Electric power storage module

Abstract

An electric 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 adjacent electrodes. A spacer (22) of the sealing body (20) includes: a body part (22M) formed in a frame shape following the external contour of a collector (15) of the electrodes; and a communication hole formation section (22) in which a portion of the spacer (22) from an outer edge (22t) thereof to an inner edge (22e) thereof is omitted, whereby a communication hole (30) is formed. The separator (14) extends so as to be sandwiched between the spacer (22) and adjacent sealing materials (21) in the sealing body (20) while being interposed between a positive-electrode active material layer (16) and a negative-electrode active material layer (17) that are adjacent to each other. The separator (14) includes a base material (14a) and a ceramic layer (14b) formed on the base material (14a) at least in a portion overlapping the communication hole formation section (22F).

Description

Energy storage module

[0001] The present disclosure relates to an energy storage module.

[0002] Patent Document 1 describes a bipolar battery. This bipolar battery has a bipolar electrode in which a positive electrode active material layer is provided on one surface of a current collector and a negative electrode active material layer is 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 the current collectors and surrounding the periphery of a unit cell constituted by 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 such unit cells are stacked.

[0003] Japanese Patent Application Laid-Open No. 2004-158343

[0004] In a storage module such as the bipolar battery described in Patent Document 1, a separator may be interposed between adjacent positive and negative electrode active material layers. In particular, by extending the separator from between the positive and negative electrode active material layers to the sealing layer, the internal space formed between adjacent current collectors can be divided into a positive electrode space on the positive electrode active material layer side and a negative electrode space on the negative electrode active material layer side. In this case, if a foreign object is present in the negative electrode space and penetrates the separator, a short circuit may occur between the uncoated portions of adjacent current collectors where no active material layer is formed through the separator. Various types of foreign object are conceivable, but one example is a precipitate formed when a metallic foreign object dissolved by an electrolyte in the positive electrode space is re-deposited in the negative electrode space.

[0005] An object of the present invention is to provide an energy storage module that can suppress short circuits.

[0006] The electricity storage module according to the present invention comprises an electrode stack including a plurality of electrodes stacked along a first direction, a sealing body provided on the electrode stack for sealing the electrode stack, and a separator interposed between adjacent electrodes along the first direction, wherein the electrodes have current collectors 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, and the sealing body is stacked along the first direction and formed into a frame shape that follows the outer shape of the current collectors as seen from the first direction, and comprises a plurality of sealing materials bonded to the first surface and the second surface at the periphery of the current collectors, and is interposed between the sealing materials adjacent along the first direction, and forms, together with the sealing materials adjacent along the first direction, an internal space for accommodating an electrolyte between the current collectors adjacent along the first direction. The separator has a plurality of spacers and a plurality of communication holes connecting each of the plurality of internal spaces to the outside, and when viewed from a first direction, the outer edge of the second active material layer is located outside the outer edge of the first active material layer, and 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 first direction, and a communication hole forming portion that is missing from the outer edge of the spacer to the inner edge when viewed from the first direction to form a communication hole, and 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, and the separator is interposed between the first active material layer and the second active material layer adjacent to each other along the first direction, and extends so as to be sandwiched between the sealing material and the spacer adjacent to each other along the first direction, and the separator includes a substrate and a ceramic layer formed on the substrate, at least in a portion that overlaps the communication hole forming portion when viewed from the first direction.

[0007] In this energy storage module, a sealing body is provided on the electrode stack, thereby forming an internal space for containing an electrolyte between the current collectors of adjacent electrodes. Furthermore, a separator is interposed between the first and second active material layers of adjacent electrodes. More specifically, the separator is interposed between the first and second active material layers and extends so as to be sandwiched between the sealing material constituting the sealing body and a spacer adjacent to the sealing material. This allows the separator to partition the internal space into a first space on the first active material layer side and a second space 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 extends 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 of the current collector adjacent to the separator, where no active material layer is formed, 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, for example, the second space of the internal space.

[0009] Here, the spacer includes, in addition to the main body portion, 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, thereby forming a communication hole. The communication hole connects the internal space to the outside, allowing for the introduction and discharge of fluids, such as electrolyte solution or test gas, into the internal space. By providing such a communication hole forming portion in the spacer, a region without a spacer can be created in the uncoated portion where the active material layer of adjacent current collectors is not formed via the separator. Therefore, in this region, the spacer is less likely to contribute to preventing short circuits between the uncoated portions due to foreign matter.

