Power storage device

Abstract

To provide a power storage device that can prevent deterioration of an electrode unit and can repair a deteriorated electrode unit.SOLUTION: A power storage unit 1 comprises a plurality of electrode units 100 laminated in a lamination direction. The plurality of electrode units each comprise at least a current collector foil 110, a positive electrode active material layer 111 formed on one surface of the current collector foil, and a negative electrode active material layer formed on the other surface of the current collector foil. The power storage device further comprises a deformable first container 20 that is arranged at least one of both sides of the plurality of electrode units in the lamination direction, and a pressure changing part 40 that changes the pressure inside the first container.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electricity storage device. [Background technology]

[0002] Patent Document 1 discloses an energy storage device including a stack having multiple bipolar electrodes, each including a positive electrode layer provided on one main surface of an electrode plate and a negative electrode layer provided on the other main surface of the electrode plate, a restraining member, and an intermediate member interposed between the restraining member and the stack. The intermediate member includes a package that is deformable in response to a restraining load and a fluid sealed in the package. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 095551 Summary of the Invention [Problem to be solved by the invention]

[0004] In the energy storage device disclosed in Patent Document 1, the intermediate member is configured to be deformable in response to a restraining load. However, depending on the magnitude of the restraining load, it may be impossible to apply an appropriate pressure to the stack. If the stack cannot be applied with an appropriate pressure, the expansion and contraction of the active material layer associated with charging and discharging the energy storage device may cause cracks in the components (active material layer, solid electrolyte layer, etc.) within the stack or voids at each interface within the stack, potentially resulting in deterioration of the bipolar electrode. Furthermore, in the configuration disclosed in Patent Document 1, the pressure applied to the stack is determined by the pressure applied from the restraining member to the fluid sealed in the intermediate member and the compression amount of the intermediate member. Therefore, if cracks or voids occur in the stack under pressure from the intermediate member, it is difficult to repair the cracks or voids.

[0005] The present invention was made by the inventor of the present application by focusing on the above-mentioned problem, and aims to provide an energy storage device that can suppress deterioration of electrode units and can repair deteriorated electrode units. [Means for solving the problem]

[0006] An energy storage device according to one aspect of the present invention is an energy storage device comprising a plurality of electrode units stacked in a stacking direction, each of the plurality of electrode units comprising at least a current collecting foil, a positive electrode active material layer formed on one side of the current collecting foil, and a negative electrode active material layer formed on the other side of the current collecting foil, and the energy storage device further comprises a deformable first container arranged on at least one side of the plurality of electrode units in the stacking direction, and a pressure change unit that changes the pressure within the first container. [Effects of the Invention]

[0007] According to the electricity storage device of the present invention, it is possible to suppress deterioration of the electrode units, and further to repair deteriorated electrode units and improve the deteriorated characteristics. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing, in a simplified form, the appearance of an electricity storage device according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing each component included in the electricity storage device according to the embodiment. [Figure 3A] FIG. 3A is a perspective view showing a configuration of an electrode unit included in a unit group of the power storage device according to the embodiment. [Figure 3B] FIG. 3B is a cross-sectional view showing the configuration of an electrode unit included in the unit group of the power storage device according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view showing components included in the power storage device according to the first modification of the embodiment. [Figure 5] FIG. 5 is a cross-sectional view showing components included in a power storage device according to a second modification of the embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing components included in a power storage device according to a third modification of the embodiment. [Figure 7] FIG. 7 is a cross-sectional view showing components included in a power storage device according to a fourth modification of the embodiment. [Figure 8] FIG. 8 is a cross-sectional view showing components included in a power storage device according to a fifth modification of the embodiment. [Figure 9] FIG. 9 is a cross-sectional view showing components included in a power storage device according to a sixth modification of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] (1) An energy storage device according to one aspect of the present invention is an energy storage device including a plurality of electrode units stacked in a stacking direction, each of the plurality of electrode units including at least a current collecting foil, a positive electrode active material layer formed on one side of the current collecting foil, and a negative electrode active material layer formed on the other side of the current collecting foil, and the energy storage device further includes a deformable first container arranged on at least one side of the plurality of electrode units in the stacking direction, and a pressure change unit that changes the pressure inside the first container.

[0010] According to one aspect of the present invention, the energy storage device includes a deformable first container disposed on at least one of both sides of a plurality of electrode units in the stacking direction, and a pressure changer that changes the pressure within the first container. This allows the plurality of electrode units to be pressurized with a more appropriate pressure in the stacking direction. This prevents cracks from occurring in components (such as active material layers and solid electrolyte layers) within the electrode units due to expansion and contraction of the electrode units, and prevents voids from occurring at each interface within the electrode units. Furthermore, even if cracks or voids occur in the components or the interfaces, the cracks or voids can be repaired by changing the pressure within the first container accordingly. Therefore, the energy storage device can prevent deterioration of the electrode units and can repair deteriorated electrode units to improve their deteriorated characteristics.

[0011] (2) The energy storage device described in (1) above may further include end members arranged at the ends of the plurality of electrode units in the stacking direction, and at least one of the plurality of current collecting foils and the end members provided on the plurality of electrode units may be deformed in response to a change in pressure in the first container caused by the pressure change section.

[0012] According to the energy storage device described in (2) above, at least one of the multiple current collector foils and end members provided on the multiple electrode units deforms in response to changes in pressure inside the first container caused by the pressure change unit, allowing the multiple electrode units to be pressurized relatively uniformly. This makes it possible to prevent cracks from occurring due to localized stress concentration on components inside the electrode units or voids from occurring at each interface within the electrode units. This deformation makes it possible to appropriately apply pressure from the first container to areas where cracks or voids have occurred, making it easier to repair the cracks or voids that have occurred.

[0013] (3) In the electricity storage device described in (1) or (2) above, a liquid may be disposed inside the first container.

[0014] According to the electricity storage device described in (3) above, by disposing a liquid inside the first container, the pressure inside the first container can be easily equalized. If a gas is disposed inside the first container, use in a manner or condition that is not normally expected could cause high pressure inside the first container to build up, leading to the first container rupturing and potentially damaging the electricity storage device itself. Therefore, by disposing a liquid inside the first container, the safety of the electricity storage device can be improved.

[0015] (4) The power storage device according to (3) above may further include a tank connected to the first container and containing the liquid.

[0016] According to the electricity storage device described in (4) above, by providing a tank connected to the first container and containing liquid, the amount of liquid in the first container can be easily adjusted, and therefore the pressure in the first container can be easily changed by the pressure change unit.

[0017] (5) The energy storage device described in any one of (1) to (4) above may further include a deformable second container arranged on at least one side of the plurality of electrode units in a direction intersecting the stacking direction, and the pressure change unit may further change the pressure within the second container.

[0018] The energy storage device described in (5) above includes a deformable second container disposed on at least one side of the plurality of electrode units in a direction intersecting the stacking direction, and the pressure changer changes the pressure within the second container. This allows the plurality of electrode units to be pressurized at a more appropriate pressure even in a direction intersecting the stacking direction, thereby further suppressing deterioration of the electrode units. In this case, the pressurized pressure of the first container and the pressurized pressure of the second container do not need to be the same, and each container may be provided with a valve, a measuring unit, a pressure changer, a tank, or the like.

[0019] Hereinafter, with reference to the drawings, a description will be given of an energy storage device according to an embodiment of the present invention (including its modified examples). The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples only and are not intended to limit the present invention. In each drawing, dimensions and the like are not strictly illustrated. In each drawing, the same or similar components are designated by the same reference numerals.

