Method for measuring the electrical characteristics of a solid-state battery, solid-state battery, and housing for a solid-state battery

Abstract

To ensure that ion conduction in the solid electrolyte layer is not hindered, that defects such as cracks do not easily occur in the solid electrolyte layer, and that the electrical characteristics of the solid battery can be accurately measured over a wide pressure range. [Solution] A method for measuring the characteristics of a solid-state battery 10 comprising a solid electrolyte layer 11, a positive electrode layer 12, and a negative electrode layer 13, wherein the voltage between the positive electrode layer 12 or the negative electrode layer 13 and the reference electrode 14 is measured with the reference electrode 14 positioned in contact with the side surface 11s between the first surface 11a and the second surface 11b of the solid electrolyte layer 11. In the measurement, the reference electrode 14 extends in a direction perpendicular to the thickness direction of the solid electrolyte layer 11.

Description

[Technical Field]

[0001] The present invention relates to a method for measuring the electrical characteristics of a solid-state battery equipped with a solid electrolyte layer, a solid-state battery, and an casing for a solid-state battery. [Background technology]

[0002] In recent years, secondary batteries have attracted attention as a means of preventing global warming by reducing carbon dioxide emissions. Among these, solid-state batteries using solid electrolytes are attracting particular attention. Solid-state batteries do not use flammable organic solvents, which allows for the simplification of safety devices and offers advantages in terms of manufacturing cost and productivity. Furthermore, because ions other than cations do not move within the solid electrolyte, solid-state batteries are advantageous from the standpoint of improving safety and durability, as they do not cause side reactions due to anion movement.

[0003] In solid-state batteries, balancing the characteristics of the positive electrode layer, solid electrolyte layer, and negative electrode layer is crucial for improving performance. Therefore, there is a need to develop methods for independently and non-destructively evaluating the characteristics of each of these layers. In particular, since the characteristics of solid-state batteries change depending on the pressure applied to the cell, there is a need for methods that can accurately evaluate the characteristics of solid-state batteries over a wide pressure range, especially in the high-pressure range.

[0004] For example, Patent Document 1 describes placing a reference electrode in a solid electrolyte portion that is connected to the solid electrolyte layer in a solid-state battery. In this solid-state battery, the potential of the positive or negative electrode can be measured by measuring the potential difference between the reference electrode and the positive or negative electrode.

[0005] Patent Document 2 describes a solid electrolyte layer having an extended portion that, in a plan view, protrudes outward from the positive and negative electrodes and circles around the periphery of the positive and negative electrodes, with a reference electrode placed on the main surface of the extended portion. The reference electrode is formed to circle at an equidistant distance from the periphery of the positive and negative electrodes in a plan view. In this solid battery, the potential of the positive electrode can be measured by measuring the potential difference between the reference electrode and the positive electrode.

[0006] Non-patent document 1 describes a solid-state battery in which a mesh-like reference electrode is placed within a solid electrolyte layer. Non-patent document 2 describes a solid-state battery in which a wire-like reference electrode is placed within a solid electrolyte layer. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2013-020915 [Patent Document 2] Japanese Patent Publication No. 2024-067195 [Non-patent literature]

[0008] [Non-Patent Document 1] Electrochemistry Communications 116 (2020) 106743 [Non-Patent Document 2] Journal of The Electrochemical Society 170 (2023) 040519 [Overview of the project] [Problems that the invention aims to solve]

[0009] In the solid-state battery described in Patent Document 1, the reference electrode is placed only in a very small portion of the solid electrolyte layer, making it sometimes impossible to accurately measure the impedance between the reference electrode and the positive or negative electrode. Furthermore, the same document does not assume that pressure will be applied to the battery. In the solid-state battery described in Patent Document 2, although the potential difference between the reference electrode and the positive electrode can be measured, there are cases where the potential difference between the reference electrode and the negative electrode cannot be accurately measured. Also, in the same document, similar to Patent Document 1 described above, applying pressure to the battery is not assumed. In the solid-state battery described in Non-Patent Document 1, since the reference electrode is disposed in the solid electrolyte layer, ion conduction between the positive electrode and the negative electrode is hindered by the reference electrode, and an accurate potential difference cannot be measured. Also, the reference electrode is deformed by pressure, further hindering ion conduction between the positive electrode and the negative electrode. Even in the solid-state battery described in Non-Patent Document 2, the reference electrode is deformed by pressure, similar to the solid-state battery described in Non-Patent Document 1. Also, defects such as cracks are likely to occur during the formation of the solid electrolyte layer. Therefore, an object of the present invention is to solve the problems of conventional solid-state batteries having a reference electrode.

Means for Solving the Problems

[0010] The present invention relates to a method for measuring the characteristics of a solid-state battery including a solid electrolyte layer having a first surface and a second surface located on the opposite side of the first surface, a positive electrode layer disposed on the first surface side of the solid electrolyte layer, a negative electrode layer disposed on the second surface side of the solid electrolyte layer, the method comprising: measuring the voltage between the positive electrode layer or the negative electrode layer and the reference electrode in a state where the reference electrode is disposed in contact with a side surface between the first surface and the second surface in the solid electrolyte layer, wherein in the measurement, the reference electrode extends in a direction orthogonal to the thickness direction of the solid electrolyte layer, and provides a method for measuring the characteristics of a solid-state battery.

[0011] The present invention also relates to a solid-state battery including a solid electrolyte layer having a first surface and a second surface located on the opposite side of the first surface, a positive electrode layer disposed on the first surface side of the solid electrolyte layer, a negative electrode layer disposed on the second surface side of the solid electrolyte layer, A reference electrode is positioned in contact with the side surface between the first and second surfaces of the solid electrolyte layer. The present invention provides a solid-state battery in which the reference electrode extends in a direction perpendicular to the thickness direction of the solid electrolyte layer.

