Electricity storage device

Abstract

To provide a power storage device capable of increasing energy density.SOLUTION: The power storage device includes a power storage part including a positive electrode including a positive electrode active material layer, a negative electrode including a negative electrode active material layer, and an electrolyte layer provided between the positive electrode and the negative electrode, and an exterior material covering the power storage part. The exterior material includes a positive electrode current collector electrically connected to the positive electrode active material layer and exposed to an outer surface of the exterior material, a negative electrode current collector electrically connected to the negative electrode active material layer and exposed to the outer surface of the exterior material, and an insulator electrically insulating the positive electrode current collector and the negative electrode current collector.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In an electricity storage device in which an electricity storage unit having an electrolyte layer provided between a positive electrode and a negative electrode is covered with an exterior material, the prior art disclosed in Patent Document 1 has terminals connected to the positive electrode and negative electrode, respectively, that are pulled out to the outside of the exterior material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-253155 Summary of the Invention [Problem to be solved by the invention]

[0004] Because the terminals do not contribute to the storage of electricity, the prior art has the problem that the energy density is lower than the theoretical energy density of the energy storage device by the amount of the terminals.

[0005] The present invention has been made to solve this problem, and has an object to provide an electricity storage device that can increase the energy density. [Means for solving the problem]

[0006] A first aspect for achieving this object includes a storage unit including a positive electrode including a positive electrode active material layer, a negative electrode including a negative electrode active material layer, and an electrolyte layer provided between the positive electrode and the negative electrode, and an exterior material covering the storage unit, wherein the exterior material includes a positive electrode current collector electrically connected to the positive electrode active material layer and exposed on the outer surface of the exterior material, a negative electrode current collector electrically connected to the negative electrode active material layer and exposed on the outer surface of the exterior material, and an insulator that electrically insulates the positive electrode current collector from the negative electrode current collector.

[0007] In the second embodiment, in the first embodiment, at least one of the connection between the positive electrode current collector and the positive electrode active material layer and the connection between the negative electrode current collector and the negative electrode active material layer is direct.

[0008] In a third embodiment, in the first embodiment, a conductor is interposed between at least one of the connection between the positive electrode current collector and the positive electrode active material layer and the connection between the negative electrode current collector and the negative electrode active material layer.

[0009] In a fourth aspect, in any of the first to third aspects, the power storage unit includes a first cell and a second cell, each including a positive electrode, an electrolyte layer, and a negative electrode, the first cell and the second cell are electrically connected, the positive electrode current collector is connected to the positive electrode active material layer included in the first cell, and the negative electrode current collector is connected to the negative electrode active material layer included in the second cell. [Effects of the Invention]

[0010] According to the present invention, the exterior packaging material includes a positive electrode current collector electrically connected to the positive electrode active material layer of the power storage unit and exposed on the outer surface of the exterior packaging material, and a negative electrode current collector electrically connected to the negative electrode active material layer of the power storage unit and exposed on the outer surface of the exterior packaging material. Since terminals extending to the outside of the exterior packaging material can be omitted, the energy density can be increased by the amount of the terminals. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view of an electricity accumulation device according to a first embodiment. [Figure 2] FIG. 10 is a cross-sectional view of an electricity accumulation device according to a second embodiment. [Figure 3] FIG. 10 is a cross-sectional view of an electricity accumulation device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a cross-sectional view of an electricity storage device 10 according to a first embodiment. The electricity storage device 10 includes an electricity storage unit 11 that has a function of storing electricity by converting chemical energy into electrical energy and vice versa, and an exterior material 19 that covers the electricity storage unit 11.

[0013] The electricity storage unit 11 includes a positive electrode 12, a negative electrode 15, and an electrolyte layer 18 provided between the positive electrode 12 and the negative electrode 15. In the electricity storage unit 11, charge carriers move to carry charges between the positive electrode 12 and the negative electrode 15. Examples of charge carriers include metal ions such as lithium ions, sodium ions, potassium ions, rubidium ions, cesium ions, and calcium ions. The metal ions are preferably ions of alkali metals, and lithium ions are particularly preferred.

[0014] The positive electrode 12 includes a positive electrode active material layer 13. A positive electrode current collector 14 is in contact with the positive electrode active material layer 13. The positive electrode active material layer 13 includes an active material. The active material is appropriately selected depending on the type of charge carrier. Examples of the active material include metal oxides containing transition metals, sulfur-based active materials, and organic active materials.

[0015] The positive electrode current collector 14 is a conductive member. Examples of the material of the positive electrode current collector 14 include a metal selected from Ni, Ti, Fe, and Al, an alloy containing two or more of these elements, stainless steel, and a carbon material.

