Energy storage device

Abstract

To provide an energy storage device that can reduce the influence of stress from potting material while improving vibration resistance. [Solution] The energy storage device 100 comprises an energy storage pack 2, a case 200 that houses the energy storage pack 2, and a potting material 300 filled in the space between the outer surface 2s of the energy storage pack 2 and the inner surface 200s of the case 200 when viewed from a first direction D1. The potting material 300 is composed of a plurality of filling portions 300p that are along the outer surface 2s when viewed from a first direction D1. The coefficient of linear expansion of the potting material 300 is greater than the coefficient of linear expansion of the energy storage pack 2.

Description

Technical Field

[0001] The present invention relates to a power storage device.

Background Art

[0002] Patent Document 1 describes a battery pack. This battery pack has a configuration in which a plurality of thin laminate batteries (element batteries) are arranged in a stainless steel case in 2 parallel - 4 series, and each tab protruding from the cell body of these thin laminate batteries is electrically connected by a copper bus bar. The bus bar and the tab are connected by welding using an ultrasonic welder. Further, the internal space of the case is filled with a potting material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the battery pack described in Patent Document 1, as described above, the internal space of the case is filled with a potting material to improve vibration resistance. In this battery pack, the cell body is surrounded by the potting material over the entire circumference. Generally, since the potting material and the cell body are made of different materials, the linear expansion coefficient of the potting material is different from that of the cell body. Therefore, the amount of expansion and contraction due to temperature change in the potting material and the cell body is different. As a result, there is a possibility that stress is applied from the potting material to the cell body with a temperature change.

[0005] An object of the present invention is to provide a power storage device capable of reducing the influence of stress from the potting material while improving vibration resistance.

Means for Solving the Problems

[0006] The energy storage device according to the present invention comprises an energy storage pack having an energy storage module including a plurality of electrodes stacked along a first direction, a case for housing the energy storage pack, and a potting material filled in the space between the outer surface of the energy storage pack and the inner surface of the case when viewed from the first direction, wherein the potting material is composed of a plurality of filling portions along the outer surface when viewed from the first direction, and the coefficient of linear expansion of the potting material is greater than the coefficient of linear expansion of the energy storage pack.

[0007] In this energy storage device, potting material is filled into the space between the outer surface of the energy storage pack and the inner surface of the case that houses the energy storage pack. Therefore, the vibration resistance of the energy storage pack is improved. On the other hand, the potting material has a coefficient of thermal expansion that is larger than that of the energy storage pack. Therefore, at low temperatures, the potting material will contract more than the energy storage pack. However, in this energy storage device, the potting material is composed of multiple filling sections that follow the outer surface of the energy storage pack when viewed from the first direction, which is the stacking direction of the electrodes. Therefore, even when the potting material contracts more than the energy storage pack, each of the multiple filling sections can contract independently, and stress that would constrict the energy storage pack from the potting material is suppressed. Thus, in this energy storage device, vibration resistance can be improved by the potting material while the influence of stress from the potting material can be reduced.

[0008] In the energy storage device according to the present invention, the outer surface has a plurality of corners when viewed from a first direction, and the unfilled portion of the potting material formed between the filled portions of the potting material may be located at at least one of the plurality of corners.

[0009] In the energy storage device according to the present invention, the potting material may be in contact with the outer surface of the energy storage pack.

[0010] The energy storage device according to the present invention comprises a plurality of energy storage packs stacked via conductive plates along a first direction, and the potting material may be provided across the plurality of energy storage packs.

[0011] The energy storage device according to the present invention includes a sealing member for sealing the space sandwiched between adjacent energy storage packs in the first direction, viewed from a direction intersecting the first direction, from the outside of the energy storage packs, wherein the sealing member has a frame shape when viewed from the first direction, and the outer periphery of the sealing member may be in contact with the potting material.

[0012] In the energy storage device according to the present invention, the energy storage pack comprises an energy storage module and an outer casing that houses the energy storage module and has a laminate film including a metal layer, and the outer surface of the energy storage pack may be made of laminate film.

[0013] In the energy storage device according to the present invention, the outer casing has a flange portion that extends outward from the housing portion of the energy storage module when viewed from a first direction, the flange portion has a bent portion, and the outer casing and the potting material may be locked together by the bent portion of the flange being embedded in the potting material.

[0014] In the energy storage device according to the present invention, the energy storage pack has a first protective member that is positioned opposite to the first side surface of the energy storage module when viewed from a first direction, and the first protective member may be made of resin and positioned between the first side surface and the inner surface of the outer casing.

[0015] In the energy storage device according to the present invention, the first protective member may be fixed to the inner surface of the outer casing.

[0016] In the energy storage device according to the present invention, the energy storage pack may have a second protective member positioned opposite to the second side surface of the energy storage module, when viewed from a first direction, on the side opposite to the first side surface. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide an energy storage device that can reduce the influence of stress from the potting material while improving vibration resistance. [Brief explanation of the drawing]

[0018] [Figure 1] FIG. 1 is a schematic cross-sectional view of a power storage device according to the present embodiment. FIG. 2 is a schematic plan view of the power storage device shown in FIG. 1. [Figure 2] FIG. 2 is a schematic cross-sectional view of the power storage device shown in FIG. 1. [Figure 3] FIG. 3 is a schematic cross-sectional view showing the power storage pack shown in FIG. 1. [Figure 4] FIG. 4 is a schematic cross-sectional view showing the power storage module included in the power storage pack shown in FIG. 3. [Figure 5] FIG. 5 is a schematic diagram showing the amount of shrinkage in each part of the power storage device and the stress applied to the power storage device.

MODE FOR CARRYING OUT THE INVENTION

[0019] Hereinafter, a power storage device according to an embodiment will be described with reference to the drawings. In the description of each figure, the same or corresponding elements are denoted by the same reference numerals, and redundant descriptions may be omitted. In addition, in each figure, a rectangular coordinate system defining a first direction D1, a second direction D2 orthogonal to the first direction D1, and a third direction D3 orthogonal to both the first direction D1 and the second direction D2 may be shown.