[0010] In contrast, in this energy storage module, the separator includes a substrate and a ceramic layer formed on the substrate at least in the portion that overlaps the communication hole formation portion (i.e., the spacer missing portion) when viewed from the stacking direction, ensuring rigidity compared to a case where only the substrate is used. Therefore, even in the above-mentioned region where no spacer is present, foreign matter is prevented from penetrating the separator, and short circuits between uncoated portions of adjacent current collectors are prevented. As described above, this energy storage module can prevent short circuits.

[0011] Here, the separator is sandwiched between a sealant provided on the current collector and a spacer laminated on the sealant. Therefore, for example, when welding the sealant and the spacer, heat input to the sealant is conducted via the current collector and is therefore not easily transferred to the separator, whereas heat input to the spacer is easily transferred to the separator, which may cause deterioration of the separator.

[0012] In contrast, in the energy storage module according to the present invention, the ceramic layer may be formed on the spacer side of the seal material and spacer that sandwich the separator in the substrate. In this case, the ceramic layer is formed on the spacer side of the seal material and spacer that sandwich the separator in the substrate. This makes it difficult for heat input to the spacer to be transferred to the substrate, thereby suppressing deterioration of the separator. In this case, even if the separator and spacer slide against each other when the spacer expands and contracts due to heat generated during charging and discharging, for example, the ceramic layer suppresses wear (or damage) of the separator.

[0013] In the energy storage module according to the present invention, the ceramic layer may have a thickness of 2 μm or more, which makes it possible to more reliably prevent short circuits.

[0014] In the energy storage module according to the present invention, the electrolyte may contain LiFSI (lithium bisfluorosulfonylimide) as an electrolyte salt. An electrolyte containing LiFSI (lithium bisfluorosulfonylimide) is likely to dissolve metallic foreign matter in the positive electrode space, which is one of the positive electrode space and the negative electrode space, and therefore likely to produce precipitates in the negative electrode space. Therefore, suppressing short circuits as described above is more effective.

[0015] In the energy storage module according to the present invention, a reinforcing portion may be provided on the current collector of the terminal electrode, which is the outermost electrode of the electrode stack in the first direction. The reinforcing portion may be provided in a portion of the current collector of the terminal electrode between at least the outer edge of the first active material layer and the inner edge of the sealing material when viewed from the first direction. In this case, the reinforcing portion is formed in at least the uncoated portion of the current collector of the terminal electrode, ensuring rigidity. As a result, for example, when the internal space is depressurized, the current collector of the terminal electrode is prevented from bending inward in the stacking direction and reducing the distance between it and another current collector (i.e., the distance between the current collectors is ensured). As a result, short circuits between the current collectors are more reliably prevented, and a fluid flow path in the internal space is reliably ensured.

[0016] According to the present invention, it is possible to provide an energy storage module that can suppress short circuits.

[0017] Fig. 1 is a schematic cross-sectional view of an energy storage module according to this embodiment. Fig. 2 is a schematic plan view of the energy storage module shown in Fig. 1. Fig. 3 is a schematic cross-sectional view showing an enlarged portion of the energy storage module shown in Fig. 1. Fig. 4 is a plan view of the spacer shown in Figs. 1 and 3. Fig. 5 is a schematic cross-sectional view showing an enlarged portion of the energy storage module. Fig. 6 is a schematic cross-sectional view of an energy storage module according to a modified example.

[0018] An energy storage module according to one embodiment will be described below with reference to the drawings. In the description of each drawing, the same or corresponding elements are denoted by the same reference numerals, and redundant description may be omitted. In addition, each drawing may show an orthogonal coordinate system that defines an X direction, a Y direction perpendicular to the X direction, and a Z direction perpendicular to the X and Y directions.

[0019] Fig. 1 is a schematic cross-sectional view of an energy storage module according to this embodiment. Fig. 2 is a schematic plan view of the energy storage module shown in Fig. 1. The energy storage module 1 shown in Figs. 1 and 2 is an energy storage module used in batteries for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The energy storage module 1 is a secondary battery such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery. The energy storage module 1 may be an electric double layer capacitor or an all-solid-state battery. Here, a case where the energy storage module 1 is a lithium-ion secondary battery is illustrated as an example.

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

[0021] The bipolar electrode 11 includes 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 that intersects with the Z direction, and the second surface 15b is a surface that intersects with the Z direction and is opposite to the first surface 15a. That is, the first surface 15a faces one side of the Z direction (the direction from the positive electrode terminal electrode 12 toward the negative electrode terminal electrode 13 in FIG. 1 ), and the second surface 15b of the current collector 15 faces the other side of the Z direction (the direction from the negative electrode terminal electrode 13 toward the positive electrode terminal electrode 12 in FIG. 1 ).

