Solid secondary battery and manufacturing method for the same

Abstract

To provide a solid secondary battery with less gap between a positive electrode layer and an insulating frame body, and a manufacturing method for the same.SOLUTION: A solid secondary battery includes an electrode laminate body including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer stacked between the positive electrode layer and the negative electrode layer, and an insulating frame body disposed with a gap from a side surface of the positive electrode layer. At least a part of the insulating frame body is pressed in a lamination direction of the electrode laminate body and expands toward the positive electrode layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a solid secondary battery and a method for manufacturing the same. [Background technology]

[0002] In recent years, research and development into secondary batteries that contribute to energy efficiency has been conducted to ensure that more people have access to affordable, reliable, sustainable, and advanced energy. Among secondary batteries, solid-state secondary batteries, which have 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, insulators are disposed around the positive electrode layer to insulate the side of the positive electrode layer in order to prevent misalignment or short-circuiting of the positive electrode layer, solid electrolyte layer, and negative electrode layer of the electrode stack. The use of a multilayer structure, which includes a first resin layer and a second resin layer in this order from the side closest to the side of the electrode stack, and in which the elastic modulus of the first resin layer is smaller than that of the second resin layer, has been considered (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-153535 Summary of the Invention [Problem to be solved by the invention]

[0004] However, extending the lifespan of solid-state secondary batteries is an issue. To extend the lifespan, it is effective to place an insulator around the positive electrode layer of the solid-state secondary battery. Using an insulating frame with high shape stability as the insulator is effective in extending the lifespan of solid-state secondary batteries. However, it is difficult to place an insulating frame with high shape stability on the side of the positive electrode layer without any gaps. If there is a gap between the side of the positive electrode layer and the insulating frame, the position of the positive electrode layer is likely to move when the solid-state secondary battery vibrates, which can cause misalignment of the facing positions of the positive electrode layer and the negative electrode layer, variations in the surface pressure of the positive electrode layer, etc.

[0005] The present invention has been made in view of the above circumstances, and aims to provide a solid secondary battery with a small gap between the positive electrode layer and the insulating frame, and a method for manufacturing the same, which will ultimately contribute to improving energy efficiency. [Means for solving the problem]

[0006] The present inventors have found that the above-mentioned problems can be solved by arranging an easily deformable insulating frame that can be deformed by pressure on a side surface of a positive electrode layer with a gap therebetween and expanding the insulating frame so as to fill at least a part of the gap, and have thus completed the present invention.

[0007] (1) A solid secondary battery comprising: an electrode stack including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer stacked between the positive electrode layer and the negative electrode layer; and an insulating frame disposed on a side surface of the positive electrode layer with a gap therebetween, wherein at least a portion of the insulating frame is pressurized in the stacking direction of the electrode stack and expands toward the positive electrode layer.

[0008] According to the solid secondary battery of (1), at least a portion of the insulating frame expands toward the positive electrode layer due to pressure applied in the stacking direction of the electrode stack, thereby reducing the gap between the positive electrode layer and the insulating frame.

[0009] (2) The solid secondary battery according to (1), wherein the insulating frame includes a low Young's modulus body and a high Young's modulus body arranged on the outer periphery of the low Young's modulus body, the low Young's modulus body is expandable and deformable in a direction perpendicular to the direction of application of pressure, the high Young's modulus body has a higher Young's modulus than the low Young's modulus body, and at least a part of the low Young's modulus body of the insulating frame is expanded and deformed toward the positive electrode layer side by being pressurized in the stacking direction of the electrode stack.

[0010] In the solid secondary battery of (2), since the high Young's modulus body is disposed on the outer periphery of the low Young's modulus body, the low Young's modulus body is less likely to expand and deform toward the periphery and more likely to expand and deform toward the positive electrode layer. Therefore, the expansion and deformation of the low Young's modulus body can reduce the gap between the positive electrode layer and the insulating frame.

[0011] (3) The solid secondary battery according to (1), wherein the insulating frame includes a composite having a porous body and a gel insulating material impregnated inside the porous body, the composite is capable of extruding the gel insulating material in a direction perpendicular to the direction of pressure application by applying pressure, and at least a portion of the composite of the insulating frame is pressurized in the stacking direction of the electrode stack, so that the gel insulating material is extruded toward the positive electrode layer.

