Solid secondary battery

Abstract

To provide a solid secondary battery capable of insulating a side surface of a positive electrode layer over a long period of time without generating a gap.SOLUTION: A solid secondary battery comprises: an electrode laminate 1 including a positive electrode layer 10, a negative electrode layer 20, and a solid electrolyte layer 30 disposed between the positive electrode layer 10 and the negative electrode layer 20, in which at least one of the negative electrode layer 20 and the solid electrolyte layer 30 includes a projection part 32a projected from the positive electrode layer in a plan view; an insulating frame 40 disposed on an outer periphery of the positive electrode layer 10; and an elastic body 50 disposed between the insulating frame 40 and the projection part 32a.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a solid secondary battery. [Background technology]

[0002] In recent years, research and development has been conducted on secondary batteries that contribute to energy efficiency, ensuring that more people have access to affordable, reliable, sustainable, and advanced energy. Among secondary batteries, solid-state secondary batteries having an electrode stack in which a solid electrolyte layer is disposed between a positive electrode layer and a negative electrode layer have attracted particular attention due to their superior safety due to the non-flammable solid electrolyte and their higher energy density. In solid-state secondary batteries, an insulating frame is disposed around the positive electrode layer to prevent misalignment or short-circuiting of the positive electrode layer, solid electrolyte layer, and negative electrode layer of the electrode stack, and the negative electrode layer is disposed on the positive electrode layer surrounded by the insulating frame via the solid electrolyte layer (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-77228 Summary of the Invention [Problem to be solved by the invention]

[0004] However, extending the lifespan of solid-state secondary batteries is an issue. Placing an insulating frame around the positive electrode layer of a solid-state secondary battery is effective for achieving this. However, maintaining a consistent basis weight of the positive electrode active material layer during industrial production of the positive electrode layer results in slight variations in the thickness of the positive electrode layer. Furthermore, the solid electrolyte layer and the insulating frame have roughness. This can lead to gaps between the solid electrolyte layer and the insulating frame. Furthermore, the use of lithium as the negative electrode active material has been considered to increase the capacity of solid-state secondary batteries. When lithium is used as the negative electrode active material, the thickness of the negative electrode layer changes during charging and discharging, which can cause deformation of the solid electrolyte layer between the positive and negative electrode layers and lead to gaps between the solid electrolyte layer and the insulating frame. If a gap forms between the solid electrolyte layer and the insulating frame, the solid electrolyte layer may be deformed and cracked due to external pressure or impact, such as pressing during solid-state secondary battery manufacturing, restraint of the solid-state secondary battery, or vibration during transportation of the solid-state secondary battery. Furthermore, if a gap occurs between the solid electrolyte layer and the insulating frame, foreign matter may get mixed in with the side surface of the positive electrode layer.

[0005] The present invention has been made in view of the above circumstances, and aims to provide a solid secondary battery in which an insulating frame can be stably disposed around a positive electrode layer for a long period of time without generating a gap between the insulating frame and the solid electrolyte layer, thereby contributing to improved energy efficiency. [Means for solving the problem]

[0006] The present inventors discovered that the above-mentioned problems can be solved by providing a protrusion on at least one of the negative electrode layer and the solid electrolyte layer that protrudes from the positive electrode layer in a plan view, and by disposing an elastic body between the protrusion and an insulating frame that is disposed around the outer periphery of the positive electrode layer, and thus completed the present invention.

[0007] (1) A solid secondary battery comprising: an electrode laminate including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein at least one of the negative electrode layer and the solid electrolyte layer has a protruding portion protruding from the positive electrode layer in a plan view; an insulating frame disposed on an outer periphery of the positive electrode layer; and an elastic body disposed between the insulating frame and the protruding portion.

[0008] In the solid secondary battery (1), an elastic body is disposed between the protruding portion of the electrode laminate and the insulating frame disposed on the outer periphery of the positive electrode layer, so that the insulating frame can be stably insulated around the positive electrode layer for a long period of time without generating a gap between the insulating frame and the solid electrolyte layer.

[0009] (2) The solid secondary battery according to (1), wherein the width of the elastic body is equal to or smaller than the width of the insulating frame body.

