22r. More specifically, the overlapping portion 22r of the outermost spacer 22 in the Z direction may contact the first surface 15a of the current collector 15 and the separator 14 facing the first surface 15a. In this case, the outermost spacer 22 in the Z direction may be joined (for example, welded) to the first surface 15a of the current collector 15 in the overlapping portion 22r.

[0052] Here, in the present embodiment, among the plurality of spacers 22, the spacers 22 other than the outermost spacer 22 in the Z direction (the spacers 22 in the middle part) are configured not to contact the current collectors 15 of the adjacent bipolar electrodes 11 in the overlapping portion 22r. That is, the thickness Ts of the spacer 22 in the Z direction is made thinner than the thickness Tp of the positive electrode active material layer 16 in the Z direction. In other words, an internal space S is interposed between the spacer 22 in the middle part and the first surface 15a of the current collector 15 of the adjacent bipolar electrode. In the present embodiment, the thickness Ts of the overlapping portion 22r of the spacer 22 may be equal to the thickness of the portion of the spacer 22 that overlaps the sealing material 21 as viewed from the Z direction.

[0053] Further, the negative electrode active material layer 17 includes a rectangular first portion 171 that overlaps the positive electrode active material layer 16 as viewed from the Z direction, and a frame-shaped (here, rectangular frame-shaped) second portion 172 that is located outside the outer edge 16e of the positive electrode active material layer 16 as viewed from the Z direction and includes the outer edge 17e of the negative electrode active material layer 17. The thickness Tn of the negative electrode active material layer 17 in the Z direction may be constant or different between the first portion 171 and the second portion 172. In the present embodiment, the thickness T1 of the first portion 171 in the Z direction and the thickness T2 of the second portion 172 in the Z direction are the same as each other, but the thickness T2 of the second portion 172 may be made larger than the thickness T1 of the first portion 171 by fitting the positive electrode active material layer 16 into the negative electrode active material layer 17 side.

[0054] Further, the current collector 15 includes a first region 151 (an uncoated portion where no active material layer is formed) that does not overlap the negative electrode active material layer 17 and the sealing material 21 as viewed from the Z direction, and a second region 152 that overlaps the negative electrode active material layer 17 as viewed from the Z direction and does not overlap the positive electrode active material layer 16. The first region 151 is a region between the outer edge 17e of the negative electrode active material layer 17 and the inner edge 21e of the sealing material 21. That is, the first region 151 coincides with the non-overlapping portion 22p of the spacer 22 as viewed from the Z direction.

[0055] The second region 152 is the region between the outer edge 16e of the positive electrode active material layer 16 and the outer edge 17e of the negative electrode active material layer 17. In the present embodiment, the width W1 of the first region 151 when viewed from the Z direction is made narrower than the width W2 of the second region 152 when viewed from the Z direction. As described above, since the spacer 22 includes the overlapping portion 22r, the spacer 22 is disposed between the current collectors 15 adjacent to each other in the Z direction in the first region 151.

[0056] Furthermore, the electrode laminate 10 includes a first laminated portion 101 where the negative electrode active material layer 17 and the positive electrode active material layer 16 overlap when viewed from the Z direction, and a second laminated portion 102 including a portion where the negative electrode active material layer 17 and the spacer 22 (overlapping portion 22r) overlap when viewed from the Z direction. The second laminated portion 102 coincides with the region combining the first region 151 and the second region 152 when viewed from the Z direction. The sealing body 20 includes a first sealing portion 201 where the sealing material 21 and the spacer 22 overlap when viewed from the Z direction. The first sealing portion 201 does not overlap with the overlapping portion 22r and the non-overlapping portion 22p of the spacer 22 when viewed from the Z direction. And in the present embodiment, the thicknesses in the Z direction are thin in the order of the first laminated portion 101, the second laminated portion 102, and the first sealing portion 201. That is, the thickness of the second laminated portion 102 in the Z direction is thinner than the thickness of the first laminated portion 101 in the Z direction, and the thickness of the first sealing portion 201 in the Z direction is thinner than the thickness of the second laminated portion 102 in the Z direction.