[0012] Furthermore, the present invention provides a solid electrolyte layer having a first surface and a second surface located opposite the first surface, A positive electrode layer disposed on the first surface side of the solid electrolyte layer, A negative electrode layer disposed on the second surface side of the solid electrolyte layer, A solid battery casing comprising a cell-containing space including a reference electrode positioned on a side surface between a first surface and a second surface of the solid electrolyte layer, said to extend along the circumferential direction of the side surface, The aforementioned exterior provides an exterior for a solid-state battery, wherein the exterior has a groove on a surface defining the space, at a position corresponding to the reference electrode when the cell is housed within the space, that is capable of accommodating the reference electrode. [Effects of the Invention]

[0013] According to the present invention, ion conduction in the solid electrolyte layer is not hindered, defects such as cracks are less likely to occur in the solid electrolyte layer, and accurate measurement of electrical properties becomes possible over a wide pressure range. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a longitudinal cross-sectional view showing the structure of the solid-state battery of the present invention. [Figure 2] Figure 2 is an exploded perspective view of the solid-state battery shown in Figure 1. [Figure 3] Figure 3 is a cross-sectional view taken along line III-III in Figure 1. [Figure 4] Figure 4 is a schematic diagram illustrating a method for measuring the electrical characteristics of the solid-state battery shown in Figure 1. [Figure 5] Figure 5 is a graph showing the measured potential and impedance results for the solid-state battery obtained in Example 1. [Figure 6]Figure 6 is a graph showing the measured potential and impedance results for the solid-state battery obtained in Example 2. [Figure 7] Figure 7 is a graph showing the measured potential and impedance results for the solid-state battery obtained in Example 3. [Figure 8] Figure 8 is a graph showing the potential measurement results for the solid-state battery obtained in Comparative Example 1. [Figure 9] Figure 9 is a graph showing the potential measurement results for the solid-state battery obtained in Comparative Example 2. [Figure 10] Figure 10 is a graph showing the measured potential and impedance results for the solid-state battery obtained in Comparative Example 3. [Modes for carrying out the invention]

[0015] The present invention will be described below with reference to the drawings, based on preferred embodiments thereof. The present invention relates to a method for measuring the electrical characteristics of a solid-state battery. In this specification, "solid-state battery" includes not only solid-state batteries that do not contain any liquid or gel-like substances as an electrolyte, but also embodiments that contain, for example, 50% by mass or less, 30% by mass or less, or 10% by mass or less of a liquid or gel-like substance as an electrolyte.

[0016] Figures 1 to 3 show an embodiment of a solid-state battery suitably used in the measurement method of the present invention. The solid-state battery 10 shown in these figures comprises a solid electrolyte layer 11. The solid electrolyte layer 11 can be made, for example, from a molded body of solid electrolyte powder or a sheet containing solid electrolyte powder. The solid electrolyte is made of an ion-conducting material. For example, the solid electrolyte can be made from lithium-ion conductive, sodium-ion conductive, magnesium-ion conductive, proton conductive, or oxide-ion conductive materials, but is not limited to these ions.

[0017] When the solid electrolyte has, for example, lithium ion conductivity, the solid electrolyte may contain, for example, lithium (Li) element and sulfur (S) element and have lithium ion conductivity, or may contain lithium (Li) element, phosphorus (P) element and sulfur (S) element and have lithium ion conductivity. The sulfide solid electrolyte may be any of a crystalline material, glass ceramics, and glass. The sulfide solid electrolyte may have a crystal phase with an argyrodite-type structure. Examples of such sulfide solid electrolytes include Li2S-P2S5, Li2S-P2S5-LiX (X is at least one halogen element), Li2S-P2S5-P2O5, Li2S-Li3PO4-P2S5, Li3PS4, Li4P2S6, Li 10 GeP2S 12 、Li 3.25 Ge 0.25 P 0.75 S4、Li7P3S 11 、Li 3.25 P 0.95 S4、Li a PS b X c (X is at least one halogen element. a represents a number of 3.0 or more and 9.0 or less. b represents a number of 3.5 or more and 6.0 or less. c represents a number of 0.1 or more and 3.0 or less.) Compounds represented thereby, etc. are mentioned. In addition to this, for example, sulfide solid electrolytes described in WO2013 / 099834A1 and WO2015 / 001818A1 are mentioned.

[0018] The solid electrolyte layer 11 has a flat shape having two main surfaces 11a and 11b, and is circular in plan view. However, the shape of the solid electrolyte layer 11 in plan view is not limited to a circle, and other shapes such as an ellipse or a polygon may be acceptable. The two main surfaces 11a and 11b of the solid electrolyte layer 11 are the first surface 11a and the second surface 11b located on the opposite side thereof. The first surface 11a and the second surface 11b are separated by a distance, and the distance between both surfaces corresponds to the thickness of the solid electrolyte layer 11. Therefore, the solid electrolyte layer 11 has a side surface 11s between the first surface 11a and the second surface 11b.

[0019] A reference electrode 14 is positioned in contact with the side surface 11s of the solid electrolyte layer 11. In this embodiment, since the solid electrolyte layer 11 is a flattened cylindrical shape, there is only one side surface 11s. However, depending on the shape of the solid electrolyte layer 11 (for example, if it is a prismatic shape), the solid electrolyte layer 11 may have two or more side surfaces. The reference electrode 14 is used for measuring the electrical characteristics of the solid battery 10. Details of the reference electrode 14 will be described later. The reference electrode 14 is arranged to extend along the circumferential direction of the side surface 11s within the thickness range of the solid electrolyte layer 11. If there are multiple side surfaces, it extends along all of them. In this embodiment, the tip of the reference electrode 14 in the direction of extension is in contact with itself, forming a closed shape. That is, the reference electrode 14 is arranged to form a closed annular shape along the circumferential direction of the side surface 11s. However, it is not prevented that the reference electrode 14 is arranged along the circumferential direction of the side surface 11s only on a part of the side surface 11s. In this specification, "extending" means that, when L is the circumference of the side surface 11s (i.e., the length of the side surface 11s along the direction perpendicular to the thickness direction of the solid electrolyte layer 11), the length of the reference electrode 14 along the circumferential direction of the side surface 11s (i.e., the length of the reference electrode 14 along the direction perpendicular to the thickness direction of the solid electrolyte layer 11) is, for example, 5% or more of L. From the viewpoint of reducing variations in the spacing between the positive electrode layer 12 or the negative electrode layer 13 and the reference electrode 14 and enabling accurate measurement of characteristics such as potential and impedance, the length of the reference electrode 14 is preferably 20% or more of L, more preferably 50% or more, and even more preferably 80% or more. The length of the reference electrode 14 may be 100% of L as described above. The length of the reference electrode 14 may exceed 100% of L.

[0020] A positive electrode layer 12 is located on the first surface 11a side of the solid electrolyte layer 11. The solid electrolyte layer 11 and the positive electrode layer 12 are in direct contact. On the other hand, a negative electrode layer 13 is located on the second surface 11b side. The solid electrolyte layer 11 and the negative electrode layer 13 are in direct contact. Both the positive electrode layer 12 and the negative electrode layer 13 have a flattened shape and are circular in plan view. The diameters of the positive electrode layer 12 and the negative electrode layer 13 are approximately equal to the diameter of the solid electrolyte layer 11. However, the diameters of the positive electrode layer 12 and / or the negative electrode layer 13 may be larger or smaller than the diameter of the solid electrolyte layer 11. Furthermore, while it is desirable that the plan view shapes of the positive electrode layer 12 and the negative electrode layer 13 be the same as the plan view shapes of the solid electrolyte layer 11, they may be different shapes if necessary.