[0010] In the solid secondary battery (2), the width dimension of the elastic body is the same as or smaller than the width dimension of the insulating frame body. Therefore, even if pressure is applied to the elastic body and the elastic body is deformed, the elastic body is unlikely to jump out beyond the insulating frame body.

[0011] (3) The solid secondary battery according to (1) or (2), wherein the positive electrode layer has a positive electrode current collector and two positive electrode active material layers stacked on both sides of the positive electrode current collector, the negative electrode layer and the solid electrolyte layer are disposed opposite each other with the positive electrode layer interposed therebetween, the protrusions are disposed opposite each other with the positive electrode layer interposed therebetween, and the insulating frame is disposed between the protrusions disposed opposite each other.

[0012] In the solid secondary battery (3), an insulating frame is disposed between the protrusions arranged opposite each other so as to sandwich the positive electrode layer of the electrode laminate, with an elastic body interposed therebetween, so that the side surface of the positive electrode layer can be insulated more stably.

[0013] (4) The solid secondary battery according to (1) or (2), wherein the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer laminated on one surface of the positive electrode current collector, the positive electrode current collector has a protruding portion protruding from the positive electrode active material layer in a plan view, and the insulating frame is disposed between the protruding portion of the positive electrode current collector and the protruding portion of at least one of the negative electrode layer and the solid electrolyte layer.

[0014] In the solid secondary battery (4), an insulating frame is disposed between the protruding portion of the positive electrode current collector of the positive electrode layer and the protruding portion of at least one of the negative electrode layer and the solid electrolyte layer, via an elastic body, so that the side surface of the positive electrode active material layer can be insulated more stably. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a solid secondary battery in which an insulating frame can be stably disposed around a positive electrode layer for a long period of time without generating a gap between the insulating frame and the solid electrolyte layer. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a plan view showing a solid secondary battery according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 2 is a cross-sectional view showing the charged state of the solid secondary battery shown in FIG. [Figure 5] 2A to 2C are cross-sectional views illustrating a method for manufacturing the solid secondary battery shown in FIG. [Figure 6] FIG. 2 is a cross-sectional view showing a solid secondary battery according to a first modified example of the present invention. [Figure 7] FIG. 7 is a cross-sectional view showing the charged state of the solid secondary battery shown in FIG. [Figure 8] FIG. 10 is a cross-sectional view showing a solid secondary battery according to a second modified example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments described below are merely examples of the present invention, and the present invention is not limited to the following.

[0018] Fig. 1 is a plan view showing a solid secondary battery according to one embodiment of the present invention, Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1, and Fig. 3 is a cross-sectional view taken along line III-III in Fig. 1. As shown in FIGS. 1 to 3, the solid secondary battery includes an electrode laminate 1, an insulating frame 40, and an elastic body 50.

[0019] The electrode laminate 1 is a laminate including a positive electrode layer 10, a negative electrode layer 20, and a solid electrolyte layer 30 disposed between the positive electrode layer 10 and the negative electrode layer 20. The positive electrode layer 10 includes a positive electrode current collector 11 and two positive electrode active material layers 12 disposed on both surfaces of the positive electrode current collector 11. The negative electrode layer 20 and the solid electrolyte layer 30 are disposed opposite each other with the positive electrode layer 10 interposed therebetween. Each of the two opposing negative electrode layers 20 includes a negative electrode current collector 21 and a metal layer 22 disposed on the surface of the negative electrode current collector 21 facing the solid electrolyte layer 30. The solid electrolyte layer 30 includes a first solid electrolyte layer 31 disposed on the positive electrode layer 10 side and a second solid electrolyte layer 32 disposed on the negative electrode layer 20 side. The first solid electrolyte layer 31 has the same dimensions as the positive electrode layer 10 in a plan view. The second solid electrolyte layer 32 has a protruding portion 32a protruding from the positive electrode layer 10 in a plan view. The protruding portion 32a is disposed opposite to the positive electrode layer 10. The negative electrode current collector 21 and the metal layer 22 have the same dimensions as the second solid electrolyte layer 32 in a plan view and have protruding portions 21a, 22a. The insulating frame 40 is disposed between the protruding portions 32a of the second solid electrolyte layer 32 disposed opposite to each other. An elastic body 50 is disposed between the insulating frame 40 and the protruding portion 32a of the second solid electrolyte layer 32. A portion of the elastic body 50 in contact with the second solid electrolyte layer 32 is pressurized by the second solid electrolyte layer 32 to form a recessed portion 51. The elastic body 50 is pressurized by the second solid electrolyte layer 32 to form the recessed portion 51, thereby making it less likely that a gap will be formed between the elastic body 50 and the second solid electrolyte layer 32.