[0020] In the following description and drawings, when the unit group or the outer casing is rectangular, the longitudinal direction of the unit group or the outer casing, the opposing direction of a pair of short side surfaces of the unit group or the outer casing, or the opposing direction of a pair of short sides on the surface of the current collecting foil is defined as the X-axis direction. When the unit group or the outer casing is rectangular, the opposing direction of a pair of long side surfaces of the unit group or the outer casing, or the opposing direction of a pair of long sides on the surface of the current collecting foil is defined as the Y-axis direction. When the surface of the current collecting foil is square, the opposing direction of one pair of sides is defined as the X-axis direction, and the opposing direction of another pair of sides is defined as the Y-axis direction. When the unit group and the outer casing are not rectangular, the direction in which the length between the ends of the surface of the current collecting foil is longest is defined as the X-axis direction, and the direction in which the length between the ends of the surface of the current collecting foil is shortest is defined as the Y-axis direction. The thickness direction of the unit group or the exterior body, the stacking direction of the multiple electrode units, the stacking direction of the current collecting foil and the active material layers, the arrangement direction of the pair of end members, the arrangement direction of the pair of first containers, or the up-down direction is defined as the Z-axis direction. The X-axis direction, Y-axis direction, and Z-axis direction intersect with each other (orthogonal in this embodiment). Depending on the mode of use, the Z-axis direction may not be the up-down direction; however, for convenience of explanation, the following description will be given assuming the Z-axis direction to be the up-down direction. When explaining the configuration of the energy storage device, the X-axis direction and Y-axis direction are defined for convenience, but the positions of individual components may be interchanged with the X-axis direction and the Y-axis direction. In the content described by defining the X-axis direction and Y-axis direction other than the positions of components, the X-axis direction and Y-axis direction may also be interchanged.

[0021] In the following explanation, the positive X-axis direction refers to the direction of the X-axis arrow, and the negative X-axis direction refers to the direction opposite to the positive X-axis direction. When simply referring to the X-axis direction, it refers to both or either of the positive X-axis direction and the negative X-axis direction. The same applies to the Y-axis and Z-axis directions. Expressions indicating relative directions or attitudes, such as parallel and perpendicular, also include cases where the direction or attitude is not strictly that. When two directions are parallel (or perpendicular), it does not only mean that the two directions are completely parallel (or perpendicular), but also means that the directions are substantially parallel (or perpendicular), that is, there is a difference of, for example, a few percent. In the following explanation, when the term "insulation" is used, it means "electrical insulation." An insulating material has a volume resistivity of 1×10 6 Ωm or more, more preferably 1×10 7 Ωm or more, more preferably 1×10 10 It is preferable that the material be made of a material with a resistance of Ωm or more.

[0022] (Embodiment) [1. Description of the Energy Storage Device 1] First, a description will be given of an energy storage device 1 according to the present embodiment. FIG. 1 is a perspective view showing a simplified appearance of the energy storage device 1 according to the present embodiment. FIG. 2 is a cross-sectional view showing each component included in the energy storage device 1 according to the present embodiment. FIG. 2 is a cross-sectional view of the energy storage device 1 shown in FIG. 1 cut along a YZ plane passing through line II-II. FIG. 3A is a perspective view showing the configuration of an electrode unit 100 included in a unit group 10 of the energy storage device 1 according to the present embodiment, and FIG. 3B is a cross-sectional view showing the configuration of the electrode unit 100 included in the unit group 10 of the energy storage device 1 according to the present embodiment. FIG. 3A is a perspective view showing the appearance of the electrode unit 100, and FIG. 3B is a cross-sectional view showing the configuration of the electrode unit 100 of FIG. 3A cut along a YZ plane passing through line IIIB-IIIB. For ease of explanation, a seal portion 210 included in the electrode unit 100 is omitted from FIGS. 3A and 3B. 1, 2, 4, 5, 6, and 7, the pressurizing unit 41, the measuring unit 44, and the tank 50 are each shown as one unit, but the present invention is not limited to this. Although valves are not shown in the figures, the valves can be provided at any location, and by closing these valves, the pressure from the first container 20 or the second container 70 (see FIG. 5) can be maintained even when pressurization is not being performed from the pressurizing unit 41. The valves are disposed at any location in the pipes 42 and 43 connecting the first container 20 or the second container 70, the pressurizing unit 41, the measuring unit 44, and the tank 50. This minimizes energy loss related to pressurization.

[0023] The power storage device 1 is a device that can charge with electricity from an external source and discharge electricity to an external source. The power storage device 1 is used as a battery for driving or starting the engine of a moving object such as an automobile, a motorcycle, a personal watercraft, a ship, a snowmobile, an agricultural machine, a construction machine, an automatic guided vehicle (AGV), or a rolling stock for an electric railway. Examples of the automobile include an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicle. Examples of the rolling stock for an electric railway include an electric train, a monorail, a linear motor car, and a hybrid electric train equipped with both a diesel engine and an electric motor. The power storage device 1 can also be used as a stationary battery for home or business use.

[0024] 1 and 2, the electricity storage device 1 includes a unit group 10, a first container 20 (21 and 22), an exterior body 30, a pressure change section 40, and a tank 50. The pressure change section 40 includes a pressurizing section 41, pipes 42 and 43, and a measuring section 44 (not shown in FIG. 1, see FIG. 2). First, the configuration of the unit group 10 will be described in detail.

[0025] [1.1 Explanation of Unit Group 10] The unit group 10 is a bipolar battery in which a plurality of electrode units 100 are stacked, and in this embodiment, is a solid electrolyte all-solid-state battery. In this embodiment, the unit group 10 has a substantially rectangular parallelepiped shape. The unit group 10 is housed in an exterior body 30 and is disposed between two first containers 20 (21 and 22) within the exterior body 30. Specifically, the unit group 10 includes a plurality of electrode units 100, end units 101 and 102, a plurality of solid electrolyte layers 140, and a pair of end members 300. The unit group 10 also includes terminals, wiring, etc. for extracting current from the electrode units 100, etc., but these are not relevant to the present invention and are therefore not shown in the drawings.

[0026] The multiple electrode units 100, the end units 101 and 102, the multiple solid electrolyte layers 140, and the pair of end members 300 are each a rectangular plate-like portion in a plan view, and are stacked in the Z-axis direction. In this embodiment, a plan view refers to a view from the stacking direction (Z-axis direction). The direction in which the multiple electrode units 100, the end units 101 and 102, etc. are stacked (Z-axis direction) is also referred to as the stacking direction. The solid electrolyte layers 140 are arranged between the electrode units 100, between the electrode unit 100 and the end unit 101, and between the electrode unit 100 and the end unit 102. The end members 300 are arranged at the ends of the multiple electrode units 100 in the stacking direction (Z-axis direction). Specifically, the pair of end members 300 are arranged outside the end units 101 and 102 in the stacking direction (Z-axis direction). In this embodiment, two electrode units 100 are stacked in the stacking direction between end unit 101 and end unit 102, but the number of stacked electrode units 100 is not particularly limited. The shape of the electrode unit 100, end units 101 and 102, etc. in a plan view is not particularly limited, and may be a plate-like portion having a polygonal, circular, or partially curved shape.

[0027] [1.1.1 Description of the electrode unit 100] The configuration of the electrode unit 100 will be described in detail below with reference to Figures 3A and 3B. The electrode unit 100 is a single unit in which active material layers are formed on both sides of a single current collector foil. Each of the multiple electrode units 100 includes at least a current collector foil 110, a positive electrode active material layer 120 formed on one side of the current collector foil 110, a negative electrode active material layer 130 formed on the other side of the current collector foil 110, and a seal portion 210. In this embodiment, the thickness of the electrode unit 100 (thickness in the stacking direction) is approximately 100 µm to 200 µm.