[0021] The positive electrode layer 12 contains a positive electrode active material. In addition, the positive electrode layer 12 may contain other components, such as a solid electrolyte, a conductive additive, and a binder. The positive electrode active material is selected appropriately depending on the ion species conducted by the solid electrolyte layer 11. If the solid electrolyte layer 11 has lithium ion conductivity, for example, a material capable of intercalating and releasing lithium ions is used as the positive electrode active material. Examples include lithium transition metal composite oxides having a layered rock salt structure or a spinel structure. Specifically, LiCoO2, LiNiO2, LiMn2O4, LiNi 0.5 Mn 1.5 O4, Li(Co 1 / 3 Ni 1 / 3 Mn 1 / 3 ) O2 and LiNi 0.6 Co 0.2 Mn 0.2 Examples include O2. Alternatively, LiFePO4 may also be used. If a solid electrolyte is included in the positive electrode layer 12, the solid electrolyte may be of the same type as the solid electrolyte included in the solid electrolyte layer 11, or it may be of a different type.

[0022] The negative electrode layer 13 contains a negative electrode active material. In addition, the negative electrode layer 13 may contain other components, such as a solid electrolyte, a conductive additive, and a binder. The negative electrode active material is selected appropriately depending on the ion species conducted by the solid electrolyte layer 11. If the solid electrolyte layer 11 is, for example, lithium ion conductive, a material capable of intercalating and releasing lithium ions is used as the negative electrode active material. Examples include, but are not limited to, carbon-based materials such as graphite, artificial graphite, natural graphite, and non-graphitizable carbon (hard carbon), silicon, metallic lithium, lithium alloys, lithium titanate, and lithium vanadium composite oxide. If a solid electrolyte is included in the negative electrode layer 13, the solid electrolyte may be of the same type as the solid electrolyte included in the solid electrolyte layer 11, or it may be of a different type.

[0023] A positive electrode current collector 15 is positioned on the side of the positive electrode layer 12 opposite to the surface facing the solid electrolyte layer 11. The positive electrode layer 12 and the positive electrode current collector 15 are in direct contact. The positive electrode current collector 15 is made of an electronically conductive material that does not affect the electrode reaction in the positive electrode layer 12. Aluminum is an example of such a material. On the other hand, a negative electrode current collector 16 is positioned on the surface of the negative electrode layer 13 opposite to the surface facing the solid electrolyte layer 11. The negative electrode layer 13 and the negative electrode current collector 16 are in direct contact. The negative electrode current collector 16 is made of an electronically conductive material that does not affect the electrode reaction in the negative electrode layer 13. Stainless steel is an example of such a material.

[0024] The solid-state battery 10 of this embodiment comprises a cell 17 in which a negative electrode current collector 16, a negative electrode layer 13, a solid electrolyte layer 11, a positive electrode layer 12, and a positive electrode current collector 15 are stacked in this order, and a reference electrode 14 is arranged on the side surface 11s of the solid electrolyte layer 11, and a solid-state battery casing 20. The casing 20 is cylindrical. The casing 20 has a space 20a inside in which the cell 17 can be housed. In other words, the cylindrical space formed in the cylinder is the space 20a in which the cell 17 can be housed. The shape of the outer casing 20 is not limited to a cylindrical shape; it may also be other shapes, such as a rectangular tube. The shape of the accommodating space 20a is not limited to a cylindrical shape; it may also be other shapes, such as a rectangular prism.

[0025] The outer casing 20 is designed so that, when the cell 17 is housed in it, the outer surfaces of the positive electrode layer 12 and the negative electrode layer 13 are exposed, and the positive electrode current collector 15 and the negative electrode current collector 16 are in contact with the outer surfaces of the positive electrode layer 12 and the negative electrode layer 13.

[0026] The outer casing 20 is made of an insulating material that does not conduct electricity. Examples of such materials include various ceramics and synthetic resins. In this case, the outer casing 20 may be a rigid body that is difficult to deform under external forces.

[0027] In the state in which the cell 17 is housed in the outer casing 20, it is preferable that the outer casing 20 has a groove 20b capable of accommodating the reference electrode 14 at a position corresponding to the reference electrode 14 on the surface defining the cell 17 housing space 20a, i.e., the inner surface of the cylinder, as shown in Figure 1. The groove 20b is formed on the inner surface of the cylinder along the entire circumference. The depth of the groove 20b, i.e., the degree of the recess along the left-right direction in Figure 1, should be sufficient to accommodate the entire reference electrode 14. When the solid battery 10 is assembled, the reference electrode 14 is housed in the groove 20b, which allows the reference electrode 14 to be stably held on the side surface 11s of the solid electrolyte layer 11. Furthermore, it is possible to prevent the reference electrode 14 from being crushed by pressure when pressure is applied to the solid battery 10.

[0028] The solid-state battery 10 of this embodiment is used with the cell 17 housed in the accommodable space 20a of the outer casing 20. In this case, in order to improve the adhesion between each component constituting the cell 17, it is preferable to place pressing members 18 on the outer surface of the positive electrode current collector 15 and the outer surface of the negative electrode current collector 16, respectively, and press the cell 17 with the cell 17 interposed between the two pressing members 18, 18. In other words, it is preferable that the cell 17 is pressurized by applying external force to both current collectors 15, 16 by the two pressing members 18, 18 so that the positive electrode current collector 15 and the negative electrode current collector 16 are brought closer together.

[0029] The pressing member 18 consists of a base portion 18a and a projection portion 18b. The base portion 18a has a flat shape. The projection portion 18b is cylindrical. The base portion 18a has two opposing planes, and the projection portion 18b is provided on one of these planes. In a plan view of the pressing member 18, the projection portion 18b is located within the contour line of the base portion 18a. The cylindrical projection 18b has a cross-sectional diameter that is approximately the same as the cross-sectional diameter of the cylindrical storable space 20a provided in the outer casing 20, and the projection 18b can be inserted into the storable space 20a. When the projection 18b is inserted into the storable space 20a, the upper surface of the base portion 18a comes into contact with the outer casing 20, which restricts the projection 18b from being inserted too far into the storable space 20a.

[0030] The pressing member 18 is preferably made of a material that can withstand the pressure applied by the cell 17. Examples of such materials include metal materials and ceramic materials. If the pressing member 18 is made of a metal material, such as stainless steel, then the pressing member 18 is conductive, and therefore it is not necessary to use the positive electrode current collector 15 and / or the negative electrode current collector 16 described above. In other words, if the pressing member 18 is conductive, then the pressing member 18 can be used interchangeably with the positive electrode current collector 15 and / or the negative electrode current collector 16.

[0031] The solid battery 10 of this embodiment may further include a fixing device 19 that allows the reference electrode 14 to be pressed toward the solid electrolyte layer 11 and fixed to the solid electrolyte layer 11, as shown in Figures 1 to 3. The fixing device 19 is capable of fixing the reference electrode 14 to the solid electrolyte layer 11 while in direct contact with the reference electrode 14. For this purpose, in the solid battery 10, it is preferable that the outer casing 20 has through holes 20c that connect the outer surface of the outer casing 20 to the surface that defines the space 20a in which the cell 17 can be housed, i.e., the inner surface of the cylinder.