[0020] FIG. 1 is a schematic cross-sectional view of a power storage device according to the present embodiment. FIG. 2 is a schematic cross-sectional view of the power storage device shown in FIG. 1. In FIG. 2, for the sake of convenience, the hatching other than the potting material shown in FIG. 1 is omitted. As shown in FIGS. 1 and 2, the power storage device 100 includes a plurality (here, four) of power storage packs 2 stacked along the first direction D1, a case 200 that houses the plurality of power storage packs 2 together, and a potting material 300 provided between the outer surface 2s of the power storage pack 2 and the inner surface 200s of the case 200 (that is, the space between the outer surface 2s and the inner surface 200s) when viewed from the first direction D1.

[0021] The power storage device 100 also includes a conductive plate 110 and a cooler 120 disposed on one side and the other side of each of the power storage packs 2 in the first direction D1. The conductive plate 110 and the cooler 120 are alternately arranged along the first direction D1. That is, a conductive plate 110 is provided on one side of one power storage pack 2 in the first direction D1, and a cooler 120 is provided on the other side of the one power storage pack 2 in the first direction D1.

[0022] The conductive plate 110 is interposed between a pair of adjacent power storage packs 2 along the first direction D1 and is adhered to the pair of power storage packs 2 by a conductive adhesive 130 to be electrically connected. Also, the cooler 120 is interposed between a pair of adjacent power storage packs 2 along the first direction D1 and is adhered to the pair of power storage packs 2 by a conductive adhesive 130 to be electrically connected. Thereby, the conductive plate 110 and the cooler 120 electrically connect a plurality of power storage packs 2 in series.

[0023] The conductive plate 110 and the cooler 120 have substantially the same external shape. For example, the conductive plate 110 is formed in the shape of a solid plate from a conductive material such as metal, and the cooler 120 is configured to include a plate-shaped member made of a conductive material such as metal and a coolant flow path formed in the plate-shaped member. The conductive plate 110 and the cooler 120 extend to the outside of the energy storage pack 2 when viewed from the first direction D1. Between the outer periphery of the conductive plate 110 and the cooler 120 when viewed from the first direction D1 and the outer periphery of the energy storage pack 2 when viewed from the first direction D1, a frame-shaped potting seal 150 (sealing member) is interposed to prevent the inflow of potting material 300 during manufacturing. That is, the energy storage device 100 has a frame shape when viewed from the first direction D1 and is equipped with a potting seal 150 for sealing between adjacent energy storage packs 2 along the first direction D1. Furthermore, sealing the space between the energy storage packs 2 means, for example, sealing the space between two adjacent energy storage packs 2 in the first direction D1, when viewed from a direction intersecting the first direction D1 (for example, the second direction D2 and the third direction D3), from the outside of the energy storage packs 2 (to prevent the potting material 300 from flowing into that space). Therefore, the outer periphery of the potting seal 150 is in contact with the potting material 300.

[0024] The case 200 includes an upper case 210, which is a rectangular box shape with a bottom and one side open, and a lower case 220, which is a rectangular box shape with a bottom and one side open. The upper case 210 has a frame-shaped flange portion 211 that extends outward at its open portion when viewed from a first direction D1, and the lower case 220 has a frame-shaped flange portion 221 that extends outward at its open portion when viewed from a first direction D1. The upper case 210 and the lower case 220 can be integrated by fixing the flange portions 211 and 221 together when their respective flange portions 211 and 221 overlap each other.

[0025] As described above, a conductive plate 110 is interposed between the bottom of the lower case 220 and the bottom of the lower case 220, and a structural adhesive 140 is provided between the conductive plate 110 and the bottom of the lower case 220, thereby bonding the conductive plate 110 to the lower case 220. This fixes the laminate of the power storage packs 2 to the case.

[0026] Figure 3 is a schematic cross-sectional view showing the energy storage pack shown in Figure 1. Figure 4 is a schematic cross-sectional view showing the energy storage module included in the energy storage pack shown in Figure 3. As shown in Figures 3 and 4, the energy storage pack 2 comprises an energy storage module 1, a first protective member 3, a second protective member 4, and an outer casing 40 that houses the energy storage module 1, the first protective member 3, and the second protective member 4. The energy storage pack 2 is constructed by sealing the energy storage module 1, the first protective member 3, and the second protective member 4 with the outer casing 40.

[0027] The energy storage module 1 includes an electrode stack 10 formed by stacking a plurality of electrodes along a first direction D1, and a sealing body 20 provided on the outer circumference of the electrode stack 10. The electrode stack 10 includes a plurality of electrodes stacked along the first direction D1. The plurality of electrodes include a plurality of bipolar electrodes 11, a negative terminal electrode (second terminal electrode) 12, and a positive terminal electrode (first terminal electrode) 13. A separator 14 is interposed between adjacent electrodes.

[0028] The bipolar electrode 11 includes a current collector 15, a positive electrode active material layer (first active material layer) 16, and a negative electrode active material layer (second active material layer) 17. The current collector 15 is, for example, in the shape of a rectangular sheet. The current collector 15 includes a first surface 15a and a second surface 15b. For example, the first surface 15a is a surface that intersects the first direction D1, and the second surface 15b intersects the first direction D1 and is the surface opposite to the first surface 15a. Here, the first surface 15a of the current collector 15 is a surface facing one direction of the first direction D1 (the direction from the positive electrode terminal electrode 13 to the negative electrode terminal electrode 12 in Figure 4), and the second surface 15b of the current collector 15 is a surface facing the other direction of the first direction (the direction from the negative electrode terminal electrode 12 to the positive electrode terminal electrode 13 in Figure 4).