[0016] The negative electrode 15 includes a negative electrode active material layer 16. A negative electrode current collector 17 is in contact with the negative electrode active material layer 16. The negative electrode active material layer 16 includes an active material capable of absorbing and releasing metal ions (charge carriers). The active material may be a carbon-based material such as porous carbon, natural graphite, artificial graphite, graphitizable carbon, non-graphitizable carbon, or carbon fiber, or Li4Ti5O 12 lithium transition metal oxides such as lithium transition metal nitrides, metallic lithium, lithium alloys such as Li-Al alloy, Li-Sn alloy, Li-Mg alloy, antimony alloys such as In-Sb alloy, tin alloys such as SnFe, Si, SiC, compounds containing Si and O as constituent elements (hereinafter referred to as "SiO x" where x is 0.5≦x≦1.5) is an example of a silicon-based material. x Examples of the material include oxides of Si and those having a structure in which microcrystalline or amorphous Si is dispersed in an amorphous SiO2 matrix.

[0017] The negative electrode current collector 17 is a conductive member. Examples of the material of the negative electrode current collector 17 include a metal selected from Ni, Ti, Fe, and Cu, an alloy containing two or more of these elements, and stainless steel.

[0018] In order to reduce the resistance of the positive electrode active material layer 13 or the negative electrode active material layer 16, a conductive additive may be contained in the positive electrode active material layer 13 or the negative electrode active material layer 16. Examples of the conductive additive include carbon black, acetylene black, ketjen black, carbon nanotubes, carbon fiber, Ni, Pt, and Ag.

[0019] The positive electrode active material layer 13 and the negative electrode active material layer 16 may contain a binder that binds the active material. Examples of binders include fluorinated resins, polyolefins, polyimides, polyvinylpyrrolidone, polyvinyl alcohol, cellulose ethers, and rubber-like polymers such as styrene-butadiene rubber. Examples of fluorinated resins include vinylidene fluoride polymers, polychlorotrifluoroethylene, polyvinyl fluoride, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers, tetrafluoroethylene-hexafluoropropylene copolymers, ethylene-tetrafluoroethylene copolymers, and ethylene-chlorotrifluoroethylene copolymers.

[0020] The electrolyte layer 18 is a layer through which charge carriers can move but which does not have electronic conductivity. Examples of the electrolyte layer 18 include those made of a solid electrolyte and those containing a polymer or gel electrolyte. The solid electrolyte includes one or more selected from oxide-based, sulfide-based, hydride-based, and organic-based electrolytes. Examples of organic electrolytes include polyethylene oxide, polypropylene oxide, and polyacrylonitrile. Examples of the power storage unit 11 include all-solid-state batteries, semi-solid-state batteries, quasi-solid-state batteries, and clay batteries in which part of the positive electrode active material layer 13 or the negative electrode active material layer 16 is clay-like.

[0021] The size of the negative electrode active material layer 16 is preferably larger than the size of the positive electrode active material layer 13. This is to reduce electrodeposition caused by charge carriers that move from the positive electrode 12 to the negative electrode 15 when the electricity storage device 10 is charged.

[0022] The exterior material 19 includes a positive electrode current collector 14, a negative electrode current collector 17, and an insulator 20 that electrically insulates the positive electrode current collector 14 and the negative electrode current collector 17. The insulator 20 includes, for example, a surface layer, a barrier layer, and an adhesive layer (none of which are shown), in that order. Examples of materials for the surface layer include polyester-based resins such as polyethylene terephthalate and polyimide. Examples of materials for the barrier layer include metal foils such as aluminum and vapor-deposited layers. Examples of materials for the adhesive layer include olefin-based resins such as polyethylene, polypropylene, and copolymers mainly composed of ethylene-propylene.

[0023] The insulator 20 covers the outer peripheries of the positive electrode active material layer 13, the negative electrode active material layer 16, and the electrolyte layer 18, and is bonded to the entire peripheries of the positive electrode current collector 14 and the negative electrode current collector 17. A sealing material (not shown) seals the gap between the edge of the positive electrode current collector 14 and the edge of the insulator 20, and the gap between the edge of the negative electrode current collector 17 and the edge of the insulator 20. An example of the sealing material is epoxy resin. The positive electrode active material layer 13, the negative electrode active material layer 16, and the electrolyte layer 18 are vacuum-sealed in an exterior material 19, and the positive electrode current collector 14 and the negative electrode current collector 17 are exposed to the outer surface of the exterior material 19.