[0028] The current collector foil 110 is a plate-like member that is rectangular in plan view. The current collector foil 110 is a metal foil. As shown in FIG. 3B , the current collector foil 110 includes two metal layers 111 and 112 that are aligned in the stacking direction (Z-axis direction). The metal layers 111 and 112 are plate-like portions that have the same size and shape in plan view. Hereinafter, of the metal layers 111 and 112, the metal layer 111 on which the positive electrode active material layer 120 is formed will also be referred to as the positive electrode metal layer 111, and the metal layer 112 on which the negative electrode active material layer 130 is formed will also be referred to as the negative electrode metal layer 112. The positive electrode metal layer 111 is a metal layer that is located in the positive direction of the current collector foil 110 along the Z axis, and the negative electrode metal layer 112 is a metal layer that is located in the negative direction of the current collector foil 110 along the Z axis. The current collector foil 110 is formed by laminating the positive electrode metal layer 111 and the negative electrode metal layer 112 in a stacking direction, with the positive electrode metal layer 111 and the negative electrode metal layer 112 connected (contacting or bonded) to each other. One of the positive electrode metal layer 111 and the negative electrode metal layer 112 may be a metal foil, and the other may be a plated layer plated on the metal foil. Alternatively, both the positive electrode metal layer 111 and the negative electrode metal layer 112 may be metal foil. When both the positive electrode metal layer 111 and the negative electrode metal layer 112 are metal foils, the current collector foil 110 may be a clad material formed by bonding two metal foils together, or may include two metal foils that are connected (contacting) without being bonded to each other.

[0029] The material for the positive electrode metal layer 111 may be a metal such as aluminum, titanium, tantalum, or stainless steel, or an alloy thereof. Among these, aluminum or an aluminum alloy is preferred as the material for the positive electrode metal layer 111 from the perspective of a balance between potential resistance, high conductivity, and cost. The positive electrode metal layer 111 may be in the form of a plated layer, but a foil is preferred from the perspectives of processability and cost. In other words, aluminum foil is preferred as the positive electrode metal layer 111. The material for the negative electrode metal layer 112 may be a metal such as copper, nickel, stainless steel, or nickel-plated steel, or an alloy thereof, and among these, copper or a copper alloy is preferred. The negative electrode metal layer 112 may be in the form of a plated layer or foil (copper foil), and examples of copper foil include rolled copper foil and electrolytic copper foil. The thickness (thickness in the lamination direction) of the current collector foil 110 is approximately 20 μm to 30 μm. The thickness of the positive electrode metal layer 111 (thickness in the stacking direction) is about 5 μm to 20 μm, and the thickness of the negative electrode metal layer 112 (thickness in the stacking direction) is about 5 μm to 15 μm.

[0030] At least one of the positive electrode metal layer 111 and the negative electrode metal layer 112 may be formed of a soft material that is deformable in the stacking direction (Z-axis direction). Examples of such soft materials include those that are sufficiently thin in the stacking direction (thinner than the thickness described above), or resin mixed with metal or carbon powder. Suitable known materials can be used for the resin, metal, and carbon powder. In this embodiment, the current collector foil 110 is described as two metal foils connected together, but when stainless steel foil is used, it may be formed of a single layer of metal foil, as in Modification 3 described below.

[0031] The positive electrode active material layer 120 is a positive electrode active material layer formed on one surface (the surface in the positive direction of the Z axis) of the current collector foil 110. Specifically, the positive electrode active material layer 120 is formed on the positive electrode metal layer 111 (the outer surface (the surface in the positive direction of the Z axis) of the positive electrode metal layer 111). The positive electrode active material layer 120 is smaller in size than the positive electrode metal layer 111 in a planar view, and is formed in a rectangular shape in this embodiment. "Small in size in a planar view" means that the area in the XY plane is small and that no part protrudes from the target area when viewed transparently from the Z axis direction. The same applies below. The shape of the positive electrode active material layer 120 in a planar view may be polygonal, circular, partially curved, or the like. In a planar view, the positive electrode metal layer 111 and the positive electrode active material layer 120 have the same or similar shapes. The thickness of the positive electrode active material layer 120 (thickness in the stacking direction) is approximately 70 μm to 100 μm.

[0032] The positive electrode active material layer 120 contains a positive electrode active material and, if necessary, optional components such as a conductive agent, binder, thickener, and filler. Examples of the positive electrode active material include layered lithium transition metal oxides such as LiM1O2 (M1 is one or more metal elements selected from Li, Fe, Ni, Mn, Co, etc.), spinel-type lithium transition metal oxides such as LiM22O4 (M2 is one or more metal elements selected from Li, Fe, Ni, Mn, Co, etc.), and polyanion compounds such as LiM3PO4, LiM3SiO4, and LiM3BO3 (M3 is one or more metal elements selected from Li, Fe, Ni, Mn, Co, etc.). As the positive electrode active material, one of these compounds may be used alone, or two or more may be used in combination. The conductive agent contained in the positive electrode active material layer 120 is not particularly limited as long as it is conductive. Examples of conductive agents include carbon black such as furnace black, acetylene black, and Ketjen black, as well as natural or artificial graphite. Examples of binders include fluororesins (polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc.), sulfonated EPDM, and styrene butadiene rubber (SBR). Examples of thickeners include polysaccharide polymers such as carboxymethyl cellulose (CMC) and methyl cellulose.

[0033] The negative electrode active material layer 130 is a negative electrode active material layer formed on the other surface (the surface in the negative Z-axis direction) of the current collector foil 110. Specifically, the negative electrode active material layer 130 is formed on the negative electrode metal layer 112 (the outer surface (the surface in the negative Z-axis direction) of the negative electrode metal layer 112). The negative electrode active material layer 130 is smaller in size than the negative electrode metal layer 112 in a planar view and is formed in a rectangular shape in this embodiment. The negative electrode active material layer 130 is formed to be larger in size than the positive electrode active material layer 120 in a planar view. "Large in size in a planar view" means that the area in the XY plane is large and does not protrude into the corresponding smaller-sized portion when viewed transparently from the Z-axis direction. The same applies below. In other words, the area in the XY plane of the negative electrode active material layer 130 is larger than that of the positive electrode active material layer 120. When the positive electrode active material layer 120 and the negative electrode active material layer 130 formed on adjacent current collector foils 110 facing each other via the solid electrolyte layer 140 are viewed transparently from the Z-axis direction, the positive electrode active material layer 120 is formed so as not to protrude from the negative electrode active material layer 130. The shape of the positive electrode active material layer 120 in a planar view may be a polygonal shape, a circular shape, a partially curved shape, or the like. In a planar view, the negative electrode metal layer 112 and the negative electrode active material layer 130 have the same or similar shapes. The thickness (thickness in the stacking direction) of the negative electrode active material layer 130 is approximately 50 μm to 100 μm.

[0034] The negative electrode active material layer 130 contains a negative electrode active material and, if necessary, optional components such as a conductive agent, binder, thickener, and filler. The optional components such as the conductive agent, binder, thickener, and filler can be the same as those used in the positive electrode active material layer 120. The negative electrode active material is typically a material capable of absorbing and releasing charge-transporting ions such as lithium ions. Examples of negative electrode active materials include metals or semimetals such as Si and Sn; metal oxides or semimetal oxides such as Si oxide and Sn oxide; and carbon materials such as graphite and non-graphitic carbon (easily graphitizable carbon or non-graphitizable carbon).

[0035] The sealing portion 210 is a portion disposed around the positive electrode active material layer 120 or the negative electrode active material layer 130. In the present embodiment, the sealing portion 210 is an annular portion disposed around the positive electrode active material layer 120 and the negative electrode active material layer 130 over the entire periphery of the positive electrode active material layer 120 and the negative electrode active material layer 130 when viewed from the Z-axis direction. Specifically, the sealing portion 210 is formed in a rectangular annular shape along the outer periphery of the current collector foil 110 so as to cover the outer periphery of the current collector foil 110. In the present embodiment, the sealing portion 210 is disposed so that no gaps are formed between the current collector foil 110, the positive electrode active material layer 120, the negative electrode active material layer 130, and the solid electrolyte layer 140. In other words, the positive electrode active material layer 120 and the negative electrode active material layer 130 are configured so that no gaps are formed between the sealing portion 210 and the positive electrode active material layer 120 and the negative electrode active material layer 130.

[0036] The sealing portion 210 is formed from an insulating material that has flexibility, such as polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyether ether ketone (PEEK), tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), polyamide (PA), ABS resin, or silicone rubber, fluororubber, urethane rubber, acrylic rubber, isoprene rubber, styrene rubber, styrene-butadiene rubber, butadiene rubber, or a composite material thereof.