[0029] 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 peripheral area surrounding the positive electrode active material layer 16 on the first surface 15a of the current collector 15 and the peripheral area surrounding the negative electrode active material layer 17 on the second surface 15b of the current collector 15 are unformed regions (uncoated regions) where no active material layer is provided. Multiple bipolar electrodes 11 are stacked such that the positive electrode active material layer 16 of one bipolar electrode 11 and the negative electrode active material layer 17 of another bipolar electrode 11 face each other via a separator 14. Grooves may be formed in the positive electrode active material layer 16 and the negative electrode active material layer 17 of each bipolar electrode 11 to improve liquid injection and gas escape.

[0030] The positive electrode active material layer 16 and the negative electrode active material layer 17 are rectangular in shape when viewed from a first direction D1. The negative electrode active material layer 17 is slightly larger than the positive electrode active material layer 16 when viewed from a first direction D1. In a plan view from a first direction D1, 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 a first direction D1, 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.

[0031] The negative electrode terminal electrode 12 comprises 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 electrode terminal electrode 12 does not have a positive electrode active material layer 16 or a negative electrode active material layer 17 on the first surface 15a of the current collector 15. In other words, the first surface 15a of the current collector 15 of the negative electrode terminal electrode 12 does not have an active material layer and constitutes the negative electrode terminal surface of the energy storage module 1. The negative electrode terminal electrode 12 is laminated on the bipolar electrode 11 at one end of the electrode laminate 10 in the first direction D1. The negative electrode terminal electrode 12 is laminated on the bipolar electrode 11 via a separator 14 such that its negative electrode active material layer 17 faces the positive electrode active material layer 16 of the bipolar electrode 11.

[0032] The positive terminal electrode 13 comprises 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 13 does not have a positive electrode active material layer 16 or a negative electrode active material layer 17 on the second surface 15b, which is the opposite surface 15a of the current collector 15. In other words, the second surface 15b of the current collector 15 of the positive terminal electrode 13 does not have an active material layer and constitutes the positive terminal surface of the energy storage module 1. The positive terminal electrode 13 is laminated on the bipolar electrode 11 at the other end of the electrode laminate 10 in the first direction D1. The positive terminal electrode 13 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 via a separator 14.

[0033] In this embodiment, the current collectors of the bipolar electrode 11, the negative terminal electrode 12, and the positive terminal electrode 13 are all denoted by the same reference numeral as current collector 15. However, the materials constituting the current collectors of the bipolar electrode 11, the negative terminal electrode 12, and the positive terminal electrode 13 may be the same or different.

[0034] The separator 14 is positioned between adjacent bipolar electrodes 11 in the first direction D1, between the negative electrode terminal electrode 12 and the bipolar electrode 11, and between the positive electrode terminal electrode 13 and the bipolar electrode 11. In other words, the separator 14 is interposed between the positive electrode surface of the current collector 15, where the positive electrode active material layer 16 is provided, and the negative electrode surface, where the negative electrode active material layer 17 is provided. The separator 14 is a component that allows charge carriers such as lithium ions to pass through, and by separating the positive electrode surface and the negative electrode surface, it prevents short circuits caused by contact between adjacent electrodes.

[0035] The current collector 15 is a chemically inert 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 the 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. Examples of conductive resin materials include conductive polymer materials or resins to which conductive fillers are optionally added to non-conductive polymer materials. The current collector 15 may comprise multiple layers. In this case, each layer of the current collector 15 may contain the above-mentioned metal material and / or conductive resin material.

[0036] A coating layer may be formed on the surface of the current collector 15. This coating layer may be formed by known methods such as plating or spray coating. The current collector 15 may be in the form of a plate, foil, film, or mesh. Examples of metal foils 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 metals or a foil formed by integrating multiple metal foils. If the current collector 15 is in the form of a foil, its thickness may be, for example, 1 μm to 200 μm. The current collector 15 may be a foil formed by bonding aluminum foil and copper foil together with a conductive adhesive, or a foil in which a copper layer is vapor-deposited on one side of aluminum foil.

[0037] The positive electrode active material layer 16 contains a positive electrode active material capable of intercalating and releasing charge carriers such as lithium ions. Examples of positive electrode active materials include lithium composite metal oxides having a layered rock salt structure, metal oxides having a spinel structure, and polyanionic compounds. The positive electrode active material can be any material suitable for use in lithium-ion secondary batteries. The positive electrode active material layer 16 may contain multiple positive electrode active materials. In this embodiment, the positive electrode active material layer 16 contains olivine-type lithium iron phosphate (LiFePO4) as a composite oxide.

[0038] The negative electrode active material layer 17 contains a negative electrode active material capable of intercalating and releasing charge carriers such as lithium ions. The negative electrode active material may be an element, an alloy, or a compound. Examples of negative electrode active materials include Li, carbon, and metal compounds. The negative electrode active material may also be an element or compound thereof that can be alloyed with lithium. Examples of carbon include natural graphite, artificial graphite, hard carbon (carbon that is difficult to graphitize), or soft carbon (carbon that is easily graphitized). 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 contains graphite as a carbon-based material.

[0039] 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, a binder, an electrolyte, an electrolyte support salt, etc. Conductive additives are added to enhance electrical conductivity. Examples of conductive additives include acetylene black, carbon black, or graphite. Electrolyte support salts are added to enhance ionic conductivity.

[0040] Examples of binders include fluororesins 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; alginates such as carboxymethylcellulose, sodium alginate, and ammonium alginate; water-soluble cellulose ester crosslinked polymers; and starch-acrylic acid graft polymers. These binders can be used individually or in combination. Examples of solvents for the binders include water and N-methyl-2-pyrrolidone.

[0041] The separator 14 may be, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains electrolytes. Examples of materials for the separator 14 include polypropylene, polyethylene, polyolefin, and polyester. The separator 14 may have a single-layer structure or a multilayer structure. The multilayer 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 into the separator 14 is a liquid electrolyte (electrolyte solution) containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent.