[0024] In the electricity storage device 10, an external circuit (not shown) is connected to the positive electrode current collector 14 and the negative electrode current collector 17 exposed on the outer surface of the exterior packaging material 19. In the electricity storage device 10, there is no need to connect terminals to the electricity storage unit 11 and extend the terminals to the outside of the exterior packaging material 19, so terminals can be omitted. This allows the energy density of the electricity storage device 10 to be increased by the amount of the terminals omitted.

[0025] A second embodiment will be described with reference to Fig. 2. In the first embodiment, a case was described in which a positive electrode current collector 14 of an exterior material 19 is directly connected to a positive electrode active material layer 13 of a power storage unit 11, and a negative electrode current collector 17 of an exterior material 19 is directly connected to a negative electrode active material layer 16 of a power storage unit 11. In contrast, in the second embodiment, a case will be described in which a conductor 24 is interposed between a positive electrode active material layer 13 of a power storage unit 22 and a positive electrode current collector 14 of an exterior material 27, and a conductor 26 is interposed between a negative electrode active material layer 16 of a power storage unit 22 and a negative electrode current collector 17 of an exterior material 27. In the second embodiment, the same parts as those described in the first embodiment are designated by the same reference numerals, and the following description will be omitted.

[0026] 2 is a cross-sectional view of an electricity storage device 21 according to the second embodiment. The electricity storage device 21 includes an electricity storage unit 22 having a function of storing electricity, and an exterior material 27 that covers the electricity storage unit 22. The electricity storage unit 22 includes a positive electrode 23, a negative electrode 25, and an electrolyte layer 18 provided between the positive electrode 23 and the negative electrode 25.

[0027] The positive electrode 23 includes a positive electrode active material layer 13 and a conductor 24. The conductor 24 is a conductive member. Examples of materials for the conductor 24 include a metal selected from Ni, Ti, Fe, and Al, an alloy containing two or more of these elements, stainless steel, and a carbon material. The conductor 24 is in contact with the positive electrode active material layer 13.

[0028] The negative electrode 25 includes a negative electrode active material layer 16 and a conductor 26. The conductor 26 is a member having electrical conductivity. Examples of the material of the conductor 26 include a metal selected from Ni, Ti, Fe, and Cu, an alloy containing two or more of these elements, and stainless steel. The conductor 26 is in contact with the negative electrode active material layer 16.

[0029] The exterior material 27 includes a positive electrode current collector 14, a negative electrode current collector 17, and an insulator 28 that electrically insulates the positive electrode current collector 14 from the negative electrode current collector 17. The insulator 28 includes, for example, a surface layer, a barrier layer, and an adhesive layer (none of which are shown), in that order. The positive electrode current collector 14 is in contact with the conductor 24, and the negative electrode current collector 17 is in contact with the conductor 26.

[0030] The insulator 28 covers the outer peripheries of the positive electrode active material layer 13, the negative electrode active material layer 16, the electrolyte layer 18, and the conductors 24, 26, and is bonded to the entire peripheries of the positive electrode current collector 14 and the negative electrode current collector 17. A sealing material (not shown) seals the gap between the edge of the positive electrode current collector 14 and the edge of the insulator 28, and the gap between the edge of the negative electrode current collector 17 and the edge of the insulator 28. The positive electrode active material layer 13, the negative electrode active material layer 16, the electrolyte layer 18, and the conductors 24, 26 are vacuum-sealed in an exterior material 27, and the positive electrode current collector 14 and the negative electrode current collector 17 are exposed to the outer surface of the exterior material 27.

[0031] In the electricity storage device 21, an external circuit (not shown) is connected to the positive electrode current collector 14 and the negative electrode current collector 17 exposed on the outer surface of the exterior material 27. Since the terminals can be omitted, the energy density of the electricity storage device 21 can be increased by the amount corresponding to the elimination of the terminals.

[0032] Comparing the power storage device 10 and the power storage device 21 in the first embodiment, the power storage device 10 can omit the conductors 24 and 26 of the power storage device 21. Compared to the power storage device 21, the power storage device 10 can increase the energy density by the amount corresponding to the elimination of the conductors 24 and 26.

[0033] Since the electricity storage device 21 includes the conductors 24 and 26, the electricity storage unit 22 can be produced by preparing a positive electrode sheet in which the positive electrode active material layer 13 is provided on the conductor 24 and a negative electrode sheet in which the negative electrode active material layer 16 is provided on the conductor 26, and providing an electrolyte layer 18 between the positive electrode sheet and the negative electrode sheet. This makes it easy to manufacture the electricity storage unit 22 housed in the exterior material 27.

