Electrochemical element

Abstract

To provide an electrochemical element which can secure an excellent reliability.SOLUTION: An electrochemical element 1 includes: a case 10 having a recessed container 11 with a bottom part 111 and a side wall part 112 and having a lid material 12 for covering an opening of the recessed container 11; a power generation element 20 having a laminate body in which an electrode layer 21, an electrode layer 22, and a solid electrolyte layer 23 are laminated, a bottom part 111 and the electrode layer 21 facing each other and being stored in the internal space of the case 11; and a conductive plate 30 arranged between the electrode layer 22 and the lid material 12 in an opening side of the recessed container 11. The lid material 12 is recessed to the conductive plate in such a manner that the internal space of the case 10 is decompressed. The depth D of the recess in the lid material 12 is at least 0.02 mm. There is a gap G of the size of at least 0.05 mm between the conductive plate and the lid material.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an electrochemical device in which a power generating element is sealed in a case. [Background technology]

[0002] 2. Description of the Related Art Various types of batteries have been disclosed in the past, in which a power generating element is housed in an internal space formed by a concave container and a lid material that covers the opening of the concave container.

[0003] JP 2012-69508 A (Patent Document 1) discloses an electrochemical cell with stable electrochemical characteristics. The electrochemical cell has a sealed container. The sealed container is made of a base member and a lid member. A storage space for storing an electrochemical element (electrode body) is formed between the two members. An elastic member for pressing the electrochemical element is disposed between the lid member and the electrochemical element. Patent Document 1 discloses an embodiment using, as the elastic member, a leaf spring bent into a V shape in cross section, a torsion bar unit that utilizes an elastic restoring force caused by twisting, or a diaphragm-shaped spring formed into a concave curved shape that warps from the center toward the outer periphery.

[0004] Also, International Publication No. 2022 / 030424 (Patent Document 2) discloses a battery package and a battery module. The battery package includes an insulating substrate made of ceramics with a recess formed in the center of a first surface, a frame surrounding the recess on the first surface, and a lid covering the frame. A battery module is formed by the battery package and the battery housed therein. A metal conductive sheet that maintains an electrical connection with the battery while pressing the battery is disposed between the lid of the battery package and the battery. The conductive sheet is bonded to a second electrode provided on the first surface via a conductive bonding material made of a conductive adhesive or the like, and the second external electrode, which is an external terminal, is electrically connected to one electrode of the battery. Also, in Patent Document 2, in order to prepare for cases where external stress is applied to the lid, the gap amount between the flat lid and the conductive sheet is set to, for example, 0.1 mm to 0.8 mm during assembly. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2012-69508 A [Patent Document 2] International Publication No. 2022 / 030424 Summary of the Invention [Problem to be solved by the invention]

[0006] When the battery contained in the battery package contains a material that easily reacts with moisture, it is possible to seal the battery package in a vacuum environment. However, it has been found that when the battery module of Patent Document 2 is sealed in a vacuum environment, the metal lid body is deformed inward (toward the battery) when the assembled battery module is placed in a normal pressure environment. Therefore, even if a certain gap is provided in advance between the lid body and the conductive sheet during assembly, the lid body and the conductive sheet are more likely to come into contact with each other when a strong impact is applied to the battery module, compared to when the battery module is sealed in a normal pressure environment, making it difficult to ensure the reliability of the battery module. Note that a vacuum is a state where the pressure is reduced below normal pressure (1 atm).

[0007] It is also possible to check whether the battery module is securely sealed from the state of deformation of the lid. However, even if the battery module is properly sealed in a vacuum environment, if the amount of deformation of the lid is small when the battery module is placed in a normal pressure environment, it is difficult to determine whether the battery module is properly sealed. In other words, it is difficult to ensure the reliability of the battery module. Therefore, in consideration of checking the good sealing state, it is desirable for the lid to deform to a certain degree or more when the battery module sealed in a vacuum environment is placed in a normal pressure environment.

[0008] Patent Document 2 does not propose how to set the deformation amount of the lid body and the gap amount between the lid body and the conductive sheet after deformation in order to ensure the reliability of the above-mentioned battery module when the battery module is sealed in a vacuum environment.

[0009] Therefore, an object of the present disclosure is to ensure excellent reliability in an electrochemical element in which the internal space of a case composed of a concave container and a metal lid material is sealed under reduced pressure. [Means for solving the problem]

[0010] In order to solve the above problems, the present disclosure is configured as follows. That is, the electrochemical element according to the present disclosure includes a case having a concave container having a bottom and a side wall and a metal lid covering the opening of the concave container, a power generating element sealed in the case and having a first electrode layer arranged on the bottom side, a second electrode layer arranged on the lid side, and an isolation layer arranged between the first electrode layer and the second electrode layer, and a conductive plate arranged between the power generating element and the lid. The first electrode layer is electrically connected to a first conductive path leading from the inside of the case to the outside. The second electrode layer is electrically connected to a second conductive path leading from the inside of the case to the outside via the conductive plate. The lid is recessed toward the conductive plate because the internal space of the case is reduced in pressure compared to the external space of the case. The depth of the recess in the lid is 0.02 mm or more. A gap of 0.05 mm or more is formed between the conductive plate and the lid. Effect of the Invention

[0011] The electrochemical element according to the present disclosure can prevent a reaction between the power generating element and moisture in the internal space of the case, can easily check the sealing property, and can prevent electrical continuity between the cover material and the second electrode layer due to contact between the cover material and the conductive plate when subjected to an impact, etc. As a result, the electrochemical element according to the present disclosure can ensure excellent reliability. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view showing an electrochemical device according to a first embodiment. [Diagram 2] FIG. 2 is an external perspective view showing the concave container of the electrochemical device of FIG. [Diagram 3] FIG. 3 is an external perspective view showing another concave container of an electrochemical device. [Figure 4] FIG. 4 is a plan view showing the electrochemical device of FIG. 1 (excluding the cover and the conductive plate). [Diagram 5] FIG. 5 is a cross-sectional view showing a conductive plate according to a modified example. [Figure 6] FIG. 6 is a cross-sectional view showing an electrochemical device according to a second embodiment. [Figure 7] FIG. 7 is a cross-sectional view showing an electrochemical device according to a third embodiment. [Figure 8] FIG. 8 is a cross-sectional view showing the state immediately after sealing of the electrochemical element of FIG. 1, that is, the state before the lid member is recessed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] (Configuration 1) The electrochemical element according to the embodiment of the present disclosure includes a case having a concave container having a bottom and a side wall and a metal lid covering the opening of the concave container, a power generating element sealed in the case and having a first electrode layer disposed on the bottom side, a second electrode layer disposed on the lid side, and an isolation layer disposed between the first electrode layer and the second electrode layer, and a conductive plate disposed between the power generating element and the lid. The first electrode layer is electrically connected to a first conductive path leading from the inside of the case to the outside. The second electrode layer is electrically connected to a second conductive path leading from the inside of the case to the outside via the conductive plate. The lid is recessed toward the conductive plate because the internal space of the case is reduced in pressure compared to the external space of the case. The depth of the recess in the lid is 0.02 mm or more. A gap of 0.05 mm or more is formed between the conductive plate and the lid.