[0037] The seal portions 210 of two adjacent electrode units 100 are connected to each other. The seal portions 210 may be connected to each other by being formed as a continuous, integral unit, or may be connected to each other by joining the seal portions 210 by heat sealing (thermal welding), ultrasonic welding, laser welding, an adhesive, or the like. As a result, the seal portion 210 is disposed around the positive electrode active material layer 120 of one of the two electrode units 100 and the negative electrode active material layer 130 of the other of the two electrode units 100, and the seal portion 210 is provided between the current collector foils 110 of the two electrode units 100. In other words, the seal portion 210 is provided continuously between the current collector foils 110 of the two electrode units 100, sealing the space between the current collector foils 110.

[0038] [1.1.2 Description of end units 101 and 102] Next, the configuration of the end units 101 and 102 will be described in detail. The end unit 101 is arranged at an end in the negative Z-axis direction relative to the multiple electrode units 100. The end unit 102 is arranged at an end in the positive Z-axis direction relative to the multiple electrode units 100. The end units 101 and 102 are parts that sandwich the multiple electrode units 100 in the Z-axis direction.

[0039] The end unit 101 includes at least a positive electrode metal layer 111, a positive electrode active material layer 120 formed on the surface of the positive electrode metal layer 111 in the Z-axis positive direction, and a seal portion 220. The positive electrode metal layer 111 and the positive electrode active material layer 120 included in the end unit 101 have the same configuration as the positive electrode metal layer 111 and the positive electrode active material layer 120 of the current collector foil 110 included in the electrode unit 100 described above.

[0040] The sealing portion 220 is a portion disposed around the positive electrode active material layer 120. In the present embodiment, the sealing portion 220 is an annular portion disposed around the positive electrode active material layer 120 over the entire circumference of the positive electrode active material layer 120 as viewed from the Z-axis direction. Specifically, the sealing portion 220 is formed in a quadrangular annular shape along the outer periphery of the positive electrode metal layer 111 and the end member 300 so as to cover the outer periphery of the positive electrode metal layer 111 and the end member 300 in the X-axis direction and the Y-axis direction. In the present embodiment, the sealing portion 220 is formed so that no gaps are formed among the positive electrode metal layer 111, the positive electrode active material layer 120, the solid electrolyte layer 140, and the end member 300. The sealing portion 220 is made of the same material as the sealing portion 210.

[0041] The seal portion 220 and the seal portion 210 adjacent to the seal portion 220 are connected to each other. This seal portion 210 is included in the electrode unit 100 adjacent to the end unit 101. The connection between the seal portion 220 and the seal portion 210 is similar to the connection between the seal portions 210 described above, and therefore a detailed description thereof will be omitted. As a result, the gap between the positive electrode metal layer 111 of the end unit 101 and the current collecting foil 110 of the electrode unit 100 is sealed by the seal portion 210 and the seal portion 220.

[0042] The end unit 102 includes at least a current collector foil 110, a negative electrode active material layer 130 disposed on the surface of the current collector foil 110 facing in the negative Z-axis direction, and a seal portion 230. The configurations of the current collector foil 110 and negative electrode active material layer 130 in the end unit 102 are similar to the configurations of the current collector foil 110 and negative electrode active material layer 130 in the electrode unit 100 described above.

[0043] The sealing portion 230 is a portion disposed around the negative electrode active material layer 130. In the present embodiment, the sealing portion 230 is an annular portion disposed around the negative electrode active material layer 130 over the entire periphery of the negative electrode active material layer 130 when viewed from the Z-axis direction. Specifically, the sealing portion 230 is formed in a rectangular annular shape along the outer periphery of the current collector foil 110 and the end member 300 so as to cover the outer periphery of the current collector foil 110 and the end member 300 in the X-axis direction and the Y-axis direction. In the present embodiment, the sealing portion 230 is disposed so that no gaps are formed among the current collector foil 110, the negative electrode active material layer 130, the solid electrolyte layer 140, and the end member 300. The sealing portion 230 is made of the same material as the sealing portion 210.

[0044] The seal portion 230 and the seal portion 210 adjacent to the seal portion 230 are connected to each other. This seal portion 210 is included in the electrode unit 100 adjacent to the end unit 102. The connection between the seal portion 230 and the seal portion 210 is similar to the connection between the seal portions 210 described above, and therefore a detailed description will be omitted. As a result, the gap between the current collecting foil 110 of the end unit 102 and the current collecting foil 110 of the electrode unit 100 is sealed by the seal portion 210 and the seal portion 230.

[0045] In this manner, the sealing portions 210 and 210, the sealing portions 210 and 220, and the sealing portions 210 and 230 are connected to one another to form the sealing member 200. The sealing member 200 is a cylindrical (quadratic cylindrical) member that is arranged to surround the positive electrode metal layer 111, the negative electrode metal layer 112, the positive electrode active material layer 120, the negative electrode active material layer 130, the solid electrolyte layer 140, and the end member 300 entirely in the X-axis direction and the Y-axis direction (so that no gaps are formed), and seals these from the outside.

[0046] [1.1.3 Description of the solid electrolyte layer 140 and the end member 300] The solid electrolyte layer 140 is a layered (sheet-shaped) member made of a solid electrolyte. The solid electrolyte layer 140 is disposed between the electrode units 100, between the end unit 101 and the electrode unit 100, and between the end unit 102 and the electrode unit 100. Specifically, the solid electrolyte layer 140 is disposed between the positive electrode active material layer 120 and the negative electrode active material layer 130. The solid electrolyte layer 140 is formed in a rectangular shape that is larger in size than the positive electrode active material layer 120 and the negative electrode active material layer 130 in a planar view. In this embodiment, the size of the solid electrolyte layer 140 is smaller than the size of the current collector foil 110 in a planar view, but may be larger than the size of the current collector foil 110 in a planar view. The thickness of the solid electrolyte layer 140 (thickness in the stacking direction) is approximately 1 μm to 100 μm. As the material for the solid electrolyte layer 140, a known material can be used as appropriate. The material for the solid electrolyte layer 140 can be a material represented by the general formula Li 1+x Al x Ge 2-x Compounds with NASICON structure represented by (PO4)3(0≦x≦2), γ-Li3PO4 type compounds represented by Li4SiO4-Li3PO4 system, Li 4-2x Zn x LISICON-type compounds, such as GeO4 (0≦x≦1), 1.3 Al 0.3 Ti 1.7 Examples of sulfide-based solid electrolyte materials include LTAP-based compounds, such as (PO4)3-based compounds. 7-x PS 6-x Cl x Argyrodite-type compounds, such as Li4GeS4-Li3PS4 solid solutions, 3.25 Ge 0.25 P 0.75Examples include LGPS-based compounds represented by S4, and α-Li3PS4, which is formed by crystallizing Li3PS4 glass by rapidly heating it. Novel lithium ion conductive polymers, such as lithium ion conductive polymers in which lithium salts such as LiFSI (lithium bis(fluorosulfonylimide)) and LiTFSI (lithium bis(trifluoromethanesulfonylimide)) are dissolved in PEO (polyethylene oxide), a polymer solid electrolyte, and alternating copolymer single ion conductor (SIC) polymers (pMISt-Li) are also possible.

[0047] The end members 300 are members disposed closer to the ends of the unit group 10 in the stacking direction (Z-axis direction) than the multiple electrode units 100. In this embodiment, a pair of end members 300 are disposed at the ends of the unit group 10 closest to the negative Z-axis direction and the positive Z-axis direction. The pair of end members 300 are connected to the end units 101 and 102 (the positive electrode metal layers 111 provided therein). As a result, the pair of end members 300 sandwich the multiple electrode units 100 and the end units 101 and 102 located therebetween from both sides in the stacking direction (Z-axis direction). The end members 300 are flat plate-shaped members (end plates). The end members 300 are formed of a conductive metal member such as aluminum, aluminum alloy, copper, copper alloy, or nickel, or a combination thereof, or a conductive material other than metal. Since the end members 300 are connected to the positive electrode metal layer 111, they are preferably formed of the same material as the positive electrode metal layer 111, such as aluminum. The thickness (thickness in the stacking direction) of the end member 300 is about 0.01 mm to 1 mm. The unit group 10 may include other conductive members on the outside of the end member 300 (outside in the Z-axis direction).

