Solid-state battery

Abstract

Provided is a solid-state battery including a laminate obtained by laminating multiple power generation elements each comprising a positive electrode layer, a positive electrode current collector foil in contact with one surface of the positive electrode layer, a negative electrode layer, a negative electrode current collector foil in contact with one surface of the negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer so as to be in contact with the other surface of the positive electrode layer and the other surface of the negative electrode layer. The solid-state battery is provided with elastic bodies at both ends of the laminate in the lamination direction. Pressure is applied on the laminate in the lamination direction through the elastic bodies. Outer circumferential ends of the elastic bodies are located at positions inward of outer circumferential ends of the positive electrode layer when viewed in the lamination direction of the laminate. In addition, outer circumferential ends of the negative electrode layer are located at positions overlapping outer circumferential ends of the solid electrolyte layer or at positions inward of the same and inward of the outer circumferential ends of the elastic bodies when viewed in the lamination direction of the laminate.

Description

solid state battery

[0001] The present invention relates to a solid-state battery.

[0002] JP2023-106356A discloses a solid-state battery in which a plurality of unit cells are stacked, each unit cell including a laminate in which a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and an elastic body are sequentially arranged. In this solid-state battery, pressure is applied uniformly to the entire stack of cells via the elastic body during discharge.

[0003] In the solid-state battery described in JP2023-106356A, the entire cell is pressurized by an elastic body. Therefore, if a space is generated at the end (outer peripheral end) of the cell due to misalignment of the stacking, pressure is applied to the space, which may cause the electrode to break and short-circuit.

[0004] On the other hand, if the size of the elastic body is changed so that the outer edge of the elastic body is positioned inside the outer edge of the electrode (positive and negative electrode layer) when viewed from the stacking direction to prevent electrode breakage, the portion of the electrode outside the elastic body will not be pressurized. In this case, for example, in a precipitation-type solid-state battery in which lithium metal is precipitated in the negative electrode layer during charge, lithium in the pressurized portion (pressurized portion) returns to the positive electrode during discharge, while lithium in the unpressurized portion (non-pressurized portion) remains in the negative electrode layer. This creates a step between the pressurized portion and the non-pressurized portion, which can cause the electrode to break due to shear stress and lead to a short circuit.

[0005] The present invention has been made in view of the above problems, and has an object to provide a solid-state battery that prevents short circuits.

[0006] According to one aspect of the present invention, there is provided a solid-state battery including a laminate formed by stacking a plurality of power-generating elements, each of which includes a positive electrode layer, a positive electrode current collector foil in contact with one surface of the positive electrode layer, a negative electrode layer, a negative electrode current collector foil in contact with one surface of the negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer so as to be in contact with the other surface of the positive electrode layer and the other surface of the negative electrode layer. This solid-state battery includes elastic bodies on both ends of the laminate in the stacking direction, the laminate is pressurized in the stacking direction via the elastic bodies, and the outer peripheral edge of the elastic bodies is located inside the outer peripheral edge of the positive electrode layer as viewed from the stacking direction of the laminate. Furthermore, the outer peripheral edge of the negative electrode layer is located at a position overlapping with or inside the outer peripheral edge of the solid electrolyte layer as viewed from the stacking direction of the laminate, and is also located inside the outer peripheral edge of the elastic body as viewed from the stacking direction of the laminate.

[0007] FIG. 1 is a schematic diagram of a solid-state battery according to a first embodiment of the present invention. FIG. 2 is a diagram showing a solid-state battery according to a conventional example. FIG. 3 is a diagram showing a solid-state battery according to a comparative example. FIG. 4 is a diagram explaining the arrangement of each layer of a laminate and an elastic body. FIG. 5 is a diagram showing a power-generating element. FIG. 6 is a diagram showing a solid-state battery according to a modified example. FIG. 7 is a diagram showing a solid-state battery according to a modified example. FIG. 8 is a diagram showing a solid-state battery according to a modified example. FIG. 9 is a diagram showing a power-generating element according to a modified example. FIG. 10 is a diagram showing a power-generating element according to a modified example. FIG. 11 is a diagram showing a power-generating element according to a modified example. FIG. 12 is a diagram showing a power-generating element according to a modified example. FIG. 13 is a diagram showing a power-generating element according to a modified example. FIG. 14 is a diagram showing a power-generating element of a solid-state battery according to a second embodiment. FIG. 15 is a diagram showing a power-generating element according to a modified example of the second embodiment. FIG. 16 is a diagram showing a power-generating element according to a modified example of the second embodiment. FIG. 17 is a diagram showing a power-generating element according to a modified example of the second embodiment. FIG. 18 is a diagram showing a power-generating element of a solid-state battery according to a third embodiment. FIG. 19 is a diagram showing a power-generating element according to a modified example of the third embodiment. Fig. 20 is a diagram showing a power generating element according to a modification of the third embodiment. Fig. 21 is a diagram showing a power generating element according to a modification of the third embodiment. Fig. 22 is a diagram showing a power generating element according to a modification of the third embodiment. Fig. 23 is a diagram showing a power generating element according to a modification of the third embodiment. Fig. 24 is a diagram showing a power generating element according to a modification of the third embodiment. Fig. 25 is a diagram showing a power generating element according to a modification of the third embodiment. Fig. 26 is a diagram showing a power generating element according to a modification of the third embodiment. Fig. 27 is a diagram showing a power generating element according to a modification of the third embodiment. Fig. 28 is a diagram showing a power generating element of a solid state battery according to the fourth embodiment. Fig. 29 is a diagram showing a power generating element according to a modification of the fourth embodiment.

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0009] 1 is a schematic cross-sectional view of a solid state battery 100 according to a first embodiment of the present invention. The solid state battery 100 is a chargeable and dischargeable secondary battery, and is a so-called lithium deposition type solid state battery in which lithium metal is deposited on a negative electrode current collector foil 14 (described later) during charging.

