Laminate, electrode and power storage device

Abstract

To provide a laminate, an electrode and a power storage device, capable of reducing occurrence of peeling of a current collector and an active material layer.SOLUTION: An electrode includes an active material layer including a positive electrode active material, and a current collector having a back surface attached to a surface of the active material layer. The active material layer includes a first edge surrounding at least part of the outer periphery of the current collector. The surface of the first edge is located on a surface side of the current collector with reference to the back surface of the current collector. A laminate includes an active material layer including a positive electrode active material and an electrolyte layer having a surface attached to a back surface of the active material layer. The electrolyte layer includes a second edge surrounding at least part of the outer periphery of the active material layer. The surface of the second edge is located on a surface side of the active material layer with reference to the back surface of the active material layer.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a laminate, a laminate-type electrode, and an electricity storage device. [Background technology]

[0002] Prior art relating to an electrode including, in order, an active material layer containing a positive electrode active material and a current collector, and a laminate including, in order, an active material layer containing a positive electrode active material and an electrolyte layer, is disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-32294 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the prior art, the active material layer and the current collector are of the same size, so there is a risk of peeling off to the current collector, and the electrolyte layer and the active material layer are of the same size, so there is also a risk of peeling off from the active material layer.

[0005] The present invention has been made to solve this problem, and has an object to provide a laminate, an electrode, and an electricity storage device that can reduce the occurrence of peeling of the current collector and the active material layer. [Means for solving the problem]

[0006] A first aspect for achieving this object is a laminate comprising an active material layer containing a positive electrode active material, and an electrolyte layer having a surface attached to the back surface of the active material layer, wherein the electrolyte layer includes a second edge portion surrounding at least a portion of the outer periphery of the active material layer, and the surface of the second edge portion is located on the front surface side of the active material layer with respect to the back surface of the active material layer.

[0007] A second aspect is the first aspect, comprising a current collector having a back surface attached to a front surface of an active material layer, the active material layer including a first edge portion surrounding at least a portion of an outer periphery of the current collector, and a second edge portion surrounding at least a portion of the outer periphery of the first edge portion.

[0008] A third embodiment is the second embodiment, wherein the first edge becomes gradually thinner as it approaches the second edge.

[0009] The fourth aspect is the second or third aspect, wherein, in a cross section perpendicular to the back surface of the current collector, an angle between a line including a portion of the interface between the active material layer and the electrolyte layer where the edge of the current collector overlaps in the thickness direction and a line including the back surface of the current collector is 45° or less.

[0010] In a fifth aspect, in any of the second to fourth aspects, the active material layer includes, at a portion where the current collector overlaps in the thickness direction, a sloped portion in which the thickness gradually increases from the portion where the edge of the current collector overlaps in the thickness direction, in a direction away from the second edge portion, based on the thickness of the active material layer at the portion where the edge of the current collector overlaps in the thickness direction.

[0011] In a sixth aspect, in the fifth aspect, the electrolyte layer includes an overlapping portion where the inclined portion overlaps in the thickness direction, the thickness of which gradually increases in a direction approaching the second edge portion.

[0012] A seventh aspect is an electrode including an active material layer containing a positive electrode active material, and a current collector having its back surface attached to the front surface of the active material layer, wherein the active material layer includes a first edge portion surrounding at least a portion of the outer periphery of the current collector, and the surface of the first edge portion is located on the front surface side of the current collector with respect to the rear surface of the current collector.

[0013] An eighth aspect is an electricity storage device comprising a positive electrode layer, a negative electrode layer, and a separator separating the positive electrode layer and the negative electrode layer, wherein the positive electrode layer and the separator include a laminate of any of the first to sixth aspects.

[0014] A ninth aspect is an electricity storage device comprising a positive electrode layer, a negative electrode layer, and a separator separating the positive electrode layer and the negative electrode layer, where the positive electrode layer includes the electrode of the seventh aspect. Effect of the Invention