[0048] The end member 300 may be made of a soft material that is deformable in the stacking direction (Z-axis direction). The soft material may be the same as that which can be used for the positive electrode metal layer 111 or the negative electrode metal layer 112 described above.

[0049] In the above configuration, the solid electrolyte layer 140, the positive electrode active material layer 120 and the negative electrode active material layer 130 sandwiching the solid electrolyte layer 140 in the Z-axis direction, and the positive electrode metal layer 111 and the negative electrode metal layer 112 sandwiching these in the Z-axis direction may be referred to as a single energy storage element. In this case, the unit group 10 can also be said to be an energy storage element group having a configuration in which a plurality of energy storage elements stacked in the Z-axis direction are sandwiched between a pair of end members 300 in the Z-axis direction and are surrounded by the sealing member 200.

[0050] 1.2 Description of the first container 20 and the exterior body 30 Next, the configurations of the first container 20 (21 and 22) and the exterior body 30 will be described in detail.

[0051] As shown in FIGS. 1 and 2 , the first container 20 is disposed on at least one of both sides of the plurality of electrode units 100 in the stacking direction (Z-axis direction). Specifically, the first container 20 is housed in an exterior body 30, and is disposed on at least one of both sides of the unit group 10 in the Z-axis direction. In this embodiment, two first containers 20, that is, first containers 21 and 22, are disposed on both sides of the unit group 10 (positions sandwiching the unit group 10 in the Z-axis direction) within the exterior body 30. The first containers 20 (21 and 22) are formed in a rectangular shape that is larger in size than the unit group 10 (the plurality of electrode units 100) in a plan view. As a result, the first containers 20 (21 and 22) cover the entire surface of the unit group 10 in the Z-axis direction.

[0052] Specifically, the first container 21 is disposed in the positive Z-axis direction of the unit group 10 (plurality of electrode units 100) and covers the entire surface of the unit group 10 in the positive Z-axis direction. The first container 21 is disposed in contact with the inner surface of the wall of the exterior body 30 in the positive Z-axis direction (the surface in the negative Z-axis direction) and the surface of the unit group 10 in the positive Z-axis direction. The first container 22 is disposed in the negative Z-axis direction of the unit group 10 (plurality of electrode units 100) and covers the entire surface of the unit group 10 in the negative Z-axis direction. The first container 22 is disposed in contact with the inner surface of the wall of the exterior body 30 in the negative Z-axis direction (the surface in the positive Z-axis direction) and the surface of the unit group 10 in the negative Z-axis direction.

[0053] The first container 20 (21 and 22) is a deformable container. The first container 20 is connected to the pressure change unit 40, and is deformed when the internal pressure is changed by the pressure change unit 40. The first container 20 is a bag-shaped member and is formed of an insulating material such as any resin material that can be used for the seal unit 210. The first container 20 may be formed of a conductive material such as a soft metal material, as long as the insulation of the unit group 10 can be ensured. A fluid (gas, liquid, etc.) supplied by the pressure change unit 40 is disposed inside the first container 20. In this embodiment, a liquid is disposed inside the first container 20. The first container 20 is deformed when the pressure of the liquid inside is changed by the pressure change unit 40, and presses the unit group 10 in the Z-axis direction. In this manner, the first container 20 is a pressurized pack.

[0054] The liquid placed inside the first container 20 is preferably an insulating organic substance, a fire extinguishing agent, a non-flammable material, or a flame-retardant material, from the viewpoint of safety in the event of leakage from the first container 20. Liquid paraffin, flame-retardant oil, or other known substances can be appropriately used as the insulating organic substance. Known substances can also be appropriately used as the fire extinguishing agent and non-flammable material. The flame-retardant material is a material that exhibits flame retardancy against flammable gases upon vaporization. Flame-retardant materials are preferably those that have a large heat of vaporization, are corrosion-resistant, and do not generate toxic gases. Flame-retardant materials that include at least one of acyclic fluorinated ethers, fluorinated phosphate esters, and phosphazene derivatives are preferably used from the viewpoint of exhibiting high flame retardancy upon vaporization.

[0055] The exterior body 30 is a rectangular parallelepiped (box-shaped) container that forms a housing (outer shell) that houses the unit group 10 and the first container 20 (21 and 22). The exterior body 30 is arranged outside the unit group 10 and the first container 20, fixes the unit group 10 and the first container 20 in predetermined positions, and protects them from impacts and the like. The exterior body 30 is formed of an insulating material such as any resin material that can be used for the seal portion 210. This prevents the unit group 10 from coming into contact with external metal members and the like. The exterior body 30 may be formed of a conductive material such as a metal material, as long as the insulation properties of the unit group 10 can be ensured.

[0056] A pipe 42 that connects the first container 20 and the pressure change section 40 is disposed to pass through the exterior body 30. A conductive member such as a terminal for electrically connecting (for charging and discharging) the unit group 10 to the outside of the exterior body 30 may be disposed to pass through the exterior body 30.

[0057] [1.3 Explanation of the pressure change unit 40 and the tank 50] The pressure change unit 40 is a device that changes the pressure inside the first container 20. The pressure change unit 40 is disposed outside the first container 20. As described above, the pressure change unit 40 includes the pressurizing unit 41, the pipes 42 and 43, and the measuring unit 44.

[0058] The pressurizing unit 41 is a device that increases the pressure inside the first container 20. In this embodiment, the pressurizing unit 41 is a pump that sends liquid to the first container 20. The pressurizing unit 41 changes (adjusts) the pressure inside the first container 20 by changing (adjusting) the amount (pressure) of liquid sent to the first container 20. The pressurizing unit 41 changes (adjusts) the internal pressure of each of the first containers 21 and 22. Specifically, the pressurizing unit 41 takes out the liquid stored in the tank 50 via a pipe 43, and sends the liquid to the first containers 21 and 22 via a pipe 42 connected to each of the first containers 21 and 22. The pipes 42 and 43 are pipes made of metal or the like, or hoses or tubes made of resin or the like.

[0059] In this embodiment, one pressurizing unit 41 is provided for two first containers 20 (two pipes 42). In order to enable one pressurizing unit 41 to individually increase the pressures inside the two first containers 20, the pressurizing unit 41 may be configured to be connected to only one of the two pipes 42 and to be switchable to connect to the other pipe 42 under a predetermined condition. A pressurizing unit 41 may be provided for each of the two first containers 20 (two pipes 42) (i.e., two pressurizing units 41 may be provided).

[0060] The measurement unit 44 is a device that measures the pressure or flow rate of the liquid in the pipe 42. The measurement unit 44 is a pressure gauge, a flow meter, a pressure sensor, a flow sensor, or the like. In this embodiment, the two pipes 42 connected to the first containers 21 and 22 join together and are connected to the pressurizing unit 41, so the pressures and flow rates of the liquid in the two pipes 42 are equal. Therefore, the measurement unit 44 is disposed in one of the two pipes 42 to measure the pressure or flow rate of the liquid in that one pipe 42. In this embodiment, the measurement unit 44 is disposed in the pipe 42 connected to the first container 21 in the positive direction of the Z axis, but may also be disposed in the pipe 42 connected to the first container 22 in the negative direction of the Z axis. In cases where the pressures or flow rates of the liquid in the two pipes 42 are different because the two pipes 42 are connected to the pressurizing unit 41 without joining each other, or because a pressurizing unit 41 is disposed for each of the two pipes 42, the measurement unit 44 may be disposed in both of the two pipes 42.