[0032] As shown in Figures 1 and 2, the through-hole 20c is open at a position facing the reference pole 14 on the surface that defines the accommodating space 20a of the cell 17. The fastener 19 is made of screws. On the other hand, the inner surface of the through hole 20c is provided with screw grooves corresponding to the screw threads formed on the fastener 19. Therefore, the fastener 19 can be screwed into the through hole 20c.

[0033] Because the outer casing 20 has the above-described configuration, the fastener 19 is screwed into the through hole 20c, and as the screwing of the two proceeds, the fastener 19 enters the through hole 20c. As a result, the tip of the fastener 19 in the direction of travel comes into contact with the reference electrode 14, and as it enters further, the fastener 19 presses against the reference electrode 14. The pressure of the fastener 19 against the reference electrode 14 improves the adhesion between the reference electrode 14 and the solid electrolyte layer 11, and further stabilizes the position of the reference electrode 14. The stabilization of the position of the reference electrode 14 is even more pronounced by combining the pressure of the reference electrode 14 by the fastener 19 with the accommodation of the reference electrode 14 in the groove 20b.

[0034] From the viewpoint of ensuring more reliable pressing of the reference pole 14 by the fixing device 19, it is preferable that the reference pole 14 be made of a wire. Alternatively, it is also preferable that the reference pole 14 be made of a strip-shaped body. If the reference electrode 14 consists of a wire, the diameter of the wire can be, for example, 0.01 mm or more, preferably 0.10 mm or more, and more preferably 0.50 mm or more, provided that it is smaller than the thickness of the solid electrolyte layer 11. The diameter of the wire can also be, for example, 3.00 mm or less, preferably 2.00 mm or less, and more preferably 1.50 mm or less. If the reference electrode 14 consists of a strip, the width of the strip (length along the direction perpendicular to the direction in which the strip extends) can be, for example, 0.01 mm or more, preferably 0.10 mm or more, and more preferably 0.50 mm or more, provided that it is smaller than the thickness of the solid electrolyte layer 11. The width of the strip can also be, for example, 3.00 mm or less, preferably 2.00 mm or less, and more preferably 1.50 mm or less. Furthermore, the thickness of the strip-like material can be, for example, 0.01 mm or more, preferably 0.10 mm or more, and more preferably 0.50 mm or more. Also, the thickness of the strip-like material can be, for example, 3.00 mm or less, preferably 2.00 mm or less, and more preferably 1.50 mm or less.

[0035] When the reference electrode 14, which consists of a wire or a strip, extends circumferentially along the side surface of the solid electrolyte layer 11, one end of the wire or strip may be joined to form a ring shape. While being ring-shaped is not an essential structure for the reference electrode 14, it is advantageous from the viewpoint of stably positioning the reference electrode 14 on the side surface 11s of the solid electrolyte layer 11.

[0036] Figure 4 schematically shows a method for measuring the electrical characteristics of the solid-state battery 10 of this embodiment. As shown in the figure, the open-circuit voltage of the solid-state battery 10 can be obtained by measuring the voltage between the positive electrode current collector 15 and the negative electrode current collector 16. In this case, the potential of the positive electrode layer 12 and the potential of the negative electrode layer 13 cannot be known, and only the potential difference between the positive electrode layer 12 and the negative electrode layer 13 can be known. In contrast, by measuring the voltage between the reference electrode 14 and the positive electrode layer 12, the potential of the positive electrode layer 12 with respect to the reference electrode 14 can be known. Also, by measuring the voltage between the reference electrode 14 and the negative electrode layer 13, the potential of the negative electrode layer 13 with respect to the reference electrode 14 can be known. Thus, with the solid-state battery 10 of this embodiment, the potentials of the positive electrode layer 12 and the negative electrode layer 13 can be known with respect to the reference electrode 14, making it possible to measure and evaluate the electrical characteristics of the solid-state battery 10 with greater accuracy than before.

[0037] The potential of the positive electrode layer 12 with respect to the reference electrode 14, and the potential of the negative electrode layer 13 with respect to the reference electrode 14, may be measured in an open-circuit state, or in a charged or discharged state of the solid battery 10. Furthermore, instead of measuring the voltage between the reference electrode 14 and the positive electrode layer 12, and / or the voltage between the reference electrode 14 and the negative electrode layer 13, or in addition to measuring these, the electrical characteristics of the solid-state battery 10 can also be measured by measuring the electrical resistance between the reference electrode 14 and the positive electrode layer 12, and / or the electrical resistance between the reference electrode 14 and the negative electrode layer 13.

[0038] From the viewpoint of making the above advantages even more pronounced, in the solid battery 10, it is preferable that the distance D1 between the reference electrode 14 and the first surface 11a of the solid electrolyte layer 11 is equal to the distance D2 between the reference electrode 14 and the second surface 11b of the solid electrolyte layer 11. In order to set D1 and D2 to equal values, it is advantageous to house the reference electrode 14 in the groove 20b described above, and / or to press the reference electrode 14 against the side surface of the solid electrolyte layer 11 with the fixing device 19 described above. In particular, if the fixing device 19 is conductive, it is very convenient that the conductive fixing device 19 is brought into contact with the reference electrode 14, and the rear end of the fixing device 19 in contact with the reference electrode 14 protrudes from the outer surface of the casing 20, thereby allowing the protruding portion to be used as a terminal of the reference electrode 14. Alternatively, instead of using the conductive fixing device 19, one end of the wire may be attached to a part of the reference pole 14, the wire may be brought out to the outside of the solid battery 10 through the through hole 20c, and the other end of the wire may be used as the terminal of the reference pole 14.

[0039] In this specification, D1 and D2 being equal means not only that their values ​​are exactly the same, but also that the value of D1 is within ±5% of the value of D2, i.e., 0.95D2 ≤ D1 ≤ 1.05D2.

[0040] Incidentally, techniques for measuring the potential between the reference electrode and the positive electrode layer or between the reference electrode and the negative electrode layer by arranging a reference electrode in a solid-state battery are described in the aforementioned Patent Documents 1 and 2 and Non-Patent Documents 1 and 2. In solid-state batteries, it is known that the characteristics of the battery change when the pressure applied to the cell changes, but with the techniques described in the above-mentioned documents, it was not easy to measure the electrical characteristics of the solid-state battery over a wide pressure range. In particular, it was not easy to measure the electrical characteristics of the solid-state battery under high pressure. In contrast, with the solid-state battery 10 of this embodiment having the above-described configuration, a reference electrode 14 is arranged on the side surface of the solid electrolyte layer 11 so as to extend along the circumferential direction of the side surface, making it possible to measure the electrical characteristics of the solid-state battery 10 over a wide pressure range. In particular, by using a pair of pressing members 18, 18, the pressure applied to the cell 17 can be easily changed, and it is also easy to apply high pressure to the cell 17. The pressure that can be applied to the cell 17 by the pair of pressing members 18, 18 depends on the type of each component constituting the cell 17 and the material of the outer casing 20, but can generally be between 100 MPa and 700 MPa.