[0010] As shown in FIG. 1, the solid-state battery 100 includes a laminate 10 formed by stacking a plurality of power generating elements 1, an exterior body 20 that houses the laminate 10, a positive electrode tab 30, a negative electrode tab 40, and elastic bodies 50 arranged on both ends of the laminate 10 in the stacking direction.

[0011] The power generating element 1 includes a positive electrode layer 11, a positive electrode current collector foil 12 in contact with one surface of the positive electrode layer 11, a negative electrode layer 13, a negative electrode current collector foil 14 in contact with one surface of the negative electrode layer 13, and a solid electrolyte layer 15 interposed between the positive electrode layer 11 and the negative electrode layer 13 and in contact with the other surface of the positive electrode layer 11 and the other surface of the negative electrode layer 13.

[0012] The positive electrode layer 11 contains a positive electrode active material and is laminated on one surface of the solid electrolyte layer 15 in the lamination direction. The positive electrode layer 11 is produced by weighing and mixing predetermined amounts of the positive electrode active material, sulfide solid electrolyte, conductive additive, binder, and xylene to prepare a slurry, which is then applied to both sides of a carbon-coated Al foil and dried. The positive electrode layer 11 contains lithium ions and lithium metal. The positive electrode layer 11 is supported by a positive electrode frame 111 from the outside of its outer circumferential edge.

[0013] The positive electrode current collector foil 12 is a thin plate made of a metal material such as aluminum, nickel, stainless steel (SUS), or an alloy thereof, but is not limited to these and may be any material that has a current collecting function. The positive electrode current collector foil 12 is pressure-bonded to the surface of the positive electrode layer 11 opposite to the surface that contacts the solid electrolyte layer 15, and the positive electrode layer 11 and the positive electrode current collector foil 12 constitute the positive electrode of the solid-state battery 100. The positive electrode current collector foil 12 is joined to a positive electrode tab 30.

[0014] The negative electrode layer 13 contains a negative electrode active material and is laminated on the other surface in the lamination direction of the solid electrolyte layer 15. The negative electrode layer 13 is produced by weighing and mixing predetermined amounts of the negative electrode active material, binder, and NMP to prepare a slurry, applying the slurry to both sides of a stainless steel foil, and then drying the resulting slurry. The negative electrode active material includes, for example, carbon and metallic lithium or a lithium-containing alloy.

[0015] During charging, lithium metal is deposited on the surface of the negative electrode layer 13 that is in contact with the negative electrode current collector foil 14, forming a lithium metal layer. The lithium metal layer is configured to disappear during discharge.

[0016] The anode layer 13 also includes an anode intermediate layer for preventing lithium metal that deposits during charging from coming into direct contact with the solid electrolyte layer 15. The anode intermediate layer only needs to have the function of protecting the solid electrolyte layer 15 from lithium metal that is generated on the anode side during charging, and is, for example, a layer containing a lithium-reactive material.

[0017] The negative electrode current collector foil 14 is a thin plate made of a metal material such as aluminum, nickel, stainless steel (SUS), or an alloy thereof, but is not limited thereto and may be any material having a current collecting function. The positive electrode current collector foil 12 and the negative electrode current collector foil 14 may be made of the same material or different materials. The negative electrode current collector foil 14 is laminated on the surface of the negative electrode layer 13 opposite to the surface that contacts the solid electrolyte layer 15 in the lamination direction, and together with the negative electrode layer 13, constitutes the negative electrode of the solid-state battery 100. The negative electrode current collector foil 14 is joined to the negative electrode tab 40.

[0018] The solid electrolyte layer 15 is an ion-conductive layer (ion-conducting layer) containing a solid electrolyte as a main component, and is interposed between the positive electrode layer 11 and the negative electrode layer 13. The solid electrolyte layer 15 is fabricated by weighing and mixing predetermined amounts of a sulfide solid electrolyte as a solid electrolyte, a binder, and xylene to form a slurry, which is then coated on one side of a stainless steel foil and dried. While the present embodiment uses a sulfide solid electrolyte as the solid electrolyte, this is not limiting and any known solid electrolyte may be used. For example, an oxide solid electrolyte may be used. The solid electrolyte layer contains an inorganic solid electrolyte as a main component, but may also contain a polymer electrolyte, a gel electrolyte, a liquid electrolyte, or the like. The term "main component" refers to a component that accounts for at least 50% of the total.

[0019] The power generating element 1 is produced by superposing and press-molding a solid electrolyte layer 15 applied to SUS foil on a positive electrode layer 11 applied on both sides, and then superposing and press-molding the negative electrode layer 13 on top of this. That is, the power generating element 1 is constructed by fixing a positive electrode (positive electrode layer 11 and positive electrode current collector foil 12) and a negative electrode (negative electrode layer 13 and negative electrode current collector foil 14) to the solid electrolyte layer 15. A plurality of power generating elements 1 are stacked to form a laminate 10.

[0020] The exterior body 20 is a bag-shaped case that vacuum-seals the laminated body 10, and is made of, for example, a laminate film containing aluminum.

[0021] The positive electrode tab 30 and the negative electrode tab 40 are provided to electrically connect the power generating element 1 to the outside. One end of the positive electrode tab 30 and the negative electrode tab 40 is located inside the exterior body 20, and the other end is located outside the exterior body 20. The positive electrode tab 30 is, for example, an Al tab, and the positive electrode current collector foil 12 is joined to the positive electrode tab 30 by an ultrasonic welder or the like. The negative electrode tab 40 is, for example, a Ni-plated copper tab, and the negative electrode current collector foil 14 is joined to the negative electrode tab 40 by an ultrasonic welder or the like.

[0022] The elastic bodies 50 are, for example, flexible hyper sheets, and are arranged on both ends of the laminate 10 in the stacking direction. That is, the elastic bodies 50 are arranged so as to sandwich the laminate 10 in the stacking direction. The laminate 10 is pressed in the stacking direction via the elastic bodies 50 from the outside of the elastic bodies 50 (the surface opposite to the surface in contact with the laminate 10) by a pressure plate (not shown) or the like. Note that a restraining force is applied to the pressure plate by a restraining mechanism (not shown).