[0061] The pressurizing unit 41 includes a control unit (not shown) that acquires the pressure or flow rate of the liquid in the pipe 42 from the measurement unit 44 and calculates the pressure or flow rate of the liquid to be sent to the first container 20 using the acquired pressure or flow rate. The pressurizing unit 41 operates to send the liquid at the pressure or flow rate calculated by the control unit to the first container 20. The pressure changing unit 40 may include the control unit in the measurement unit 44 instead of in the pressurizing unit 41, or may be provided outside the pressurizing unit 41 and the measurement unit 44. The control unit may be incorporated into the function of a BMU (Battery Management Unit) that monitors and controls the state of the unit group 10 (electrode unit 100), or may be incorporated into another control device.

[0062] In this configuration, the pressure change unit 40 controls (adjusts) the pressure inside the first container 20 by changing it. Specifically, the pressure change unit 40 normally controls (adjusts) the pressure inside the first container 20 to a constant pressure, and periodically increases or pulsates the pressure inside the first container 20 when the unit group 10 deteriorates, etc. Pulsating the pressure inside the first container 20 means increasing or decreasing the degree of pressure increase inside the first container 20, and the pressure change unit 40 increases or decreases the pressure inside the first container 20 at predetermined time intervals and by a predetermined pressure range. The pressure change unit 40 may be configured to individually control the internal pressures of the two first containers 20 (21 and 22). By pulsating the pressure inside the first container 20 or increasing the degree of pressure increase, even if cracks or voids occur in the electrode unit 100, the cracks or voids can be repaired. The degree of repair of the cracks or voids can be monitored by the reduction in resistance or the degree of capacity recovery of the electricity storage device 1.

[0063] As described above, the positive electrode metal layer 111, the negative electrode metal layer 112, or the end member 300 may be formed of a soft material that is deformable in the stacking direction (Z-axis direction). In this embodiment, at least one of the multiple current collector foils 110 and the end member 300 included in the multiple electrode units 100 is formed of this soft material, and thereby deforms in response to a change in pressure inside the first container 20 caused by the pressure change unit 40. The seal member 200 is formed of a soft material such as resin, and deforms in response to a change in pressure inside the first container 20 caused by the pressure change unit 40. The solid electrolyte layer 140 may also be formed of a soft material so that it deforms in response to a change in pressure inside the first container 20 caused by the pressure change unit 40. In this way, the unit group 10 (multiple electrode units 100) is uniformly pressurized in response to a change in pressure inside the first container 20 caused by the pressure change unit 40, and even if a crack or void occurs in the electrode unit 100, the crack or void can be repaired.

[0064] The tank 50 is a tank connected to the first container 20 and stores a liquid. Specifically, the tank 50 is disposed outside the exterior body 30, and is connected to the pressurizing unit 41 of the pressure change unit 40 via the pipe 43, and is thereby connected to the first container 20 (21 and 22) via the pipe 43, the pressurizing unit 41, and the pipe 42. The tank 50 stores the same type of liquid as the liquid disposed inside the first container 20 described above, as a liquid to be supplied to the first container 20 (21 and 22). The tank 50 may be made of metal or resin, and the material is not particularly limited, and the shape, size, etc. of the tank 50 are also not particularly limited.

[0065] [2. Explanation of effects] As described above, the energy storage device 1 according to the embodiment of the present invention includes a deformable first container 20 disposed on at least one side of the plurality of electrode units 100 in the stacking direction (Z-axis direction), and a pressure change unit 40 that changes the pressure inside the first container 20. This allows the plurality of electrode units 100 to be pressurized with a more appropriate pressure in the stacking direction (Z-axis direction). This prevents cracks from occurring in the components (such as the positive electrode active material layer 120, the negative electrode active material layer 130, and the solid electrolyte layer 140) inside the electrode unit 100 due to expansion and contraction of the electrode unit 100, and prevents voids from occurring at each interface inside the electrode unit 100. Therefore, the energy storage device 1 can prevent deterioration of the electrode unit 100. Furthermore, even if cracks or voids occur in the above components or the above interfaces, the cracks or voids can be repaired by changing the pressure inside the first container 20 accordingly, thereby recovering from an increase in resistance or a decrease in capacity of the energy storage device 1.

[0066] In this embodiment, the first container 20 is disposed separately from the unit group 10 (electrode unit 100) (the unit group 10 is disposed outside the first container 20). Therefore, this embodiment has the following advantages compared to a case where the first container 20 is integrated with the unit group 10 (electrode unit 100) (the unit group 10 is disposed inside the first container 20). When the unit group 10 is disposed inside the first container 20, the unit group 10 can only be pressurized with the same pressure from above, below, left, and right. However, by disposing the unit group 10 outside the first container 20, the unit group 10 can be individually pressurized with a desired pressure from a desired direction. When the unit group 10 is disposed inside the first container 20, a conductive member connected to the unit group 10 needs to penetrate the first container 20 in order to extract power from the unit group 10. In contrast, by disposing the unit group 10 outside the first container 20, power from the unit group 10 can be easily extracted.

[0067] At least one of the multiple current collector foils 110 and end members 300 included in the multiple electrode units 100 deforms in response to changes in pressure inside the first container 20 caused by the pressure change unit 40, allowing the multiple electrode units 100 to be pressurized relatively uniformly. This makes it possible to prevent cracks from occurring due to localized stress concentration on components inside the electrode units 100, or to prevent voids from occurring at each interface inside the electrode units 100. The above deformation makes it possible to appropriately apply pressure from the first container 20 to areas where cracks or voids have occurred, making it easier to repair the cracks or voids that have occurred.

[0068] By disposing a liquid inside the first container 20, it is possible to easily equalize the pressure inside the first container 20. If a gas is disposed inside the first container 20, there is a risk that the pressure inside the first container 20 will rise due to use that is not in a normally foreseeable manner or state of use, causing the first container 20 to burst and leading to damage to the electricity storage device 1 itself. For this reason, by disposing a liquid inside the first container 20, it is possible to improve the safety of the electricity storage device.

[0069] The energy storage device 1 is provided with a tank 50 that is connected to the first container 20 and contains liquid, so that the amount of liquid in the first container 20 can be easily adjusted, and therefore the pressure in the first container 20 can be easily changed by the pressure change unit 40.

[0070] [3 Explanation of Variations] Although the energy storage device 1 according to the present embodiment has been described above, the present invention is not limited to the above embodiment. The embodiment disclosed herein is illustrative in all respects and is not restrictive, and the scope of the present invention includes all modifications within the meaning and scope of the claims.

[0071] (Variation 1) In the above embodiment, in the energy storage device 1, the first container 20 (21 and 22) is formed to be larger than the unit group 10 in plan view so as to cover the entire surface of the unit group 10 in the Z-axis direction. Therefore, a space is formed between the unit group 10 and the exterior body 30 (on both sides of the unit group 10 in the X-axis direction and on both sides of the unit group 10 in the Y-axis direction). In this case, if the pressure inside the first container 20 becomes too high, the end of the first container 20 may be deformed and damaged so as to enter the space. Therefore, to prevent the space from being formed, the first container 20 may be formed to be the same size as the unit group 10 in plan view or smaller than the unit group 10. Alternatively, as shown in FIG. 4, a spacer may be disposed in the space. FIG. 4 is a cross-sectional view showing components included in an energy storage device 1A according to a first modification of the present embodiment. FIG. 4 is a view corresponding to FIG. 2.

[0072] As shown in FIG. 4, the energy storage device 1A of this modification includes spacers 60 on the sides of the unit group 10 in addition to the configuration of the energy storage device 1 of the above embodiment. In this modification, spacers 60 (i.e., four spacers 60) are arranged on both sides of the unit group 10 in the X-axis direction and on both sides of the unit group 10 in the Y-axis direction. The spacers 60 have the same shape (rectangular parallelepiped, plate-like, etc.) as the spaces formed on both sides of the unit group 10 in the X-axis direction and on both sides of the unit group 10 in the Y-axis direction, and are members that are arranged in the spaces to fill the spaces. The spacers 60 are preferably formed of a member such as resin or metal that has a higher strength (hardness) in the Z-axis direction than the unit group 10 or the sealing member 200. The other configuration of this modification is the same as that of the above embodiment, and therefore detailed description thereof will be omitted.