[0022] The positive electrode active material layer 16 is provided on a first surface 15a of the current collector 15. The negative electrode active material layer 17 is provided on a second surface 15b of the current collector 15. The multiple bipolar electrodes 11 are stacked 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 a first surface 15a of the current collector 15. The positive terminal electrode 12 does not have a positive electrode active material layer 16 or a negative electrode active material layer 17 on a second surface 15b of the current collector 15. In other words, 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 in the Z direction of the electrode laminate 10, and is laminated on the bipolar electrode 11. The positive terminal electrode 12 is laminated on the bipolar electrode 11 so that the positive electrode active material layer 16 faces the negative electrode active material layer 17 of the bipolar electrode 11.

[0025] The negative electrode terminal electrode 13 (terminal electrode) has a current collector 15 and a negative electrode active material layer 17 provided on a second surface 15b of the current collector 15. The negative electrode terminal electrode 13 does not have a positive electrode active material layer 16 or a negative electrode active material layer 17 on a first surface 15a of the current collector 15. In other words, no active material layer is provided on the first surface 15a of the current collector 15 of the negative electrode terminal electrode 13. The negative electrode terminal electrode 13 is located at the outermost side of the electrode laminate 10 in the opposite direction to the Z direction (negative Z direction), and is laminated on the bipolar electrode 11. The negative electrode terminal electrode 13 is laminated on the bipolar electrode 11 so that the 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, 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 or different from one another. Furthermore, the surface of the positive terminal electrode 12 on which the positive active material layer 16 is not provided and the surface of the negative terminal electrode 13 on which the negative active material layer 17 is not provided come into contact with, for example, a tab for extracting current, and therefore do not come into contact with the electrolyte.

[0027] The separators 14 are disposed between adjacent bipolar electrodes 11, between the positive terminal electrode 12 and the bipolar electrode 11, and between the negative terminal electrode 13 and the bipolar electrode 11. The separators 14 are interposed between the positive electrode active material layer 16 and the negative electrode active material layer 17, and extend to the sealing body 20. The separators 14 are 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, they prevent short circuits due to contact between adjacent electrodes.

[0028] The current collector 15 is a chemically inactive electrical conductor that allows current to continue to flow through the positive electrode active material layer 16 and the negative electrode active material layer 17 during discharge or charge 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. Examples of conductive resin materials include resins obtained by adding a conductive filler to a conductive polymer material or a non-conductive polymer material as needed. The current collector 15 may have multiple 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, for example, in the form of a plate, foil (e.g., metal foil), film, or mesh. Examples of metal foils include aluminum foil, copper foil, nickel foil, titanium foil, and stainless steel foil. The current collector 15 may be an alloy foil of the above metals or a foil obtained by integrating multiple 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 this embodiment, the current collector 15 is a foil obtained by integrating aluminum foil and copper foil, or a foil obtained by vapor-depositing copper onto aluminum foil.

[0030] The positive electrode active material layer 16 contains a positive electrode active material capable of absorbing 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, and polyanion compounds. The positive electrode active material may be any material that can be used in lithium ion secondary batteries. The positive electrode active material layer 16 may contain a plurality of positive electrode active materials. In this embodiment, the positive electrode active material layer 16 contains an olivine-type lithium iron phosphate (LiFePO ) as a composite oxide. ４ )

[0031] The negative electrode active material layer 17 includes a negative electrode active material capable of absorbing and releasing charge carriers such as lithium ions. The negative electrode active material may be a simple substance, an alloy, or a compound. Examples of the negative electrode active material include Li, carbon, and metal compounds. The negative electrode active material may be an element or a compound thereof that can be alloyed with lithium. Examples of carbon include natural graphite, artificial graphite, hard carbon (non-graphitizable carbon), and soft carbon (easily graphitizable carbon). Examples of artificial graphite include highly oriented graphite and mesocarbon microbeads. Examples of elements that can be alloyed with lithium include silicon and tin. In this embodiment, the negative electrode active material layer 17 includes 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 sometimes simply referred to as "active material layer") may further contain, as necessary, a conductive additive for improving electrical conductivity, a binder, an electrolyte (polymer matrix, ion-conductive polymer, electrolyte solution, etc.), an electrolyte supporting salt (lithium salt) for improving ionic conductivity, etc. The conductive additive is added to improve the conductivity of each electrode (bipolar electrode 11, positive terminal electrode 12, negative terminal electrode 13). Examples of the conductive additive include acetylene black, carbon nanotubes (CNT), carbon black, graphite, etc.