[0020] The electrode laminate 1 shown in Figures 1 to 3 is in a discharged state. When the electrode laminate 1 is charged, lithium ions, which serve as a charge transfer medium, released from the positive electrode active material layer 12 pass through the solid electrolyte layer 30 and are deposited on the surface of the metal layer 22 of the negative electrode layer 20, forming a lithium deposit layer, and the thickness of the negative electrode layer 20 increases. The lithium deposit layer acts as a negative electrode active material layer and releases lithium ions during discharge. Therefore, the thickness of the negative electrode layer 20 of the electrode laminate 1 changes as the electrode laminate 1 is charged and discharged.

[0021] FIG. 4 is a cross-sectional view showing a charged state of a solid secondary battery according to one embodiment of the present invention. 4, in the electrode laminate 1 in a charged state, a lithium deposit layer 23 is formed on the surface of the metal layer 22 of the negative electrode layer 20, and the thickness of the negative electrode layer 20 facing the positive electrode layer 10 increases. The formation of the lithium deposit layer 23 forms a gap 24 between the protruding portion 22a of the metal layer 22 and the protruding portion 32a of the second solid electrolyte layer 32.

[0022] The electrode stack 1 is housed in an exterior body (not shown). The exterior body is provided with a positive electrode terminal connected to the positive electrode current collector tab 15 and a negative electrode terminal connected to the negative electrode current collector tab 25.

[0023] There are no particular limitations on the material or shape of the positive electrode current collector 11, as long as it has the function of collecting current from the positive electrode layer 10. Examples of materials for the positive electrode current collector 11 include aluminum, aluminum alloys, stainless steel, nickel, iron, and titanium, and among these, aluminum, aluminum alloys, and stainless steel are preferred. Examples of the shape of the positive electrode current collector 11 include a foil shape and a plate shape.

[0024] The positive electrode active material layer 12 contains at least one type of positive electrode active material. There are no particular limitations on the positive electrode active material, and any material used in the positive electrode layers of general solid-state secondary batteries can be used. Examples of the positive electrode active material that can be used include layered active materials containing lithium, spinel-type active materials, and olivine-type active materials. Specific examples of the positive electrode active material include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and LiNi pMn q Co r O2(p+q+r=1), LiNi p Al q Co r O2 (p+q+r=1), lithium manganese oxide (LiMn2O4), Li 1+x Mn 2-x-y Examples include heteroelement-substituted Li-Mn spinel represented by MO4 (x+y=2, M=at least one selected from Al, Mg, Co, Fe, Ni, and Zn), lithium titanate (oxide containing Li and Ti), and lithium metal phosphate (LiMPO4, M=at least one selected from Fe, Mn, Co, and Ni).

[0025] The positive electrode active material layer 12 may optionally contain a solid electrolyte to improve lithium ion conductivity. It may also optionally contain a conductive additive to improve conductivity. Furthermore, it may also optionally contain a binder to achieve flexibility. There are no particular restrictions on the solid electrolyte, conductive additive, and binder, and those used in the positive electrode layers of general solid secondary batteries can be used.

[0026] The material of the positive electrode current collector tab 15 may be the same as or different from the material of the positive electrode current collector 11. The positive electrode current collector tab 15 may be integrally connected to the positive electrode current collector 11. In this embodiment, the positive electrode current collector tab 15 is formed by extending the positive electrode current collector 11, and is integrally connected to the positive electrode current collector 11.

[0027] The material and shape of the negative electrode current collector 21 are not particularly limited as long as it has the function of collecting current from the negative electrode layer 20. Examples of materials for the negative electrode current collector 21 include nickel, copper, and stainless steel. Examples of the shape of the negative electrode current collector 21 include a foil shape, a plate shape, and the like.