[0034] A third embodiment will be described with reference to Fig. 3. In the first and second embodiments, the power storage devices 10, 21 including the power storage units 11, 22 each consisting of a single cell were described. In contrast, in the third embodiment, a power storage device 30 including the power storage unit 31 consisting of a plurality of cells will be described. In the third embodiment, the same parts as those described in the first embodiment are designated by the same reference numerals, and the following description will be omitted.

[0035] 3 is a cross-sectional view of an electricity storage device 30 according to a third embodiment. The electricity storage device 30 includes an electricity storage unit 31 that has a function of storing electricity, and an exterior material 38 that covers the electricity storage unit 31. The electricity storage unit 31 includes a first cell 32, a third cell 33, and a second cell 34. The first cell 32, the third cell 33, and the second cell 34 each include a positive electrode 12, a negative electrode 15, and an electrolyte layer 18 provided between the positive electrode 12 and the negative electrode 15.

[0036] The first cell 32, the third cell 33, and the second cell 34 are arranged horizontally, and the direction in which the first cell 32, the third cell 33, and the second cell 34 are arranged is a direction (width direction of the positive electrode 12, the electrolyte layer 18, and the negative electrode 15) perpendicular to the direction in which the positive electrode 12, the electrolyte layer 18, and the negative electrode 15 are stacked in order (thickness direction of the positive electrode 12, the electrolyte layer 18, and the negative electrode 15). The conductor 35 connects the negative electrode current collector 17 of the first cell 32 and the positive electrode current collector 14 of the third cell 33. The conductor 36 connects the negative electrode current collector 17 of the third cell 33 and the positive electrode current collector 14 of the second cell 34.

[0037] The first cell 32, the third cell 33, and the second cell 34 are connected in series. Insulators 37 are arranged between the first cell 32 and the third cell 33, and between the third cell 33 and the second cell 34. An example of the material of the insulator 37 is an insulating synthetic resin, which is filled in an exterior material 38. The first cell 32, the third cell 33, and the second cell 34 are isolated from each other by the insulators 37.

[0038] The exterior material 38 includes a positive electrode current collector 14, a negative electrode current collector 17, and an insulator 39 that electrically insulates the positive electrode current collector 14 and the negative electrode current collector 17. The insulator 39 includes, for example, a surface layer, a barrier layer, and an adhesive layer (none of which are shown), in that order. The positive electrode current collector 14 is in contact with the positive electrode active material layer 13 of the first cell 32, and the negative electrode current collector 17 is in contact with the negative electrode active material layer 16 of the second cell 34.

[0039] The insulator 39 covers the first cell 32, the second cell 34, and the third cell 33, and is bonded to the entire periphery of the positive electrode current collector 14 and the negative electrode current collector 17. A sealant (not shown) seals the gap between the edge of the positive electrode current collector 14 and the edge of the insulator 39, and the gap between the edge of the negative electrode current collector 17 and the edge of the insulator 39. The first cell 32, the second cell 34, and the third cell 33 are vacuum-sealed in an exterior material 38, and the positive electrode current collector 14 and the negative electrode current collector 17 are exposed to the outer surface of the exterior material 38.

[0040] In the electricity storage device 30, an external circuit (not shown) is connected to the positive electrode current collector 14 and the negative electrode current collector 17 exposed on the outer surface of the exterior packaging material 38. In the electricity storage device 30, there is no need to connect terminals to the electricity storage unit 31 and extend the terminals outside the exterior packaging material 38, and therefore the energy density of the electricity storage device 30 can be increased by the amount of the terminals omitted.

[0041] In the electricity storage device 30, the first cell 32, the second cell 34, and the third cell 33 are connected in series, and therefore the discharge capacity can be made larger than that of an electricity storage device provided with a single cell. The first cell 32, the third cell 33, and the second cell 34 are aligned in the width direction of the positive electrode 12, the electrolyte layer 18, and the negative electrode 15, and therefore the thickness of the electricity storage device 30 can be made thinner than when the first cell 32, the third cell 33, and the second cell 34 are aligned in the thickness direction of the positive electrode 12, the electrolyte layer 18, and the negative electrode 15.

[0042] The present invention has been described above based on the embodiments, but the present invention is not limited to the above embodiments, and it can be easily inferred that various improvements and modifications are possible within the scope of the present invention.