[0033] Examples of binders 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 and methacrylic acid; styrene-butadiene rubber (SBR); carboxymethyl cellulose; alginates such as sodium alginate and ammonium alginate; water-soluble cellulose ester crosslinked bodies; and starch-acrylic acid graft polymers. These binders can be used alone or in combination. Examples of solvents for binders include water and N-methyl-2-pyrrolidone (NMP).

[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 materials for the separator 14 include polypropylene, polyethylene, polyolefin, and polyester. The separator 14 may have a single-layer structure or a multi-layer structure. The multi-layer structure may include, for example, a ceramic layer as an adhesive layer or a heat-resistant layer. The separator 14 may be impregnated with an electrolyte. The electrolyte impregnated in the separator 14 is a liquid electrolyte (electrolytic solution) containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent.

[0035] The electrolyte salt of the electrolyte solution is LiClO ４ , LiAsF ６ , LiPF ６ , LiBF ４ , LiCF ３ SO３ , LiN(FSO ２ ) ２ , LiN(CF ３ SO ２ ) ２ Known lithium salts such as those listed above may also 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] Lithium salt: LiFSI 1.6 (mol / L) Non-aqueous solvent: EC (ethylene carbonate) 15 (vol %) MP (methyl propionate) 85 (vol %)

[0037] The non-aqueous solvent may be a known solvent such as a cyclic carbonate, a cyclic ester, a chain carbonate, a chain ester, or an ether, or two or more of these known solvent materials may be used in combination.

[0038] The sealing body 20 is provided on the electrode stack 10 so as to surround the electrode stack 10 when viewed from the Z direction, and is formed in a rectangular tubular shape on the peripheral portion of the electrode stack 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 portion 15c of each current collector 15. The sealing body 20 forms an internal space S between adjacent current collectors 15 in the Z direction and seals each of the internal spaces S (i.e., the electrode stack 10). Each internal space S contains an electrolyte (e.g., an electrolytic solution). The sealing body 20 can prevent the electrolytic solution contained in the internal space S from leaking to the outside. The sealing body 20 can also prevent air, moisture, and the like from entering the internal space S from outside the electrode stack 10.

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

[0040] The sealing body 20 includes a plurality of resin sealants 21 and a plurality of resin spacers 22. A sealant 21 is provided on each current collector 15. Therefore, the plurality of sealants 21 are stacked along the Z direction. The sealant 21 has a frame shape (here, a rectangular frame shape) that follows the outer shape of the current collector 15 when viewed from the Z direction, and is provided on the peripheral portion 15c of the current collector 15. The sealant 21 is provided so as to extend from the first surface 15a of the current collector 15, passing through the end face, to the second surface 15b, and covers the peripheral portion 15c.

[0041] That is, the sealing material 21 has an inner portion 21a that overlaps the current collector 15 on the first surface 15a and the second surface 15b of the current collector 15, and an outer portion 21b that is located outside the edge of the current collector 15, when viewed from the Z direction. A pair of adjacent portions of the sealing material 21 that sandwich the current collector 15 are connected to each other at the outer portion 21b. The inner portions 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 this 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 this embodiment, the sealing materials provided on the current collector 15 of the bipolar electrode 11, the current collector 15 of the positive terminal electrode 12, and the current collector 15 of the negative terminal electrode 13 are each given the same reference numeral as a sealing material 21. However, the sealing materials provided on the current collector 15 of the bipolar electrode 11, the sealing material provided on the current collector 15 of the positive terminal electrode 12, and the sealing material provided on the current collector 15 of the negative terminal electrode 13 may be the same as or different from one another.

[0043] The spacers 22 are arranged so as to be interposed between the respective sealing materials 21 adjacent to each other in the Z direction. As a result, the spacers 22, together with a pair of sealing materials 21 adjacent to each other in the Z direction, maintain the spacing between the current collectors 15 adjacent to each other in the Z direction. An internal space S is defined by the pair of current collectors 15 adjacent to each other in the Z direction, the spacers 22, and the pair of sealing materials 21 adjacent to the spacers 22. In this way, each of the multiple spacers 22, together with the sealing materials 21 adjacent to each other in the Z direction, forms the internal space S between the current collectors 15 adjacent to each other in the Z direction.

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

[0045] The separator 14 is 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 extends so as to be 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 held by being sandwiched between the sealing material 21 and the spacer 22. In this embodiment, the outer end of the separator 14 is fixed to the sealing material 21 by welding, and no joining such as welding is formed between the separator 14 and the spacer 22.