[0014] In this way, the internal space of the case is decompressed and the lid material is recessed by 0.02 mm or more toward the conductive plate, so that moisture contained in the internal space of the case is removed to prevent reaction with the power generating element, and it is also possible to easily check in a normal pressure environment whether the electrochemical element is properly sealed, thereby improving the reliability of the electrochemical element. In addition, a gap of a certain size or larger is formed between the lid material and the conductive plate, so that it is possible to prevent the lid material from becoming conductive with the second electrode layer, thereby improving the reliability of the electrochemical element when mounted on a circuit board, etc.

[0015] (Configuration 2) In the electrochemical element of configuration 1, the conductive plate may include a flat portion facing the power generating element, and a spring portion rising from the flat portion and pressing the power generating element toward the bottom of the concave container. This allows the conductive plate to more stably conduct the power generating element to the first conduction path and the second conduction path due to the elasticity of the spring portion, even if the thickness of the power generating element changes due to charging and discharging.

[0016] (Configuration 3) In the electrochemical element of configuration 2, the spring portion may have a spring piece that is cantilevered on the flat portion and presses the power generating element toward the bottom of the concave container. This makes it possible to easily manufacture the conductive plate, i.e., the electrochemical element, since it is only necessary to form the spring piece on a part of the flat portion of the conductive plate.

[0017] (Configuration 4) In the electrochemical element of Configuration 3, the tip of the spring piece may be bent in the direction away from the power generating element, thereby preventing the sharp tip of the spring piece from coming into contact with and damaging the power generating element.

[0018] (Configuration 5) In the electrochemical element of any of the configurations 1 to 4, the conductive plate is fixed to the side wall of the concave container outside the outer edge of the power generating element in a plan view. Since the conductive plate is fixed to the side wall of the concave container outside the outer edge of the power generating element, a process such as welding of the conductive plate is not required, the part of the conductive plate facing the power generating element can be freely positioned in the height direction (thickness direction of the power generating element), and the conductive connection between the conductive plate and the second electrode layer can be made by various methods.

[0019] (Configuration 6) In the electrochemical element of any one of Configurations 1 to 5, the depth of the recess in the lid is 0.2 mm or less, thereby making it possible to reduce the gap that needs to be provided in advance between the lid and the conductive plate when assembling the electrochemical element.

[0020] (Configuration 7) In the electrochemical element of any one of Configurations 1 to 6, the size of the gap formed between the conductive plate and the lid is 0.5 mm or less, thereby making it possible to suppress an increase in the internal volume of the electrochemical element.

[0021] (Configuration 8) In any of the electrochemical elements of configurations 1 to 7, the power generating element may further have a porous metal layer on the surface of the second electrode layer. This allows the porous metal layer pressed by the conductive plate to be compressed by a certain amount, and can fully absorb variations in the thickness of the power generating element or the height of the case, etc., and as a result, can suppress variations in the value of the internal resistance. Alternatively, when the porous metal layer is integrated with the second electrode layer in advance, the electrical resistance of the conductive portion between the conductive plate and the power generating element can be reduced.

[0022] (Configuration 9) In any one of the electrochemical elements of configurations 1 to 8, the amount of helium gas leakage based on the "Helium Leak Test Method" (bombing method) described in the Japanese Industrial Standard JIS-Z2331 is 1 x 10 -10 Pa·m 3 / s or less.

[0023] (First embodiment) Hereinafter, the first embodiment of the present disclosure will be specifically described with reference to Figures 1 to 7, taking as an example a case in which the electrochemical element is an all-solid-state battery. First, as shown in Figure 1, the electrochemical element 1 is composed of a case 10, a power generating element 20 and a conductive plate 30 housed in the case 10, and external terminals 13 and 14 disposed on the outer surface of the case 10.

[0024] The case 10 has a concave container 11 and a lid 12. The concave container 11 is made of ceramics. The concave container 11 includes a rectangular bottom 111 and a rectangular tubular side wall 112 that is formed continuously from the outer periphery of the bottom 111 and has a cylindrical space for accommodating the power generating element 20 therein. The side wall 112 is provided so as to extend substantially perpendicular to the bottom 111 in a vertical cross-sectional view. A conductor 113 is formed inside the bottom 111. The conductor 113 extends between the power generating element 20 and the bottom 111 so as to be conductively connected to the power generating element 20, and forms a conductive path corresponding to the electrode layer 21. A conductor 114 is formed inside the side wall 112. As shown in FIG. 1, a part of the conductor 114 is formed on the inner circumferential surface of the side wall 112 and exposed to the lower surface and side surface of the support 115 described later, forming a conductive path corresponding to the electrode layer 22. A manufacturing method of the concave container 11 will be described later. The material of the concave container 11 is not particularly limited, and various materials such as resin, glass (borosilicate glass, glass ceramics, etc.), metal, and ceramic can be exemplified. A composite material in which ceramic or glass powder is dispersed in resin may be used. When the concave container 11 is made of a metal material, it is preferable to cover the inner surface of the bottom 111 of the concave container 11 and the inner circumferential surface of the side wall 112 with an insulating material such as a resin material or glass in order to ensure insulation between the concave container 11 and the power generating element 20. The concave container 11 is not limited to a rectangular shape in a plan view, and may be a circular shape, an elliptical shape, a polygonal shape, or the like. The internal space for accommodating the power generating element 20 is not limited to a cylindrical shape, and may be formed into a polygonal cylindrical shape, such as a rectangular cylindrical shape, depending on the shape of the power generating element 20. Furthermore, the conductor portion 114 may be formed on the inner surface of the side wall portion 112, rather than inside the side wall portion 112, and may further penetrate the inside of the bottom portion 111 to be electrically connected to the external terminal 14. In this case, it is preferable to form an insulating layer between the outer circumferential surface of the power generating element 20 and the conductor portion 114, for example, on the inner surface of the conductor portion 114, so that the outer circumferential surface of the power generating element 20 and the conductor portion 114 do not come into contact with each other.