[0023] The above is a schematic configuration of the solid-state battery 100.

[0024] In a solid-state battery including a laminate in which multiple power-generating elements (cells) each including a positive electrode layer, a solid electrolyte layer, and a negative electrode layer are stacked, when the entire cell is pressurized in the stacking direction via an elastic body, if a space has formed at the end (peripheral edge) of the laminate due to stacking misalignment, pressure is also applied to the space. This may cause the electrode to break and a short circuit. For example, in the solid-state battery 100′ shown in FIG. 2 , if a space A′ has formed at the end (peripheral edge) of the laminate 10′ due to stacking misalignment, pressurizing the entire power-generating element 1′ using an elastic body 50′ may cause pressure to be applied to the space A′, resulting in the electrode to break.

[0025] On the other hand, if the size of the elastic body is changed so that its outer peripheral edge is positioned inside the outer peripheral edge of the electrode (positive and negative electrode layers) when viewed from the stacking direction to prevent electrode fracture, and pressure is applied, the portion of the electrode outside the elastic body is not pressurized. In this case, for example, in a lithium deposition-type solid-state battery in which lithium metal is deposited in the negative electrode layer during charge, lithium in the pressurized portion (pressurized portion) returns to the positive electrode during discharge, while lithium in the unpressurized portion (unpressurized portion) remains in the negative electrode layer. This creates a step between the pressurized portion and the unpressurized portion, which can cause electrode fracture and short circuit due to shear stress. For example, in the lithium deposition-type solid-state battery 100″ shown in FIG. 3 , lithium metal is deposited in the negative electrode layer 13″ during charge ( FIG. 3(a) ), and a lithium metal layer 131″ is formed between the negative electrode layer 13″ and the negative electrode current collector foil 14″. On the other hand, during discharge (FIG. 3(b)), in the area pressurized by the elastic body 50'' located inside the electrode, the pressurized lithium returns to the positive electrode, and the lithium metal layer 131'' disappears. In contrast, in the area not pressurized, lithium metal remains, and a step is created between the area where lithium metal (lithium metal layer 131'') remains and the area where the lithium metal layer 131'' has disappeared. This raises the risk of the electrode breaking due to shear stress. Thus, even when an elastic body is placed inside the electrode and pressure is applied, there is a risk of the electrode breaking and short-circuiting.

[0026] Therefore, in the solid state battery 100 of this embodiment, the outer peripheral edge of the elastic body 50 is located inside the outer peripheral edge of the positive electrode layer 11 when viewed from the stacking direction of the laminate 10, and the outer peripheral edge of the negative electrode layer 13 is located inside the outer peripheral edge of the solid electrolyte layer 15 and the outer peripheral edge of the elastic body 50 when viewed from the stacking direction of the laminate 10. In this way, since the outer peripheral edge of the elastic body 50 is located inside the outer peripheral edge of the positive electrode layer 11 when viewed from the stacking direction of the laminate 10 (i.e., the elastic body 50 is located inside the positive electrode layer 11), even if a space is generated at the outer peripheral edge of the laminate 10 due to stacking misalignment, the outer peripheral edge of the positive electrode layer 11 is not pressurized by the elastic body 50. Therefore, pressure is not applied to the space, and the risk of a short circuit due to electrode fracture is reduced. Furthermore, since the outer peripheral edge of the negative electrode layer 13 is located inside the outer peripheral edge of the elastic body 50 when viewed from the stacking direction of the laminate 10 (i.e., the negative electrode layer 13 is located inside the elastic body 50), lithium metal deposited on the negative electrode layer 13 during charging is entirely pressurized via the elastic body 50. Therefore, the lithium metal deposited during charging returns to the positive electrode side during discharge and does not remain on the negative electrode layer 13. In other words, the lithium metal layer is prevented from remaining and creating a step, which prevents the electrode from breaking due to shear stress and causing a short circuit.

[0027] The configuration of the solid-state battery 100 will be described in detail below.

[0028] 4 is a diagram illustrating the arrangement of each layer and elastic body 50 in the laminate 10 of the solid-state battery 100, and is a schematic cross-sectional view of the solid-state battery 100. As described above, the solid-state battery 100 includes the laminate 10 formed by laminating a plurality of power generating elements 1, each including a positive electrode layer 11, a positive electrode current collector foil 12, a negative electrode layer 13, a negative electrode current collector foil 14, and a solid electrolyte layer 15. The laminate 10 also includes elastic bodies 50 on both ends in the stacking direction, and is pressurized in the stacking direction via the elastic bodies 50.

[0029] As shown in FIG. 4 , the outer peripheral edge of the elastic body 50 is located inside the outer peripheral edge of the positive electrode layer 11 when viewed from the stacking direction of the laminate 10. That is, the outer peripheral edge of the positive electrode layer 11 is located outside the outer peripheral line X of the elastic body 50. Therefore, when the laminate 10 is pressurized in the stacking direction via the elastic body 50, the pressurized area is inside the outer peripheral line X of the elastic body 50. That is, the outer peripheral edge of the positive electrode layer 11 located outside the outer peripheral line X of the elastic body 50 and the positive electrode frame 111 supporting the positive electrode layer 11 from the outside are not pressurized. Therefore, even if a space is generated at the end (outer peripheral edge) of the laminate 10 due to stacking misalignment, no pressure is applied to the space. This reduces the risk of electrode fracture and short circuiting.

[0030] Furthermore, the outer peripheral edge of the anode layer 13 is located inside the outer peripheral edge of the elastic body 50 when viewed from the stacking direction of the laminate 10. That is, the outer peripheral edge of the anode layer 13 is located inside the outer peripheral line X of the elastic body 50. Therefore, the lithium metal layer formed by lithium metal deposited on the anode layer 13 during charging is located inside the elastic body 50 (inside the outer peripheral line X). As a result, all of the lithium metal deposited on the anode layer 13 is pressurized via the elastic body 50 and returns to the positive electrode side during discharge. That is, during discharge, no lithium metal layer remains outside the outer peripheral line X of the elastic body 50. This prevents steps from being created by the remaining lithium metal layer, and prevents the electrode from breaking and short-circuiting due to shear stress.