[0046] A portion of each of the seal materials 21 located outside the outer edge 15e of the current collector 15 (i.e., the end of the outer portion 21b) and a portion of each of the spacers 22 located outside the outer edge 15e of the current collector 15 (i.e., the end of the outer portion 22b) are welded together and integrated to form a welded portion 23. That is, the sealing body 20 includes the welded portion 23 formed by welding the outer portions 21b of the seal materials 21 and the outer portions 22b of the spacers 22 together. When viewed from the Z direction, the welded portion 23 has a frame shape surrounding the electrode stack 10 and forms the outer periphery of the sealing body 20. Therefore, the outer surface of the welded portion 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 do not need to be welded to the sealing materials 21 at least at the inner portions 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] Note that conductive members (not shown) are laminated on 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, respectively, on portions exposed from the sealing body 20 (i.e., portions where the sealing material 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 energy storage modules 1 and function as terminals for extracting current from the energy storage modules 1. The conductive members can be used to electrically connect multiple energy storage modules 1. Multiple energy storage modules 1 may be arranged in series via the conductive members.

[0048] The conductive member may also be used as a member for applying a restraint load to the electrode stack 10. That is, when a restraint member (not shown) is arranged to restrain the energy storage module 1 from the Z direction, the restraint load may be applied to the electrode stack 10 via the conductive member. Furthermore, a cooling flow path may be formed in the conductive member. The energy storage module 1 can be cooled by circulating a cooling medium through the cooling flow path formed in the conductive member. Furthermore, members (not shown) configured integrally with or separately from the conductive member may be arranged on both sides of the sealing body 20 in the Z direction, and a restraint load may be applied to the sealing body 20 via these members.

[0049] Fig. 3 is a schematic cross-sectional view showing an enlarged portion of the electricity storage module shown in Fig. 1. In Fig. 1 and Fig. 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 that surface.

[0050] 1 to 3, as viewed from the Z direction, the inner edge 22e of the spacer 22 (i.e., a part of the inner portion 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. As a result, the spacer 22 includes an overlapping portion 22r that overlaps with the negative electrode active material layer 17 as viewed from the Z direction, and a non-overlapping portion 22p that does not overlap with the sealing material 21 and the negative electrode active material layer 17 as viewed from the Z direction.

[0051] Of the multiple spacers 22, the outermost spacer 22 in the Z direction (here, closest to the positive terminal electrode 12) may be sandwiched at an overlapping portion 22r between a pair of adjacent negative electrode active material layers 17 along the Z direction, with the separator 14 interposed therebetween. More specifically, the overlapping portion 22r of the outermost spacer 22 in the Z direction may be in contact with 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 (e.g., welded) to the first surface 15a of the current collector 15 at the overlapping portion 22r.

[0052] In this embodiment, among the multiple spacers 22, the spacers 22 (intermediate spacers 22) other than the outermost spacers 22 in the Z direction are configured not to contact the current collector 15 of the adjacent bipolar electrode 11 at the overlapping portion 22r. That is, the thickness Ts of the spacers 22 in the Z direction is 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 intermediate spacer 22 and the first surface 15a of the current collector 15 of the adjacent bipolar electrode. In this embodiment, the thickness Ts of the spacer 22 at the overlapping portion 22r may be equal to the thickness of the portion of the spacer 22 that overlaps with the sealing material 21 as viewed in the Z direction.

[0053] 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 16 e of the positive electrode active material layer 16 as viewed from the Z direction and includes the outer edge 17 e 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 this 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. However, the thickness T2 of the second portion 172 may be greater 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.

[0054] The current collector 15 also 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 or the sealing material 21 when viewed from the Z direction, and a second region 152 that overlaps the negative electrode active material layer 17 when viewed from the Z direction but does not overlap the positive electrode active material layer 16. The first region 151 is a region between an outer edge 17e of the negative electrode active material layer 17 and an 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 when viewed from the Z direction.

[0055] The second region 152 is a region between the outer edge 16 e of the positive electrode active material layer 16 and the outer edge 17 e of the negative electrode active material layer 17. In this embodiment, the width W1 of the first region 151 when viewed from the Z direction is narrower than the width W2 of the second region 152 when viewed from the Z direction. As described above, the spacer 22 includes the overlapping portion 22 r, and thus 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 laminate portion 101 in which the negative electrode active material layer 17 and the positive electrode active material layer 16 overlap as viewed from the Z direction, and a second laminate portion 102 including a portion in which the negative electrode active material layer 17 and the spacer 22 (overlapping portion 22r) overlap as viewed from the Z direction. As viewed from the Z direction, the second laminate portion 102 corresponds to the combined region of the first region 151 and the second region 152. The sealing body 20 includes a first sealing portion 201 in which the sealant 21 and the spacer 22 overlap as viewed from the Z direction. As viewed from the Z direction, the first sealing portion 201 does not overlap the overlapping portion 22r and the non-overlapping portion 22p of the spacer 22. In this embodiment, the thicknesses in the Z direction are thinner in the order of the first laminate portion 101, the second laminate portion 102, and the first sealing portion 201. That is, the thickness of the second stacked portion 102 in the Z direction is thinner than the thickness of the first stacked 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 stacked portion 102 in the Z direction.