[0028] The metal layer 22 is not particularly limited in material or shape as long as it has the function of densely depositing lithium ions. A metallic lithium layer or a layer of a metal that forms an alloy with lithium can be used as the metal layer 22. Examples of metals that form an alloy with lithium include Mg, Si, Au, Ag, In, Ge, Sn, Pb, Al, and Zn. The metal that forms the metal layer 22 may be in the form of a powder or a thin film. By using the anode layer 20 having this metal layer 22, a uniform lithium deposit layer can be formed on the surface of the metal layer 22.

[0029] The material of the negative electrode current collector tab 25 may be the same as or different from the material of the negative electrode current collector 21. The negative electrode current collector tab 25 may be integrally connected to the negative electrode current collector 21. In this embodiment, the negative electrode current collector tab 25 is formed by extending the negative electrode current collector 21, and is integrally connected to the negative electrode current collector 21.

[0030] The thickness of the first solid electrolyte layer 31 of the solid electrolyte layer 30 may be the same as or different from the thickness of the second solid electrolyte layer 32. The thickness of the second solid electrolyte layer 32 may be, for example, thicker than the thickness of the first solid electrolyte layer 31. The thickness of the second solid electrolyte layer 32 may be, for example, within a range of 1 to 100 times the thickness of the first solid electrolyte layer 31.

[0031] The first solid electrolyte layer 31 and the second solid electrolyte layer 32 each contain at least one type of solid electrolyte. The first solid electrolyte layer 31 and the second solid electrolyte layer 32 each conduct lithium ions between the positive electrode layer 10 and the negative electrode layer 20 via the solid electrolyte. The first solid electrolyte layer 31 and the second solid electrolyte layer 32 may contain the same solid electrolyte or different solid electrolytes.

[0032] The solid electrolyte is not particularly limited as long as it has lithium ion conductivity, but for example, a sulfide solid electrolyte, an oxide solid electrolyte, a nitride solid electrolyte, a halide solid electrolyte, etc. can be used.

[0033] Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-P2S5-LiI, etc. The sulfide solid electrolyte may have an argyrodite-type crystal structure.

[0034] Examples of oxide solid electrolytes include NASICON-type oxides, garnet-type oxides, and perovskite-type oxides. Examples of NASICON-type oxides include oxides containing Li, Al, Ti, P, and O (e.g., Li 1.5 Al 0.5 Ti 1.5 Examples of garnet-type oxides include oxides containing Li, La, Zr, and O (e.g., LiLaZrO 12 Examples of perovskite oxides include oxides containing Li, La, Ti, and O (for example, LiLaTiO3).

[0035] The solid electrolyte layer 30 may contain a binder. There are no particular restrictions on the binder, and any binder that is used in the solid electrolyte layer of a general solid secondary battery can be used.

[0036] The solid electrolyte layer 30 may have a porous substrate inside. The porous substrate may be, for example, a woven fabric or a nonwoven fabric. A solid electrolyte layer having a porous substrate inside has high strength.

[0037] The insulating frame 40 is disposed so as to surround the outer periphery of the positive electrode layer 10. The insulating frame 40 has electronic insulation properties. The melting point of the insulating frame 40 may be equal to or higher than the melting point of lithium. The insulating frame 40 preferably has chemical resistance. The insulating frame 40 preferably has higher shape stability than the elastic body 50. The insulating frame 40 preferably has a higher Young's modulus and a lower Poisson's ratio than the elastic body 50. Materials that can be used for the insulating frame 40 include, for example, resin, ceramic, and a mixture of resin and ceramic. Resins include rubber and elastomers. Examples of resins include PET, PTFE, PI, PVdF, and SBR. These resins may be used alone or in combination of two or more. Ceramics may be used alone or in combination of two or more.