[0031] Furthermore, the outer peripheral edge of the negative electrode layer 13 is located inside the outer peripheral edge of the solid electrolyte layer 15 when viewed from the stacking direction of the laminate 10. This prevents the lithium metal deposited on the negative electrode layer 13 from contacting the positive electrode layer 11 without going through the solid electrolyte layer 15, and prevents the positive electrode current collector foil 12 and the negative electrode current collector foil 14 from coming into direct contact, thereby preventing a short circuit.

[0032] Furthermore, the outer peripheral edge of the solid electrolyte layer 15 is located outside the outer peripheral edge of the positive electrode layer 11 when viewed from the stacking direction of the laminate 10. That is, the positive electrode layer 11 is located inside the solid electrolyte layer 15. This further prevents direct contact between the positive electrode current collector foil 12 and the negative electrode current collector foil 14, thereby further preventing short circuits.

[0033] In this manner, the elastic body 50 is located inside the positive electrode layer 11, and the negative electrode layer 13 is located inside the elastic body 50 and the solid electrolyte layer 15. In addition, the positive electrode layer 11 is located inside the solid electrolyte layer 15.

[0034] As shown in FIG. 4 , the distance from the outer peripheral edge (end) of the elastic body 50 to the outer peripheral edge (end) of the anode layer 13 in the lateral direction of the laminate 10 (hereinafter also referred to as the distance between the ends of the elastic body 50 and the anode layer 13) is shorter than the distance from the outer peripheral edge (end) of the elastic body 50 to the outer peripheral edge (end) of the cathode layer 11 (hereinafter referred to as the distance between the ends of the elastic body 50 and the cathode layer 11) in all power-generating elements 1. In the solid-state battery 100 of this embodiment, the anode layer 13 is located inside the elastic body 50, so a space is generated within the pressurized range outside the anode layer 13. Therefore, by making the distance between the ends of the elastic body 50 and the anode layer 13 shorter than the distance between the ends of the elastic body 50 and the cathode layer 11, the space outside the pressurized range of the anode layer 13 is narrowed. This reduces the risk of pressure being applied to the space at the end of the laminate 10, thereby reducing the risk of electrode rupture and short-circuiting.

[0035] 4 , adjacent power generating elements 1 are stacked upside down, and except for the negative electrode current collector foils 14 in the power generating elements 1 at both ends of the stacking direction of the laminate 10, the positive electrode current collector foil 12 of one power generating element 1 also serves as the positive electrode current collector foil 12 of another power generating element 1 adjacent to one side of the power generating element 1, and the negative electrode current collector foil 14 also serves as the negative electrode current collector foil 14 of another power generating element 1 adjacent to the other side of the power generating element 1. That is, the positive electrode current collector foil 12 and the negative electrode current collector foil 14 respectively constitute the positive electrode current collector foil 12 and the negative electrode current collector foil 14 of two adjacent power generating elements 1. In the power generating elements 1 at both ends of the stacking direction of the laminate 10, the negative electrode layer 13 and the negative electrode current collector foil 14 are closer to the elastic body 50 than the positive electrode layer 11 and the positive electrode current collector foil 12. In this way, since the negative electrode layer 13 and the negative electrode current collector foil 14 are arranged closer to the elastic body 50, more pressure can be applied to the negative electrode layer 13 including the lithium metal layer, improving power generation efficiency.

[0036] FIG. 5 is an enlarged cross-sectional view of the power generating element 1.

[0037] As shown in FIG. 5 , the solid-state battery 100 has an electrical insulating layer (hereinafter referred to as insulating layer) 16 on the surface of the negative electrode current collector foil 14 outside the outer circumferential edge of the negative electrode layer 13. The insulating layer 16 is adhered to the negative electrode current collector foil 14 and is in contact with the side surface of the outer circumferential edge of the negative electrode layer 13. The insulating layer 16 is, for example, an alumina film or the like, and is coated on the negative electrode current collector foil 14. Note that the position and configuration of the insulating layer 16 are not limited thereto. For example, the insulating layer 16 may be a coating of an inorganic filler, a resin, a tape, or the like, as long as it is made of an insulating material, adheres to the negative electrode current collector foil 14, and is in contact with the negative electrode layer 13.

[0038] The outer peripheral edge of the insulating layer 16 is located outside the outer peripheral edge of the solid electrolyte layer 15 when viewed from the stacking direction of the laminate 10. In other words, the solid electrolyte layer 15 is located inside the insulating layer 16.

[0039] In this way, the insulating layer 16 is adhered to the negative electrode current collector foil 14 and is in contact with the side surface of the outer peripheral edge of the negative electrode layer 13, and the solid electrolyte layer 15 is disposed inside the insulating layer 16, thereby preventing contact between the negative electrode current collector foil 14 and the solid electrolyte layer 15. This prevents lithium from being deposited between the negative electrode current collector foil 14 and the solid electrolyte layer 15, reducing the risk of performance degradation and short circuiting of the solid-state battery 100.

[0040] 5 , the thickness of the insulating layer 16 is equal to or less than the thickness of the anode layer 13. If the insulating layer 16 were thicker than the anode layer 13, the insulating layer 16 might interfere with the application of sufficient pressure to the anode layer 13. In contrast, in this embodiment, the thickness of the insulating layer 16 is equal to or less than the thickness of the anode layer 13, so that a specified pressure can be applied to the anode layer 13, improving power generation efficiency. Note that, because lithium metal can also be deposited on the anode current collector foil 14 outside the outer peripheral edge of the anode layer 13, the thickness of the lithium metal deposited outside the insulating layer 16 and the anode layer 13 is preferably equal to or less than the thickness of the anode layer 13.

[0041] With the above-described configuration, the solid-state battery 100 of this embodiment prevents short circuits and improves power generation efficiency.