[0025] The side wall portion 112 has a plurality of support portions 115 that support the conductive plate 30 described later. In this embodiment, the support portion 115 is a protruding portion formed at the upper end of the inner peripheral surface of the side wall portion 112 and protruding along the circumferential direction of the inner peripheral surface. More specifically, the support portion 115 is a top wall of a plurality of recesses formed outward from the inner peripheral surface of the side wall portion 112 in a plan view as shown in FIG. 2. As a result, the support portion 115 is formed so as to protrude in the circumferential direction of the inner peripheral surface. The lower surface of each support portion 115, i.e., the lower surface of each top wall, can engage and support a supported portion 31 of the conductive plate 30 described later, outside the outer edge of the power generating element 20 in a plan view. In addition, although two support portions 115 are provided in this embodiment, the number is not limited. For example, if the number of supported portions 31 of the conductive plate 30 is four, four support portions 115 may be provided at positions corresponding to the supported portions 31.

[0026] The lid material 12 is a rectangular metal thin plate that covers the opening of the concave container 11. The material of the lid material 12 is preferably one that has a certain level of strength while being able to deform to some extent when placed in a normal pressure environment after sealing, and is preferably made of carbon steel (cold-rolled steel sheet, hot-rolled steel sheet, etc.), iron-nickel alloy (alloy with Ni content: 36 mass%, alloy with Ni content: 42 mass%, etc.), iron-nickel-cobalt alloy (alloy with Ni content: 29 mass% and Co content: 17 weight%, alloy with Ni content: 31.5 mass% and Co content: 5 weight%, alloy with Ni content: 36 mass% and Co content: 12 weight%, etc.). The thickness of the lid material 12 is, for example, preferably 0.05 mm or more, and more preferably 0.07 mm or more, in order to ensure a certain level of strength, and is preferably 0.2 mm or less, and more preferably 0.15 mm or less, in order to make the depth D of the recess in the lid material 12 a certain value or more and to make it easier to check whether the sealing is good or not.

[0027] As shown in Figs. 1 and 3, the cover 12 is joined (seam welded) to the concave container 11 by a square frame-shaped seal ring 15 disposed between the lower surface of the outer peripheral end of the cover 12 and the upper end of the concave container 11. This completely seals the internal space of the case 10. The internal space of the case 10 is kept in a vacuum state in consideration of the effect on the power generating element 20. At this time, the pressure in the internal space of the case 10 is preferably 1 Pa or less, more preferably 0.1 Pa or less, in order to reduce moisture remaining in the internal space of the case 10. -2 It is particularly preferable that the viscosity is set to 0.1 Pa or less.

[0028] Such a reduced pressure state in the internal space of the case 10 can be achieved by joining the concave container 11 and the lid 12 in a vacuum environment and sealing the internal space of the case 10. As a result, moisture contained in the internal space of the case 10 is removed before sealing the internal space of the case 10, i.e., before sealing the case 10, and the internal space of the case 10 is maintained in a reduced pressure state even after sealing the case 10, so that a reaction between moisture and the power generation element 20 can be prevented. Furthermore, when the case 10 is placed in a normal pressure environment after sealing, the lid 12 is deformed and recessed inward (toward the power generation element) due to the external air pressure higher than the air pressure in the internal space of the case 10. Therefore, in anticipation of the depth D of the recess formed in the lid 12, it is necessary to determine the distance between the lid 12 and the conductive plate 30 in advance when joining the lid 12 to the concave container 11 so that a predetermined gap G is formed between the lid 12 and the conductive plate 30 after deformation. In the present disclosure, the depth D of the recess in the lid member 12 can be defined as the maximum amount of deformation from the position of the lid member 12 (see FIG. 8) toward the power generating element when joined.

[0029] The depth D of the recess in the lid 12 must be 0.02 mm or more, preferably 0.04 mm or more, from the viewpoint of being able to easily check whether the electrochemical element 1 is well sealed or not under normal pressure. If the depth D is less than 0.02 mm, the difference in value between well sealed and insufficient sealed becomes small, making it difficult to distinguish. Furthermore, from the viewpoint of reducing the gap provided in advance between the lid 12 and the conductive plate 30 during assembly of the electrochemical element 1 and suppressing an increase in the thickness of the electrochemical element 1, the depth D must be 0.2 mm or less, preferably 0.15 mm or less, and more preferably 0.1 mm or less.

[0030] The depth D of the recess in the lid member 12 can be adjusted by the material, thickness, size, etc. of the lid member 12. Even if the material and thickness of the lid member 12 are the same, the larger the lid member 12, the greater the depth D of the recess in the lid member 12 when the case 10 is placed in a normal pressure environment. Therefore, as long as the lid member 12 has a certain size or more, the required depth D can be achieved with various materials and thicknesses. Therefore, the size of the lid member 12, which is set according to the size of the electrochemical element 1 (the size of the concave container 11), is preferably larger than a square with one side of about 5 mm if it is rectangular, and preferably larger than a square with one side of about 7 mm. Therefore, it is desirable to set the size of the electrochemical element 1 according to the size of the lid member 12. On the other hand, if the lid material 12 becomes too large, it becomes difficult to make the depth D 0.2 mm or less. Therefore, if the lid material 12 is rectangular, the size of the lid material 12 is preferably smaller than a square with sides of approximately 30 mm, and more preferably smaller than a square with sides of approximately 20 mm. Therefore, it is desirable to make the electrochemical element 1 a size that corresponds to the size of the lid material 12.