[0015] According to the electrode of the present invention, the first edge of the active material layer surrounds at least a part of the outer periphery of the current collector, and the surface of the first edge is located on the surface side of the current collector with respect to the back surface of the current collector, so that the occurrence of peeling of the current collector can be reduced. According to the laminate of the present invention, the second edge of the electrolyte layer surrounds at least a part of the outer periphery of the active material layer, and the surface of the second edge is located on the surface side of the active material layer with respect to the back surface of the active material layer, so that the occurrence of peeling of the electrolyte layer can be reduced. Since the electricity storage device of the present invention includes an electrode and a laminate, the occurrence of peeling of the current collector and the active material layer can be reduced. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1(a) is a plan view of the electricity accumulation device according to the first embodiment, and FIG. 1(b) is a cross-sectional view of the electricity accumulation device taken along line Ib-Ib in FIG. 1(a). [Diagram 2] 5A to 5C are schematic diagrams illustrating a manufacturing process of the electricity storage device. [Diagram 3] 3 is a cross-sectional view of the electricity storage device, in which a portion indicated by III in FIG. [Figure 4] FIG. 11 is a cross-sectional view of an electricity accumulation device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Fig. 1(a) is a plan view of an electricity storage device 10 according to a first embodiment. Fig. 1(b) is a schematic cross-sectional view of the electricity storage device 10 taken along line Ib-Ib in Fig. 1(a).

[0018] 1(b), the electricity storage device 10 includes, in order, a positive electrode layer 11, an electrolyte layer 14, and a negative electrode layer 16. The electrolyte layer 14 is a separator that separates the positive electrode layer 11 and the negative electrode layer 16.

[0019] The positive electrode layer 11 (electrode) includes a current collector 12 and an active material layer 13. The current collector 12 is attached to the active material layer 13. The current collector 12 is not particularly limited as long as it has electronic conductivity and can pass current through the active material layer 13. The current collector 12 may be made of a conductive material such as C, Ti, Cr, Ni, Cu, Fe, Mo, Ru, Rh, Ta, W, Os, Ir, Pt, Al, Au, or an alloy containing two or more of these conductive materials (e.g., stainless steel). When Fe is used for the current collector 12, it is preferable that it is coated with Ni, Cu, or the like to prevent oxidation. The shape of the current collector 12 is not limited, and examples thereof include a linear, rod-like, plate-like, foil-like, and porous shape.

[0020] The active material layer 13 includes a positive electrode active material. Examples of the positive electrode active material include a metal oxide having a transition metal, a sulfur-based active material, and an organic active material. Examples of the metal oxide having a transition metal include a metal oxide containing Li and one or more elements selected from Mn, Co, Ni, Fe, Cr, and V. Examples of the metal oxide having a transition metal include LiCoO2, LiNi 0.8 Co 0.15 Al 0.05 O2, LiMn2O4, LiNiVO4, LiNi 0.5 Mn 1.5 O4, LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 Examples include O2 and LiFePO4.

[0021] Examples of sulfur-based active materials include S, TiS2, NiS, FeS2, Li2S, MoS3, and sulfur-carbon composites. Examples of organic active materials include radical compounds such as 2,2,6,6-tetramethylpiperidinoxyl-4-yl methacrylate and polytetramethylpiperidinoxyl vinyl ether, quinone compounds, radialene compounds, tetracyaquinodimethane, and phenazine oxide.

[0022] The active material layer 13 contains a binder that binds the positive electrode active material. Examples of the binder include fluorinated resins, polyolefins, polyvinylpyrrolidone, polyvinyl alcohol, cellulose ether, polyimide, polyamide, polyamideimide, and rubber-like polymers such as styrene-butadiene rubber. Examples of the fluorinated resins include vinylidene fluoride polymers, polychlorotrifluoroethylene, polyvinyl fluoride, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers, tetrafluoroethylene-hexafluoropropylene copolymers, ethylene-tetrafluoroethylene copolymers, and ethylene-chlorotrifluoroethylene copolymers. These may be used alone or in combination.

[0023] 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.

[0024] There is no particular restriction on the vinylidene fluoride polymer as long as it contains -CH2CF2-. Examples of the vinylidene fluoride polymer include a homopolymer of vinylidene fluoride and a copolymer of vinylidene fluoride and a copolymerizable monomer. Examples of the copolymerizable monomer include a halogen-containing monomer (excluding vinylidene fluoride) and a non-halogen copolymerizable monomer. Examples of the halogen-containing monomer include a chlorine-containing monomer such as vinyl chloride; a fluorine-containing monomer such as trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, and perfluoroalkyl vinyl ether. Examples of the non-halogen copolymerizable monomer include an olefin such as ethylene or propylene; an acrylic monomer such as acrylic acid, methacrylic acid, and esters or salts thereof; and a vinyl monomer such as acrylonitrile, vinyl acetate, and styrene. One or more types of copolymerizable monomers are polymerized to vinylidene fluoride to form a copolymer.