[0057] FIG. 4 is a plan view of the spacer shown in FIGS. 1 and 3 , and FIG. 5 is a schematic cross-sectional view showing an enlarged portion of the energy storage module. As shown in FIGS. 1 , 2 , 4 , and 5 , the sealing body 20 has a plurality of communication holes 30 that connect each of the plurality of internal spaces S to the outside. The communication holes 30 connect each of the internal spaces S to the outside. This allows the communication holes 30 to be used for introducing and discharging fluid into and from the internal spaces S. That is, the communication holes 30 can be used when injecting an electrolyte into the internal spaces S or when introducing or discharging a test gas into or from the internal spaces S. For example, after the injection of the electrolyte or the introduction or discharge of the test gas is completed, the communication holes 30 can be sealed with a film including a metal layer or the like via another resin member formed outside the sealing body 20.

[0058] In this embodiment, the communication holes 30 are formed by removing a portion of the spacer 22. That is, the spacer 22 includes a main body portion 22M formed in a frame shape (rectangular frame shape) that follows the outer shape of the current collector 15 when viewed from the Z direction, and communication hole forming portions 22F that form the communication holes 30 by being removed from the outer edge 22t to the inner edge 22e of the spacer 22 when viewed from the Z direction. The multiple communication holes 30 are formed and dispersed at multiple positions on one side of the plug 20 when viewed from the Z direction. Therefore, the communication hole forming portions 22F are similarly dispersed at multiple positions on one side of the plug 20. That is, the communication hole forming portions 22F of spacers 22 adjacent to each other in the Z direction are formed at different positions when viewed from the Z direction.

[0059] As described above, the separator 14 is 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 extends so as to be sandwiched between the sealing material 21 and the spacer 22 adjacent to each other along the Z direction. As a result, the separator 14 divides the internal space S between the current collectors 15 adjacent to each other in the Z direction into a positive electrode side space including the positive electrode active material layer 16 and a negative electrode side space including the negative electrode active material layer 17. In addition to the separator 14, the spacer 22 (main body portion 22M) is interposed between the current collectors 15 adjacent to each other in the Z direction in a portion of the electrode stack 10 that overlaps with the main body portion 22M of the spacer 22 as viewed from the Z direction.

[0060] On the other hand, in the portion of the electrode stack 10 that overlaps the communication hole forming portion 22F of the spacer 22 as viewed from the Z direction, a portion of the spacer 22 is missing, so that only the separator 14 is interposed between the current collectors 15 adjacent to each other in the Z direction. Therefore, for example, if a foreign object is present in the negative electrode side space and penetrates the separator 14, a short circuit may occur between the adjacent current collectors 15 via the separator 14. Note that various types of foreign object are conceivable, and one example is a precipitate that occurs when a metallic foreign object that has been dissolved by the electrolyte in the positive electrode side space is redeposited in the negative electrode side space.

[0061] In contrast, in this embodiment, the separator 14 includes a substrate 14a and a ceramic layer 14b formed on the substrate 14a, at least in a portion that overlaps the communication hole forming portion 22F when viewed from the Z direction. The substrate 14a corresponds to a conventional separator made of the various materials described above and has a thickness of, for example, approximately 10 μm. The ceramic layer 14b has a thickness of, for example, 2 μm or more (for example, approximately 4 μm). In this embodiment, the ceramic layer 14b is provided on the entire surface of the substrate 14a. Furthermore, the ceramic layer 14b is formed on the spacer 22 side of the substrate 14a, which is sandwiched between the seal material 21 and the spacer 22 that sandwich the separator 14.

[0062] As described above, in the energy storage module 1 according to this embodiment, the sealing body 20 is provided on the electrode stack 10, thereby forming an internal space S for accommodating an electrolyte between the current collectors 15 of adjacent electrodes. Furthermore, the 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 is interposed between the positive electrode active material layer 16 and the negative electrode active material layer 17, and extends so as to be sandwiched between the sealing material 21 constituting the sealing body 20 and the spacer 22 adjacent to the sealing material 21. This allows the separator 14 to partition the internal space S into a positive electrode-side space (first space) on the positive electrode active material layer 16 side and a negative electrode-side space (second space) on the negative electrode active material layer 17 side.