[0031] 1, a gap G is formed between the lid member 12 and the conductive plate 30 after the deformation. The size of the gap G needs to be 0.05 mm or more, and preferably 0.07 mm or more, in order to prevent contact between the lid member 12 and the conductive plate 30 when the electrochemical device 1 is subjected to an impact. On the other hand, the larger the gap G, the larger the internal volume of the electrochemical device 1 becomes, and an excess dead space is formed, so the size of the gap G is preferably 0.5 mm or less, and more preferably 0.3 mm or less.

[0032] The lid 12 may be bonded to the concave container 11 by an adhesive, and the method of joining the lid 12 and the concave container 11 is not particularly limited as long as it can seal the internal space of the case 10. The shape of the lid 12 is not limited to a square, and can be changed to various shapes such as a circle, an ellipse, or a polygon depending on the shape of the concave container 11 in a plan view.

[0033] The external terminal 13 is disposed on the outer surface of the bottom 111 of the concave container 11. The external terminal 13 is electrically connected to an electrode layer 21, which will be described later, via a conductor portion 113. The electrode layer 21 functions as a positive electrode layer, as will be described later. Therefore, the conductor portion 113 serves as a conductive path that connects the external terminal 13 and the positive electrode layer, and the external terminal 13 functions as a positive electrode terminal.

[0034] The external terminal 14 is disposed on the outer surface of the bottom 111 of the concave container 11, away from the external terminal 13. The external terminal 14 is electrically connected to the supported portion 31 of the conductive plate 30, which will be described later, via the conductor portion 114. As will be described later, the conductive plate 30 is electrically connected to the electrode layer 22, which functions as a negative electrode layer. Therefore, the conductor portion 114 serves as a conductive path that connects the external terminal 14 to the negative electrode layer, and the conductive plate 30 serves as a connection terminal that connects this conductive path to the electrode layer 22, so that the external terminal 14 functions as a negative electrode terminal. The arrangement of the external terminal 13 and the external terminal 14 is not limited to the above, and they may be disposed on the outer surface of the side wall portion 112 of the concave container 11, or the lid member 12 may function as the conductor portion 114, and the external terminal 14 may be formed on the outer surface of the lid member 12. However, by arranging these two terminals at a certain interval on the outer surface of the bottom 111 of the concave container 11, mounting on the surface of the circuit board becomes easier.

[0035] Here, a method for manufacturing the concave container 11 will be described. First, a metal paste is printed and applied to a ceramic green sheet to form a printed pattern that will become the conductor portion 113 and the conductor portion 114. Next, a plurality of green sheets on which these printed patterns are formed are stacked and fired. The above-mentioned support portion 115 is formed by stacking a plurality of green sheets of different shapes. This makes it possible to manufacture a concave container 11 having the conductor portion 113 and the conductor portion 114 therein and the above-mentioned support portion 115 on the inner circumferential surface of the side wall portion 112. Note that the manufacturing method is not limited to this as long as the support portion 115 can be formed on the inner circumferential surface of the side wall portion 112. Note that the external terminals 13 and the external terminals 14 can also be formed by the printed pattern of this metal paste.

[0036] The power generating element 20 includes a laminated body in which an electrode layer (positive electrode layer) 21, an electrode layer (negative electrode layer) 22, and a solid electrolyte layer 23 are laminated. The solid electrolyte layer 23 is disposed between the electrode layer 21 and the electrode layer 22 as an isolating layer. That is, in this embodiment, the isolating layer is the solid electrolyte layer 23. The power generating element 20 is formed in a cylindrical shape. The power generating element 20 is laminated in the order of the electrode layer 21, the solid electrolyte layer 23, and the electrode layer 22 from the bottom 111 side (lower side in the figure) of the concave container 11. That is, the power generating element 20 is disposed so that the electrode layer 21, which is one end of the power generating element 20, faces the bottom 111 side of the concave container 11, and the electrode layer 22, which is the other end of the power generating element 20, faces the lid member 12 side, and is accommodated in the internal space of the case 10. The power generating element 20 is not limited to a cylindrical shape, and can be variously modified, such as a rectangular parallelepiped shape or a polygonal prism shape. The power generating element 20 may also have a plurality of laminated bodies. A plurality of laminates may be stacked so as to be connected in series.

[0037] The electrode layer 21 is a positive electrode pellet formed into a cylindrical shape from a positive electrode mixture containing lithium cobalt oxide, a sulfide-based solid electrolyte, and graphene as a conductive additive in a mass ratio of 65:30:5 as a positive electrode active material. The positive electrode active material of the electrode layer 21 is not particularly limited as long as it can function as the positive electrode layer of the power generation element 20, and may be, for example, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese composite oxide, olivine type composite oxide, or the like, or may be a suitable mixture of these. Other constituent materials and their ratios are also not particularly limited. The size and shape of the electrode layer 21 are not limited to a cylindrical shape, and may be variously changed according to the size and shape of the electrochemical element 1.

[0038] The electrode layer 22 is made of LTO (Li4Ti5O 12The negative electrode pellet is a negative electrode pellet formed into a cylindrical shape from a negative electrode mixture containing lithium carbide (lithium titanate), a sulfide-based solid electrolyte, and graphene in a weight ratio of 50:40:10. The negative electrode active material of the electrode layer 22 is not particularly limited as long as it can function as the negative electrode layer of the power generation element 20, and may be, for example, metallic lithium, a lithium alloy, a carbon material such as graphite or low-crystalline carbon, an oxide such as SiO, or an appropriate mixture of these. The other constituent materials and their ratios are also not particularly limited. The size and shape of the electrode layer 22 are not limited to a cylindrical shape, and can be variously changed according to the size and shape of the electrochemical element 1.

[0039] The solid electrolyte layer (separation layer) 23 includes a sulfide-based solid electrolyte. The solid electrolyte layer 23 is formed into a cylindrical shape. The solid electrolyte included in the electrode layer 21, the electrode layer 22, and the solid electrolyte layer 23 is not particularly limited, but a sulfide-based solid electrolyte, particularly an argyrodite-type sulfide-based solid electrolyte, is preferably used in terms of ion conductivity. When using a sulfide-based solid electrolyte, it is preferable to cover the surface of the positive electrode active material with a lithium ion conductive material such as niobium oxide in order to prevent a reaction with the positive electrode active material. The solid electrolyte included in the solid electrolyte layer 23, the electrode layer 21, and the electrode layer 22 may be a hydride-based solid electrolyte, an oxide-based solid electrolyte, or the like. The size and shape of the solid electrolyte layer 23 are not limited to a cylindrical shape, and can be variously changed according to the size and shape of the electrochemical device 1.