[0038] The elastic body 50 may be disposed in a non-adhered state on the insulating frame 40. The elastic body 50 may be easily deformed to the extent that it is pressurized by the second solid electrolyte layer 32 to form a recess 51. The Poisson's ratio of the elastic body 50 may be, for example, in the range of 0.20 to 0.49. The material of the elastic body 50 is not particularly limited as long as it has a lower Young's modulus than the insulating frame 40. A resin may be used as the material of the elastic body 50. The resin is not particularly limited as long as it is more easily deformable than the insulating frame 40. The thickness of the elastic body 50 may be thicker than the lithium deposition layer 23 formed during charging of the electrode stack 1, for example. The thickness of the elastic body 50 may be, for example, in the range of 1 to 100 times the thickness of the lithium deposition layer 23 formed during charging of the electrode stack 1.

[0039] The exterior body 60 is expandable and contractible in accordance with changes in the thickness of the negative electrode layer 20 due to charging and discharging. A laminate film can be used as the material for the exterior body 60. The laminate film can be a three-layer laminate film having an inner resin layer, a metal layer, and an outer resin layer stacked in this order from the inside. The outer resin layer can be, for example, a polyamide (nylon) layer or a polyethylene terephthalate (PET) layer, the metal layer can be, for example, an aluminum layer, and the inner resin layer can be, for example, a polyethylene layer or a polypropylene layer.

[0040] Next, a method for manufacturing the solid secondary battery of this embodiment will be described. 5 is a cross-sectional view illustrating a method for manufacturing a solid secondary battery according to one embodiment of the present invention. As shown in FIG. 5, the solid secondary battery can be manufactured as follows.

[0041] First, the first solid electrolyte layer 31 is laminated on the upper and lower end faces of the positive electrode layer 10. Next, an insulating frame 40 is placed around the positive electrode layer 10 on which the first solid electrolyte layer 31 is laminated, and elastic bodies 50a are placed on the upper and lower end faces of the insulating frame 40. The elastic bodies 50a have a smaller width than the insulating frame 40. Next, the second solid electrolyte layer 32, the metal layer 22, and the negative electrode current collector 21 are laminated in this order on each end face of the first solid electrolyte layer 31 laminated on the upper and lower end faces of the positive electrode layer 10.

[0042] The resulting stack is then pressed in the stacking direction (the direction of the arrow in FIG. 5). Pressurization by the protruding portion 32a of the second solid electrolyte layer 32 forms a recessed portion 51 in the elastic body 50a, and the elastic body 50a expands in the width direction until it becomes the same width as the insulating frame 40 (see FIG. 3).

[0043] In the solid secondary battery of this embodiment configured as described above, the insulating frame body 40 is disposed between the protruding portions 32a of the second solid electrolyte layers 32 arranged opposite each other with the positive electrode layer 10 of the electrode stack 1 sandwiched therebetween, via the elastic body 50, and therefore the side surfaces of the positive electrode layer 10 can be stably insulated.

[0044] In the solid secondary battery of this embodiment, the insulating frame 40 and the elastic body 50 have the largest outer diameters in a plan view, followed by the anode layer 20 and the second solid electrolyte layer 32, and the smallest outer diameters are those of the cathode layer 10 and the first solid electrolyte layer 31. The outer diameter of the insulating frame 40 is larger than that of the second solid electrolyte layer 32, and the second solid electrolyte layer 32 does not protrude from the insulating frame 40. This makes it possible to suppress cracking of the second solid electrolyte layer 32 and to prevent impurities from being mixed into the periphery of the cathode layer 10 due to cracking of the second solid electrolyte layer 32. Furthermore, by making the outer diameter of the elastic body 50 larger than that of the second solid electrolyte layer 32, it becomes possible to form a recess 51 in the elastic body 50 by applying pressure to the second solid electrolyte layer 32, thereby ensuring the insulating function of the elastic body 50.

[0045] In the solid secondary battery of this embodiment, the upper end face of the first solid electrolyte layer 31 is positioned higher than the upper end face of the insulating frame 40, and the upper end face of the elastic body 50 is positioned higher than the upper end face of the first solid electrolyte layer 31. By positioning the upper end face of the elastic body 50 higher than the upper end face of the first solid electrolyte layer 31, it becomes possible to form a recess 51 in the elastic body 50 by applying pressure to the second solid electrolyte layer 32, and the insulating function of the elastic body 50 can be ensured.