[0042] As the electrolyte salt of the electrolyte solution, known lithium salts such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, and LiN(CF3SO2)2 may be used. Furthermore, as the non-aqueous solvent, known solvents such as cyclic carbonates, cyclic esters, linear carbonates, linear esters, and ethers may be used. In addition, two or more of these known solvent materials may be used in combination.

[0043] The sealant 20 is provided on the electrode stack 10 so as to surround the electrode stack 10 when viewed from the Z direction. For example, the sealant 20 is formed on the periphery of the electrode stack 10 as a rectangular cylindrical member so as to surround the four sides of the electrode stack 10, which is substantially rectangular in shape. The sealant 20 can be joined (welded) to the first surface 15a and the second surface 15b of the current collector 15 at the periphery 15c of each current collector 15. The sealant 20 insulates adjacent current collectors 15 in the first direction D1 and cooperates with these adjacent current collectors 15 to form an internal space S. The sealant 20 is also intended to seal each of these internal spaces S. An electrolyte is contained in each internal space S. The sealant 20 can suppress the outflow of the electrolyte contained in the internal space S to the outside. Furthermore, the sealing body 20 can suppress the intrusion of air, moisture, and other elements from the outside of the electrode stack 10 into the internal space S.

[0044] The sealant 20 contains an insulating material. Examples of materials for the sealant 20 include various resin materials such as polypropylene, polyethylene, polystyrene, ABS resin, acid-modified polypropylene, acid-modified polyethylene, and acrylonitrile styrene resin.

[0045] The sealing body 20 includes a plurality of resin sealing materials 21 and a plurality of resin spacers 22. The sealing material 21 is provided on each of the plurality of electrodes. More specifically, the sealing material 21 is provided on each peripheral edge 15c of the current collector 15. Therefore, the plurality of sealing materials 21 are stacked along the first direction D1. The sealing material 21 provided on the peripheral edge 15c of the current collector 15 is formed in a frame shape that follows the outer shape of the current collector 15 when viewed from the first direction D1. Here, since the current collector 15 is rectangular in plan view, the sealing material 21 is rectangular in plan view. The sealing material 21 includes an inner portion that overlaps the peripheral edge 15c of the current collector 15 when viewed from the first direction D1, and an outer portion that extends beyond the edge of the current collector 15. The sealing material 21 is constructed by joining together the outer portion of one resin member joined to the first surface 15a of the current collector 15 and another resin member joined to the second surface 15b of the current collector 15, thereby integrating them into one unit. In other words, the sealing material 21 covers the peripheral edge 15c of the current collector 15.

[0046] In this embodiment, the sealing material provided on the current collector 15 of the bipolar electrode 11, the current collector 15 of the negative terminal electrode 12, and the current collector 15 of the positive terminal electrode 13 are all denoted by the same reference numeral as sealing material 21. However, the sealing material provided on the current collector 15 of the bipolar electrode 11, the sealing material provided on the current collector 15 of the negative terminal electrode 12, and the sealing material provided on the current collector 15 of the positive terminal electrode 13 may be the same as or different from each other.

[0047] The spacer 22 is formed in a substantially frame shape so as to surround the positive electrode active material layer 16 when viewed from the first direction D1. The spacer 22 has an inner portion that overlaps the current collector 15 and an outer portion that extends beyond the edge of the current collector 15 when viewed from the first direction D1. The spacer 22 is positioned to be interposed between each of the sealing materials 21 provided on adjacent electrodes in the first direction D1. In this way, the spacer 22, together with the pair of sealing materials 21 adjacent in the first direction D1, maintains the spacing between the adjacent current collectors 15 in the first direction D1. The internal space S is defined by the pair of adjacent current collectors 15 in the first direction D1, the spacer 22, and the pair of sealing materials 21 adjacent to the spacer 22.

[0048] Furthermore, the spacer 22 is formed in a frame shape that follows the outer shape of the current collector 15 when viewed from the first direction D1. Therefore, the sealant 20 is constructed by stacking multiple resin frames (sealant 21 and spacer 22) provided on the peripheral edge 15c of the current collector 15 along the first direction D1, and seals the internal space S between adjacent electrodes in the first direction D1.

[0049] Furthermore, when viewed from the first direction D1, the inner edge 22e of the spacer 22 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. That is, the inner edge 22e of the spacer 22 is located inside the outer edge 17e of the negative electrode active material layer 17. As a result, the spacer 22 includes a portion that overlaps with the negative electrode active material layer 17 when viewed from the first direction D1. Multiple spacers 22 may be configured so that they do not come into contact with the current collector 15 of adjacent bipolar electrodes 11. In other words, a small gap may be provided between the spacer 22 and the first surface 15a of the current collector 15 of the adjacent bipolar electrode.

[0050] The outer edges of the multiple sealing materials 21 and the outer edges of the multiple spacers 22 are welded together to form a welded portion 23. That is, the sealing body 20 includes a welded portion 23 formed by the welding and integration of the multiple sealing materials 21 and the multiple spacers 22. When viewed from the first direction D1, the welded portion 23 has a frame shape (here, a rectangular frame shape) that surrounds the electrode stack 10 and constitutes the outer periphery of the sealing body 20. Therefore, the outer surface 23s of the welded portion 23 form the outer surface of the sealing body 20. That is, in this embodiment, the sealing body 20 has four outer surface 23s that extend along the first direction D1. The spacers 22 do not need to be welded to the sealing material 21 in at least the inner portion of the sealing material 21 adjacent to the first direction D1.

[0051] The end of the separator 14 may be held in place between the sealing material 21 and the spacer 22. The separator 14 may be fixed by welding its end to at least one of the sealing material 21 and the spacer 22.