[0057] FIG. 4 is a plan view of the separator shown in FIGS. 1 and 3, and FIG. 5 is a schematic cross-sectional view showing a part of the power storage module in an enlarged manner. As shown in FIGS. 1, 2, 4, and 5, the sealing body 20 has a plurality of communication holes 30 that communicate each of the plurality of internal spaces S to the outside. The communication holes 30 communicate each of the internal spaces S to the outside. Thereby, the communication holes 30 can be used for introducing and discharging fluid to and from the internal space S. That is, the communication holes 30 can be used when injecting electrolyte into the internal space S, or when introducing or discharging inspection gas to and from the internal space S. The communication holes 30 can be sealed, for example, by a film containing a metal layer or the like via another resin member formed outside the sealing body 20 after the injection of the electrolyte and the introduction and discharge of the inspection gas are completed.

[0058] In the present embodiment, the communication holes 30 are formed by cutting a part of the spacer 22. That is, the spacer 22 includes a main body portion 22M formed in a frame shape (rectangular frame shape) along the outer shape of the current collector 15 as viewed from the Z direction, and a communication hole forming portion 22F that forms the communication holes 30 by being cut out from the outer edge 22t to the inner edge 22e of the spacer 22 when viewed from the Z direction. The plurality of communication holes 30 are formed to be dispersed at a plurality of positions on one side of the sealing body 20 when viewed from the Z direction. Therefore, the communication hole forming portions 22F are also dispersed at a plurality of positions on one side of the sealing body 20. That is, the communication hole forming portions 22F of the adjacent spacers 22 along the Z direction are formed at different positions when viewed from the Z direction.

[0059] As described above, the separator 14 extends while being interposed between the adjacent positive electrode active material layer 16 and negative electrode active material layer 17 along the Z direction, and is sandwiched between the adjacent sealing material 21 and spacer 22 along the Z direction. Thereby, the separator 14 partitions the internal space S between the adjacent current collectors 15 in the Z direction into a positive electrode region including the positive electrode active material layer 16 and a negative electrode region including the negative electrode active material layer 17. And, in the portion overlapping the main body portion 22M of the spacer 22 when viewed from the Z direction in the electrode laminate 10, in addition to the separator 14, the spacer 22 (main body portion 22M) is interposed between the adjacent current collectors 15 in the Z direction.

[0060] On the other hand, in the portion overlapping the communication hole forming portion 22F of the spacer 22 when viewed from the Z direction in the electrode laminate 10, a part of the spacer 22 is removed, so that only the separator 14 is interposed between the adjacent current collectors 15 in the Z direction. Therefore, for example, if a foreign object exists in the negative electrode region and the foreign object penetrates the separator 14, there is a risk of short circuit between the adjacent current collectors 15 through the separator 14. Note that various objects are assumed as the foreign object. As an example, precipitates generated by re-precipitation of metal foreign objects dissolved by the electrolytic solution in the positive electrode region in the negative electrode region are considered.

[0061] In contrast, in the present embodiment, the separator 14 includes a base material 14a and a ceramic layer 14b formed on the base material 14a, at least in the portion overlapping the communication hole forming portion 22F when viewed from the Z direction. The base material 14a corresponds to a conventional separator composed of the above-described various materials, and has a thickness of about 10 μm, for example. The ceramic layer 14b has a thickness of 2 μm or more (about 4 μm as an example). In the present embodiment, the ceramic layer 14b is provided on the entire surface of the base material 14a. Further, the ceramic layer 14b is formed on the spacer 22 side of the sealing material 21 and the spacer 22 that sandwich the separator 14 in the base material 14a.

[0062] As described above, in the power storage module 1 according to the present embodiment, since the sealing body 20 is provided on the electrode laminate 10, an internal space S for storing an electrolytic solution is formed between the current collectors 15 of adjacent electrodes. Further, a separator 14 is interposed between the positive electrode active material layer 16 and the negative electrode active material layer 17 of adjacent electrodes. More specifically, the separator extends while being sandwiched between the sealing material 21 constituting the sealing body 20 and the spacer 22 adjacent to the sealing material 21 while intervening between the positive electrode active material layer 16 and the negative electrode active material layer 17. Thereby, the separator 14 can partition the internal space S into a positive electrode region on the positive electrode active material layer 16 side and a negative electrode region on the negative electrode active material layer 17 side.