[0042] In the solid-state battery 100 of this embodiment (FIGS. 1, 4, and 5), the cross sections of the positive electrode layer 11 and the negative electrode layer 13 are rectangular, but this is not necessarily limited to this. For example, as shown in FIG. 6, the outer peripheral edge of the positive electrode layer 11 may be rounded, or may have another shape.

[0043] In addition, although four power generating elements 1 are stacked in FIGS. 1 and 4, the number of stacked power generating elements 1 is not limited to this, and any number of power generating elements 1 may be stacked.

[0044] According to the solid state battery 100 of the first embodiment described above, the following effects can be obtained.

[0045] In the solid-state battery 100, the outer peripheral edge of the elastic body 50 is located inside the outer peripheral edge of the positive electrode layer 11 when viewed from the stacking direction of the laminate 10 (i.e., the elastic body 50 is located inside the positive electrode layer 11), and the outer peripheral edge of the negative electrode layer 13 is located inside the outer peripheral edge of the solid electrolyte layer 15 and the elastic body 50 when viewed from the stacking direction of the laminate 10 (i.e., the negative electrode layer 13 is located inside the solid electrolyte layer 15 and the elastic body 50). Because the elastic body 50 is located inside the positive electrode layer 11 in this way, even if a space is generated at the outer peripheral edge of the laminate 10 due to stacking misalignment, the outer peripheral edge of the positive electrode layer 11 is not pressurized by the elastic body 50, so no pressure is applied to the space, reducing the risk of a short circuit due to electrode fracture.

[0046] Furthermore, because the anode layer 13 is located inside the elastic body 50, all of the lithium metal deposited on the anode layer 13 during charging is pressurized via the elastic body 50. Therefore, the lithium metal deposited during charging returns to the positive electrode side during discharging and does not remain on the anode layer 13. In other words, the lithium metal layer is prevented from remaining and creating a step, which prevents the electrode from breaking due to shear stress and causing a short circuit.

[0047] Furthermore, since the anode layer 13 is located inside the solid electrolyte layer 15, the lithium metal deposited on the anode layer 13 is prevented from contacting the cathode layer 11 without going through the solid electrolyte layer 15, and the cathode current collector foil 12 and the anode current collector foil 14 are prevented from coming into direct contact with each other, thereby preventing a short circuit.

[0048] In the solid-state battery 100, the outer peripheral edge of the solid electrolyte layer 15 is located outside the outer peripheral edge of the positive electrode layer 11 when viewed from the stacking direction of the laminate 10 (i.e., the positive electrode layer 11 is located inside the solid electrolyte layer 15). This further prevents direct contact between the positive electrode current collector foil 12 and the negative electrode current collector foil 14, thereby further preventing short circuits.

[0049] In the solid-state battery 100, the distance from the outer peripheral edge (end) of the elastic body 50 to the outer peripheral edge (end) of the negative electrode layer 13 in the lateral direction of the laminate 10 is shorter than the distance from the outer peripheral edge (end) of the elastic body 50 to the outer peripheral edge (end) of the positive electrode layer 11. Therefore, the spaces generated at both ends of the lateral direction of the laminate 10 within the pressurized range are narrowed. This reduces the risk of pressure being applied to the spaces at the ends of the laminate 10, which in turn reduces the risk of electrode breakage and short circuiting.

[0050] In the solid-state battery 100, the negative electrode layer 13 and the negative electrode current collector foil 14 in the power generating elements 1 at both ends in the stacking direction of the laminate 10 are closer to the elastic body 50 than the positive electrode layer 11 and the positive electrode current collector foil 12. In this way, since the negative electrode layer 13 and the negative electrode current collector foil 14 are arranged closer to the elastic body 50, more pressure can be applied to the negative electrode layer 13 including the lithium metal layer, improving power generation efficiency.

[0051] The solid-state battery 100 includes an insulating layer (electrical insulating layer) 16 that is adhered to the negative electrode current collector foil 14 and that contacts the negative electrode layer 13, and the outer peripheral edge of the insulating layer (electrical insulating layer) 16 is located outside the outer peripheral edge of the solid electrolyte layer 15 when viewed from the stacking direction of the laminate 10 (i.e., the solid electrolyte layer 15 is located inside the insulating layer 16). This prevents contact between the negative electrode current collector foil 14 and the solid electrolyte layer 15, and prevents lithium from being deposited between the negative electrode current collector foil 14 and the solid electrolyte layer 15. This reduces the risk of performance degradation and short-circuiting of the solid-state battery 100.

[0052] In the solid-state battery 100, the thickness of the insulating layer (electrical insulating layer) 16 is equal to or less than the thickness of the anode layer 13. This allows a specified pressure to be applied to the anode layer 13, improving power generation efficiency.

[0053] In this embodiment, the solid-state battery 100 is a lithium deposition-type solid-state battery in which lithium metal is deposited on the negative electrode layer during charging, but this is not limited thereto. For example, it may be an alkali metal deposition-type solid-state battery in which other alkali metals are deposited during charging. It may also be a non-deposition-type solid-state battery. Even in the case of a non-deposition-type solid-state battery, there is a problem that pressure is applied to the space created by stacking misalignment, causing the electrode to break. Furthermore, since the negative electrode may expand during charging, there is a problem that a step is created between the pressurized and unpressurized portions, causing the electrode to break due to shear stress. These problems can be solved by configuring the elastic body to be located inside the positive electrode layer and the negative electrode layer to be located inside the solid electrolyte layer and the elastic body, as in this embodiment.

[0054] In addition, in this embodiment, the outer peripheral edge of the anode layer 13 is located inside the outer peripheral edge of the solid electrolyte layer 15 when viewed from the stacking direction of the laminate 10, but this is not necessarily limited to this. The outer peripheral edge of the anode layer 13 may be located at a position overlapping the outer peripheral edge of the solid electrolyte layer 15 when viewed from the stacking direction of the laminate 10.