[0052] The first protective member 3 and the second protective member 4 are arranged so as to sandwich the energy storage module 1 when viewed from the first direction D1. More specifically, the energy storage module 1 has a rectangular shape with four sides, including a first side 1a and a second side 1b opposite to the first side 1a, when viewed from the first direction D1. Each of the four sides is an outer surface 23s of the seal 20. The first protective member 3 is positioned opposite the first side 1a, and the second protective member 4 is positioned opposite the second side 1b.

[0053] The first protective member 3 is provided across the entire width of the first side surface 1a in the second direction D2, as viewed from the first direction D1. The second protective member 4 is provided across the entire width of the second side surface 1b in the second direction D2, as viewed from the first direction D1. Thus, the first protective member 3 and the second protective member 4 constitute the four corners of the unit consisting of the energy storage module 1, the first protective member 3, and the second protective member 4, as viewed from the first direction D1. As viewed from the first direction D1, the first protective member 3 is thicker than the second protective member 4 in the third direction D3. The first protective member 3 and the second protective member 4 are formed in a hollow shape, for example, by resin.

[0054] In the middle of the second direction D2 of the first protective member 3, a resin frame 101, a terminal block 102, and a connector 103 are arranged on the encapsulant 20 of the energy storage module 1. The resin frame 101 is integrally provided on the outer surface 23s of the encapsulant 20, for example, by resin injection molding. The resin frame 101 is the part that the nozzle of the electrolyte injection device contacts when injecting electrolyte into the internal space S. Terminals such as voltage detection lines connected to each of the current collectors 15 are drawn out from the resin frame 101. The terminal block 102 holds these terminals. The connector 103 is used when connecting wiring that is connected to the terminals held by the terminal block 102.

[0055] The exterior body 40 includes a first exterior section 41 and a second exterior section 42, which are arranged to sandwich the energy storage module 1 from both sides in a first direction D1. The first exterior section 41 and the second exterior section 42 each include a laminate member and a conductive plate. Here, the first exterior section 41 includes a first laminate member 91 (laminate film) and a first conductive plate 31, and the second exterior section 42 includes a second laminate member 92 (laminate film) and a second conductive plate 32.

[0056] The first laminate member 91 and the second laminate member 92 are laminate films each composed of an adhesive layer 93, a metal layer 94, and a resin layer 95, which are laminated in that order. The adhesive layer 93 is an insulating layer laminated on the inner surface of the metal layer 94. The adhesive layer 93 and the resin layer 95 are composed of mutually compatible resins. The adhesive layer 93 is made of, for example, an acid-modified resin, and as an example, an acid-modified polyolefin resin. The metal layer 94 is, for example, aluminum foil. The resin layer 95 is laminated on the outer surface of the metal layer 94. The resin layer 95 is made of, for example, an acid-modified resin, and as an example, an acid-modified polyolefin resin. The first laminate member 91 and the second laminate member 92 may also include layers made of other resins such as polyolefin or nylon.

[0057] A first conductive plate 31 and a second conductive plate 32 are laminated on the exposed portions of the second surface 15b of the current collector 15 of the negative terminal electrode 12 and the first surface 15a of the current collector 15 of the positive terminal electrode 13 that are not covered by the sealing material 20 (i.e., portions where the sealing material 21 is not provided when viewed from the first direction D1). Specifically, the first conductive plate 31 is laminated on the positive terminal electrode 13, which is located in the outermost layer in one direction D1 of the energy storage module 1, and the second conductive plate 32 is laminated on the negative terminal electrode 12, which is located in the outermost layer in the other direction D1 of the energy storage module 1. The first conductive plate 31 is in contact with the second surface 15b of the positive terminal electrode 13 and is laminated on the positive terminal electrode 13 so as to be electrically connected to the positive terminal electrode 13 via the second surface 15b. Furthermore, the second conductive plate 32 is in contact with the first surface 15a of the negative terminal electrode 12 and is laminated on the negative terminal electrode so as to be electrically connected to the negative terminal electrode 12 via the first surface 15a. The first conductive plate 31 and the second conductive plate 32 are electrically connected by direct contact with the surface of the current collector 15 where the active material layer is not formed.

[0058] The first conductive plate 31 includes a first surface 31s opposite to the positive terminal electrode 13, and the second conductive plate 32 includes a second surface 32s opposite to the negative terminal electrode 12. The first surface 31s of the first conductive plate 31 and the second surface 32s of the second conductive plate 32 can be used to extract current from the energy storage module 1, respectively. Furthermore, when a multiple energy storage device 100 is constructed by stacking multiple energy storage packs 2 in a first direction D1 and connecting them in series (in this embodiment), the conductive plate 110 and a cooler 120 or conductive adhesive 130 are placed between two adjacent energy storage packs 2 in the first direction D1 to electrically connect the multiple energy storage packs 2. That is, the first conductive plate 31 and the second conductive plate 32 can be used to electrically connect the multiple energy storage packs 2.

[0059] The first exterior portion 41 is composed of a first laminate member 91 and a first conductive plate 31, and includes a first recess 41p (housing portion) for housing the energy storage module 1, and a first flange portion 41f composed of the first laminate member 91 and surrounding the first recess 41p when viewed from the first direction D1. The second exterior portion 42 is composed of a second laminate member 92 and a second conductive plate 32, and includes a second recess 42p (housing portion) for housing the energy storage module 1, and a second flange portion 42f composed of the second laminate member 92 and surrounding the second recess 42p when viewed from the first direction D1. The first exterior portion 41 and the second exterior portion 42 are bonded together by bonding adhesive layers 93 to each other at the first flange portion 41f and the second flange portion 42f which are superimposed on each other. In other words, the peripheral edges of the first exterior portion 41 and the peripheral edges of the second exterior portion 42 are bonded together by the bonding of the adhesive layers 93 of the first laminate member 91 and the second laminate member 92.