[0012] In the solid secondary battery of (3), the gel insulating material is extruded from the composite, causing the insulating frame to expand, thereby reducing the gap between the positive electrode layer and the insulating frame.

[0013] (4) The solid secondary battery according to (3), wherein the insulating frame further includes a non-porous member covering the outer peripheral surface of the composite opposite to the positive electrode layer side.

[0014] According to the solid secondary battery of (4), when the composite is pressurized, the gelled insulating material can be efficiently extruded between the positive electrode layer and the insulating frame, so that the gap between the positive electrode layer and the insulating frame can be more reliably reduced.

[0015] (5) The solid secondary battery according to any one of (1) to (4), wherein at least one of the solid electrolyte layer and the negative electrode layer has a protruding portion that protrudes from an edge of the positive electrode layer in a plan view, and at least a portion of the insulating frame is pressurized via the protruding portion.

[0016] According to the solid secondary battery of (5), the insulating frame can be pressed via the protruding portion of the electrode laminate, so that the insulating frame can be pressed stably for a long period of time.

[0017] (6) The solid secondary battery according to any one of (1) to (5), wherein the positive electrode layer has a positive electrode current collector and a positive electrode active material layer laminated on one or both surfaces of the positive electrode current collector, and the negative electrode layer and the solid electrolyte layer are disposed opposite each other with the positive electrode active material layer sandwiched therebetween.

[0018] According to the solid secondary battery of (6), the insulating frame can be stably pressurized for a long period of time by pressing the insulating frame with the negative electrode layers and / or negative electrode layers arranged opposite each other so as to sandwich the positive electrode active material layer of the electrode laminate.

[0019] (7) A method for manufacturing a solid secondary battery including an electrode stack including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer stacked between the positive electrode layer and the negative electrode layer, and an insulating frame placed on a side surface of the positive electrode layer, the method comprising: placing the solid electrolyte layer between the positive electrode layer and the negative electrode layer; pressurizing the insulating frame on a side surface of the positive electrode layer with a gap therebetween to obtain the electrode stack; and pressurizing at least a portion of the insulating frame to deform it so as to fill at least a portion of the gap.

[0020] According to the method for producing a solid secondary battery of (7), since an electrode laminate is obtained and at least a portion of the insulating frame is compressed to fill the gap between the side surface of the positive electrode layer and the insulating frame, there is no particular need to strictly match the size of the insulating frame to the size of the positive electrode layer, and therefore a solid secondary battery with a small gap between the side surface of the positive electrode layer and the insulating frame can be produced industrially advantageously. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a solid secondary battery with a small gap between the positive electrode layer and the insulating frame, and a method for manufacturing the same. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a plan view showing a solid secondary battery according to a first 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] FIG. 2 is a cross-sectional view showing one step of the method for manufacturing the solid secondary battery according to the first embodiment of the present invention. [Figure 6] FIG. 3 is a cross-sectional view showing a modified example of the solid secondary battery according to the first embodiment of the present invention. [Figure 7] 7 is a cross-sectional view showing a charged state of the solid secondary battery of the modified example shown in FIG. 6. FIG. [Figure 8] FIG. 4 is a plan view showing a solid secondary battery according to a second embodiment of the present invention. [Figure 9] 9 is a cross-sectional view showing the charged state of the solid secondary battery shown in FIG. 8. FIG. [Figure 10A] FIG. 4 is a cross-sectional view showing one step of a method for manufacturing a solid secondary battery according to a second embodiment of the present invention. [Figure 10B] FIG. 10 is a cross-sectional view showing another step of the method for manufacturing a solid secondary battery according to the second embodiment of the present invention. [Figure 11] FIG. 10 is a cross-sectional view showing a modified example of the solid secondary battery according to the second embodiment of the present invention. [Figure 12] 12 is a cross-sectional view showing one step of a method for manufacturing the solid secondary battery of the modified example shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0023] 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.

[0024] [First embodiment] Fig. 1 is a plan view showing an electrode laminate used in a solid secondary battery according to a first 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.