[0041] In the solid-state battery 10 of this embodiment, a reference electrode 14 is simply arranged on the side surface of the solid electrolyte layer 11, extending along the circumferential direction of the side surface, and it is advantageous that there is no reference electrode inside the solid electrolyte layer 11. This prevents ion conduction within the solid electrolyte layer 11 from being hindered, thus avoiding a decrease in the rate characteristics of the solid-state battery 10. Furthermore, the absence of a reference electrode inside the solid electrolyte layer 11 is advantageous in that it makes it less likely for defects such as cracks to occur in the solid electrolyte layer 11, and allows the use of a soft material as the reference electrode.

[0042] As described above, in the solid battery 10 of this embodiment, the potential of the positive electrode layer 12 and / or the potential of the negative electrode layer 13 can be measured with reference to the reference electrode 14. Therefore, it is desirable that the potential of the reference electrode 14 is almost constant and that the potential is stable during measurement. From this viewpoint, if the solid electrolyte layer 11 has lithium ion conductivity, for example, the reference electrode 14 is Li +It is advantageous to include a material capable of electrode reactions with Li. + Suitable materials for the / Li electrode reaction include, for example, at least one of lithium, indium, indium-lithium alloy, aluminum, copper, nickel, gold, reduced LTO, oxidized LFP, and ferrocene. Reduced LTO is Li4Ti5O with lithium inserted. 12 Alternatively, it refers to LiTi2O4. Oxidized LFP refers to LiFePO4, which is formed by the removal of Li.

[0043] Next, a preferred manufacturing method for the solid-state battery 10 of this embodiment will be described. First, a wire-shaped reference pole 14 is placed in the groove 20b of the outer casing 20. Next, the lower opening of the outer casing 20 is closed with one pressing member 18, solid electrolyte powder is placed on top of it, and the upper opening is closed with the other pressing member 18. Then, the pair of pressing members 18, 18 are uniaxially pressed to form the solid electrolyte layer 11. At this time, some of the solid electrolyte powder is pushed out into the groove 20b, causing the side surface 11s of the solid electrolyte layer 11 to come into contact with the reference electrode 14. To ensure this contact is made, the degree to which the pressing members 18 are inserted is adjusted so that the reference electrode 14 is positioned on the side surface of the solid electrolyte layer 11. One of the pressing members 18 is temporarily removed, the positive electrode layer 12 and the positive electrode current collector 15 are placed on top of the solid electrolyte layer 11, and then the pressing member 18 is used to close the gap. Next, the outer casing 20 is inverted, the other pressing member 18 is temporarily removed, the negative electrode layer 13 and the negative electrode current collector 16 are placed on the solid electrolyte layer 11, and the pressing member 18 is used to close it. Subsequently, the pair of pressing members 18, 18 are restrained with a predetermined pressure. Finally, the fastener 19 is inserted into the through hole 20c provided in the outer casing 20 and screwed in, and the fastener 19 presses the reference electrode 14 toward the side surface 11s of the solid electrolyte layer 11. Through the above operations, the desired solid-state battery 10 can be obtained.

[0044] Although the present invention has been described above based on its preferred embodiments, the present invention is not limited to the above embodiments. For example, in the above embodiment, it is preferable that the reference electrode 14 is a closed annular shape, but the shape of the reference electrode 14 is not limited to this. For example, the reference electrode 14 may be a wire-like or strip-like shape, which is elongated in one direction, and has a pair of ends, the pair of ends being spaced apart at a distance in the thickness direction of the solid battery 10, and when the reference electrode 14 is projected, it may be circular along the circumferential direction of the side surface 11s of the solid electrolyte layer 11. In this case, a conductive wire may be connected to one of the pair of ends of the reference electrode 14. Alternatively, a conductive wire may be connected to a position other than the pair of ends of the reference electrode 14. In either case, the conductive wire may be integrated with the reference electrode 14 or may be a separate component. Furthermore, when the reference electrode 14 is projected, the pair of ends may be in the same position or in different positions. In the latter case, the end region including one end of the reference electrode 14 and the end region including the other end overlap when the reference electrode 14 is projected.

[0045] Furthermore, the reference electrode 14 may have a unidirectional elongated shape, such as a wire or strip, and have a pair of ends, and may be spiral in shape, advancing along the thickness direction of the solid battery 10 while drawing a circle with the same radius as the solid electrolyte layer 11. In this case, the pair of ends are spaced apart at a distance in the thickness direction of the solid battery 10. In this embodiment as well, similar to the embodiment described above, a conductive wire may be connected to either one of the pair of ends of the reference electrode 14, or a conductive wire may be connected to a position other than the pair of ends of the reference electrode 14. In either case, the conductive wire may be integrated with the reference electrode 14 or may be a separate component. Also, the pair of ends may be in the same position or in different positions when the reference electrode 14 is viewed as a projection.

[0046] With regard to the embodiments described above, the present invention further discloses the following solid-state battery, a housing for a solid-state battery, and a method for measuring the electrical characteristics of a solid-state battery. [1] A solid electrolyte layer having a first surface and a second surface located opposite the first surface, A positive electrode layer disposed on the first surface side of the solid electrolyte layer, A method for measuring the characteristics of a solid-state battery comprising a negative electrode layer disposed on the second surface side of the solid electrolyte layer, With a reference electrode positioned in contact with the side surface between the first and second surfaces of the solid electrolyte layer, the voltage between the positive electrode layer or the negative electrode layer and the reference electrode is measured. A method for measuring the characteristics of a solid-state battery, wherein in the measurement, the reference electrode extends in a direction perpendicular to the thickness direction of the solid electrolyte layer. [2] The solid electrolyte layer has one or more sides, The reference electrode extends to all sides of the solid electrolyte layer, The measurement method according to [1], wherein the tip of the reference electrode in the direction of extension is in contact with the reference electrode itself, forming a closed shape. [3] The measurement method according to [1] or [2], wherein the distance D1 between the reference electrode and the first surface along the thickness direction of the solid battery is made equal to the distance D2 between the reference electrode and the second surface along the thickness direction of the solid battery. [4] The solid electrolyte layer has lithium ion conductivity, The aforementioned reference electrode is Li + A measurement method according to any one of [1] to [3], comprising a material capable of electrode reaction with / Li. [5] The Li + The measurement method according to [4], wherein the material capable of the / Li electrode reaction is at least one of lithium, indium, indium-lithium alloy, aluminum, copper, nickel, gold, reduced LTO, oxidized LFP, and ferrocene.