[0073] As described above, according to the electricity storage device 1A of this modified example, the spacer 60 can prevent the end of the first container 20 from being deformed and damaged.

[0074] (Variation 2) In the above-described first modification, the spacer 60 is arranged on the side of the unit group 10, but a container similar to the first container 20 may be arranged on the side of the unit group 10. Fig. 5 is a cross-sectional view showing each component included in a power storage device 1B according to a second modification of the present embodiment. Fig. 5 is a view corresponding to Fig. 4.

[0075] 5, the energy storage device 1B of this modification includes a second container 70 instead of the spacer 60 of the energy storage device 1A of the above-described modification 1. Furthermore, the pressure change section 40 of the energy storage device 1B includes a pipe 45 that connects the second container 70 and the pressurizing section 41. The other configurations of this modification are the same as those of the above-described modification 1, and therefore detailed description thereof will be omitted.

[0076] The second containers 70 are deformable containers arranged on at least one of both sides of the plurality of electrode units 100 in a direction intersecting the stacking direction (Z-axis direction). Specifically, the second containers 70 are housed in the exterior body 30 and arranged on at least one of both sides of the unit group 10 in the X-axis direction and both sides of the unit group 10 in the Y-axis direction. In this modification, the second containers 70 (i.e., four second containers 70) are arranged on both sides of the unit group 10 in the X-axis direction and both sides of the unit group 10 in the Y-axis direction within the exterior body 30. The second containers 70 are bag-shaped members (pressurized packs) having the same shape as the spaces formed on both sides of the unit group 10 in the X-axis direction and both sides of the unit group 10 in the Y-axis direction, and are arranged in the spaces to fill the spaces. The second containers 70 are formed of any material that can be used for the first container 20.

[0077] The second container 70 is connected to the pressure change unit 40 via piping 45, and is deformed when its internal pressure is changed by the pressure change unit 40. A fluid (gas, liquid, etc.) supplied by the pressure change unit 40 is disposed inside the second container 70. In this modified example, the same type of liquid as the liquid in the first container 20 is disposed inside the second container 70. The second container 70 is deformed when the pressure of the liquid inside is changed by the pressure change unit 40, and presses the unit group 10 in the X-axis or Y-axis direction.

[0078] In this way, the pressure change unit 40 further changes the pressure inside the second container 70. That is, the pressurizing unit 41 also increases the pressure inside the second container 70. The pressurizing unit 41 changes (adjusts) the pressure inside the second container 70 by changing (adjusting) the amount (pressure) of liquid sent to the second container 70. The pressurizing unit 41 sends the liquid to the second container 70 via piping 45 connected to the second container 70. In this modified example, four piping 45 are arranged for four second containers 70. The piping 45 is a pipe made of metal or the like, or a hose or tube made of resin or the like.

[0079] In this modified example, one pressurizing unit 41 is provided for two first containers 20 (two pipes 42) and four second containers 70 (four pipes 45). In order to enable one pressurizing unit 41 to individually increase the pressures in the two first containers 20 and the four second containers 70, the pressurizing unit 41 may be connected to only one of the two pipes 42 and four pipes 45 and may be configured to be switchable so as to be connected to the other pipe under a predetermined condition. A pressurizing unit 41 may be provided for each of the two first containers 20 (two pipes 42) and four second containers 70 (four pipes 45) (i.e., six pressurizing units 41 may be provided), or another number of pressurizing units 41 may be provided.

[0080] In this modified example, the measurement unit 44 may be disposed in the pipe 45. The four pipes 45 are connected to the pressurizing unit 41 after merging with two pipes 42, but may also be connected to the pressurizing unit 41 without merging with two pipes 42. In cases where the pressures or flow rates of the liquid in the two pipes 42 and the four pipes 45 are different, the measurement unit 44 may be disposed in all of the two pipes 42 and the four pipes 45. The pressurizing unit 41 also has a function of calculating the pressure or flow rate of the liquid to be sent to the second container 70.

[0081] In this configuration, the pressure change unit 40, like the first container 20, normally controls (adjusts) the pressure inside the second container 70 to be a constant pressure, and periodically increases or pulsates the pressure inside the second container 70 when the unit group 10 deteriorates, etc. The pressure change unit 40 may be configured to individually control the internal pressures of the four second containers 70, but preferably controls the internal pressures of the four second containers 70 to be the same. The pressure change unit 40 preferably controls the pressure inside the second container 70 to be lower than the pressure inside the first container 20.

[0082] As described above, the energy storage device 1B in this modified example includes a deformable second container 70 disposed on at least one side of the plurality of electrode units 100 in directions (X-axis direction and Y-axis direction) intersecting the stacking direction (Z-axis direction). The pressure changer 40 changes the pressure inside the second container 70. This allows the plurality of electrode units 100 to be pressurized with a more appropriate pressure even in directions (X-axis direction and Y-axis direction) intersecting the stacking direction, thereby further suppressing deterioration of the electrode units 100.

[0083] (Variation 3) In the above embodiment, the current collector foil 110 included in the unit group 10 is formed of multiple layers (two layers) of the positive electrode metal layer 111 and the negative electrode metal layer 112, but the current collector foil 110 may be formed of a single layer (one metal foil). Fig. 6 is a cross-sectional view showing each component included in a power storage device 1C according to Modification 3 of the present embodiment. Fig. 6 is a view corresponding to Fig. 2.

[0084] 6, an energy storage device 1C in this modification includes a unit group 11 instead of the unit group 10 of the energy storage device 1 in the above embodiment. The unit group 11 includes a plurality of current collector foils 113 and a pair of end members 301, 302 instead of the plurality of current collector foils 110 and the pair of end members 300 included in the unit group 10 in the above embodiment.

[0085] The current collecting foil 113 is a single metal foil in which the positive electrode metal layer 111 and the negative electrode metal layer 112 in the above embodiment are integrated into a single layer. The current collecting foil 113 is formed from a single stainless steel foil or the like, and has the functions of the positive electrode metal layer 111 and the negative electrode metal layer 112 in the above embodiment. The end member 301 is a single metal member in which the end member 300 and the positive electrode metal layer 111 in the above embodiment are integrated. The end member 302 is a single metal member in which the end member 300 and the current collecting foil 110 in the above embodiment are integrated. The end members 301 and 302 are formed from any metal material that can be used for the end member 300. There are no particular limitations on the thickness of the current collecting foil 113 and the end members 301 and 302 in the Z-axis direction. The other configurations of this modified example are the same as those in the above embodiment, and therefore detailed description thereof will be omitted.

[0086] As described above, according to the electricity storage device 1C of this modification, the current collector foil 113 and the end members 301 and 302 are formed by integrating a plurality of metal layers, thereby simplifying the configuration.

[0087] In this modification, similarly to the above embodiment, the current collector foils 113, the end member 301, or the end member 302 may be made of a soft material that is deformable in the stacking direction (Z-axis direction). That is, by being made of such a soft material, at least one of the multiple current collector foils 113 and the pair of end members 301, 302 is deformed in accordance with a change in pressure inside the first container 20 caused by the pressure change unit 40. As a result, in accordance with a change in pressure inside the first container 20 caused by the pressure change unit 40, the unit group 11 (multiple electrode units 100) is uniformly pressurized.

[0088] (Variation 4) In the above embodiment, the positive electrode active material layer 120 and the negative electrode active material layer 130 included in the unit group 10 are formed to be large enough to prevent a gap from being formed between them and the sealing member 200, but they may be formed to be large enough to prevent a gap from being formed between them and the sealing member 200. Fig. 7 is a cross-sectional view showing each component included in a power storage device 1D according to Modification 4 of the present embodiment. Fig. 7 is a view corresponding to Fig. 2.