[0025] As shown in FIGS. 1 to 3, the solid secondary battery includes an electrode laminate 1, a low Young's modulus body 40 that is an insulating frame body, and a high Young's modulus body 50.

[0026] 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 second solid electrolyte layer protrusion 32a that protrudes from the edge of the positive electrode layer 10 in a plan view. The second solid electrolyte layer protrusions 32a are disposed opposite each other with the positive electrode layer 10 interposed therebetween. 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 a negative electrode current collector protrusion 21a and a metal layer protrusion 22a.

[0027] The low Young's modulus body 40 is disposed on a side surface of the positive electrode layer 10. The low Young's modulus body 40 is a member that can expand and deform in a direction perpendicular to the direction of pressure application. The end surface of the low Young's modulus body 40 in the thickness direction is in contact with the second solid electrolyte layer protrusion 32a. The outer periphery of the low Young's modulus body 40 is positioned beyond the second solid electrolyte layer protrusion 32a. The low Young's modulus body 40 is compressed in the stacking direction of the electrode stack 1 by the second solid electrolyte layer protrusion 32a, forming a deformed portion 41 and expanding and deforming toward the positive electrode active material layer 12 of the positive electrode layer 10. The expansion and deformation of the low Young's modulus body 40 fills the gap between the side surface of the positive electrode layer 10 and the low Young's modulus body 40. The expansion and deformation of the low Young's modulus body 40 until it comes into contact with the positive electrode layer 10 eliminates the gap between the positive electrode layer 10 and the low Young's modulus body 40. The low Young's modulus body 40 does not have to be in contact with the entire positive electrode active material layer 12, and may be in contact with a portion of the positive electrode layer 10. Furthermore, by forming the deformed portion 41, the adhesion between the low Young's modulus body 40 and the second solid electrolyte layer protrusion 32a is increased, making it difficult for foreign matter to get in between the positive electrode layer 10 and the low Young's modulus body 40. The Young's modulus of the low Young's modulus body 40 is, for example, 5×10 -4 The pressure may be in the range of 20 GPa or more and 20 GPa or less.

[0028] The low Young's modulus body 40 has electronic insulating properties. The melting point of the low Young's modulus body 40 may be equal to or higher than the melting point of lithium. The low Young's modulus body 40 preferably has chemical resistance. The Poisson's ratio of the low Young's modulus body 40 may be, for example, in the range of 0.2 to 0.49. The low Young's modulus body 40 may be an elastic body. A resin can be used as the material for the low Young's modulus body 40. 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.

[0029] The high Young's modulus body 50 is disposed on the outer periphery of the low Young's modulus body 40 (the surface opposite to the positive electrode layer 10 side). The high Young's modulus body 50 may or may not be adhered to the low Young's modulus body 40. The high Young's modulus body has a higher Young's modulus than the low Young's modulus body 40, and is less likely to deform than the low Young's modulus body 40. Therefore, the low Young's modulus body 40 is less likely to expand and deform toward the high Young's modulus body 50 side, and is more likely to expand and deform toward the positive electrode layer 10 side. Therefore, by disposing the high Young's modulus body 50, the low Young's modulus body 40 and the positive electrode layer 10 are more closely attached to each other. The Young's modulus of the high Young's modulus body 50 is, for example, 5×10 -3 The ratio of the Young's modulus of the high Young's modulus body 50 to the Young's modulus of the low Young's modulus body 40 may be, for example, 10 times or more and 10 times or less. 6 It may be in the range of 2 times or less.

[0030] The high Young's modulus body 50 has electronic insulating properties. The melting point of the high Young's modulus body 50 may be equal to or higher than the melting point of lithium. The high Young's modulus body 50 preferably has chemical resistance. There are no particular restrictions on the material of the high Young's modulus body 50, as long as it has a higher Young's modulus than the low Young's modulus body 40. Materials that can be used for the high Young's modulus body 50 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. The resins and ceramics may be used alone or in combination of two or more.

[0031] 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.

[0032] 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.

[0033] 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. As the positive electrode active material, for example, a layered active material containing lithium, a spinel-type active material, an olivine-type active material, etc. can be used. Specific examples of the positive electrode active material include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), LiNi p Mn 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).