[0055] Furthermore, as in this embodiment, it is preferable that the positive electrode layer 11 be located inside the solid electrolyte layer 15, but this is not necessarily limited to this. For example, the outer peripheral edge of the solid electrolyte layer 15 may be located so as to overlap the outer peripheral edge of the positive electrode layer 11 when viewed from the stacking direction of the laminate 10. In this case, too, direct contact between the positive electrode current collector foil 12 and the negative electrode current collector foil 14 can be prevented. Furthermore, for example, as shown in FIGS. 7 and 8 , the outer peripheral edge of the solid electrolyte layer 15 may be located inside the outer peripheral edge of the positive electrode layer 11 when viewed from the stacking direction of the laminate 10. Even in this case, the risk of a short circuit due to electrode fracture can be reduced if the elastic body 50 is located inside the positive electrode layer 11 and the negative electrode layer 13 is located inside the elastic body 50 and the solid electrolyte layer 15.

[0056] Furthermore, as in this embodiment, it is preferable that the distance between the ends of the elastic body 50 and the negative electrode layer 13 is shorter than the distance between the ends of the elastic body 50 and the positive electrode layer 11, but this is not necessarily limited to this. Even if the distance between the ends of the elastic body 50 and the negative electrode layer 13 is equal to or greater than the distance between the ends of the elastic body 50 and the positive electrode layer 11, the risk of a short circuit due to electrode fracture can be reduced as long as the elastic body 50 is located inside the positive electrode layer 11 and the negative electrode layer 13 is located inside the elastic body 50 and the solid electrolyte layer 15.

[0057] Furthermore, as in this embodiment, it is preferable that the negative electrode layer 13 and the negative electrode current collector foil 14 in the power generation elements 1 at both ends of the stacking direction of the laminate 10 are closer to the elastic body 50 than the positive electrode layer 11 and the positive electrode current collector foil 12, but this is not necessarily limited to this. For example, adjacent power generation elements 1 may be stacked without being turned upside down, and the power generation element 1 at one end of the stacking direction of the laminate 10 may have the negative electrode layer 13 and the negative electrode current collector foil 14 closer to the elastic body 50 than the positive electrode layer 11 and the positive electrode current collector foil 12, and the power generation element 1 at the other end may have the positive electrode layer 11 and the positive electrode current collector foil 12 closer to the elastic body 50 than the negative electrode layer 13 and the negative electrode current collector foil 14.

[0058] 5 of the present embodiment, in the solid-state battery 100 in which the positive electrode layer 11 and the negative electrode layer 13 have rectangular cross sections, the insulating layer (electrical insulating layer) 16 having a rectangular cross section is bonded to the negative electrode current collector foil 14 and is in contact with a portion of the side surface of the outer circumferential end of the negative electrode layer 13. However, this is not necessarily limited to this. For example, even when the outer circumferential end of the positive electrode layer 11 has a rounded shape as shown in FIG. 9, the insulating layer (electrical insulating layer) 16 can be similarly configured to be bonded to the negative electrode current collector foil 14 and in contact with a portion of the side surface of the outer circumferential end of the negative electrode layer 13. Furthermore, for example, as shown in FIGS. 10 and 11, the insulating layer 16 may extend into the negative electrode layer 13, or as shown in FIGS. 12 and 13, the insulating layer 16 may be bent and in contact with the side surface of the outer circumferential end of the negative electrode layer 13. That is, each layer may have any shape as long as the insulating layer (electrical insulating layer) 16 is adhered to the negative electrode current collector foil 14 and is in contact with the negative electrode layer 13. Also, a configuration without the insulating layer (electrical insulating layer) 16 is not necessary.

[0059] Furthermore, as in this embodiment, the outer peripheral edge of the insulating layer (electrical insulating layer) 16 is preferably located outside the outer peripheral edge of the solid electrolyte layer 15 when viewed from the stacking direction of the laminate 10, but this is not necessarily limited to this. That is, the outer peripheral edge of the insulating layer (electrical insulating layer) 16 may be located at a position overlapping with the outer peripheral edge of the solid electrolyte layer 15 when viewed from the stacking direction of the laminate 10, or may be located inside that position.

[0060] Furthermore, as in the present embodiment, it is preferable that the thickness of the insulating layer (electrical insulating layer) 16 is equal to or less than the thickness of the negative electrode layer 13, but this is not necessarily limited to this, and the thickness of the insulating layer (electrical insulating layer) 16 may be equal to the thickness of the negative electrode layer 13.

[0061] Furthermore, in the present embodiment, the elastic body 50 is disposed on the outside of the exterior body 20, but this is not limiting. For example, the elastic body 50 may be disposed on both the inside and outside of the exterior body 20. That is, the elastic body 50 may include a first elastic body disposed on the inside of the exterior body 20 and a second elastic body disposed on the outside of the exterior body 20, and may be configured to pressurize the stacked body 10 in the stacking direction via the second elastic body and the first elastic body. Using such a configuration allows the stacked body 10 to be pressurized more uniformly, improving the power generation efficiency of the solid-state battery 100.

[0062] Second Embodiment A solid state battery 100 according to a second embodiment will be described with reference to Fig. 14. In this embodiment, the position of the insulating layer (electrical insulating layer) 16 differs from that of the first embodiment. Note that elements similar to those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0063] FIG. 14 is an enlarged cross-sectional view of the power generating element 1 in the solid state battery 100 of the second embodiment.

[0064] 14 , in this embodiment, an insulating layer (electrical insulating layer) 16 is provided on the surface of the solid electrolyte layer 15 outside the outer peripheral edge of the anode layer 13. The insulating layer 16 is adhered to the solid electrolyte layer 15 and is in contact with the side surface of the outer peripheral edge of the anode layer 13.

[0065] As in the first embodiment, the outer peripheral edge of the insulating layer 16 is located outside the outer peripheral edge of the solid electrolyte layer 15 when viewed from the stacking direction of the laminate 10. That is, the solid electrolyte layer 15 is located inside the insulating layer 16. As in the first embodiment, the thickness of the insulating layer 16 is equal to or less than the thickness of the negative electrode layer 13.