[0025] To improve the ionic conductivity of the active material layer 13, an electrolyte is contained in the active material layer 13. The electrolyte is exemplified by solid electrolyte particles and an electrolytic solution. The solid electrolyte includes at least one selected from sulfide-based, oxide-based, hydride-based, halide-based, and organic-based solid electrolytes. The sulfide-based solid electrolyte includes crystalline thiolithium type, Li 10 GeP2S 12 type, argyrodite type, Li7P3S 11 Examples include glass and glass ceramics such as Li2S-P2S5.

[0026] Examples of oxide-based solid electrolytes include NASICON-based materials, LISICON-based materials, oxides having a perovskite structure, and oxides having a garnet structure. NASICON-based materials are represented by the general formula A x It is a material represented by M2(TO4)3. A is exemplified by Na and Li, M is exemplified by Zr, Ti, V, Mn, Cr, Fe, Ni, Al, Ge, and T is exemplified by P, Si, As. For example, Na3V2(PO4)3, Li 1+x Al x Ti 2-x (PO4)3, Li 1+x Ge x Ti 2-x (PO4)3 is an example.

[0027] LISICON-based materials are Li 4-2x Zinc x GeO4 (0≦x≦1). Oxides with a perovskite structure include Li x La (1-x) / 3 NbO3, La 2 / 3-X Li 3X TiO3 (0≦x≦1). The crystal structure of garnet-type oxides is represented by the general formula C3A2B3O 12 The oxides having a garnet structure are preferred because they have excellent resistance to reduction.

[0028] The garnet-type crystal structure can be identified by X-ray diffraction. The garnet-type crystal structure is found in the Cambridge Structural Database (CSD) X-ray diffraction file No. 422259 (Li7La3Zr2O12 ) has an XRD pattern similar to that of No. 422259. The solid electrolyte may differ in the type of constituent elements and Li concentration, and therefore the diffraction angle and intensity ratio may differ when compared to No. 422259. The typical crystal structure of this type is a cubic system (space group Ia-3d (- indicates an overline that means a reversal operation), JCPDS: 84-1753).

[0029] Solid electrolytes with a garnet-type crystal structure are typically Li7La3Zr2O 12 The solid electrolyte is Li7La3Zr2O 12 A part of the constituent elements may be replaced with other elements, or a small amount of other elements may be added without replacing the constituent elements. Examples of the other elements include at least one element selected from the group consisting of Mg, Al, Si, Ca, Ti, V, Ga, Sr, Y, Nb, Sn, Sb, Ba, Hf, Ta, W, Bi, Rb, and lanthanoids (excluding La).

[0030] Examples of hydride-based solid electrolytes include solid solutions of LiBH4 with lithium halide compounds (LiI, LiBr, LiCl) and lithium amide (LiNH2). Examples of halide solid electrolytes include Li3YCl6. Examples of organic solid electrolytes include polyethylene oxide, polypropylene oxide, and polyacrylonitrile.

[0031] The electrolyte is a medium in which carrier ions move, and is a solution in which a metal salt is dissolved in a solvent. There is no particular limitation on the solvent as long as the metal salt is soluble in the solvent. Aqueous solvents and non-aqueous solvents can be used without limitation. Examples of non-aqueous solvents include carbonate esters, aliphatic carboxylate esters, phosphate esters, γ-lactones, ethers, nitriles, sulfolane, dimethyl sulfoxide, fluorous solvents, and ionic liquids. A mixture of these may also be used.

[0032] The ionic liquid may be a solvated ionic liquid, for example, a metal salt dissolved in a sulfone-based solvent such as sulfolane or a sulfolane derivative, or a glyme-based solvent such as tetraglyme.

[0033] The anion of the metal salt is a halide ion (I - ,Cl - ,Br - etc.),SCN - ,BF4 - ,BF3(CF3) - ,BF3(C2F5) - ,PF6 - ,ClO4 - ,SbF6 - ,N(SO2F)2 - ,N(SO2CF3)2 - ,N(SO2C2F5)2 - ,B(C6H5)4 - ,B(O2C2H4)2 - ,C(SO2F)3 - ,C(SO2CF3)3 - ,CF3COO - ,CF3SO2O - ,C6F5SO2O - ,B(O2C2O2)2 - ,RCOO - (R is an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a naphthyl group). The metal salt may be a mixture of these.