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] The solid electrolyte layer 30 contains at least one type of solid electrolyte. The solid electrolyte layer 30 can 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.

[0041] 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.

[0042] Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-P2S5-LiI, etc. The sulfide solid electrolyte may have an argyrodite-type crystal structure.

[0043] 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).

[0044] 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.

[0045] 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.

[0046] The exterior body 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. As the laminate film, a laminated film having a three-layer structure in which an inner resin layer, a metal layer, and an outer resin layer are laminated in this order from the inside can be used. 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.

[0047] 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.

[0048] FIG. 4 is a cross-sectional view showing a charged state of an electrode stack of a solid secondary battery according to one embodiment of the present invention. 4, in the charged electrode laminate 1, 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. As a result, a small gap 24 may be formed between the metal layer protrusion 22a and the second solid electrolyte layer protrusion 32a. However, if the pressure applied from the second solid electrolyte layer protrusion 32a to the low Young's modulus body 40 is constant, a gap is unlikely to be formed between the low Young's modulus body 40 and the positive electrode layer 10.

[0049] The method for manufacturing the solid secondary battery according to the first embodiment will be described with reference to Fig. 5. Fig. 5 is a cross-sectional view showing one step of the method for manufacturing the solid secondary battery according to the first embodiment. First, a first solid electrolyte layer 31 is laminated on each surface of the two positive electrode active material layers 12 of the positive electrode layer 10. Next, low Young's modulus bodies 40 are arranged on the side surfaces of the positive electrode layer 10, and high Young's modulus bodies 50 are arranged around the periphery of the low Young's modulus bodies 40. Next, a second solid electrolyte layer 32 is laminated on the surface of the first solid electrolyte layer 31. The second solid electrolyte layer 32 is arranged so that the protruding portions 32a of the second solid electrolyte layer are in contact with the low Young's modulus bodies 40. Next, the negative electrode layer 20 is laminated on the surface of the second solid electrolyte layer 32. Then, the resulting laminate is compressed in the lamination direction of the layers. By applying pressure, the electrode laminate 1 is produced, deformed portions 41 are formed in the low Young's modulus bodies 40, and the low Young's modulus bodies 40 expand and deform toward the positive electrode layer 10, filling the gap between the low Young's modulus bodies 40 and the positive electrode layer 10. The electrode laminate 1 is housed in an exterior material while being constrained so that the gap between the low Young's modulus body 40 and the positive electrode layer 10 is kept filled, and is used as a solid secondary battery.

[0050] In the solid secondary battery of the first embodiment configured as described above, the low Young's modulus body 40 expands and deforms toward the positive electrode layer 10 due to pressure applied by the second solid electrolyte layer protrusion 32a, thereby reducing the gap between the positive electrode layer 10 and the low Young's modulus body 40. The low Young's modulus body 40 expands and deforms in a direction perpendicular to the pressure direction due to pressure applied, and the high Young's modulus body 50 is disposed on the outer periphery of the low Young's modulus body 40. Therefore, the low Young's modulus body 40, which is compressed by the second solid electrolyte layer protrusion 32a, is more likely to expand and deform toward the positive electrode layer 10. Therefore, the low Young's modulus body 40 is more likely to adhere closely to the positive electrode layer 10, and the side surface of the positive electrode layer 10 can be insulated without generating gaps for a longer period of time.

[0051] According to the method for manufacturing a solid secondary battery of the first embodiment, a laminate in which a solid electrolyte layer is disposed between a positive electrode layer and a negative electrode layer is pressurized to obtain an electrode laminate 1, and a portion of the low Young's modulus body 40 is pressurized to be in close contact with the side surface of the positive electrode layer 10, so that a solid secondary battery can be manufactured industrially advantageously.

[0052] In the electrode stack 1, the solid electrolyte layer 30 is a stack of the first solid electrolyte layer 31 and the second solid electrolyte layer 32, but the solid electrolyte layer 30 may be a single layer. A modified example in which the solid electrolyte layer 30 is a single layer will be described with reference to Figs. 6 and 7.