[0046] In this embodiment, the width dimension of the elastic body 50 is the same as the width dimension of the insulating frame 40, but the width dimension of the elastic body 50 may be smaller than the width dimension of the insulating frame 40. A solid secondary battery of a first modified example in which the width dimension of the elastic body 50 is smaller than the width dimension of the insulating frame 40 will be described with reference to Figs. 6 and 7.

[0047] Fig. 6 is a cross-sectional view showing a solid secondary battery according to a first modified example, and Fig. 7 is a cross-sectional view showing the charged state of the solid secondary battery. The solid secondary battery of the first modified example is the same as the solid secondary battery shown in Figs. 1 to 5 except that the width dimension of the elastic body 150 arranged on the outer periphery of the positive electrode layer 10 of the electrode laminate 1a is smaller than the width dimension of the insulating frame body 40. For this reason, the other parts are given the same reference numerals as in Figs. 1 to 5, and redundant explanations will be omitted.

[0048] As shown in FIG. 6, in the solid secondary battery of the first modified example, an elastic body 150 is disposed between the protruding portion 32a of the second solid electrolyte layer 32 of the electrode laminate 1a and the insulating frame 40. The width dimension of the elastic body 150 is smaller than the width dimension of the insulating frame 40. The elastic body 150 is pressed by the protruding portion 32a of the second solid electrolyte layer 32, forming a recessed portion 151. As shown in FIG. 7, in the electrode laminate 1a in a charged state, a lithium precipitate layer 23 is formed on the surface of the metal layer 22 of the negative electrode layer 20, and the thickness of the negative electrode layer 20 facing the positive electrode layer 10 increases.

[0049] In the solid secondary battery of the first modification, the elastic body 150 is pressurized by the protruding portion 32a of the second solid electrolyte layer 32, and therefore, similar to the effect of the solid secondary battery described above, the side surface of the positive electrode layer 10 can be stably insulated. Furthermore, in the solid secondary battery of the first modification, the dimension in the width direction of the elastic body 150 is smaller than the width dimension of the insulating frame 40, and the volume of the outer portion of the elastic body 150 can be reduced, thereby improving the volumetric energy density.

[0050] In this embodiment, the solid electrolyte layer 30 is configured of two layers, the first solid electrolyte layer 31 and the second solid electrolyte layer 32, but may be configured of either the first solid electrolyte layer 31 or the second solid electrolyte layer 32. A second modified example of a solid secondary battery using only the first solid electrolyte layer 31 as the solid electrolyte layer 30 will be described with reference to FIG.

[0051] Fig. 8 is a cross-sectional view showing a solid secondary battery according to Modification 2. The solid secondary battery according to Modification 2 is similar to Modification 1 shown in Fig. 6, except that in solid electrolyte layer 30, only first solid electrolyte layer 31 is a single layer. For this reason, the other parts are given the same reference numerals as in Fig. 6, and redundant explanations will be omitted.

[0052] 8, the solid secondary battery of the second modified example shown in FIG. 8 has a solid electrolyte layer 30 of the electrode stack 1b consisting only of a first solid electrolyte layer 31. The elastic body 150 is pressed by the protruding portion 22a of the metal layer 22, forming a recessed portion 151. The upper end face of the first solid electrolyte layer 31 is positioned higher than the upper end face of the insulating frame 40, and the upper end face of the elastic body 50 is positioned higher than the upper end face of the first solid electrolyte layer 31.

[0053] In the solid secondary battery of the second modification, the elastic body 150 is pressurized by the protrusion 32a of the metal layer 22 of the negative electrode layer 20, and therefore, similar to the effect of the solid secondary battery described above, the side surface of the positive electrode layer 10 can be stably insulated. Furthermore, in the solid secondary battery of the second modification, the thickness of the solid electrolyte layer 30 can be made thinner, and the volume of the electrode stack 1b can be reduced, thereby improving the volumetric energy density.