[0034] A conductive material may be contained in the active material layer 13 to reduce the resistance of the active material layer 13. Examples of the conductive material include carbon black, acetylene black, ketjen black, carbon fiber, Ni, Pt, and Ag.

[0035] The electrolyte layer 14 contains particles of a solid electrolyte. The solid electrolyte contains one or more types selected from sulfides, oxides, hydrides, halides, and organics. The electrolyte layer 14 contains a binder that binds the solid electrolyte particles together. The electrolyte layer 14 may also contain an electrolytic solution. The solid electrolyte, binder, and electrolytic solution contained in the electrolyte layer 14 are the same as those contained in the active material layer 13. The laminate 15 contains the active material layer 13 and the electrolyte layer 14.

[0036] The negative electrode layer 16 includes a current collector 17 and an active material layer 18. The current collector 17 is attached to the active material layer 18. The current collector 17 is not particularly limited as long as it has electronic conductivity and can pass current through the active material layer 18. The current collector 17 may be made of a conductive material such as C, Ti, Cr, Ni, Cu, Fe, Mo, Ru, Rh, Ta, W, Os, Ir, Pt, Al, Au, or an alloy containing two or more of these conductive materials (e.g., stainless steel). When Fe is used for the current collector 17, it is preferable that it is coated with Ni, Cu, or the like to prevent oxidation. The shape of the current collector 17 is also not limited, and examples thereof include a linear, rod-like, plate-like, foil-like, and porous shape.

[0037] The active material layer 18 includes a negative electrode active material. The negative electrode active material is not particularly limited as long as it is a material capable of reversibly absorbing and releasing cations. The mechanism of absorbing and releasing ions may be dissolution and precipitation of a substance, insertion and desorption of ions between crystal layers, or the like. The negative electrode active material may be, for example, one or more elements selected from the group consisting of Li, Na, K, C, Mg, Al, Si, P, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Pd, Ag, Cd, In, Sn, Sb, W, Pb, and Bi, or an alloy, composite, oxide, chalcogenide, or halide using these elements.

[0038] The negative electrode active material is used to change the electrode potential from 0V to 1V (vs. Li +From the viewpoint of keeping the range of the negative electrode active material content (wt. / Li), at least one element selected from the group consisting of Li, Na, K, C, Mg, Al, Si, Ti, Zn, Ge, Fe, Mn, Ag, Cu, In, Sn, and Pb, or an allotrope, alloy, or oxide of these elements is preferred. From the viewpoint of increasing the energy density, the negative electrode active material preferably contains an element such as Al, Si, Zn, Ge, Ag, or Sn.

[0039] The alloy as the negative electrode active material is preferably Si-Al, Al-Zn, Si-Mg, Si-La, Al-Ge, Si-Ge, Si-Ag, Si-Sn, Si-Ti, Si-Y, Si-Cr, Si-Ni, Si-Zr, Si-V, Si-Nb, Si-Mo, Zn-Sn, Ge-Ag, Ge-Sn, Ge-Sb, Ag-Sn, Ag-Ge, Sn-Sb, etc., and may be a complete solid solution type alloy, a eutectic alloy, a hypoeutectic alloy, a hypereutectic alloy, or a peritectic type alloy. The oxide is Fe2O3, CuO, MnO2, NiO, Li4Ti5O 12 , H2Ti 12 O 25 , Na2Ti3O7, etc. are preferred. The negative electrode active material may be coated with a material or ceramics having excellent electronic conductivity. The negative electrode active material may be made of two or more materials. The shape of the negative electrode active material is not particularly limited, and may be spherical, elliptical, faceted, strip-shaped, fibrous, scaly, torus-shaped, or hollow.

[0040] The active material layer 18 may contain a binder that binds the negative electrode active material. The active material layer 13 may contain an electrolyte to improve the ionic conductivity of the active material layer 18. The active material layer 18 may contain a conductive material to reduce the resistance of the active material layer 18. The electrolyte, binder, and conductive material contained in the active material layer 18 are the same as those contained in the active material layer 13.

[0041] The size of the current collector 12 of the positive electrode layer 11 is smaller than the size of the active material layer 13, which is smaller than the size of the electrolyte layer 14. The size of the current collector 17 of the negative electrode layer 16 is approximately the same as the size of the active material layer 18. The size of the electrolyte layer 14 is approximately the same as the size of the negative electrode layer 16. The current collector 12 is embedded in the active material layer 13, and the active material layer 13 is embedded in the electrolyte layer 14.