[0066] In this way, by adhering the insulating layer 16 to the solid electrolyte layer 15 and contacting the side surface of the outer peripheral edge of the anode layer 13, and by disposing the solid electrolyte layer 15 inside the insulating layer 16, the anode current collector foil 14 and the solid electrolyte layer 15 are prevented from contacting each other. This prevents lithium from being deposited between the anode current collector foil 14 and the solid electrolyte layer 15, reducing the risk of performance degradation and short-circuiting of the solid battery 100.

[0067] 14 shows a solid-state battery 100 in which the cathode layer 11 and the anode layer 13 have rectangular cross sections, and the insulating layer (electrical insulating layer) 16 having a rectangular cross section is bonded to the solid electrolyte layer 15 and is in contact with a portion of the side surface of the outer circumferential edge of the anode layer 13. However, this is not necessarily limited to this. For example, as shown in FIG. 15 , even when the outer circumferential edge of the cathode layer 11 has a rounded shape, the insulating layer (electrical insulating layer) 16 can be similarly configured to be bonded to the solid electrolyte layer 15 and to be in contact with a portion of the side surface of the outer circumferential edge of the anode layer 13. Furthermore, as shown in FIGS. 16 and 17 , the insulating layer 16 may be configured to be bent and to be in contact with the side surface of the outer circumferential edge of the anode layer 13. That is, as long as the insulating layer (electrical insulating layer) 16 is bonded to the solid electrolyte layer 15 and in contact with the anode layer 13, each layer may have any shape.

[0068] Third Embodiment A solid state battery 100 according to a second embodiment will be described with reference to Fig. 18. In this embodiment, the position of the insulating layer (electrical insulating layer) 16 differs from that of the other embodiments. Elements similar to those of the other embodiments are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0069] FIG. 18 is an enlarged cross-sectional view of the power generating element 1 in the solid state battery 100 of the third embodiment.

[0070] 18 , in this embodiment, an insulating layer (electrical insulating layer) 16 is provided on the surface of the negative electrode current collector foil 14 outside the outer peripheral edge of the negative electrode layer 13 and on the surface of the solid electrolyte layer 15 outside the outer peripheral edge of the negative electrode layer 13. The insulating layer 16 is adhered to the negative electrode current collector foil 14 and the solid electrolyte layer 15, and is bent to contact the entire side surface of the outer peripheral edge of the negative electrode layer 13.

[0071] As in the other embodiments, the outer peripheral edge of the insulating layer 16 (the outer peripheral edge of each of the insulating layers 16 on the surface of the negative electrode current collector foil 14 and on the surface of the solid electrolyte layer 15) is located outside the outer peripheral edge of the solid electrolyte layer 15 when viewed from the stacking direction of the laminate 10. That is, the solid electrolyte layer 15 is located inside the insulating layer 16. As in the other embodiments, the thickness of the insulating layer 16 is equal to or less than the thickness of the negative electrode layer 13.

[0072] In this way, the insulating layer 16 is adhered to the negative electrode current collector foil 14 and the solid electrolyte layer 15, and is in contact with the side surface of the outer peripheral edge of the negative electrode layer 13, and the solid electrolyte layer 15 is disposed inside the insulating layer 16, thereby preventing contact between the negative electrode current collector foil 14 and the solid electrolyte layer 15. This prevents lithium from being deposited between the negative electrode current collector foil 14 and the solid electrolyte layer 15, reducing the risk of performance degradation and short-circuiting of the solid battery 100.

[0073] 18 , in the solid-state battery 100 in which the positive electrode layer 11 and the negative electrode layer 13 have rectangular cross sections, the insulating layer (electrical insulating layer) 16 having a rectangular cross section is bonded to the negative electrode current collector foil 14 and the solid electrolyte layer 15 and is in contact with the entire side surface of the outer circumferential edge of the negative electrode layer 13, but this is not necessarily limited to this. For example, even in the case in which the positive electrode layer 11 has a rounded outer circumferential edge as shown in FIG. 19 , the insulating layer (electrical insulating layer) 16 can be similarly configured to be bonded to the negative electrode current collector foil 14 and the solid electrolyte layer 15 and to be in contact with the side surface of the outer circumferential edge of the negative electrode layer 13.

[0074] 20 and 21 , the insulating layer 16 adhered to the negative electrode current collector foil 14 may be bent to contact the entire side surface of the outer peripheral end of the negative electrode layer 13, and the tip of the insulating layer 16 may be adhered to the solid electrolyte layer 15.

[0075] 22 and 23 , the insulating layer 16 bonded to the solid electrolyte layer 15 may be bent to contact the entire side surface of the outer peripheral edge of the negative electrode layer 13, and the tip of the insulating layer 16 may be bonded to the negative electrode current collector foil 14.

[0076] 24 and 25 , the insulating layer 16 may be configured to be in contact with the entire side surface of the outer peripheral end of the negative electrode layer 13, and to be bonded to the surface of the solid electrolyte layer 15 on the outside of the outer peripheral end of the negative electrode layer 13 and to the surface of the negative electrode current collector foil 14 extending from the outside to the inside of the outer peripheral end of the negative electrode layer 13.

[0077] 26 and 27, the inner peripheral ends of two insulating layers 16 bonded to the negative electrode current collector foil 14 and the solid electrolyte layer 15, respectively, may be configured to contact the side surfaces of the negative electrode layer 13.

[0078] That is, as long as the insulating layer (electrical insulating layer) 16 adheres to the negative electrode current collector foil 14 and the solid electrolyte layer 15 and is in contact with the negative electrode layer 13, each layer may have any shape.

[0079] Fourth Embodiment A solid state battery 100 according to a fourth embodiment will be described with reference to Fig. 28. In this embodiment, the shape of the insulating layer (electrical insulating layer) 16 differs from that of the other embodiments. Note that elements similar to those in the other embodiments are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0080] FIG. 28 is an enlarged cross-sectional view of the power generating element 1 in the solid state battery 100 of the fourth embodiment.