[0054] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, in this embodiment, the electrode stack 1 is a stack including a positive electrode layer 10, a negative electrode layer 20, and a solid electrolyte layer 30 disposed between the positive electrode layer 10 and the negative electrode layer 20. However, the configuration of the electrode stack 1 is not limited to this. An intermediate layer may be provided between the negative electrode layer 20 and the solid electrolyte layer 30. The intermediate layer may include a lithium ion conductive material and an electronically conductive material, and may be an electronically conductive layer having voids through which lithium ions can pass. Examples of the lithium ion conductive material include amorphous carbon particles. Examples of the electronically conductive material include metal particles.

[0055] In this embodiment, the negative electrode layer 20 includes the metal layer 22. However, the metal layer 22 may be omitted, and lithium may be deposited on the surface of the negative electrode current collector 21. Alternatively, the metal layer 22 may be replaced with a layer containing a negative electrode active material capable of absorbing and releasing lithium ions. Examples of the negative electrode active material include lithium transition metal oxides such as lithium titanate, transition metal oxides such as TiO2, Nb2O3, and WOn, Si, SiO2, metal sulfides, metal nitrides, and carbon materials such as artificial graphite, natural graphite, graphite, soft carbon, and hard carbon. The negative electrode active material layer may optionally contain a solid electrolyte to improve lithium ion conductivity. It may also optionally contain a conductive additive to improve conductivity. It may also optionally contain a binder to provide flexibility. The solid electrolyte, conductive additive, and binder may be those commonly used in solid-state secondary batteries.

[0056] In this embodiment, the positive electrode layer 10 has the positive electrode active material layer 12 laminated on both surfaces of the positive electrode current collector 11. However, the positive electrode active material layer 12 may be laminated on only one surface of the positive electrode current collector 11. When the positive electrode active material layer 12 is laminated on only one surface of the positive electrode current collector 11, the positive electrode current collector 11 of the positive electrode layer 10 may have a protruding portion that protrudes from the positive electrode active material layer 12 in a planar view, and an insulating frame 40 may be disposed between the protruding portion of the positive electrode current collector 11 and at least one of the protruding portions of the negative electrode layer 20 and the solid electrolyte layer 30, with the insulating frame 40 interposed between the protruding portion of the positive electrode current collector 11 and at least one of the protruding portions of the negative electrode layer 20 and the solid electrolyte layer 30. By applying pressure to the elastic body 50 between the protruding portion of the positive electrode current collector 11 and one of the protruding portions of the negative electrode layer 20 and the solid electrolyte layer 30, the side surface of the positive electrode active material layer 12 can be more stably insulated. [Explanation of symbols]

[0057] 1 Electrode laminate 10 Positive electrode layer 11 Positive electrode current collector 12 Cathode active material layer 15 Positive electrode current collecting tab 20 negative electrode layer 21 Negative electrode current collector 21a Projection 22 Metal layer 22a Projection 23 Lithium deposit layer 24 Gap 25 Negative electrode current collecting tab 30 Solid electrolyte layer 31 First solid electrolyte layer 32 Second solid electrolyte layer 32a Protrusion 40 Insulating frame 50, 50a, 150 elastic body 51, 151 recess

Claims

1. an electrode stack including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein at least one of the negative electrode layer and the solid electrolyte layer has a protruding portion protruding from the positive electrode layer in a plan view; an insulating frame disposed on the outer periphery of the positive electrode layer; an elastic body disposed between the insulating frame and the protrusion.

2. The solid secondary battery according to claim 1 , wherein the width of the elastic body is equal to or smaller than the width of the insulating frame.

3. the positive electrode layer includes a positive electrode current collector and two positive electrode active material layers stacked on both sides of the positive electrode current collector, the negative electrode layer and the solid electrolyte layer are disposed opposite each other with the positive electrode layer interposed therebetween, The protrusions are disposed opposite each other with the positive electrode layer interposed therebetween, The solid secondary battery according to claim 1 , wherein the insulating frame is disposed between the protrusions disposed opposite to each other.

4. the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer laminated on one surface of the positive electrode current collector, the positive electrode current collector has a protruding portion that protrudes from the positive electrode active material layer in a plan view, 3. The solid secondary battery according to claim 1, wherein the insulating frame is disposed between the protruding portion of the positive electrode current collector and the protruding portion of at least one of the negative electrode layer and the solid electrolyte layer.

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