[0060] The outer casing 40 has a bent portion B formed by bending the first flange portion 41f and the second flange portion 42f which are joined together. In the illustrated example, the outer casing 40 (first flange portion 41f and second flange portion 42f) is bent 90° at the bent portion B, but the outer casing 40 may be bent 180° at the bent portion B. Also, the bent portion B may be located at the boundary portion 90p (base) between the first recess 41p and the second recess 42p of the first flange portion 41f and the second flange portion 42f. Furthermore, the outer casing 40 may have multiple bent portions B (it may be bent multiple times).

[0061] In other words, the outer casing 40 has flange portions (first flange portion 41f, second flange portion 42f) that extend outward from recesses (first recess 41p, second recess 42p) which are housings for the energy storage module 1 (and the first protective member 3, second protective member 4) when viewed from the first direction D1, and these flange portions have bent portions B.

[0062] As described above, the energy storage pack 2 is constructed by housing the energy storage module 1, the first protective member 3, and the second protective member 4 in an outer casing 40. The first protective member 3 is positioned between the first side surface 1a of the energy storage module 1 and the inner surface of the outer casing 40 and can be fixed to the inner surface of the outer casing 40. The second protective member 4 is positioned between the second side surface 1b of the energy storage module 1 and the inner surface of the outer casing 40 and can be fixed to the inner surface of the outer casing 40.

[0063] The outer surface 2s of the energy storage pack 2, as viewed from the first direction D1, is composed of the outer casing 40. In particular, the outer surface 2s is composed of the first laminate member 91 and the second laminate member 92 of the outer casing 40. That is, the energy storage pack 2 has a laminate film including a metal layer 94, and the outer surface 2s of the energy storage pack 2 is composed of this laminate film.

[0064] Here, as shown in Figure 2, the potting material 300 is formed in a frame shape so as to extend around the entire circumference of the outer surface 2s of the energy storage pack 2 when viewed from the first direction D1. Here, when viewed from the first direction D1, the outer surface 2s of the energy storage pack 2 is rectangular, and the inner surface 200s of the case 200 is rectangular, so the space between the outer surface 2s and the inner surface 200s is rectangular and annular. The potting material 300 fills this space and is similarly rectangular and annular.

[0065] On the other hand, the potting material 300 is provided with an unfilled portion 300s extending from one end to the other in the first direction D1, thereby making the potting material 300 discontinuous along the outer surface 2s. In other words, the potting material 300 consists of a plurality of filled portions 300p divided by the unfilled portion 300s. The plurality of filled portions 300p are arranged along the outer surface 2s when viewed from the first direction D1. In this embodiment, the outer surface 2s has a plurality (four in this case) of corners 2p when viewed from the first direction D1, and the unfilled portion 300s is located at each of the four corners 2p of the outer surface 2s when viewed from the first direction D1. Therefore, the potting material 300 consists of four filled portions 300p. Each of the four filled portions 300p extends along each of the four surfaces constituting the outer surface 2s and is arranged to cover substantially the entirety of the four surfaces.

[0066] Thus, although the potting material 300 is formed intermittently by the interposition of the unfilled portion 300s, the proportion of the unfilled portion 300s to the entire potting material 300 is small, so overall it can be said to form a rectangular annular shape that extends around the entire circumference of the outer surface 2s.

[0067] The unfilled portion 300s can be formed, for example, by pouring the potting material 300 into the space between the outer surface 2s and the inner surface 200s, with a partition placed in the space between the outer surface 2s and the inner surface 200s at a position corresponding to the unfilled portion 300s, and then removing the partition after the material has hardened. However, the partition may be left in place. In other words, a different component from the potting material 300 may be placed in the unfilled portion 300s. In this case, for example, the unfilled portion 300s may be filled with a different component that does not adhere to the potting material 300.

[0068] Furthermore, the unfilled portion 300s is not limited to being formed in multiple locations as shown in the illustrated example, but may be just one. That is, the unfilled portion 300s may be located at at least one of the multiple corners 2p of the outer surface 2s when viewed from the first direction D1. Also, at least one of the unfilled portions 300s does not have to be located at a corner 2p of the outer surface 2s, but may be located on one of the four surfaces constituting the outer surface 2s. Furthermore, the unfilled portion 300s does not have to extend along the first direction D1, but may extend at an angle to the first direction D1, for example. In addition, the potting material 300 may be in contact with (and even adhered to) the outer surface 2s of the energy storage pack 2, or in contact with (and even adhered to) the inner surface 200s of the case 200.

[0069] As shown in Figure 1, the bent portion B (and flange portion) of the outer casing 40 is embedded in the potting material 300. This allows the outer casing 40 and the potting material 300 to be locked together by an anchoring effect. The potting material 300 is provided to extend along the first direction D1 across multiple energy storage packs 2 stacked via the conductive plate 110 and the cooler 120. In this embodiment, the potting material 300 extends along the first direction D1 from the bottom surface of the lower case 220 to the bottom surface of the upper case 210.

[0070] Figure 5 is a schematic diagram showing the amount of contraction in each part of the energy storage device and the stress applied to the energy storage device. Figure 5(a) shows an enlarged view of a part of the energy storage device 100A according to the comparative example, and Figure 5(b) shows an enlarged view of a part of the energy storage device 100 according to the present embodiment. As shown in Figure 5, the energy storage device 100A according to the comparative example differs from the energy storage device 100 according to the present embodiment in that the potting material 300 does not have an unfilled portion 300s, and the potting material 300 is formed continuously along the outer surface 2s of the energy storage pack 2 (configured as a single part).

[0071] In the energy storage devices 100 and 100A, the coefficient of linear expansion of the potting material 300 is greater than that of the energy storage pack 2. Therefore, at low temperatures (e.g., -40°C), the amount of shrinkage A300 of the potting material 300 is greater than the amount of shrinkage A2 of the energy storage pack 2. Consequently, in the energy storage device 100A, where the potting material 300 is formed continuously, a stress F is applied to the energy storage pack 2, causing the potting material 300 to tighten around it. In particular, the stress F tends to concentrate at the corners 2p of the energy storage pack 2.