[0063] On the other hand, in the power storage module 1 according to the present embodiment, the spacer 22 includes a main body portion 22M formed in a frame shape along the outer shape of the current collector 15 as viewed from the stacking direction (Z direction), and the inner edge of the main body portion 22M is located inside the outer edge 17e of the negative electrode active material layer 17 that protrudes outside the positive electrode active material layer 16. In other words, the main body portion 22M of the spacer 22 extends so as to overlap the negative electrode active material layer 17 from between adjacent sealing materials 21. Therefore, in the uncoated portion (first region 151) where the active material layers of adjacent current collectors 15 are not formed via the separator 14, the main body portion 22M of the spacer 22 intervenes in the Z direction in addition to the separator 14, so that, for example, a short circuit due to foreign matter present in the negative electrode region of the internal space S is suppressed.

[0064] Here, in addition to the main body portion 22M, the spacer 22 includes a communication hole forming portion 22F that forms a communication hole 30 by being cut out from the outer edge 22t to the inner edge 22e of the spacer 22 when viewed from the Z direction. By providing such a communication hole forming portion 22F in the spacer 22, a region where the spacer 22 does not intervene can occur in the uncoated portion (first region 151) where the active material layers of adjacent current collectors 15 are not formed via the separator 14. Therefore, in this region, it is difficult for the spacer 22 to contribute to suppressing a short circuit between uncoated portions due to foreign matter.

[0065] In contrast, in the power storage module 1 according to the present embodiment, the separator 14 includes the base material 14a and the ceramic layer 14b formed on the base material 14a at least in a portion overlapping the communication hole forming portion 22F (that is, the missing portion of the spacer) when viewed from the Z direction, and rigidity is ensured as compared with the case of only the base material 14a (that is, the conventional separator). Therefore, even in the region where the spacer 22 is not interposed, penetration of foreign matter through the separator 14 is suppressed, and as a result, a short circuit between the non-coated portions of the adjacent current collectors 15 is suppressed. As described above, according to the power storage module 1 according to the present embodiment, a short circuit can be suppressed.

[0066] Here, the separator 14 is sandwiched between the sealing material 21 provided on the current collector 15 and the spacer 22 laminated on the sealing material 21. Therefore, for example, when the sealing material 21 and the spacer 22 are welded (for example, when forming the welded portion 23), the heat input to the sealing material 21 is quickly lost by being conducted through the current collector 15 and is difficult to be transmitted to the separator 14, while the heat input to the spacer 22 is easily transmitted to the separator 14, which may cause deterioration of the separator 14.

[0067] In contrast, in the separator 14 of the power storage module 1 according to the present embodiment, the ceramic layer 14b is formed on the spacer 22 side of the sealing material 21 and the spacer 22 that sandwich the separator 14 in the base material 14a. For this reason, the heat input to the spacer 22 is less likely to be transmitted to the base material 14a, and deterioration of the separator 14 is suppressed. According to this configuration, for example, when the spacer 22 expands and contracts due to heat generation during charge and discharge, even if the separator 14 and the spacer 22 slide, wear (or damage) of the separator 14 is suppressed by the ceramic layer 14b.

[0068] Further, in the power storage module 1 according to the present embodiment, the thickness of the ceramic layer 14b is 2 μm or more. Therefore, a short circuit can be more reliably suppressed.

[0069] Furthermore, in the power storage module 1 according to the present embodiment, the electrolytic solution may contain LiFSI as an electrolyte salt. Thus, in the electrolytic solution containing LiFSI (lithium bis(fluorosulfonyl)imide), since it is easy to dissolve metal foreign matters on the positive electrode side of the positive electrode region and the negative electrode region, precipitates are likely to occur on the negative electrode side of the positive electrode region and the negative electrode region. Therefore, it becomes more effective to suppress a short circuit as described above.

[0070] The above embodiments illustrate one aspect of the present invention. Therefore, the present invention is not limited to the above embodiments and can be arbitrarily modified. Subsequently, modification examples will be described.