[0047] [6] The measurement method according to any one of [1] to [5], wherein the reference electrode consists of a wire. [7] The measurement method according to any one of [1] to [6], wherein the solid battery further comprises a fixing device that allows the reference electrode to be pressed toward the solid electrolyte layer and fixed to the solid electrolyte layer. [8] The measurement method according to [7], wherein the fixing device is capable of fixing the reference electrode to the solid electrolyte layer in direct contact with the reference electrode and is conductive. [9] The solid battery further comprises an outer casing capable of housing a cell including the positive electrode layer, the solid electrolyte layer, the negative electrode layer, and the reference electrode. The exterior body has through holes that connect the outer surface of the exterior body with the surface that defines the space for housing the cell, The through-hole is open at a position facing the reference pole on the surface that defines the space for housing the cell. The fastener is designed to be screwable into the through hole. The measurement method according to [7], wherein the fixing device enters the through hole as the screwing of the fixing device and the through hole progresses, so that the tip of the fixing device in the direction of progression presses against the reference pole.

[10] The solid battery further comprises an outer casing capable of housing a cell including the positive electrode layer, the solid electrolyte layer, the negative electrode layer, and the reference electrode. The measurement method according to any one of [1] to [9], wherein the outer casing has a groove portion capable of accommodating the reference pole at a position corresponding to the reference pole on a surface that defines a space for accommodating the cell.

[0048]

[11] The solid battery further comprises an outer casing capable of housing a cell including the positive electrode layer, the solid electrolyte layer, the negative electrode layer, and the reference electrode. The measurement method according to any one of [1] to

[10] , wherein the outer casing is configured such that, when the cell is housed, the outer surface of the positive electrode layer and the outer surface of the negative electrode layer are exposed, and the current collector can be positioned in contact with the outer surface of the positive electrode layer and the outer surface of the negative electrode layer.

[12] The measurement method according to

[11] , wherein the cell is pressurized by applying an external force to both current collectors so that the current collector of the positive electrode layer and the current collector of the negative electrode layer move closer together.

[13] A solid electrolyte layer having a first surface and a second surface located opposite the first surface, A positive electrode layer disposed on the first surface side of the solid electrolyte layer, A solid battery comprising a negative electrode layer disposed on the second surface side of the solid electrolyte layer, A reference electrode is positioned in contact with the side surface between the first and second surfaces of the solid electrolyte layer. A solid-state battery in which the reference electrode extends in a direction perpendicular to the thickness direction of the solid electrolyte layer.

[14] The solid electrolyte layer has one or more sides, The reference electrode extends to all sides of the solid electrolyte layer, The solid battery according to

[13] , wherein the tip of the reference electrode in the direction of extension is in contact with the reference electrode itself, forming a closed shape.

[15] The solid battery according to

[13] or

[14] , wherein the distance D1 between the reference electrode and the first surface along the thickness direction of the solid battery is equal to the distance D2 between the reference electrode and the second surface along the thickness direction of the solid battery.

[0049]

[16] The solid electrolyte layer has lithium ion conductivity, The aforementioned reference electrode is Li + A solid battery according to any one of

[13] to

[15] , comprising a material capable of electrode reaction with / Li.

[17] The Li + The solid battery according to

[16] , wherein the material capable of the / Li electrode reaction is at least one of lithium, indium, indium-lithium alloy, aluminum, copper, nickel, gold, reduced LTO, oxidized LFP, and ferrocene.

[18] A solid battery according to any one of

[13] to

[17] , wherein the reference electrode consists of a wire.

[19] A solid battery according to any one of

[13] to

[18] , further comprising a fixing device for pressing the reference electrode toward the solid electrolyte layer and fixing it to the solid electrolyte layer.

[20] The solid battery according to

[19] , wherein the fixing device is capable of fixing the reference electrode to the solid electrolyte layer in direct contact with the reference electrode and is conductive.

[0050] 〔twenty one〕 The exterior further comprises an outer casing capable of housing a cell including the positive electrode layer, the solid electrolyte layer, the negative electrode layer, and the reference electrode, The exterior body has through holes that connect the outer surface of the exterior body with the surface that defines the space for housing the cell, The through-hole is open at a position facing the reference pole on the surface that defines the space for housing the cell. The fastener is designed to be screwable into the through hole. The solid battery according to

[19] , wherein the fixing device enters the through hole as the screwing of the fixing device and the through hole progresses, so that the tip of the fixing device in the direction of progress presses against the reference pole. 〔twenty two〕 The exterior further comprises an outer casing capable of housing a cell including the positive electrode layer, the solid electrolyte layer, the negative electrode layer, and the reference electrode, The solid battery according to any one of

[13] to

[21] , wherein the outer casing has a groove portion in a surface that defines a space for housing the cell, at a position corresponding to the reference electrode, into which the reference electrode can be accommodated. 〔twenty three〕 The exterior further comprises an outer casing capable of housing a cell including the positive electrode layer, the solid electrolyte layer, the negative electrode layer, and the reference electrode, The solid battery according to any one of

[13] to

[22] , wherein the outer casing is configured such that, when the cell is housed, the outer surface of the positive electrode layer and the outer surface of the negative electrode layer are exposed, and a current collector can be positioned to contact the outer surface of the positive electrode layer and the outer surface of the negative electrode layer. 〔twenty four〕 The solid battery according to

[23] , wherein the cell is pressurized by applying an external force to both current collectors so that the current collector of the positive electrode layer and the current collector of the negative electrode layer move closer together. 〔twenty five〕 A solid electrolyte layer having a first surface and a second surface located opposite the first surface, A positive electrode layer disposed on the first surface side of the solid electrolyte layer, A negative electrode layer disposed on the second surface side of the solid electrolyte layer, A solid battery casing comprising a cell-containing space including a reference electrode positioned on a side surface between a first surface and a second surface of the solid electrolyte layer, said to extend along the circumferential direction of the side surface, The exterior body is an exterior body for a solid battery, wherein the exterior body has a groove portion on a surface defining the space, at a position corresponding to the reference electrode when the cell is housed in the space, the groove portion capable of accommodating the reference electrode. [Examples]

[0051] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to these examples.