[0042] An example of a method for producing the electricity storage device 10 will be described with reference to Fig. 2. Fig. 2 is a schematic diagram showing the manufacturing process of the electricity storage device 10.

[0043] A solution in which a binder is dissolved is mixed with a mixture of positive electrode active material and solid electrolyte particles to prepare a slurry for the active material layer 13. The slurry is applied onto a current collector 12 such as an aluminum foil, and then dried to obtain a positive electrode sheet 19 (green sheet) for the positive electrode layer 11.

[0044] A solution in which a binder is dissolved is mixed with the mixture of the negative electrode active material and conductive material to prepare a slurry for the active material layer 18. The slurry is applied onto a current collector 17 such as copper foil and then dried. A solution in which a binder is dissolved is mixed with particles of a solid electrolyte to prepare a slurry for the electrolyte layer 14. The slurry is applied onto the active material layer 18 and then dried to obtain a negative electrode sheet 20 (green sheet).

[0045] The positive electrode sheet 19 and the negative electrode sheet 20 are cut so that the size of the positive electrode sheet 19 is smaller than the size of the negative electrode sheet 20, and then the positive electrode sheet 19 is overlapped on the negative electrode sheet 20 so that the active material layer 13 of the positive electrode sheet 19 is in contact with the electrolyte layer 14 of the negative electrode sheet 20, thereby obtaining a laminate 21.

[0046] When a force is applied to laminate 21 using a pressing device such as a roll press in a direction pressing current collectors 12, 17 against each other, active material layer 13 containing the binder is sandwiched between current collector 12 and electrolyte layer 14 and stretches in a direction intersecting with the direction of the force, and current collector 12 bites into active material layer 13. Electrolyte layer 14 containing the binder deforms, and active material layer 13 bites into electrolyte layer 14. In this state, electricity storage device 10 is obtained in which positive electrode layer 11, electrolyte layer 14, and negative electrode layer 16 are in close contact with each other.

[0047] The electricity storage device 10 has terminals (not shown) connected to the current collectors 12 and 17, respectively, and is sealed in a case (not shown). Since the area of ​​the negative electrode layer 16 is larger than the area of ​​the positive electrode layer 11, it is possible to reduce metal deposition in the negative electrode layer 16 when the electricity storage device 10 is charged.

[0048] Fig. 3 is a cross-sectional view of the electricity storage device 10 in which a portion indicated by III in Fig. 1 is enlarged. In each part of the electricity storage device 10, the surface facing upward in Fig. 3 is referred to as the front surface, and the surface facing downward in Fig. 3 is referred to as the back surface. Fig. 3 is a cross section perpendicular to the back surface 22 of the current collector 12.

[0049] The back surface 22 of the current collector 12 included in the positive electrode layer 11 (electrode) is attached to the surface of the active material layer 13. The active material layer 13 includes a first edge 26 that surrounds at least a part of the outer periphery 24 of the current collector 12. In this embodiment, as shown in FIG. 1(a), the first edge 26 surrounds the entire outer periphery 24 of the current collector 12. The surface 27 of the first edge 26 is located on the front surface 23 side of the current collector 12 with respect to the back surface 22 of the current collector 12. The current collector 12 is embedded in the active material layer 13 such that the back surface 22 of the current collector 12 is lower than the surface 27 of the first edge 26.

[0050] As electricity storage device 10 is charged and discharged, active material layer 13 expands and contracts in the thickness direction and in the planar direction perpendicular to the thickness direction, but because current collector 12 bites into active material layer 13, peeling of current collector 12 from active material layer 13, which expands and contracts in the planar direction, can be reduced. In addition, because outer periphery 24 of current collector 12 is inside first edge 26, current collector 12 is less likely to get caught on hands, etc., when electricity storage device 10 is handled. This reduces peeling of current collector 12.

[0051] The ratio of the height of front surface 27 of first edge portion 26 relative to back surface 22 of current collector 12 (the thickness from front surface 27 of first edge portion 26 to back surface 22) to the thickness of current collector 12 may be 0% or more, but is particularly preferably 10% or more. This is because the effect of reducing peeling of current collector 12 increases as the ratio increases, but becomes significant when the ratio is 10% or more.