[0071] FIG. 6 is a schematic cross-sectional view of a power storage module according to a modification example. As shown in FIG. 6, in the power storage module 1, a reinforcing portion 40 is provided (for example, by adhesion or welding) on a current collector 15 of a positive electrode terminal electrode 12 which is one of the electrodes located at the outermost part of the electrode laminate 10 in the Z direction. The reinforcing portion 40 is formed in a plate shape from a metal such as aluminum, for example. The reinforcing portion 40 is provided on a second surface 15b facing the outside in the Z direction of the current collector 15 of the positive electrode terminal electrode 12. The reinforcing portion 40 is provided in at least a portion between an outer edge 16e of the positive electrode active material layer 16 and an inner edge 21e of the sealing material 21 in the current collector 15 of the positive electrode terminal electrode 12 when viewed from the Z direction.

[0072] However, the reinforcing portion 40 may be provided on the entire surface (excluding the portion covered by the sealing material 21) of the second surface 15b of the current collector 15 of the positive electrode terminal electrode 12, or may be provided in a rectangular frame shape when viewed from the Z direction. Further, the reinforcing portion 40 may be further provided on a first surface 15a facing the outside of a current collector 15 of a negative electrode terminal electrode 13 which is another one of the electrodes located at the outermost part of the electrode laminate 10 in the Z direction.

[0073] According to this modification example, a reinforcing portion 40 is formed at least in the non-coated portion of the current collector 15 of the positive terminal electrode 12, ensuring rigidity. As a result, for example, when the internal space S is depressurized, the current collector 15 of the positive terminal electrode 12 is suppressed from bending inward in the Z direction and the distance between the current collectors 15 is reduced (that is, the distance between the current collectors 15 is ensured). As a result, a short circuit between the current collectors 15 is more reliably suppressed, and a fluid flow path (that is, the permeability of gas and electrolyte) in the internal space S is reliably ensured.

[0074] In the illustrated example, a case is shown where a reinforcing portion 40, which is a member formed separately from the current collector 15, is provided for the current collector 15. However, the reinforcing portion 40 may be integrally formed with the current collector 15. In this case, the thickness of the current collector 15 of the positive terminal electrode 12 (and the negative terminal electrode 13) is made thicker than the thickness of the current collector 15 of the other electrodes (that is, the bipolar electrode 11), so that the reinforcing portion 40 is integrally formed.

[0075] Here, in the above embodiment, an example has been described in which the width W1 of the first region 151 of the current collector 15 as viewed from the Z direction is narrower than the width W2 of the second region 152 of the current collector 15 as viewed from the Z direction. However, the width W1 of the first region 151 as viewed from the Z direction and the width W2 of the second region 152 as viewed from the Z direction may be the same, or the width W1 of the first region 151 as viewed from the Z direction may be wider than the width W2 of the second region 152 as viewed from the Z direction.

[0076] Also, in the above embodiment, an example has been described in which the outermost spacer 22 in the Z direction is in contact with the current collector 15 of the positive terminal electrode 12 at the overlapping portion 22r. However, the spacer 22 does not have to be in contact with the current collector 15 of the positive terminal electrode 12 at the overlapping portion 22r.

[0077] Regarding the above embodiments, the following is appended.

[0078] The power storage module is "[1] an electrode laminate including a plurality of electrodes laminated along a first direction, a sealing body provided on the electrode laminate for sealing the electrode laminate, and a separator interposed between the electrodes adjacent to each other along the first direction. The electrode includes a current collector including a first surface intersecting the first direction and a second surface opposite to the first surface, a first active material layer provided on the first surface, and a second active material layer provided on the second surface and having a polarity different from that of the first active material layer. The sealing body is laminated along the first direction and is formed in a frame shape along the outer shape of the current collector as viewed from the first direction. The sealing body includes a plurality of sealing materials joined to the first surface and the second surface at the peripheral portion of the current collector, and a plurality of spacers interposed between the sealing materials adjacent to each other along the first direction. Together with the sealing materials adjacent to each other along the first direction, the spacers form an internal space for storing an electrolytic solution between the current collectors adjacent to each other along the first direction. The sealing body also has a plurality of communication holes for communicating each of the plurality of internal spaces to the outside. When viewed from the first direction, the outer edge of the second active material layer is located outside the outer edge of the first active material layer. The spacer includes a main body portion formed in a frame shape along the outer shape of the current collector as viewed from the first direction, and a communication hole forming portion that forms the communication hole by being cut out from the outer edge to the inner edge of the spacer when viewed from the first direction. When viewed from the first direction, the inner edge of the main body portion is located inside the outer edge of the second active material layer. The separator extends while being interposed between the first active material layer and the second active material layer adjacent to each other along the first direction and being sandwiched between the sealing material and the spacer adjacent to each other along the first direction. The separator includes a base material and a ceramic layer formed on the base material at least in a portion overlapping the communication hole forming portion when viewed from the first direction, the power storage module."