[0052] [Example 1] A solid-state battery having the structure shown in Figures 1 to 3 was fabricated. First, an indium wire-shaped reference electrode 14 with a diameter of 1.0 mm was placed in the groove 20b of the polypropylene outer casing 20. The groove 20b had a rectangular cross-sectional shape, a depth of 2.0 mm, and a width of 1.0 mm. Next, the protruding portion 18b of the SUS pressing member 18 was inserted into the lower opening of the outer casing 20 to close it. The inner diameter of the outer casing 20 was 10.5 mm. 400 mg of sulfide solid electrolyte powder was placed on top of the inserted SUS pressing member 18, and the upper opening was closed with the other pressing member 18. Then, the pair of pressing members 18, 18 were uniaxially pressed at a pressure of 100 MPa to form the solid electrolyte layer 11. This uniaxial pressing brought the side surface 11s of the solid electrolyte layer 11 into contact with the reference electrode 14. One of the pressing members 18 is temporarily removed, and on the solid electrolyte layer 11, the composition formula LiNi 0.6 Co 0.2 Mn 0.2 A positive electrode layer 12, consisting of a powder of an oxide represented by O2 (hereinafter referred to as "NCM"), vapor-processed carbon fiber (VGCF), and a sulfide solid electrolyte, was placed on top and closed with the pressing member 18. Next, the outer casing 20 was inverted, the other pressing member 18 was temporarily removed, and a negative electrode layer 13, consisting of a powder mixture of graphite powder and sulfide solid electrolyte, was placed on top of the solid electrolyte layer 11, and then closed with the pressing member 18. Subsequently, the pair of pressing members 18, 18 were restrained with a pressure of 480 MPa. Finally, a fastener 19 made of SUS M1.4 screws was inserted into the through hole 20c provided in the outer casing 20 and screwed in, and the reference electrode 14 was pressed towards the side surface 11s of the solid electrolyte layer 11 by the fastener 19.

[0053] [Example 2] In this example, a lithium metallic wire-type reference electrode (1.0 mm in diameter) was used instead of the indium wire-type reference electrode used in Example 1. Otherwise, the solid-state battery was fabricated in the same manner as in Example 1.

[0054] [Example 3] In Example 1, the diameter of the indium wire-shaped reference electrode was changed from 1.0 mm to 0.5 mm. Furthermore, instead of a negative electrode layer consisting of a mixture of graphite powder and sulfide solid electrolyte powder, a negative electrode layer made of indium-lithium alloy was used. Additionally, the constraint was changed from 480 MPa to 250 MPa. Apart from these changes, the solid-state battery was fabricated in the same manner as in Example 1.

[0055] [Comparative Example 1] This comparative example corresponds to Non-Patent Document 1. In Example 1, the wire-shaped reference electrode 14 was not used. Instead, a mesh-shaped reference electrode was used. The solid electrolyte layer 11 was formed so that this mesh-shaped reference electrode was embedded within the solid electrolyte layer 11. The solid battery was manufactured in the same manner as in Example 1, except for this difference. The mesh-like reference electrode is made of Li4Ti5O, which has lithium inserted into the surface of a nickel mesh. 12 A coated material was used. Li4Ti5O 12 The coating is Li4Ti5O 12 The procedure was carried out by preparing a PVDF slurry containing [a specific substance] and immersing a nickel mesh in this slurry. A conductive nickel wire was connected to the mesh-like reference electrode. A portion of the nickel wire was exposed to the outside through a hole formed in the solid electrolyte layer 11. The portion of the nickel wire exposed to the outside of the solid electrolyte layer 11 was connected to the measuring instrument.

[0056] [Comparative Example 2] This comparative example corresponds to Non-Patent Document 2. In Example 1, the wire-shaped reference electrode 14 was not placed on the side surface of the solid electrolyte layer 11. Instead, the solid electrolyte layer 11 was formed so that a nickel wire-shaped reference electrode was embedded within the solid electrolyte layer 11. The solid battery was manufactured in the same manner as in Example 1, except for this difference. A portion of the wire-shaped reference electrode was exposed to the outside through a hole formed in the solid electrolyte layer 11. The portion of the wire-shaped reference electrode that was exposed to the outside of the solid electrolyte layer 11 was connected to the measuring instrument.

[0057] [Comparative Example 3] In Example 1, the wire-shaped reference electrode 14 was not arranged circumferentially on the side surface of the solid electrolyte layer 11. Instead, 3.2 mg of metallic lithium was inserted into the through hole 20c, and a fixing device 19 made of SUS screws was inserted and screwed in, as in Example 1, to fix the metallic lithium to the side surface of the solid electrolyte layer 11. Therefore, the metallic lithium does not extend circumferentially along the side surface of the solid electrolyte layer 11. The solid battery was manufactured in the same manner as in Example 1 except for this difference. The length of the reference electrode 14 was less than 5% of the circumference L of the side surface 11s.

[0058] 〔evaluation〕 For the solid batteries obtained in Examples 1 to 3 and Comparative Examples 1 to 3, the potentials of the positive electrode layer 12 and the negative electrode layer 13, with reference to the reference electrode 14, were measured using the following method. The results are shown in Figures 5 to 10. Furthermore, the impedance was measured for Examples 1 to 3 and Comparative Example 3 using the following method. The Nyquist plots obtained from these measurements are shown in Figures 5 to 7 and Figure 10. The horizontal axis represents the real component Z of the impedance. re The vertical axis represents the imaginary component of impedance -Z. im This indicates.

[0059] [Methods for measuring electric potential and impedance] The fabricated solid-state battery was connected to a potentiometer / galvanostat (VSP-300, BioLogic), and charged and discharged at a current of 0.15 mA in a 25°C environment. The potentials of the positive and negative electrodes relative to the reference electrode were measured. Subsequently, the impedance was measured by electrochemical impedance spectroscopy.

[0060] As is clear from the results shown in Figures 5 to 7, the potential and impedance of the positive electrode layer 12 and the negative electrode layer 13 were correctly measured in the solid-state batteries of Examples 1 to 3. In Comparative Examples 1 and 2, shown in Figures 8 and 9, disturbances in the potential of the positive and negative electrode layers are observed. In Comparative Example 3 shown in Figure 10, the potentials of the positive and negative electrode layers are measured stably, but disturbances in the impedance are observed. [Explanation of symbols]

[0061] 10 solid state battery 11 Solid electrolyte layer 11a First face 11b Second face 11s side 12 Positive electrode layer 13. Negative electrode layer 14 Reference pole 15 Positive electrode current collector 16 Negative electrode current collector 17 cells 18 Pressing member 19 Fixtures 20 outer body 20b Ditch 20c through hole

Claims

1. A solid electrolyte layer having a first surface and a second surface located opposite the first surface, A positive electrode layer disposed on the first surface side of the solid electrolyte layer, A method for measuring the characteristics of a solid-state battery comprising a negative electrode layer disposed on the second surface side of the solid electrolyte layer, With a reference electrode positioned in contact with the side surface between the first and second surfaces of the solid electrolyte layer, the voltage between the positive electrode layer or the negative electrode layer and the reference electrode is measured. A method for measuring the characteristics of a solid-state battery, wherein in the measurement, the reference electrode extends in a direction perpendicular to the thickness direction of the solid electrolyte layer.