[0052] In the laminate 15, the back surface 29 of the active material layer 13 is attached to the surface of the electrolyte layer 14. The electrolyte layer 14 includes a second edge portion 30 surrounding at least a part of the outer periphery 28 of the active material layer 13. In this embodiment, as shown in FIG. 1(a), the second edge portion 30 surrounds the entire outer periphery 28 of the active material layer 13. The surface 31 of the second edge portion 30 is located on the surface 27 side of the active material layer 13 with respect to the back surface 29 of the active material layer 13. The back surface 29 is a substantially flat surface where a central portion 36 (described later) of the active material layer 13 contacts the electrolyte layer 14. The active material layer 13 is embedded in the electrolyte layer 14 so that the back surface 29 of the active material layer 13 is lower than the surface 31 of the second edge portion 30.

[0053] Although active material layer 13 expands and contracts as electricity storage device 10 is charged and discharged, peeling of active material layer 13 can be reduced because active material layer 13 bites into electrolyte layer 14. Furthermore, current collector 12 biting into active material layer 13 reduces the expansion and contraction of active material layer 13 in the planar direction, so peeling of active material layer 13 can be reduced.

[0054] The interface 32 between the active material layer 13 and the electrolyte layer 14 is inclined so that the distance between the surface 27 of the first edge 26 and the interface 32 becomes shorter as it approaches the second edge 30. Therefore, the first edge 26 gradually becomes thinner as it approaches the second edge 30. This increases the interface 32 (bonding area) compared to when the surface 27 of the first edge 26 and the interface 32 are approximately parallel, thereby further reducing peeling of the first edge 26.

[0055] A straight line including a portion 33 of the interface 32 where the edge 25 (edge ​​of the back surface 22) of the current collector 12 overlaps in the thickness direction is inclined with respect to a straight line 34 including the back surface 22 of the current collector 12. If the vicinity of the portion 33 of the interface 32 is a straight line, the straight line including the portion 33 is an extended straight line (the interface 32 in this embodiment), and if the vicinity of the portion 33 is not a straight line, the straight line is a tangent to the portion 33 (point). If the back surface 22 is a straight line, the straight line 34 including the back surface 22 of the current collector 12 is an extended straight line of the back surface 22, and if the back surface 22 is not a straight line, it is an approximation straight line of the back surface 22.

[0056] The angle θ between the line including portion 33 of interface 32 (interface 32) and line 34 is greater than 0° (θ>0°). A smaller angle θ can reduce peeling of first edge portion 26 due to expansion and contraction in the planar direction of active material layer 13. An angle θ of 45° or less is preferable because peeling of first edge portion 26 can be particularly reduced.

[0057] The active material layer 13 includes, in a portion where the current collector 12 overlaps in the thickness direction, an inclined portion 35 in which the thickness gradually increases from the portion 33 as it moves away from the first edge portion 26 or the second edge portion 30, based on the thickness T of the active material layer 13 at the portion 33, and a central portion 36 adjacent to the inclined portion 35. The thickness of the central portion 36 is thicker than the thickness T and is almost constant. Since the thickness of the active material layer 18 of the negative electrode layer 16 is almost constant, the back surface 37 of the electrolyte layer 14 is almost straight. Since the distance between the active material layer 18 and the inclined portion 35 is longer than the distance between the active material layer 18 and the central portion 36, the electrolyte layer 14 includes, in a portion where the inclined portion 35 overlaps in the thickness direction, a first overlapping portion 38 in which the thickness gradually increases toward the second edge portion 30. Even if dendrites generated in the negative electrode layer 16 grow in the electrolyte layer 14, the first overlapping portion 38 located between the edge 25 of the current collector 12, which is prone to short-circuiting, and the negative electrode layer 16 is thick, so that the occurrence of short-circuiting due to dendrite growth can be reduced.

[0058] The electrolyte layer 14 has a second overlapping portion 39 between the second edge portion 30 and the first overlapping portion 38. The second overlapping portion 39 has a thickness that gradually increases in a direction approaching the second edge portion 30. The second overlapping portion 39 adjacent to the first overlapping portion 38 is thicker than the first overlapping portion 38, so that a short circuit caused by dendrites growing in the second overlapping portion 39 can be reduced.