[0081] 28 , in this embodiment, an insulating layer (electrical insulating layer) 16 is provided between the negative electrode current collector foil 14 on the outside of the outer peripheral edge of the negative electrode layer 13 and the solid electrolyte layer 15 on the outside of the outer peripheral edge of the negative electrode layer 13. The inner peripheral surface of the insulating layer 16 is in contact with the negative electrode layer 13, and one entire surface in the stacking direction is bonded to the negative electrode current collector foil 14, and the other entire surface is bonded to the solid electrolyte layer 15. In other words, the thickness of the insulating layer 16 is equal to the thickness of the negative electrode layer 13.

[0082] As in the other embodiments, the outer peripheral edge of the insulating layer 16 is located outside the outer peripheral edge of the solid electrolyte layer 15 when viewed from the stacking direction of the laminate 10. That is, the solid electrolyte layer 15 is located inside the insulating layer 16. Note that the outer peripheral edge of the solid electrolyte layer 15 is located outside the outer peripheral edge of the positive electrode layer 11 when viewed from the stacking direction of the laminate 10, and the elastic body 50 is located inside the positive electrode layer 11.

[0083] In this way, by disposing the insulating layer 16 on the outside of the outer peripheral edge of the negative electrode layer 13 so that one surface is adhered to the negative electrode current collector foil 14 and the other surface is adhered to the solid electrolyte layer 15, and by configuring the solid electrolyte layer 15 to be located inside the insulating layer 16, the space between the negative electrode current collector foil 14 and the solid electrolyte layer 15 within the pressure range is filled with the insulating layer 16. Although this may weaken the pressure applied to the negative electrode layer 13, the space within the pressure range is reduced, so that the risk of pressurizing the space at the outer peripheral edge of the laminate 10, causing the electrode to break and resulting in a short circuit, can be further reduced.

[0084] Furthermore, since the space between the negative electrode current collector foil 14 and the solid electrolyte layer 15 is filled with the insulating layer 16, lithium does not precipitate between the negative electrode current collector foil 14 and the solid electrolyte layer 15, reducing the risk of performance degradation and short circuiting of the solid battery 100.

[0085] 28 illustrates a solid-state battery 100 in which the cross sections of the positive electrode layer 11 and the negative electrode layer 13 are rectangular, but this is not limiting. For example, as shown in FIG. 29 , even when the outer peripheral edge of the positive electrode layer 11 has a rounded shape, the space between the negative electrode current collector foil 14 and the solid electrolyte layer 15 can be filled with the insulating layer 16. In this case, the thickness of the insulating layer 16 is equal to or greater than the thickness of the negative electrode layer 13.

[0086] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0087] Furthermore, although the above-described embodiments have been described as separate embodiments, they may be combined as appropriate.

Claims

1. A solid-state battery including a laminate formed by laminating a plurality of power generating elements, each of which includes a positive electrode layer, a positive electrode current collecting foil in contact with one surface of the positive electrode layer, a negative electrode layer, a negative electrode current collecting foil in contact with one surface of the negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer so as to be in contact with the other surface of the positive electrode layer and the other surface of the negative electrode layer; wherein the laminate is provided with elastic bodies on both ends in the stacking direction, the laminate is pressed in the stacking direction via the elastic bodies, the outer peripheral edge of the elastic body is located inside the outer peripheral edge of the positive electrode layer when viewed from the stacking direction of the laminate, and the outer peripheral edge of the negative electrode layer is located at a position overlapping with or inside the outer peripheral edge of the solid electrolyte layer when viewed from the stacking direction of the laminate, and is also located inside the outer peripheral edge of the elastic body when viewed from the stacking direction of the laminate.

2. A solid-state battery according to claim 1, wherein the outer peripheral edge of the solid electrolyte layer is located at a position overlapping with or outside the outer peripheral edge of the positive electrode layer when viewed from the stacking direction of the laminate.

3. A solid-state battery according to claim 2, wherein the distance from the outer peripheral edge of the elastic body to the outer peripheral edge of the negative electrode layer in the lateral direction of the laminate is shorter than the distance from the outer peripheral edge of the elastic body to the outer peripheral edge of the positive electrode layer.

4. A solid-state battery according to claim 1, wherein the power generating elements at both ends of the stack in the stacking direction of the stack are such that the negative electrode layer and the negative electrode current collecting foil are closer to the elastic body than the positive electrode layer and the positive electrode current collecting foil.

5. A solid-state battery as claimed in claim 1, further comprising an electrical insulating layer adhered to said negative electrode current collecting foil and in contact with said negative electrode layer, wherein the outer peripheral edge of said electrical insulating layer is located outside the outer peripheral edge of said solid electrolyte layer when viewed from the stacking direction of said laminate.

6. A solid-state battery according to claim 1, further comprising an electrical insulating layer that is adhered to the solid electrolyte layer and in contact with the negative electrode layer, the outer peripheral edge of the electrical insulating layer being located outside the outer peripheral edge of the solid electrolyte layer when viewed in the stacking direction of the laminate.

7. A solid-state battery as claimed in claim 1, further comprising an electrical insulating layer that is adhered to the negative electrode current collecting foil and the solid electrolyte layer and that is in contact with the negative electrode layer, and the outer circumferential edge of the electrical insulating layer is located outside the outer circumferential edge of the solid electrolyte layer when viewed in the stacking direction of the laminate.

8. A solid-state battery according to any one of claims 5 to 7, wherein the distance from the outer peripheral edge of the elastic body to the outer peripheral edge of the negative electrode layer in the lateral direction of the laminate is shorter than the distance from the outer peripheral edge of the elastic body to the outer peripheral edge of the positive electrode layer.

9. A solid-state battery according to any one of claims 5 to 7, wherein the thickness of the electrical insulating layer is equal to or less than the thickness of the negative electrode layer.

10. A solid-state battery according to any one of claims 1 to 7, further comprising an exterior body that houses the laminate, wherein the elastic body includes a first elastic body arranged inside the exterior body and a second elastic body arranged outside the exterior body, and the laminate is pressurized in the stacking direction via the second elastic body and the first elastic body.

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