2. The solid electrolyte layer has one or more sides, The reference electrode extends to all sides of the solid electrolyte layer, The measurement method according to claim 1, wherein the tip of the reference pole in its extending direction is in contact with the reference pole itself, forming a closed shape.

3. The measurement method according to claim 1 or 2, wherein the distance D1 between the reference electrode and the first surface along the thickness direction of the solid battery is made equal to the distance D2 between the reference electrode and the second surface along the thickness direction of the solid battery.

4. The solid electrolyte layer has lithium ion conductivity, The aforementioned reference pole is Li ＋ The measurement method according to claim 1 or 2, comprising a material capable of electrode reaction with / Li.

5. The Li ＋ The measurement method according to claim 4, wherein the material capable of the / Li electrode reaction is at least one of lithium, indium, indium-lithium alloy, aluminum, copper, nickel, gold, reduced LTO, oxidized LFP, and ferrocene.

6. The measurement method according to claim 1 or 2, wherein the reference electrode is made of a wire.

7. The measurement method according to claim 1 or 2, wherein the solid battery further comprises a fixing device that allows the reference electrode to be pressed toward the solid electrolyte layer and fixed to the solid electrolyte layer.

8. The measurement method according to claim 7, wherein the fixing device is capable of fixing the reference electrode to the solid electrolyte layer in direct contact with the reference electrode and is electrically conductive.

9. The solid battery further comprises an outer casing capable of housing a cell including the positive electrode layer, the solid electrolyte layer, the negative electrode layer, and the reference electrode. The exterior body has through holes that connect the outer surface of the exterior body with the surface that defines the space for housing the cell, The through-hole is open at a position facing the reference pole on the surface that defines the space for housing the cell. The fastener is designed to be screwable into the through hole. The measurement method according to claim 7, wherein the fixing device enters the through hole as the screwing of the fixing device and the through hole progresses, so that the tip of the fixing device in the direction of progression presses against the reference pole.

10. The solid battery further comprises an outer casing capable of housing a cell including the positive electrode layer, the solid electrolyte layer, the negative electrode layer, and the reference electrode. The measurement method according to claim 1 or 2, wherein the outer casing has a groove portion capable of accommodating the reference pole at a position corresponding to the reference pole on a surface defining the space for accommodating the cell.

11. The solid battery further comprises an outer casing capable of housing a cell including the positive electrode layer, the solid electrolyte layer, the negative electrode layer, and the reference electrode. The measurement method according to claim 1 or 2, wherein the outer casing is configured such that, when the cell is housed, the outer surface of the positive electrode layer and the outer surface of the negative electrode layer are exposed, and the current collector can be positioned in contact with the outer surface of the positive electrode layer and the outer surface of the negative electrode layer.

12. The measurement method according to claim 11, wherein the cell is pressurized by applying an external force to both current collectors so that the current collector of the positive electrode layer and the current collector of the negative electrode layer move closer together.

13. A solid electrolyte layer having a first surface and a second surface located opposite the first surface, A positive electrode layer disposed on the first surface side of the solid electrolyte layer, A solid battery comprising a negative electrode layer disposed on the second surface side of the solid electrolyte layer, A reference electrode is positioned in contact with the side surface between the first surface and the second surface of the solid electrolyte layer. A solid-state battery in which the reference electrode extends in a direction perpendicular to the thickness direction of the solid electrolyte layer.

14. The solid electrolyte layer has one or more sides, The reference electrode extends to all sides of the solid electrolyte layer, The solid battery according to claim 13, wherein the tip of the reference electrode in its extending direction is in contact with the reference electrode itself, forming a closed shape.

15. The solid battery according to claim 13 or 14, wherein the distance D1 between the reference electrode and the first surface along the thickness direction of the solid battery is equal to the distance D2 between the reference electrode and the second surface along the thickness direction of the solid battery.

16. The solid electrolyte layer has lithium ion conductivity, The aforementioned reference pole is Li ＋ A solid-state battery according to claim 13 or 14, comprising a material capable of performing an electrode reaction with Li.

17. The Li ＋ The solid-state battery according to claim 16, wherein the material capable of the Li electrode reaction is at least one of lithium, indium, indium-lithium alloy, aluminum, copper, nickel, gold, reduced LTO, oxidized LFP, and ferrocene.

18. The solid battery according to claim 13 or 14, wherein the reference electrode is made of a wire.

19. The solid battery according to claim 13 or 14, further comprising a fixing device for pressing the reference electrode toward the solid electrolyte layer and fixing it to the solid electrolyte layer.

20. The solid battery according to claim 19, wherein the fixing device is capable of fixing the reference electrode to the solid electrolyte layer in direct contact with the reference electrode and is electrically conductive.

21. The exterior further comprises an outer casing capable of housing a cell including the positive electrode layer, the solid electrolyte layer, the negative electrode layer, and the reference electrode, The exterior body has through holes that connect the outer surface of the exterior body with the surface that defines the space for housing the cell, The through-hole is open at a position facing the reference pole on the surface that defines the space for housing the cell. The fastener is designed to be screwable into the through hole. The solid battery according to claim 19, wherein the fixing device enters the through hole as the screwing of the fixing device and the through hole progresses, causing the tip of the fixing device in the direction of progress to press against the reference pole.

22. The exterior further comprises an outer casing capable of housing a cell including the positive electrode layer, the solid electrolyte layer, the negative electrode layer, and the reference electrode, The solid battery according to claim 13 or 14, wherein the outer casing has a groove portion in a surface defining a space for housing the cell, at a position corresponding to the reference electrode, into which the reference electrode can be accommodated.

23. The exterior further comprises an outer casing capable of housing a cell including the positive electrode layer, the solid electrolyte layer, the negative electrode layer, and the reference electrode, The solid battery according to claim 13 or 14, wherein the outer casing is configured such that, when the cell is housed, the outer surface of the positive electrode layer and the outer surface of the negative electrode layer are exposed, and a current collector can be positioned to contact the outer surface of the positive electrode layer and the outer surface of the negative electrode layer.

24. The solid battery according to claim 23, wherein the cell is pressurized by applying an external force to both current collectors so that the current collector of the positive electrode layer and the current collector of the negative electrode layer move closer together.

25. A solid electrolyte layer having a first surface and a second surface located opposite the first surface, A positive electrode layer disposed on the first surface side of the solid electrolyte layer, A negative electrode layer disposed on the second surface side of the solid electrolyte layer, A solid battery casing comprising a cell-containing space including a reference electrode positioned on a side surface between a first surface and a second surface of the solid electrolyte layer, extending along the circumferential direction of the side surface, The exterior body is an exterior body for a solid battery, wherein the exterior body has a groove portion on a surface defining the space, at a position corresponding to the reference electrode when the cell is housed in the space, the groove portion capable of accommodating the reference electrode.

Images