[0063] On the other hand, in the energy storage module 1 according to this embodiment, the spacer 22 includes a main body portion 22M formed in a frame shape that follows the outer shape of the current collector 15 when 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 outward beyond the positive electrode active material layer 16. In other words, the main body portion 22M of the spacer 22 extends from between adjacent sealing materials 21 so as to overlap the negative electrode active material layer 17. Therefore, in the uncoated portion (first region 151) where the active material layer of the current collector 15 adjacent to each other via the separator 14 is not formed, the presence of the main body portion 22M of the spacer 22 in addition to the separator 14 in the Z direction suppresses short circuits caused by foreign matter present in the negative electrode side space of the internal space S, for example.

[0064] Here, in addition to the main body portion 22M, the spacer 22 includes a communication hole forming portion 22F that is missing from the outer edge 22t to the inner edge 22e of the spacer 22 when viewed from the Z direction, thereby forming the communication hole 30. By providing such communication hole forming portion 22F in the spacer 22, a region without the spacer 22 can be generated in the uncoated portion (first region 151) where the active material layer of the adjacent current collector 15 across the separator 14 is not formed. Therefore, in this region, the spacer 22 is less likely to contribute to preventing short circuits between the uncoated portions due to foreign matter.

[0065] In contrast, in the energy storage module 1 according to this embodiment, the separator 14 includes a substrate 14a and a ceramic layer 14b formed on the substrate 14a at least in the portion that overlaps the communication hole forming portion 22F (i.e., the missing portion of the spacer) when viewed from the Z direction, ensuring rigidity compared to a separator that includes only the substrate 14a (i.e., a conventional separator). Therefore, even in the above region where the spacer 22 is not present, foreign matter is prevented from penetrating the separator 14, thereby preventing short circuits between uncoated portions of adjacent current collectors 15. As described above, the energy storage module 1 according to this embodiment can prevent short circuits.

[0066] Here, the separator 14 is sandwiched between a sealant 21 provided on the current collector 15 and a spacer 22 laminated on the sealant 21. Therefore, for example, when the sealant 21 and the spacer 22 are welded together (for example, when forming the welded portion 23), heat input to the sealant 21 is quickly lost as it is conducted through the current collector 15 and is not easily transmitted to the separator 14, whereas 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 energy storage module 1 according to this embodiment, the ceramic layer 14b is formed on the spacer 22 side of the base material 14a, between the seal material 21 and the spacer 22 that sandwich the separator 14. This makes it difficult for heat input to the spacer 22 to be transferred to the base material 14a, thereby suppressing deterioration of the separator 14. Furthermore, with this configuration, even if the separator 14 and the spacer 22 slide against each other when the spacer 22 expands and contracts due to heat generated during charging and discharging, for example, the ceramic layer 14b suppresses wear (or damage) of the separator 14.

[0068] Furthermore, in the energy storage module 1 according to this embodiment, the ceramic layer 14b has a thickness of 2 μm or more, which makes it possible to more reliably prevent short circuits.

[0069] Furthermore, in the energy storage module 1 according to this embodiment, the electrolyte may contain LiFSI as an electrolyte salt. In this way, an electrolyte containing LiFSI (lithium bisfluorosulfonylimide) is likely to dissolve metallic foreign matter in the positive electrode space, which is one of the positive electrode space and the negative electrode space, and therefore is likely to produce precipitates in the negative electrode space, which is one of the positive electrode space and the negative electrode space. Therefore, suppressing short circuits as described above is more effective.

[0070] The above embodiment has described one aspect of the present invention. Therefore, the present invention is not limited to the above embodiment and can be modified as desired. Next, modifications will be described.

[0071] 6 is a schematic cross-sectional view of an energy storage module according to a modified example. As shown in FIG. 6 , in the energy storage module 1, a reinforcing portion 40 is provided (e.g., by adhesion or welding) on ​​the current collector 15 of the positive terminal electrode 12, which is one of the electrodes located at the outermost position in the Z direction of the electrode stack 10. The reinforcing portion 40 is formed in a plate shape using a metal such as aluminum. The reinforcing portion 40 is provided on a second surface 15b of the current collector 15 of the positive terminal electrode 12 that faces outward in the Z direction. When viewed from the Z direction, the reinforcing portion 40 is provided on at least a portion of the current collector 15 of the positive terminal electrode 12 between the outer edge 16e of the positive electrode active material layer 16 and the inner edge 21e of the sealant 21.