[0059] Since the distance between active material layer 18 and central portion 36 is shorter than the distance between active material layer 18 and inclined portion 35, the migration distance of ions in electrolyte layer 14 between central portion 36 and active material layer 18 can be made shorter than the migration distance of ions between inclined portion 35 and active material layer 18. Since the volume of central portion 36 is larger than the volume of inclined portion 35, the resistance of electrolyte layer 14 can be reduced, and the internal resistance of electricity storage device 10 can be reduced.

[0060] The second embodiment will be described with reference to Fig. 4. In the first embodiment, the active material layer 13 includes an inclined portion 35 at a portion where the current collector 12 overlaps in the thickness direction. In contrast, in the second embodiment, the active material layer 13 does not have an inclined portion. In the second embodiment, the same parts as those described in the first embodiment are denoted by the same reference numerals, and the following description will be omitted. Fig. 4 is a schematic cross-sectional view perpendicular to the back surface 22 of the current collector 12 of an electricity storage device 40 in the second embodiment.

[0061] The electricity storage device 40 includes, in this order, a positive electrode layer 11, an electrolyte layer 14, and a negative electrode layer 16. A surface 27 of a first edge portion 26 of the active material layer 13 is located on the surface 23 side of the current collector 12 with respect to a back surface 22 of the current collector 12. The current collector 12 is embedded in the active material layer 13 such that the back surface 22 of the current collector 12 is lower than the surface 27 of the first edge portion 26. Since the surface 23 of the current collector 12 and the surface 27 of the first edge portion 26 are located in substantially the same plane, the current collector 12 is less likely to be caught by a hand or the like when the electricity storage device 40 is handled. This further reduces peeling of the current collector 12.

[0062] In laminate 15 (see FIG. 1(b)), surface 31 of second edge portion 30 of electrolyte layer 14 is located on the surface 27 side of active material layer 13 with respect to back surface 29 of active material layer 13. In other words, active material layer 13 is embedded in electrolyte layer 14.

[0063] The interface 41 between the active material layer 13 and the electrolyte layer 14 is inclined so that the distance between the surface 27 of the first edge 26 and the interface 32 becomes shorter as the interface approaches the second edge 30. In this embodiment, the line indicating the interface 41 is a convex curve toward the negative electrode layer 16. Since the interface 41 (bonding area) is larger than when the surface 27 of the first edge 26 and the entire interface 41 are substantially parallel, peeling of the first edge 26 can be further reduced.

[0064] A straight line including a portion 42 of interface 41 where edge 25 (edge ​​of back surface 22) of current collector 12 overlaps in the thickness direction is approximately parallel to a straight line including back surface 22 of current collector 12. Active material layer 13 has many portions where the distance between active material layer 18 and active material layer 13 is short, so that the internal resistance of electricity storage device 40 can be reduced.

[0065] The present invention has been described above based on an embodiment, but the present invention is in no way limited to the above embodiment, and it can be easily inferred that various improvements and modifications are possible within the scope of the present invention without departing from the spirit of the present invention.

[0066] In the embodiment, the electricity storage device 10, 40 in which the electrolyte layer 14 containing solid electrolyte particles is disposed between the positive electrode layer 11 and the negative electrode layer 16 has been described, but the present invention is not necessarily limited to this. It is of course possible to dispose a separator not containing a solid electrolyte between the positive electrode layer 11 and the negative electrode layer 16 instead of the electrolyte layer 14. The separator is exemplified by a porous body that allows metal ions contained in the electrolyte solution to pass through but does not have electronic conductivity. The porous body is exemplified by a nonwoven fabric or a porous membrane made of cellulose, polypropylene, polyethylene, or the like. The electrolyte layer 14 may be one in which a gel electrolyte having ion conductivity is disposed.

[0067] It is of course possible to dispose a protective layer between the electrolyte layer 14 (separator) and the active material layer 18. The protective layer includes, for example, a solid electrolyte. The protective layer interposed between the electrolyte layer 14 and the active material layer 18 reduces short circuits caused by dendrite growth resulting from metal precipitation.

[0068] It is of course possible to dispose a protective layer between the active material layer 18 and the current collector 17. The protective layer contains, for example, a solid electrolyte. The protective layer interposed between the active material layer 18 and the current collector 17 reduces deterioration of the current collector 17.