[0043] In the first and second embodiments, the power storage devices 10 and 21 are described as including the power storage units 11 and 22 each composed of a single cell. However, this is not necessarily limited to this. In the first embodiment, it is naturally possible to stack multiple cells each including a positive electrode active material layer 13, an electrolyte layer 18, and a negative electrode active material layer 16 in the thickness direction of the cell. The power storage unit 11 is formed by interposing a conductor between the positive electrode active material layer 13 of one cell and the negative electrode active material layer 16 of another cell so that the negative electrode active material layer 16 does not come into direct contact with the positive electrode active material layer 13. In the second embodiment, it is naturally possible to stack multiple cells each including a conductor 24, a positive electrode active material layer 13, an electrolyte layer 18, a negative electrode active material layer 16, and a conductor 26 in the thickness direction of the cell. This allows the discharge capacity of the power storage devices 10 and 21 to be increased compared to a power storage device having a single cell.

[0044] In the second embodiment, the electricity storage unit 22 is described as including a positive electrode 23 in which a positive electrode active material layer 13 is provided on one side of a conductor 24, and a negative electrode 25 in which a negative electrode active material layer 16 is provided on one side of a conductor 26, but this is not necessarily limited to this. For example, it is of course possible to apply each element in the embodiment to an electricity storage unit including electrode layers (so-called bipolar electrodes) in which a positive electrode active material layer 13 and a negative electrode active material layer 16 are provided on both sides of the conductor 24. If bipolar electrodes and electrolyte layers 18 are alternately stacked and housed in an exterior material 27, an electricity storage device with a so-called bipolar structure can be obtained.

[0045] In the second embodiment, the conductor 24 is disposed between the positive electrode current collector 14 and the positive electrode active material layer 13, and the conductor 26 is disposed between the negative electrode current collector 17 and the negative electrode active material layer 16, but this is not necessarily limited to this. It is of course possible to omit one of the conductors 24, 26 and directly connect the current collector to the active material layer on the other side where the conductor is omitted. The energy density of the electricity storage device 21 can be increased by the amount of the conductor omitted.

[0046] In the third embodiment, the case where three cells 32, 33, and 34 are connected has been described, but the present invention is not necessarily limited to this. The number of cells housed in the exterior material 38 can be set as appropriate.

[0047] In the third embodiment, the cells 32, 33, and 34 are connected in series, but this is not necessarily limited to this. It is of course possible to arrange multiple cells housed in the exterior material 38 in parallel, or to arrange some of the cells arranged in parallel in series.

[0048] In the third embodiment, the case where the cells 32, 33, and 34 are arranged in the width direction of the positive electrode 12, the electrolyte layer 18, and the negative electrode 15 has been described, but this is not necessarily limited to this. It is of course possible to omit the conductors 35 and 36 and stack and connect the cells 32, 33, and 34 in the thickness direction of the positive electrode 12, the electrolyte layer 18, and the negative electrode 15. Since the electricity storage device 30 can be made thinner, the area occupied by the positive electrode 12, the electrolyte layer 18, and the negative electrode 15 of the electricity storage device 30 in the thickness direction can be reduced. [Explanation of symbols]

[0049] 10,21,30 Energy storage devices 11, 22, 31 Power storage unit 12,23 Positive electrode 13 Cathode active material layer 14 Positive electrode current collector 15,25 negative electrode 16 Negative electrode active material layer 17 Negative electrode current collector 18 Electrolyte layer 19, 27, 38 Exterior materials 20, 28, 39 Insulators 24,26 Conductors 32 First Cell 34 Second Cell

Claims

1. a power storage unit including a positive electrode including a positive electrode active material layer, a negative electrode including a negative electrode active material layer, and an electrolyte layer provided between the positive electrode and the negative electrode; an exterior material covering the power storage unit, the exterior material includes a positive electrode current collector electrically connected to the positive electrode active material layer and exposed on an outer surface of the exterior material; a negative electrode current collector electrically connected to the negative electrode active material layer and exposed to an outer surface of the exterior packaging material; an insulator that electrically insulates the positive electrode current collector from the negative electrode current collector.

2. The electricity storage device according to claim 1 , wherein at least one of the positive electrode current collector and the positive electrode active material layer and the negative electrode current collector and the negative electrode active material layer is directly connected.

3. The electricity storage device according to claim 1 , wherein at least one of the connection between the positive electrode current collector and the positive electrode active material layer and the connection between the negative electrode current collector and the negative electrode active material layer is made by interposing a conductor therebetween.

4. the power storage unit includes a first cell and a second cell, each including the positive electrode, the electrolyte layer, and the negative electrode; the first cell and the second cell are electrically connected; the positive electrode current collector is connected to the positive electrode active material layer included in the first cell, The electricity storage device according to claim 1 , wherein the negative electrode current collector is connected to the negative electrode active material layer included in the second cell.

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