[0053] Fig. 6 is a cross-sectional view showing a modified example of the solid secondary battery according to the first embodiment of the present invention, and Fig. 7 is a cross-sectional view showing the charged state of the modified solid secondary battery. The electrode stack 1a shown in Fig. 6 and Fig. 7 is the same as the electrode stack 1 except that the solid electrolyte layer 30 is a single layer, and therefore the same members are denoted by the same reference numerals and detailed description thereof will be omitted.

[0054] As shown in FIG. 6 , in the electrode laminate 1a, the solid electrolyte layer 30 has the same dimensions as the positive electrode layer 10 in a plan view. The metal layer 22 of the negative electrode layer 20 has a metal layer protrusion 22a that protrudes from the edge of the positive electrode layer 10 in a plan view. The metal layer protrusions 22a are disposed opposite each other with the positive electrode layer 10 sandwiched therebetween. The negative electrode current collector 21 has the same dimensions as the metal layer 22 in a plan view, and has a negative electrode current collector protrusion 21a. The low Young's modulus body 40 has a deformed portion 41 that is deformed by being pressed by the negative electrode current collector protrusion 21a.

[0055] 7, in the electrode laminate 1a after charging, 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. Even if the lithium deposit layer 23 is formed, no gap is formed between the metal layer protrusion 22a and the low Young's modulus body 40 as long as the pressure applied from the metal layer protrusion 22a to the low Young's modulus body 40 is constant.

[0056] In the solid secondary battery of the modified example configured as described above, the low Young's modulus body 40 is expanded and deformed toward the positive electrode layer 10 by the pressure applied by the second solid electrolyte layer protruding portion 32a, thereby reducing the gap between the positive electrode layer 10 and the low Young's modulus body 40. Furthermore, in the solid secondary battery of the modified example, the solid electrolyte layer 30 of the electrode stack 1a is a single layer body, and therefore the configuration is simplified.

[0057] [Second embodiment] Fig. 8 is a plan view showing a solid secondary battery according to a second embodiment of the present invention. Fig. 9 is a cross-sectional view showing the charged state of the solid secondary battery according to the second embodiment. Figs. 8 and 9 correspond to the cross-sectional views taken along line III-III in Fig. 1.

[0058] As shown in FIG. 8 , the solid secondary battery includes an insulating frame made of a composite 65 including a porous body 60 and a gel insulating material 70 impregnated within the porous body 60. The composite 65 is configured such that the gel insulating material 70 can be extruded from the composite 65 in a direction perpendicular to the direction of pressure application. The composite 65 is disposed on the side of the positive electrode layer 10 of the electrode stack 2. The negative electrode current collector protrusion 21 a, the metal layer protrusion 22 a, and the second solid electrolyte layer protrusion 32 a of the electrode stack 2 extend to the end of the composite 65 opposite the positive electrode layer 10 side. The composite 65 is pressed in the stacking direction of the electrode stack 2 by the second solid electrolyte layer protrusion 32 a, and the gel insulating material 70 is extruded toward the positive electrode layer 10 side. The extruded gel insulating material 70 fills the gap between the composite 65 and the positive electrode layer 10. The electrode stack 2 is the same as the electrode stack 1 except for the shapes of the negative electrode current collector protrusion 21a, the metal layer protrusion 22a, and the second solid electrolyte layer protrusion 32a. Therefore, the same components are denoted by the same reference numerals and detailed descriptions thereof are omitted.

[0059] The shape and material of the porous body 60 are not particularly limited as long as it can be impregnated with the gel insulating material 70 and can be deformed by applying pressure so that the impregnated gel insulating material 70 can be pushed out in a direction perpendicular to the pressure direction. The porous body 60 has electronic insulating properties. The melting point of the porous body 60 may be equal to or higher than the melting point of lithium. The porous body 60 preferably has chemical resistance. For example, a resin material having communicating pores can be used as the porous body 60.

[0060] The gel insulating material 70 may have electronic insulation properties and fluidity, and may have fluidity that allows it to be filled between the composite 65 and the positive electrode layer 10. The melting point of the gel insulating material 70 may be equal to or higher than the melting point of lithium. The gel insulating material 70 preferably has chemical resistance. Materials that can be used for the gel insulating material 70 include silicone resin and rubber-based materials (for example, binder solution).