[0069] In the embodiment, the positive electrode layer 11 (electrode) has the first edge portion 26 surrounding the entire outer periphery 24 of the current collector 12, but is not necessarily limited to this. This is because if the first edge portion 26 surrounds a part of the outer periphery 24 of the current collector 12, the part of the outer periphery 24 of the current collector 12 that is inside the first edge portion 26 is less likely to peel off. When the outer shape of the current collector 12 is rectangular, examples include one in which the first edge portion 26 surrounds three sides of the current collector 12, and one in which the first edge portion 26 surrounds two sides of the current collector 12.

[0070] In the embodiment, in the laminate 15, the second edge portion 30 surrounds the entire outer periphery 28 of the active material layer 13, but this is not necessarily limited to this. If the second edge portion 30 surrounds a part of the outer periphery 28 of the active material layer 13, the part of the outer periphery 28 of the active material layer 13 that is inside the second edge portion 30 will be less likely to peel off. When the outer shape of the active material layer 13 is rectangular, examples include one in which the second edge portion 30 surrounds three sides of the active material layer 13, and one in which the second edge portion 30 surrounds two sides of the active material layer 13.

[0071] In the embodiment, a case has been described in which active material layer 13 is larger than current collector 12, and electrolyte layer 14 is larger than active material layer 13, but this is not necessarily limited to this. When active material layer 13 is larger than current collector 12, active material layer 13 and electrolyte layer 14 may be the same size, and when electrolyte layer 14 is larger than active material layer 13, current collector 12 and active material layer 13 may be the same size.

[0072] In the second embodiment, the interface 41 between the active material layer 13 and the electrolyte layer 14 has a convex curve toward the negative electrode layer 16, but this is not necessarily limited to this. The shape of the interface 41 is just one example, and it may be curved or linear. [Explanation of symbols]

[0073] 10,40 Energy storage devices 11 Positive electrode layer (electrode) 12 Current collector 13 Active material layer 14 Electrolyte layer (separator) 15 Laminate 16 Negative electrode layer 22 Back side of current collector 24 Outer circumference of current collector 25 Edge of current collector 26 First edge 27 First edge surface 28 Outer periphery of active material layer 29 Back side of active material layer 30 Second edge 31 second edge surface 32 Interface 33 parts 34 straight line 35 Slope 38 First overlapping part (overlapping part) T Thickness θ angle

Claims

1. an active material layer including a positive electrode active material; a laminate comprising: an electrolyte layer having a surface attached to a back surface of the active material layer, the electrolyte layer includes a second edge portion surrounding at least a portion of an outer periphery of the active material layer, A laminate in which a surface of the second edge portion is located on the surface side of the active material layer with respect to the back surface of the active material layer.

2. a current collector having a back surface attached to the front surface of the active material layer, the active material layer includes a first edge portion surrounding at least a portion of an outer periphery of the current collector, The laminate of claim 1 , wherein the second edge surrounds at least a portion of an outer periphery of the first edge.

3. 3. The laminate of claim 2, wherein the first edge becomes thinner as it approaches the second edge.

4. In a cross section perpendicular to the back surface of the current collector, 4. The laminate according to claim 2, wherein an angle formed by a straight line including a portion of an interface between the active material layer and the electrolyte layer where an edge of the current collector overlaps in a thickness direction and a straight line including the back surface of the current collector is 45° or less.

5. 4. The laminate according to claim 2 or 3, wherein the active material layer includes an inclined portion in which the thickness gradually increases from a portion where the current collector overlaps in the thickness direction, in a direction away from the second edge portion, based on a thickness of the active material layer at a portion where the edge of the current collector overlaps in the thickness direction.

6. The laminate according to claim 5 , wherein the electrolyte layer includes an overlapping portion where the inclined portion overlaps in the thickness direction, the thickness of the overlapping portion gradually increasing in a direction approaching the second edge portion.

7. An electrode comprising an active material layer including a positive electrode active material and a current collector having a back surface attached to a front surface of the active material layer, the active material layer includes a first edge portion surrounding at least a portion of an outer periphery of the current collector, An electrode in which a surface of the first edge portion is located on the surface side of the current collector with respect to the back surface of the current collector.

8. An electricity storage device comprising a positive electrode layer, a negative electrode layer, and a separator separating the positive electrode layer and the negative electrode layer, The positive electrode layer and the separator include the laminate according to claim 1 .

9. An electricity storage device comprising a positive electrode layer, a negative electrode layer, and a separator separating the positive electrode layer and the negative electrode layer, The positive electrode layer comprises the electrode according to claim 7 .

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