[0089] 7, the energy storage device 1D of this modification includes a unit group 12 instead of the unit group 10 of the energy storage device 1 of the above embodiment. The positive electrode active material layer 120 and the negative electrode active material layer 130 included in the unit group 12 are formed to have shorter lengths in the Y-axis direction (and X-axis direction) than the positive electrode active material layer 120 and the negative electrode active material layer 130 included in the unit group 10 of the above embodiment. As a result, gaps are formed between the positive electrode active material layer 120 and the negative electrode active material layer 130 and the sealing member 200. The other configurations of this modification are similar to those of the above embodiment, and therefore detailed description thereof will be omitted.

[0090] As described above, in the energy storage device 1D of this modification, gaps are formed between the positive electrode active material layer 120 and the negative electrode active material layer 130 and the sealing member 200. Therefore, if the energy storage device 1D is a battery that uses a non-aqueous liquid or gel electrolyte (electrolytic solution) rather than a battery that uses a solid electrolyte, the electrolyte (electrolytic solution) can be placed in the gaps. In this case, the energy storage device 1D will include a separator 140 instead of a solid electrolyte layer 140.

[0091] Any known electrolyte (electrolytic solution) can be used. The electrolyte (non-aqueous electrolyte) may be a solution in which an electrolyte salt is dissolved in a non-aqueous solvent. Examples of non-aqueous solvents include cyclic carbonates such as ethylene carbonate (EC) and propylene carbonate (PC), and chain carbonates such as diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC). The electrolyte salt is preferably a lithium salt. Examples of the lithium salt include inorganic lithium salts such as LiPF6, LiPO2F2, LiBF4, LiClO4, LiN(SO2F)2, and LiN(SO2CF3). The separator 140 is a microporous sheet made of resin. Examples of materials for the separator 140 include woven fabric, non-woven fabric, and porous resin film. Among these, porous resin film is preferred. From the viewpoint of strength, polyolefins such as polyethylene and polypropylene are preferred as the main component of the porous resin film. Separator 140 may be a multi-layer film in which a layer containing a filler is formed on the surface of such a porous resin film.

[0092] (Variations 5 and 6) In the above embodiment, one unit group 10 is arranged between a pair of first containers 20 (21 and 22), but an electricity storage pack including a plurality of unit groups 10 may be arranged. Fig. 8 is a cross-sectional view showing each component included in an electricity storage device 1E according to a fifth modification of the present embodiment. Fig. 9 is a cross-sectional view showing each component included in an electricity storage device 1F according to a sixth modification of the present embodiment. In Figs. 8 and 9, the exterior body 30, the pressure change section 40, and the tank 50 are not shown, and the internal configuration of the unit group 10 is also not shown.

[0093] As shown in FIG. 8 , the energy storage device 1E of the fifth modification includes a stacked body 2 in which a plurality of unit groups 10 are stacked, and a conductive member 3. The stacked body 2 in which a plurality of unit groups 10 are stacked is disposed between a pair of first containers 20 (21 and 22). Two adjacent unit groups 10 in the stacked body 2 are electrically connected by contact or bonding (welding, etc.). The conductive member 3 is made of a metal such as stainless steel, and the unit group 10 located at the end in the stacking direction (Z-axis direction) and the conductive member 3 are electrically connected by contact or bonding (welding, etc.). An adhesive may be used for bonding. The plurality of unit groups 10 in the stacked body 2 are connected in series, and charging and discharging are performed via the conductive member 3. The stacked body 2 and the conductive member 3 may be constrained in the stacking direction (Z-axis direction). In this case, a constraining member such as a screw, a resin band, or a metal band may be used. The other configurations of this modification are similar to those of the above-described embodiment, and therefore detailed description thereof will be omitted.

[0094] As shown in FIG. 9, in a power storage device 1F in Modification 6, each unit group 10 is housed in an exterior body 4. The unit group 10 has a connection portion 5 exposed from the exterior body 4. A laminate film or the like can be used as the exterior body 4. The connection portions 5 of adjacent unit groups 10 are electrically connected to each other by contact or bonding (welding, etc.). The connection portion 5 of the unit group 10 located at the end in the stacking direction (Z-axis direction) and the conductive member 3 are electrically connected to each other by contact or bonding (welding, etc.). The other configurations of this modification are the same as those of Modification 5 described above, and therefore detailed description thereof will be omitted.

[0095] As described above, according to the power storage device 1E of Modification 5 and the power storage device 1F of Modification 6, the configurations of the above-described embodiments can also be applied to a power storage pack including a plurality of unit groups 10.

[0096] In the fifth and sixth modifications, a plurality of unit groups 10 may be arranged in the X-axis direction or the Y-axis direction and sandwiched between a pair of first containers 20 (21 and 22) in the Z-axis direction.

[0097] (Other variations) In the above embodiment, the first container 20 is arranged on both sides of the unit group 10 (plurality of electrode units 100), but the first container 20 may be arranged on only one side of the unit group 10. In other words, it is sufficient that the first container 20 is arranged on at least one side of the unit group 10 (plurality of electrode units 100). The same applies to the second container 70.

[0098] In the above embodiment, the energy storage device 1 has the unit group 10 sandwiched between a pair of first containers 20 (21 and 22), but the unit group 10 may be sandwiched between multiple pairs of first containers 20 (21 and 22). In this case, one pressure changer 40 may change the pressure inside the multiple pairs of first containers 20.

[0099] In the above embodiment, the power storage device 1 is provided with the tank 50, but if liquid can be taken out from a tank other than the tank 50, such as a tank that supplies liquid to a vehicle radiator, the power storage device 1 may not be provided with the tank 50. The power storage device 1 may also not be provided with the tank 50 if outside air is supplied to the first container 20 instead of liquid.

[0100] In the above embodiment, in the unit group 10, the negative electrode active material layer 130 is larger in size than the positive electrode active material layer 120 in a plan view, but it may be the same size as or smaller than the positive electrode active material layer 120. Similarly, the other members included in the unit group 10 may also have sizes different from those described above.

[0101] Any combination of the components included in the above-described embodiments and their modifications is also included within the scope of the present invention. [Industrial Applicability]

[0102] The present invention can be applied to an electricity storage device including a bipolar battery or the like. [Explanation of symbols]

[0103] 1, 1A, 1B, 1C, 1D, 1E, 1F Power storage device 2. Laminate 3 Conductive materials 4, 30 Exterior body 5 Connection part Units 10, 11, and 12 20, 21, 22 First container 40 Pressure change section 41 Pressure section 42, 43, 45 Piping 44 Measuring part 50 Tank 60 spacer 70 Second container 100 electrode units 101, 102 End units 110, 113 Current collecting foil 111 Positive electrode metal layer (metal layer) 112 Negative electrode metal layer (metal layer) 120 Cathode active material layer 130 Negative electrode active material layer 140 Solid electrolyte layer (separator) 200 sealing material 210, 220, 230 Seal part 300, 301, 302 End members

Claims

1. An electricity storage device including a plurality of electrode units stacked in a stacking direction, each of the plurality of electrode units includes at least a current collecting foil, a positive electrode active material layer formed on one surface of the current collecting foil, and a negative electrode active material layer formed on the other surface of the current collecting foil; The power storage device further comprises: a deformable first container disposed on at least one of both sides of the plurality of electrode units in the stacking direction; a pressure change unit that changes the pressure inside the first container Energy storage device.

2. further comprising end members disposed at ends of the plurality of electrode units in the stacking direction, At least one of the plurality of current collecting foils and the end member provided in the plurality of electrode units is deformed in accordance with a change in pressure inside the first container caused by the pressure change unit. The power storage device according to claim 1 .

3. A liquid is disposed inside the first container. The electricity storage device according to claim 1 or 2.

4. a tank connected to the first container and configured to contain the liquid; The power storage device according to claim 3 .

5. a deformable second container disposed on at least one of both sides of the plurality of electrode units in a direction intersecting the stacking direction, The pressure change unit further changes the pressure in the second container. The electricity storage device according to claim 1 or 2.

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