[0072] However, the reinforcing portion 40 may be provided on the entire second surface 15b of the current collector 15 of the positive terminal electrode 12 (except for the portion covered with the sealing material 21), or may be provided in the shape of a rectangular frame when viewed in the Z direction. Furthermore, the reinforcing portion 40 may also be provided on the first surface 15a facing the outside of the current collector 15 of the negative terminal electrode 13, which is another of the electrodes located at the outermost positions of the electrode stack 10 in the Z direction.

[0073] According to this modification, a reinforcing portion 40 is formed in at least the uncoated 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 prevented from bending inward in the Z direction and reducing the distance between itself and another current collector 15 (i.e., the distance between the current collectors 15 is ensured). As a result, short circuits between the current collectors 15 are more reliably prevented, and fluid flow paths in the internal space S (i.e., the ability to allow gas and electrolyte to escape) are reliably ensured.

[0074] In the illustrated example, the current collector 15 is provided with a reinforcing portion 40, which is a member formed separately from the current collector 15. However, the reinforcing portion 40 may be formed integrally 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 electrode (i.e., the bipolar electrode 11), thereby forming the reinforcing portion 40 integrally.

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

[0076] In addition, in the above embodiment, an example was 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, but 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] The following additional notes will be made regarding the above embodiment.

[0078] The energy storage module includes: [1] an electrode stack including a plurality of electrodes stacked along a first direction; a sealing body provided on the electrode stack for sealing the electrode stack; and a separator interposed between the electrodes adjacent to each other along the first direction, wherein the electrodes have current collectors 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 stacked along the first direction and formed into a frame shape that follows the outer shape of the current collector when viewed from the first direction, and includes a plurality of sealing materials bonded to the first surface and the second surface at a peripheral portion of the current collector; and a plurality of spacers interposed between the sealing materials adjacent to each other along the first direction and that, together with the sealing materials adjacent to each other along the first direction, form an internal space for accommodating an electrolyte between the current collectors adjacent to each other along the first direction. and a plurality of communication holes connecting each of the plurality of internal spaces to the outside, wherein when viewed from the first direction, an outer edge of the second active material layer is located outside of an outer edge of the first active material layer, 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 first direction, and a communication hole forming portion that is missing from the outer edge of the spacer to an inner edge when viewed from the first direction, and forms the communication holes, wherein when viewed from the first direction, an inner edge of the main body portion is located inside of an outer edge of the second active material layer, the separator is interposed between the first active material layer and the second active material layer that are adjacent to each other along the first direction, and extends so as to be sandwiched between the sealing material and the spacer that are adjacent to each other along the first direction, and the separator includes a substrate and a ceramic layer formed on the substrate at least in a portion that overlaps with the communication hole forming portion when viewed from the first direction.

[0079] The energy storage module may be [2] "the energy storage module described in the above [1], in which the ceramic layer is formed on the spacer side of the sealing material and the spacer that sandwich the separator in the base material."

[0080] The electricity storage module may be [3] "the electricity storage module according to the above [1] or [2], in which the ceramic layer has a thickness of 2 μm or more."

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

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

[0083] REFERENCE SIGNS LIST 1 Energy 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 Substrate 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 Main body portion 22F Communication hole forming portion 30 Communication hole 40 Reinforcement 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; and a separator interposed between the electrodes adjacent along the first direction, wherein the electrodes include: 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, wherein the sealing body includes: a plurality of sealants laminated along the first direction and formed in a frame shape following the outer shape of the current collector when viewed from the first direction, and joined to the first surface and the second surface at the periphery of the current collector; a plurality of spacers interposed between the sealants adjacent along the first direction and forming, together with the sealants adjacent along the first direction, an internal space for containing an electrolyte between the current collectors adjacent along the first direction; and a plurality of communication holes connecting each of the plurality of internal spaces to the outside. an outer edge of the second active material layer is located outside an outer edge of the first active material layer when viewed from the first direction, 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 first direction; and a communication hole forming portion that forms the communication hole by being missing from the outer edge to the inner edge of the spacer when viewed from the first direction, wherein an inner edge of the main body portion is located inside an outer edge of the second active material layer when viewed from the first direction, the separator is interposed between the first active material layer and the second active material layer adjacent to each other along the first direction, and extends so as to be sandwiched between the sealing material and the spacer adjacent to each other along the first direction, and the separator includes a substrate and a ceramic layer formed on the substrate at least in a portion that overlaps the communication hole forming portion when viewed from the first direction.

2. The energy storage module according to claim 1, wherein the ceramic layer is formed on the spacer side of the base material, between the seal material and the spacer, which sandwich the separator.

3. The energy storage module according to claim 1, wherein the ceramic layer has a thickness of 2 μm or more.

4. The energy storage module according to claim 1, wherein the electrolyte contains LiFSI as an electrolyte salt.

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

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