[0072] On the other hand, in the energy storage device 100 according to this embodiment, the potting material 300 is provided with an unfilled portion 300s, so that the potting material 300 is discontinuous along the outer surface 2s (divided into multiple filled portions 300p). Therefore, although the amount of shrinkage A300 of the potting material 300 is greater than the amount of shrinkage A2 of the energy storage pack 2, it is possible to avoid the potting material 300 applying stress to the energy storage pack 2 that would cause it to tighten.

[0073] In the illustrated example, the coefficient of linear expansion of case 200 is even smaller than that of energy storage pack 2. Therefore, the amount of contraction A200 of case 200 is even smaller than the amount of contraction A2 of energy storage pack 2.

[0074] As described above, in the energy storage device 100 according to this embodiment, potting material 300 is filled in the space between the outer surface 2s of the energy storage pack 2 and the inner surface 200s of the case 200 that houses the energy storage pack 2. Therefore, the seismic resistance of the energy storage pack 2 is improved.

[0075] On the other hand, the potting material 300 has a coefficient of linear expansion greater than that of the energy storage pack 2. Therefore, at low temperatures, the potting material 300 will contract more than the energy storage pack 2. However, in the energy storage device 100, the potting material 300 is divided into a plurality of filling sections 300p arranged along the outer surface 2s of the energy storage pack 2 when viewed from the first direction D1. Therefore, even when the potting material 300 contracts more than the energy storage pack 2, each of the multiple filling sections 300p can contract independently, suppressing the application of stress from the potting material 300 to the energy storage pack 2 that would constrict it. Thus, in the energy storage device 100, vibration resistance can be improved by the potting material 300 while the influence of stress from the potting material 300 can be reduced.

[0076] Furthermore, in the energy storage device 100 according to this embodiment, the outer surface 2s of the energy storage pack 2 has a plurality of corners 2p when viewed from the first direction D1, and the unfilled portion 300s of the potting material 300 formed between the divided filled portions 300p of the potting material 300 is located at at least one of the plurality of corners 2p. This prevents stress from the potting material 300 from concentrating at the corners 2p of the outer surface 2s of the energy storage pack 2.

[0077] Furthermore, the energy storage device 100 according to this embodiment includes a potting seal 150 for sealing the space between adjacent energy storage packs 2 in the first direction D1 from the outside of the energy storage packs 2 when viewed from directions intersecting the first direction D1 (for example, the second direction D2 and the third direction D3). The potting seal 150 has a frame shape when viewed from the first direction D1, and the outer periphery of the potting seal 150 may be in contact with the potting material 300. In this case, when forming the potting material 300, it is suppressed that the material of the potting material 300 enters the space between adjacent energy storage packs 2 in the first direction D1.

[0078] Furthermore, in the energy storage device 100 according to this embodiment, the energy storage pack 2 comprises an energy storage module 1 and an outer casing 40 that houses the energy storage module 1 and has a laminate film (first laminate member 91 and second laminate member 92) including a metal layer 94. The outer surface 2s of the energy storage pack 2 is made of the laminate film. In this case, when stress is applied to the outer casing 40 from the potting material 300, damage such as tearing is likely to occur in the outer casing 40. Therefore, it is more important to reduce the influence of stress from the potting material 300.

[0079] Furthermore, in the energy storage device 100 according to this embodiment, the outer casing 40 has flange portions (first flange portion 41f and second flange portion 42f) that extend outward from the housing portion (first recess 41p and second recess 42p) of the energy storage module 1 when viewed from the first direction D1, and these flange portions have a bent portion B. The outer casing 40 and the potting material 300 are locked together by the bent portion B being embedded in the potting material 300. This prevents the potting material 300 from shifting relative to the energy storage pack 2 due to vibration, for example.

[0080] Furthermore, in the energy storage device 100 according to this embodiment, the energy storage pack 2 may have a first protective member 3 positioned opposite the first side surface 1a of the energy storage module 1 when viewed from the first direction D1, and may have a second protective member positioned opposite the second side surface 1b of the energy storage module 1 on the opposite side of the first side surface 1a when viewed from the first direction D1. In this case, the first protective member 3 may be made of resin and positioned between the first side surface 1a and the inner surface of the outer casing 40. Moreover, the first protective member 3 may be fixed to the inner surface of the outer casing 40.

[0081] Furthermore, in the energy storage device 100 according to this embodiment, the potting material 300 may be bonded to the inner surface 200s of the case 200. In this case, displacement of the potting material 300 relative to the case 200 due to vibration or the like is suppressed.

[0082] Furthermore, the energy storage device 100 according to this embodiment includes a plurality of energy storage packs 2 stacked along a first direction D1 via a conductive plate 110 and a cooler 120. The potting material 300 is provided across the plurality of energy storage packs 2. This improves the seismic resistance of the plurality of energy storage packs 2.

[0083] The above embodiments describe one aspect of the energy storage device according to the present invention. Therefore, the energy storage device according to the present invention is not limited to the above embodiments and can be modified as desired.

[0084] For example, the energy storage pack 2 does not necessarily have an outer casing 40 having a laminate film (first laminate member 91 and second laminate member 92) that includes a metal layer 94.

[0085] Furthermore, even if the energy storage pack 2 has an outer casing 40, the outer casing 40 does not have to have a bent portion B. Moreover, even if the outer casing 40 has a bent portion B, the bent portion B does not have to be embedded in the potting material 300.

[0086] Furthermore, the energy storage pack 2 does not necessarily have to have the first protective member 3 and the second protective member 4. Moreover, even if the energy storage pack 2 has at least the first protective member 3, the first protective member 3 does not necessarily have to be fixed to the inner surface of the outer casing 40.

[0087] Furthermore, in the energy storage pack 2, the potting material 300 does not need to be adhered to the inner surface 200s of the case 200.