[0040] As shown in Figs. 1 and 4, the conductive plate 30 is a metal plate material having a rectangular shape in a plan view, which is placed in the opening of the concave container 11 of the case 10. The conductive plate 30 has a plurality of supported parts 31 that correspond to the positions of the above-mentioned respective supporting parts 115, outward from the outer edge of the power generating element 20 in a plan view. In this embodiment, the supported parts 31 are hook-shaped locking pieces that are locked to the above-mentioned supporting parts 115, i.e., the lower surface of the top wall. More specifically, the supported parts 31 extend from the edge of the conductive plate 30 toward the above-mentioned supporting parts 115 (downward in Fig. 1). The supported parts 31 have a tip that is folded back toward the supporting parts 115, i.e., the lower surface of the top wall. The tip of the supported parts 31 is in contact with the conductor parts 114 exposed on the lower surface and side surface of the above-mentioned top wall. As a result, the conductive plate 30 functions as a current collector and also functions as a connection terminal that electrically connects the electrode layer 22 and the conductive path leading to the external terminal 14. The conductive plate 30 is supported by a support portion 115 formed on the inner peripheral surface of the recessed container 11, and covers a part of the opening of the recessed container 11. The area of ​​the conductive plate 30 in a plan view is smaller than the area of ​​the opening of the recessed container 11. Note that even if the hook-shaped locking piece is not locked to the underside of the top wall, as long as the hook-shaped locking piece can be pressed into a recess formed on the inner peripheral surface of the side wall portion 112 to fix the conductive plate 30, the conductive plate 30 is considered to be locked to the side wall portion 112 of the recessed container 11.

[0041] As shown in FIG. 1, the conductive plate 30 has a spring portion 33 that rises from the flat portion 32 of the conductive plate 30 toward the electrode layer 22 of the power generating element 20 so as to contact the upper surface of the electrode layer 22, which is the other end of the power generating element 20. The shape of the spring portion 33 is not particularly limited as long as it can press the power generating element 20 toward the bottom portion 111 of the concave container 11. In this embodiment, the spring portion 33 is a spring piece that is inclined from the flat portion 32 toward the electrode layer 22 of the power generating element 20 (hereinafter, the spring portion 33 may be referred to as the spring piece 33). As shown in FIG. 4, the spring piece 33 is formed by cutting out a part of the flat portion 32 in a U-shape, and is supported by the flat portion 32 in a cantilever manner. That is, in this embodiment, the spring piece 33 is a leaf spring. In this way, since it is only necessary to form the spring piece 33 on a part of the flat portion 32, the conductive plate can be easily manufactured, that is, the electrochemical element can be easily manufactured. Moreover, by forming the spring piece 33 by cutting out the flat portion 32, the conductive plate can be manufactured, i.e., the electrochemical element can be manufactured more easily. The spring piece 33 has a boundary 331 with the flat portion 32 and a tip portion 332 that contacts the electrode layer 22 of the power generating element 20 to establish electrical conduction with the electrode layer 22. The spring piece 33 is bent at the boundary 331 and inclined from the boundary 331 toward the tip portion 332 toward the power generating element 20 side. The height from the bottom surface of the flat portion 32 to the tip portion 332 before the electrochemical element 1 is assembled (the height of the spring portion 33) is greater than the height from the bottom surface of the flat portion 32 to the power generating element 20 after the electrochemical element 1 is assembled. This allows the tip portion 332 of the spring piece 33 to press the power generating element 20, and a good electrical connection between the conductive plate 30 and the power generating element 20 can be maintained. Furthermore, by forming the spring portion 33 from a spring piece, the thickness of the conductive plate 30 excluding the supported portion 31 can be reduced. For example, before assembling the electrochemical element 1, the thickness of the conductive plate 30 excluding the supported portion 31 can be the sum of the thickness of the plate material constituting the flat portion 32 and the height of the spring piece 33. Specifically, the thickness of the plate material: 0.2 mm and the height of the spring piece 33: 0.5 mm are combined to make the thickness of the conductive plate 30 excluding the supported portion 31 0.7 mm. In addition, the width of the spring piece 33 can be 1.5 mm and the length can be 3 mm, for example.When multiple spring pieces 33 are provided, the shapes of the spring pieces 33, including the width and length, may be different from one another for reasons such as preventing resonance. The thickness of the conductive plate 30 excluding the supported portion 31 is preferably 1.2 mm or less, more preferably 1 mm or less, and particularly preferably 0.8 mm or less. On the other hand, in order to generate the necessary pressing force in the spring portion 33, the thickness of the conductive plate 30 excluding the supported portion 31 is preferably 0.3 mm or more, more preferably 0.4 mm or more, and particularly preferably 0.5 mm or more.

[0042] Furthermore, since the edge of the conductive plate 30, i.e., the position of the supported portion 31, can be freely set in the height direction (thickness direction of the conductive plate 30), even if a gap is formed between the cover member 12 and the conductive plate 30, the distance between the cover member 12 and the tip portion 332 of the spring piece 33 does not become large. As a result, the gap between the cover member 12 and the power generating element 20 can be prevented from becoming large, so that the capacity of the electrochemical element 1 can be increased. Here, the overall thickness of the conductive plate 30 including the supported portion 31 can be appropriately adjusted according to the height from the bottom portion 111 of the side wall portion 112 of the concave container 11. The supported portion 31 only needs to have a height required for engagement with the support portion 115. Therefore, the overall thickness of the conductive plate 30 including the supported portion 31 can be, for example, 3 mm or less, preferably 2.7 mm or less, and more preferably 2.5 mm or less. The thickness direction is the vertical direction in FIG. 1 (the height direction of the electrochemical element 1), and can also be said to be a direction perpendicular to the bottom surface of the flat surface portion 32 in the drawing. The spring piece 33 may be formed by cutting out the flat surface portion 32 as described above, and in the modified example described below, the spring piece 33 may be attached to the bottom surface of the flat surface portion 32 by welding or the like. Also, a base for attaching the spring piece 33 may be provided in advance separately from the flat surface portion 32, and the spring piece 33 may be attached to the base to form the whole as a spring portion. That is, the spring piece 33 may rise directly from the flat surface portion 32, or may rise from the flat surface portion 32 via another element such as a base. Also, both ends of the spring piece 33 may be supported by the flat surface portion 32 so as to have a convex shape toward the power generating element 20.