[0061] 9, in the charged electrode laminate 2, 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. As a result, even if a small gap 24 is formed between the metal layer protrusion 22a and the second solid electrolyte layer protrusion 32a, a gap is unlikely to occur between the gel insulating material 70 and the positive electrode layer 10 as long as the pressure applied to the composite 65 from the second solid electrolyte layer protrusion 32a is constant.

[0062] A method for manufacturing a solid secondary battery according to the second embodiment will be described with reference to Figures 10A and 10B, each of which shows one step in the method for manufacturing a solid secondary battery according to the second embodiment of the present invention.

[0063] First, a first solid electrolyte layer 31 is laminated on each surface of the two positive electrode active material layers 12 of the positive electrode layer 10. Next, a composite 65, in which a porous body 60 is impregnated with a gel insulating material 70, is placed on the side of the positive electrode layer 10. Next, a second solid electrolyte layer 32 is laminated on the surface of the first solid electrolyte layer 31. The second solid electrolyte layer 32 is positioned so that the second solid electrolyte layer protrusions 32a contact the composite 65. Next, the negative electrode layer 20 is laminated on the surface of the second solid electrolyte layer 32. Then, the resulting laminate is pressed in the stacking direction of the layers, as shown in FIG. 10A. By applying pressure, the gel insulating material 70a flows out of the composite 65 toward the positive electrode layer 10, as shown in FIG. 10B, and the gel insulating material 70a fills the gaps between the composite 65, the metal layer protrusions 22a, and the positive electrode layer 10. Then, the gel insulating material 70b that has flowed out of the outer peripheral surface of the porous body 60 opposite the positive electrode layer 10 side is removed. The electrode stack 2 is housed in an exterior material while being constrained so as to maintain the state in which the gel insulating material 70a is filled, and is used as a solid secondary battery.

[0064] In the solid secondary battery of the second embodiment configured as described above, the gel insulating material 70 extruded from the composite 65 fills the side surfaces of the positive electrode layer 10 of the electrode stack 1, thereby reducing the gap between the positive electrode layer 10 and the composite 65. Furthermore, by using a composite 65 in which the gel insulating material 70 is impregnated into the porous body 60, the gel insulating material 70 can be filled into the side surfaces of the positive electrode layer 10 simply by applying pressure to the composite 65 with the second solid electrolyte layer protrusions 32a. Furthermore, because the gel insulating material 70 is filled between the second solid electrolyte layer protrusions 32a that are arranged opposite each other so as to sandwich the positive electrode layer 10, the side surfaces of the positive electrode layer 10 can be more stably insulated.

[0065] The outer peripheral surface of the composite 65 on the side opposite to the positive electrode layer 10 side of the electrode stack 1 may be covered with a non-porous member. A modified example in which a non-porous member is provided will be described with reference to FIGS.

[0066] FIG. 11 is a cross-sectional view showing a modified example of the solid secondary battery according to the second embodiment of the present invention, and FIG. 12 is a cross-sectional view showing one step of a method for manufacturing the modified solid secondary battery. The electrode stack 2a is the same as the electrode stack 2, except that the negative electrode current collector protrusion 21a, the metal layer protrusion 22a, and the second solid electrolyte layer protrusion 32a extend to a part of the side of the composite 65 opposite to the positive electrode layer 10 side. Therefore, the same members are denoted by the same reference numerals and detailed description thereof will be omitted.

[0067] As shown in FIG. 11 , the composite 65 has a non-porous member 80 covering the outer peripheral surface of the electrode stack 1 opposite the positive electrode layer 10. The non-porous member 80 has the function of preventing the gel insulating material 70 from passing through. Materials that can be used for the non-porous member 80 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. Resins and ceramics may be used singly or in combination of two or more.

[0068] By covering the composite 65 with the non-porous member 80, as shown in FIG. 12, when the laminate is pressed in the stacking direction during the manufacture of a solid secondary battery, it is possible to prevent the gel insulating material 70 from flowing out from the outer peripheral surface of the porous body 60 on the side opposite to the positive electrode layer 10.

[0069] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.