[0079] The power storage module may be "[2] the power storage module according to [1] above, wherein the ceramic layer is formed on the spacer side of the sealing material and the spacer sandwiching the separator in the base material."

[0080] The power storage module may be the one described in [3] "The power storage module according to [1] or [2] above, wherein the thickness of the ceramic layer is 2 μm or more".

[0081] The power storage module may be the one described in [4] "The power storage module according to any one of [1] to [3] above, wherein the electrolytic solution contains LiFSI as an electrolyte salt".

[0082] The power storage module may be the one described in [5] "The power storage module according to any one of [1] to [4] above, wherein a reinforcing portion is provided on the current collector of the terminal electrode which is the electrode located at the outermost part of the electrode laminate in the first direction, and the reinforcing portion is provided in at least a portion between the outer edge of the first active material layer and the inner edge of the sealing material in the current collector of the terminal electrode when viewed from the first direction".

Explanation of Reference Numerals

[0083] 1... Power storage module, 10... Electrode laminate, 11... Bipolar electrode (electrode), 12... Positive electrode terminal electrode (terminal electrode), 13... Negative electrode terminal electrode (terminal electrode), 14... Separator, 14a... Base material, 14b... Ceramic layer, 15... Current collector, 15a... First surface, 15b... Second surface, 16... Positive electrode active material layer (first active material layer), 16e... Outer edge, 17... Negative electrode active material layer (second active material layer), 17e... Outer edge, 20... Sealing body, 21... Sealing material, 22... Spacer, 22t... Outer edge, 22e... Inner edge, 22M... Body portion, 22F... Communication hole forming portion, 30... Communication hole, 40... Reinforcing portion, S... Internal space.

Claims

1. An electrode laminate including a plurality of electrodes laminated along a first direction, A sealing body provided on the electrode laminate for sealing the electrode laminate, A separator interposed between the adjacent electrodes along the first direction, Comprising, The electrode is, A current collector including a first surface intersecting the first direction and a second surface opposite to the first surface, A first active material layer provided on the first surface, A second active material layer provided on the second surface and having a polarity different from that of the first active material layer, Having, The sealing body is, A plurality of sealing materials laminated along the first direction and formed in a frame shape along the outer shape of the current collector as viewed from the first direction, and joined to the first surface and the second surface at the peripheral portion of the current collector, A plurality of spacers interposed between the adjacent sealing materials along the first direction and forming an internal space for accommodating an electrolytic solution between the adjacent current collectors along the first direction together with the adjacent sealing materials along the first direction, A plurality of communication holes communicating each of the plurality of internal spaces to the outside, Having, When viewed from the first direction, the outer edge of the second active material layer is located outside the outer edge of the first active material layer, The spacer is, A main body portion formed in a frame shape along the outer shape of the current collector as viewed from the first direction, A communication hole forming portion that forms the communication hole by being cut out from the outer edge to the inner edge of the spacer when viewed from the first direction, Including, When viewed from the first direction, the inner edge of the main body portion is located inside the outer edge of the second active material layer, The separator extends while being interposed between the adjacent first active material layer and the second active material layer along the first direction and being sandwiched between the adjacent sealing material and the spacer along the first direction, The separator includes a base material and a ceramic layer formed on the base material at least in a portion overlapping the communication hole forming portion when viewed from the first direction, A power storage module.

2. The ceramic layer is formed on the spacer side of the sealing material and the spacer that sandwich the separator in the base material, The power storage module according to claim 1.

3. The thickness of the ceramic layer is 2 μm or more, The power storage module according to claim 1.

4. The electrolytic solution contains LiFSI as an electrolyte salt, The power storage module according to claim 1.

5. A reinforcing portion is provided on the current collector of the terminal electrode, which is the electrode located at the outermost part of the electrode laminate in the first direction. When viewed from the first direction, the reinforcing portion is provided at least in a portion between the outer edge of the first active material layer and the inner edge of the sealing material in the current collector of the terminal electrode. The power storage module according to any one of claims 1 to 4.

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