[0043] Examples of metals that can be used to form the conductive plate 30 include nickel, iron, copper, chromium, cobalt, titanium, aluminum, and alloys thereof. In order to facilitate the functioning of the plate as a leaf spring, stainless steels for springs such as SUS301-CSP, SUS304-CSP, SUS316-CSP, SUS420J2-CSP, SUS631-CSP, and SUS632J1-CSP are preferably used.

[0044] The thickness of the plate material of the conductive plate 30 is preferably 0.05 mm or more, more preferably 0.07 mm or more, and particularly preferably 0.1 mm or more, in order to ensure a certain level of pressing force on the power generating element 20. On the other hand, in order to prevent the conductive plate 30 from becoming too thick, which would increase the storage volume inside the case 10, and to make the conductive plate 30 easily deformable so that it can be easily engaged with the side wall portion 112, the thickness of the conductive plate 30 is preferably 0.5 mm or less, more preferably 0.4 mm or less, and particularly preferably 0.3 mm or less.

[0045] After the power generating element 20 is accommodated inside the concave container 11, the conductive plate 30 is placed on the upper surface of the power generating element 20. With the conductive plate 30 placed on the upper surface of the power generating element 20, the tip of the supported portion 31 is positioned between the upper surface of the power generating element 20 and the supporting portion 115, i.e., the lower surface of the top wall, in the axial direction of the power generating element 20 (the vertical direction in FIG. 1). Then, the supported portion 31 of the conductive plate 30 is pressed toward the bottom portion 111 of the concave container 11, while the supported portion 31 is supported by the supporting portion 115. More specifically, the tip of the supported portion 31 is engaged with the supporting portion 115, i.e., the lower surface of the top wall. As the supported portion 31 is pressed downward, the spring piece 33 of the conductive plate 30 is pressed in the opposite direction to the electrode layer 22 while in contact with the power generating element 20. The spring piece 33 presses the power generating element 20 toward the bottom 111 of the concave container 11 by its elastic force. This allows the conductive plate 30 to contact the power generating element 20 more stably, and maintains a good electrical connection without causing positional deviation due to vibration or the like. The spring piece 33 is not particularly limited as long as it can press the power generating element 20 toward the bottom 111 of the concave container 11 by its elastic force. In addition, the concave container 11 has two support parts 115, but the number of support parts 115 may be two or more. The supported parts 31 may be formed according to the number of support parts 115. Note that, as a method for fixing the edge of the conductive plate 30 (supported part 31) to the inner circumferential surface of the side wall part 112 of the concave container 11, a method of bonding the edge of the conductive plate 30 to the inner circumferential surface of the side wall part 112 of the concave container 11, etc., can be exemplified.

[0046] When the lid material 12 and the concave container 11 are welded via the seal ring 15 as described above, by providing a gap G between the conductive plate 30 and the lid material 12, it is possible to suppress the effect of the welding heat on the power generating element 20. Furthermore, since the conductive plate 30 and the lid material 12 do not come into contact with each other, the lid material 12 is not affected by the pressure from the conductive plate 30 when joining the lid material 12 to the upper end surface of the side wall portion 112 of the concave container 11, and the sealing property of the case 10 can be further improved.

[0047] (Modification) As shown in FIG. 5, the conductive plate 30 of the modified example has a spring piece 33 with a tip portion 332 bent in the opposite direction to the electrode layer 22. That is, the tip portion 332 is formed in a convex shape toward the electrode layer 22. The tip portion 332 preferably has a convex curved surface toward the electrode layer 22. The tip portion 332 may be bent multiple times so that the tip portion 332 and the electrode layer 22 come into contact with each other by a surface. For example, by bending the tip portion 322 twice, a contact surface with the electrode layer 22 can be formed at the tip portion 332. This makes it possible to prevent a sharp point of the tip portion 332 from coming into contact with the electrode layer 22 and causing damage.

[0048] The spring piece 33 in the first embodiment may have various shapes, and a plurality of spring pieces may be provided for the conductive plate 30.

[0049] Second embodiment Next, the electrochemical device 1 of the second embodiment will be specifically described with reference to Fig. 6. In the electrochemical device 1 of this embodiment, the description of the same configuration as that of the electrochemical device 1 of the first embodiment will basically be omitted, and only the configuration different from that of the electrochemical device 1 of the first embodiment will be described.

[0050] In the electrochemical device 1 of this embodiment, the power generating element 20 has a porous metal layer 24. The porous metal layer 24 is disposed on the surface of the electrode layer 22, and contacts the tip portion 332 of the spring piece 33, thereby providing electrical continuity between the electrode layer 22 and the conductive plate 30.

[0051] The porous metal layer 24 is a porous metal substrate having a high porosity and pores penetrating from one side to the other side, such as a foamed metal porous body, and can be compressed by pressing, and functions as a current collector. The porous metal layer 24 covers the surface of the electrode layer 22. In order to reduce the electrical resistance, it is preferable that the porous metal layer 24 is not only in contact with the electrode layer 22, but also part of it is embedded in the negative electrode mixture of the electrode layer 22 and integrated with the electrode layer 22. As shown in FIG. 6, the porous metal layer 24 may be disposed on the surface of the electrode layer 21 on the lower surface of the electrode layer 21, i.e., on the bottom 111 side, or the porous metal layer 24 may be provided so that part of it is embedded in the positive electrode mixture of the electrode layer 21 and integrated with the electrode layer 21.

[0052] The porosity of the porous metal layer 24 is preferably 80% or more, and more preferably 90% or more, in order to easily adjust variations in the thickness of the power generating element 20 due to compression. On the other hand, in order to ensure good electrical conductivity, the porosity of the porous metal layer 24 is preferably 99% or less. The thickness of the porous metal layer 24 before assembling the electrochemical device 1 is preferably 0.1 mm or more, more preferably 0.3 mm or more, and particularly preferably 0.5 mm or more, while it is preferably 3 mm or less, more preferably 2 mm or less, and particularly preferably 1.5 mm or less.