[0070] In this embodiment, the positive electrode layer 10 includes a positive electrode active material layer 12 laminated on both sides of the positive electrode current collector 11. However, the shape of the positive electrode layer 10 is not limited to this. For example, 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 a single layer, the positive electrode current collector 11 of the positive electrode layer 10 may have a protruding portion protruding from the edge of the positive electrode active material layer 12 in a planar view, and an insulating frame (low Young's modulus body 40, composite 65) 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. By applying pressure to the insulating frame with 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, and expanding the insulating frame toward the positive electrode layer 10, the side surface of the positive electrode active material layer 12 can be more stably insulated.

[0071] In this embodiment, the electrode laminates 1 and 2 are laminates 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 laminates 1 and 2 is not limited to this. For example, an intermediate layer may be provided between the negative electrode layer 20 and the solid electrolyte layer 30. The intermediate layer may be a layer containing a lithium ion conductive material and an electronically conductive material, and having electronic conductivity and 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. Alternatively, the intermediate layer may be a layer of a metal that forms an alloy with lithium.

[0072] In this embodiment, the insulating frame (low Young's modulus body 40, composite 65) is pressurized by protrusions (second solid electrolyte layer protrusions 32a, metal layer protrusions 22a) that protrude from the edge of the positive electrode layer 10 in a plan view, but this is not limiting. For example, if the insulating frame can be fixed in a state of close contact with the positive electrode layer 10 by applying pressure during the manufacture of the electrode stack, there is no need to apply pressure with the protrusions.

[0073] 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. [Explanation of symbols]

[0074] 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 Negative electrode current collector protrusion 22 Metal layer 22a Metal layer protrusion 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 Second solid electrolyte layer protrusion 40 Low Young's modulus 41 Deformed part 50 High Young's modulus 60 Porous materials 65 Complex 70, 70a, 70b Gel insulation material 80 Non-porous materials

Claims

1. an electrode stack including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer stacked between the positive electrode layer and the negative electrode layer; an insulating frame disposed on a side surface of the positive electrode layer with a gap therebetween, At least a portion of the insulating frame is pressurized in the stacking direction of the electrode stack and expands toward the positive electrode layer.

2. the insulating frame includes a low Young's modulus body and a high Young's modulus body arranged on the outer periphery of the low Young's modulus body, The low Young's modulus body is expandable and deformable in a direction perpendicular to the direction of pressure application when pressurized, the high Young's modulus body has a higher Young's modulus than the low Young's modulus body, 2. The solid secondary battery according to claim 1, wherein at least a part of the low Young's modulus body of the insulating frame is compressed in the stacking direction of the electrode stack and is expanded and deformed toward the positive electrode layer.

3. the insulating frame includes a composite body having a porous body and a gel insulating material impregnated inside the porous body, The composite is capable of extruding the gel insulating material in a direction perpendicular to a pressing direction when pressurized, 2. The solid secondary battery according to claim 1, wherein at least a portion of the composite of the insulating frame is pressed in the stacking direction of the electrode stack, so that the gel insulating material is extruded toward the positive electrode layer.

4. The solid secondary battery according to claim 3 , wherein the insulating frame further includes a non-porous member that covers an outer peripheral surface of the composite opposite to the positive electrode layer side.

5. at least one of the solid electrolyte layer and the negative electrode layer has a protruding portion that protrudes from an edge portion of the positive electrode layer in a plan view, 5. The solid secondary battery according to claim 1, wherein at least a portion of the insulating frame is pressurized via the protrusion.

6. the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer laminated on one or both surfaces of the positive electrode current collector, 5. The solid secondary battery according to claim 1, wherein the negative electrode layer and the solid electrolyte layer are disposed opposite each other with the positive electrode active material layer interposed therebetween.

7. A method for manufacturing a solid secondary battery comprising: an electrode stack including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer stacked between the positive electrode layer and the negative electrode layer; and an insulating frame disposed on a side surface of the positive electrode layer, a method for manufacturing a solid secondary battery, the method including: disposing the solid electrolyte layer between the positive electrode layer and the negative electrode layer; pressurizing the insulating frame while placing it on a side surface of the positive electrode layer with a gap therebetween, to obtain the electrode laminate; and pressurizing at least a portion of the insulating frame to expand it so as to fill at least a portion of the gap.

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