[0088] Furthermore, the energy storage device 100 is not limited to cases where it comprises multiple energy storage packs 2 and the potting material 300 is provided across the multiple energy storage packs 2.

[0089] Furthermore, the energy storage device 100 does not necessarily have to include a potting seal 150, depending on the method of forming the potting material 300. Moreover, even if the energy storage device 100 does include a potting seal 150, the potting seal 150 does not necessarily have to be frame-shaped.

[0090] The embodiments described above are described below.

[0091] The energy storage device may also be [1] an energy storage device comprising: an energy storage pack having an energy storage module including a plurality of electrodes stacked along a first direction; a case housing the energy storage pack; and a potting material filled in the space between the outer surface of the energy storage pack and the inner surface of the case when viewed from the first direction, wherein the potting material is composed of a plurality of filling portions along the outer surface when viewed from the first direction, and the coefficient of linear expansion of the potting material is greater than the coefficient of linear expansion of the energy storage pack.

[0092] The energy storage device may also be [2] "the energy storage device according to [1] above, wherein the outer surface has a plurality of corners when viewed from the first direction, and the unfilled portion of the potting material formed between the filled portions of the potting material is located at at least one of the plurality of corners."

[0093] The energy storage device may be [3] "the energy storage device described in [1] or [2] above, wherein the potting material is in contact with the outer surface of the energy storage pack."

[0094] The energy storage device may also be [4] "the energy storage device according to any of [1] to [3] above, comprising a plurality of energy storage packs stacked via conductive plates along the first direction, wherein the potting material is provided across the plurality of energy storage packs."

[0095] The energy storage device may also be [5] "the energy storage device described in [4] above, which includes a sealing member for sealing the space between adjacent energy storage packs in the first direction when viewed from a direction intersecting the first direction, wherein the sealing member has a frame shape when viewed from the first direction, and the outer periphery of the sealing member is in contact with the potting material."

[0096] The energy storage device may also be [6] "the energy storage device according to any one of [1] to [5] above, wherein the energy storage pack comprises the energy storage module and an outer casing having a laminate film including a metal layer and housing the energy storage module, and the outer surface of the energy storage pack is made of the laminate film."

[0097] The energy storage device may also be the energy storage device described in [6] above, [7] "the outer casing having a flange portion extending outward from the housing portion of the energy storage module when viewed from a first direction, the flange portion having a bent portion, and the outer casing and the potting material being locked together by the bent portion of the flange portion being embedded in the potting material."

[0098] The energy storage device may be [8] "the energy storage device according to [6] or [7] above, wherein the energy storage pack has a first protective member positioned opposite to the first side surface of the energy storage module when viewed from the first direction, the first protective member is made of resin and is positioned between the first side surface and the inner surface of the outer casing."

[0099] The energy storage device may be [9] "the energy storage device described in [8] above, wherein the first protective member is fixed to the inner surface of the outer casing."

[0100] The energy storage device may be the energy storage device described in [8] or [9] above, wherein the energy storage pack has a second protective member positioned opposite to the second side surface of the energy storage module, when viewed from the first direction. [Explanation of symbols]

[0101] 1...Energy storage module, 1a...First side, 1b...Second side, 2...Energy storage pack, 2s...Outer side, 3...First protective member, 4...Second protective member, 40...Outer casing, 41p...First recess (housing section), 42p...Second recess (housing section), 41f...First flange section (flange section), 42f...Second flange section (flange section), 91...First laminate member (laminating film), 92...Second laminate member (laminating film), 100...Energy storage device, 110...Conductive plate, 120...Cooler, 150...Potting seal, 200...Case, 200s...Inner side, 300...Potting material, 300s...Unfilled section.

Claims

1. A storage pack having a storage module including a plurality of electrodes stacked along a first direction, A case for housing the aforementioned energy storage pack, When viewed from the first direction, the potting material is filled in the space between the outer surface of the energy storage pack and the inner surface of the case, Equipped with, The potting material is composed of a plurality of filling portions along the outer surface when viewed from the first direction, The coefficient of linear expansion of the potting material is greater than that of the energy storage pack. Energy storage device.

2. The aforementioned outer surface has a plurality of corners when viewed from the first direction, The unfilled portion of the potting material, formed between the filled portions of the potting material, is located at least one of the plurality of corners. The energy storage device according to claim 1.

3. The potting material is in contact with the outer surface of the energy storage pack. The energy storage device according to claim 1.

4. The system comprises a plurality of energy storage packs stacked along the first direction via conductive plates, The potting material is provided across the plurality of energy storage packs. The energy storage device according to claim 1.

5. The device includes a sealing member for sealing the space between adjacent energy storage packs in the first direction, viewed from a direction intersecting the first direction, from the outside of the energy storage pack. The sealing member has a frame shape when viewed from the first direction, The outer periphery of the sealing member is in contact with the potting material. The energy storage device according to claim 4.

6. The aforementioned energy storage pack is The aforementioned energy storage module, An outer casing having a laminate film containing a metal layer and housing the energy storage module, It has, The outer surface of the aforementioned energy storage pack is made of the aforementioned laminate film. The energy storage device according to claim 1.

7. The exterior body has a flange portion that extends outward from the housing portion of the energy storage module when viewed from the first direction, The flange portion has a bent portion, The exterior body and the potting material are locked together by the fact that the bent portion of the flange is embedded in the potting material. The energy storage device according to claim 6.

8. The energy storage pack has a first protective member that is positioned opposite to the first side surface of the energy storage module when viewed from the first direction, The first protective member is made of resin and is positioned between the first side surface and the inner surface of the outer casing. The energy storage device according to claim 6.

9. The first protective member is fixed to the inner surface of the outer casing. The energy storage device according to claim 8.

10. The energy storage pack has a second protective member positioned opposite to the second side surface of the energy storage module, when viewed from the first direction, on the side opposite to the first side surface. The energy storage device according to claim 8 or 9.

Images