[0053] By providing the porous metal layer 24 in this manner, it is possible to sufficiently absorb variations in the thickness of the power generating element 20 or the height of the case 10, and as a result, it is possible to suppress variations in the value of the internal resistance. Alternatively, when the porous metal layer 24 is integrated with the second electrode layer in advance, it is possible to reduce the electrical resistance at the conductive points between the spring portion 33 and the power generating element 20.

[0054] Third embodiment Next, the electrochemical device 1 of the third embodiment will be specifically described with reference to Fig. 7. In the electrochemical device 1 of this embodiment, the description of the same configuration as that of the electrochemical device 1 of the first embodiment will basically be omitted, and only the configuration different from that of the electrochemical device 1 of the first embodiment will be described.

[0055] The electrochemical element 1 of this embodiment has a conductive sheet 40 between the electrode layer 22 and the conductive plate 30. In this embodiment, the conductive sheet 40 is a conductive carbon sheet made of expanded graphite, that is, a graphite sheet. The graphite sheet is manufactured as follows. First, particles of acid-treated graphite obtained by subjecting natural graphite to an acid treatment are heated. Then, the acid between the layers of the acid-treated graphite is vaporized and foamed, causing the acid-treated graphite to expand. This expanded graphite (expanded graphite) is molded into a felt shape, and a sheet body is formed by rolling using a rolling mill. The conductive sheet 40 is manufactured by hollowing out the expanded graphite sheet body into a circular shape. As described above, the expanded graphite is formed by vaporizing the acid and foaming the acid-treated graphite. Therefore, the graphite sheet is formed into a porous shape. Therefore, the graphite sheet has the conductivity of the graphite itself, as well as flexibility not found in conventional graphite products. However, the method for manufacturing the graphite sheet is not limited to this, and the graphite sheet may be made of a material other than expanded graphite, and the graphite sheet may be manufactured by any method.

[0056] The apparent density of the graphite sheet is 0.3 g / cm 3 More preferably, it is 0.7 g / cm 3 More than 1.5g / cm 3 Preferably less than or equal to 1.3 g / cm 3 It is preferable that the apparent density of the graphite sheet is less than 100%. If the apparent density of the graphite sheet is too low, the graphite sheet becomes easily damaged, and if the apparent density is too high, the flexibility decreases. Note that the apparent density is not limited to the graphite sheet, but can also be applied to conductive sheet 40 formed from other materials such as conductive tape.

[0057] The thickness of the graphite sheet is preferably 0.05 mm or more, more preferably 0.07 mm or more, and is preferably 0.5 mm or less, more preferably 0.2 mm or less. If the graphite sheet is too thin, it becomes easily damaged, and if the graphite sheet is too thick, it narrows the internal space of case 10 that houses power generating element 20, and the volume (thickness) of power generating element 20 that can be housed therein decreases.

[0058] In this way, by providing the conductive sheet 40, which is more flexible than the conductive plate 30, i.e., more easily deformable, the pressing force of the spring pieces 33 of the conductive plate 30 described above is more uniformly transmitted to the power generating element 20, which can prevent damage to the power generating element 20 and stabilize the electrical connection. Note that the conductive sheet 40 may be disposed between the electrode layer 21 and the bottom 111 of the concave container 11, as shown in Fig. 7. This can further prevent damage to the power generating element 20 and stabilize the electrical connection.

[0059] In the first to third embodiments described above, the electrode layer 21 functions as a positive electrode layer and the electrode layer 22 functions as a negative electrode layer, but the electrode layer 21 may function as a negative electrode layer and the electrode layer 22 may function as a negative electrode layer. In this case, the external terminal 13 functions as a negative electrode terminal and the external terminal 14 functions as a positive electrode terminal.

[0060] In the above-mentioned first to third embodiments, the power generating element 20 is constituted by a laminated body in which the electrode layer 21, the electrode layer 22, and the solid electrolyte layer 23 are laminated, but by providing a separator (not shown) instead of the solid electrolyte layer 23 as an isolation layer and accommodating an electrolytic solution together with the power generating element 20 in the internal space of the case 10, the electrochemical element can be a lithium ion secondary battery, a lithium ion capacitor, an electric double layer capacitor, or the like. In this case, the separator and the electrolytic solution are those typically used in lithium ion secondary batteries, lithium ion capacitors, electric double layer capacitors, or the like. Moreover, the electrode layer 21 and the electrode layer 22 may be replaced with a mixture layer of a positive electrode and a negative electrode typically used in various electrochemical elements 1.

[0061] Furthermore, the present invention can contribute to the achievement of Goal 7 "Affordable and Clean Energy" and Goal 12 "Responsible Consumption and Production" of the Sustainable Development Goals (SDGs) advocated by the United Nations. EXAMPLES

[0062] First, an electrochemical element (all-solid-state battery) shown in Fig. 8 was produced by the following procedure. The electrochemical element in Fig. 8 has the same configuration as the electrochemical element in Fig. 1, except that no recess is formed in the lid material.

[0063] More specifically, a conductive plate made of SUS304-CSP with a thickness of 0.2 mm was used, and the power generating element was housed in a ceramic concave container. The conductive plate was then engaged with the side wall of the concave container, thereby electrically connecting the negative electrode layer of the power generating element to the conductor exposed on the inner circumferential surface of the side wall of the concave container through the conductive plate. -3 In a vacuum environment of 10 Pa, a lid member made of an iron-nickel-cobalt alloy (Ni content: 29 mass %, Co content: 17 wt %) having a size of 10 mm x 10 mm and a thickness of 0.1 mm was joined to the side wall of the concave container via a seal ring to seal the inside of the case, thereby producing an electrochemical device A having a size of 10.5 mm x 10.5 mm and a height of 4 mm as shown in Fig. 8. In this state, the gap formed between the conductive plate and the lid member was 0.3 mm.

[0064] In addition, electrochemical element B was produced in the same manner as electrochemical element A, except that the lid member was not completely joined. Furthermore, electrochemical element C was produced in the same manner as electrochemical element A, except that the gap between the conductive plate and the lid member was set to 0.1 mm.

[0065] When each electrochemical element was left in the air after assembly, the lid material was deformed inward (towards the power generating element) and a dent was formed, as shown in Figure 1. When the depth D of the dent was measured using a laser displacement meter, the depth D of the dent was 0.06 mm for electrochemical element A and electrochemical element C, and 0.02 mm for electrochemical element B. Therefore, after the deformation of the lid material, the gap G formed between the conductive plate and the lid material was 0.24 mm for electrochemical element A, 0.28 mm for electrochemical element B, and 0.04 mm for electrochemical element C.

[0066] [Evaluation of sealing ability] The sealing ability of the cases of each electrochemical element was confirmed by the "Helium Leak Test Method" (bombing method) described in the Japanese Industrial Standard JIS-Z2331. After placing the electrochemical element in a tank and pressurizing it with helium gas for two hours, the area around the electrochemical element was evacuated in a vacuum chamber for one minute to determine the amount of helium gas leakage. In electrochemical element A and electrochemical element C, which have a dent depth D of 0.06 mm in the cover material, the amount of leakage was 1 x 10 -10 Pa·m 3 / s or less, demonstrating excellent sealing properties. On the other hand, in electrochemical device B, where the recess depth D was reduced to 0.02 mm, the leakage amount after 10 minutes was 1×10 -9 Pa·m 3 It was confirmed that batteries with a larger deformation of the lid than 0.1 mm / s and a small deformation of the lid were insufficiently sealed. Therefore, by measuring in advance the depth D of the depression in the lid of a properly sealed electrochemical element, it is possible to easily judge whether the electrochemical element is properly sealed or not from the amount of deformation of the lid.

[0067] In addition, even if the sealing is insufficient, as in electrochemical element B, the depth D of the recess in the cover material may be 0.02 mm or more immediately after being left in the atmosphere. However, in an electrochemical element with insufficient sealing, the pressure difference between the internal space and the external space of the case disappears over time, and the depth D of the recess actually becomes smaller than 0.02 mm. Therefore, such an electrochemical element is distinguished from the present invention.

[0068] [Relationship between the dimensions of the lid material and the depth D of the recess] The depth D of the recess in the lid when the dimensions of the lid (length of one side and thickness) were changed and the dimensions of the components such as the recessed container were changed accordingly for sealing is shown in Table 1. The results in Table 1 show that the depth D of the recess can be adjusted within a certain range by adjusting the dimensions of the lid.

[0069] [Table 1]

[0070] [Vibration test] A test was conducted in which sine wave vibration was applied to the electrochemical elements A and C in three directions, namely, vertical, horizontal, and height, in order. The sine wave was swept in a logarithmic manner, going back and forth in the range of 7 Hz to 200 Hz in 15 minutes while changing the frequency, and the sweep was repeated 12 times in each of the three directions. Between 7 Hz and 18 Hz, the sweep was performed so that the peak acceleration was maintained at 1 G, and from 18 Hz, the sweep was performed up to a frequency (about 50 Hz) where the peak acceleration reached 8 G while maintaining the total amplitude at 0.8 mm, and further, up to 200 Hz, the sweep was performed so that the peak acceleration was maintained at 1 G.

[0071] After the test, the electrochemical elements were checked to see if there was any contact between the conductive plate and the lid material. It was found that in electrochemical element A, there was a sufficient gap between the conductive plate and the lid material, so there was no contact between the conductive plate and the lid material. However, in electrochemical element C, there was insufficient gap between the conductive plate and the lid material, so that when an impact was applied to electrochemical element C, the conductive plate and the lid material came into contact, resulting in electrical conductivity between the negative electrode layer and the lid material.

[0072] Although the embodiments have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure. [Explanation of symbols]

[0073] 1 electrochemical element, 10 case, 11 concave container, 12 lid, 13 external terminal, 14 external terminal, 15 seal ring, 111 bottom, 112 side wall, 113 conductor, 114 conductor, 115 support, 20 power generating element, 30 conductive plate, 31 supported portion, 32 flat portion, 33 spring piece, 331 boundary, 332 tip, 40 conductive sheet, G gap, D depth

Claims

1. a case including a concave container having a bottom and a side wall and a metal lid covering an opening of the concave container; a power generating element sealed in the case, the power generating element including a first electrode layer disposed on the bottom side, a second electrode layer disposed on the lid side, and an isolation layer disposed between the first electrode layer and the second electrode layer; An electrochemical element comprising a conductive plate disposed between the power generating element and the lid, the first electrode layer is electrically connected to a first conductive path leading from the inside to the outside of the case; the second electrode layer is electrically connected to a second conductive path leading from the inside to the outside of the case via the conductive plate; the cover member is recessed toward the conductive plate due to a pressure reduction in an internal space of the case being lower than that in an external space of the case, The depth of the recess in the lid is 0.02 mm or more, An electrochemical element, wherein a gap of 0.05 mm or more is formed between the conductive plate and the lid.

2. The electrochemical device according to claim 1 , the conductive plate includes a flat portion facing the power generating element, and a spring portion rising from the flat portion and pressing the power generating element toward a bottom of the concave container;

3. The electrochemical device according to claim 2, the spring portion is cantilevered on the flat portion and has a spring piece that presses the power generating element toward a bottom of the concave container.

4. The electrochemical device according to claim 3 , An electrochemical element, wherein a tip of the spring piece is bent in a direction opposite to the power generating element.

5. The electrochemical device according to claim 1 , the conductive plate is engaged with a side wall portion of the concave container outwardly of an outer edge of the power generating element in a plan view.

6. The electrochemical device according to claim 1 , An electrochemical element, wherein the depth of the recess in the lid is 0.2 mm or less.

7. The electrochemical device according to claim 1 , An electrochemical element, wherein the size of a gap formed between the conductive plate and the lid is 0.5 mm or less.

8. The electrochemical device according to claim 1 , The power generating element further comprises a porous metal layer on a surface of the second electrode layer.

9. The electrochemical device according to any one of claims 1 to 8, The amount of helium gas leak based on the "Helium Leak Test Method" (bombing method) described in the Japanese Industrial Standard JIS-Z2331 is 1 x 10 －１０ P.A.M. ３ / s or less.

Images