Electrochemical elements

Abstract

To provide an electrochemical element that can maintain good electrical connections and has excellent sealing properties. [Solution] The electrochemical element 1 comprises a case 10 having a concave container 11 and a lid material 12, a power generation element 20 sealed inside the case 10 and having an electrode layer 21, an electrode layer 22 and an isolation layer 23, and a conductive plate 30 disposed between the power generation element 20 and the lid material 12. The electrode layer 21 is electrically connected to a conductive path (conductor part 113) leading to the outside. The electrode layer 22 is electrically connected to a conductive path (conductor part 114) leading to the outside via the conductive plate 30. The edge of the conductive plate 30 is fixed to the side wall 112 of the concave container 11. The power generation element 20 is pressed toward the bottom 11 of the concave container 11 by the conductive plate 30. A gap is formed between the conductive plate 30 and the lid material 12.

Description

Technical Field

[0001] The present disclosure relates to an electrochemical element in which a power generation element is sealed in a case.

Background Art

[0002] Conventionally, various batteries have been disclosed in which a power generation element is housed in an internal space formed by a concave container and a lid material covering the opening of the concave container.

[0003] Japanese Unexamined Patent Application Publication No. 2012-69508 (Patent Document 1) discloses an electrochemical cell with stable electrochemical characteristics. The electrochemical cell has a sealed container. The sealed container consists of a base member and a lid member. A storage space for housing an electrochemical element is formed between both members. An elastic member for pressing the electrochemical element is disposed between the lid member and the electrochemical element. Patent Document 1 discloses a leaf spring bent in a V shape in a cross-sectional view as the elastic member, or a diaphragm spring formed in a concave curved surface shape warped from the central portion toward the outer peripheral edge portion.

[0004] Further, Japanese Unexamined Patent Application Publication No. 2006-12792 (Patent Document 2) discloses a battery case. The battery case includes a base made of ceramics having a recess formed in the central portion of the upper surface, and a lid joined so as to cover the recess. The lid of the battery case is provided with a protruding portion that protrudes entirely toward the recess side in the central portion, and a curved portion is provided between the lid and an outer peripheral portion joined to the base around the protruding portion, and the battery element can be pressed and fixed from above.

[0005] Furthermore, International Publication No. 2022 / 030424 (Patent Document 3) discloses a battery package and a battery module. The battery package comprises an insulating substrate made of ceramics with a recess formed in the center of a first surface, a frame portion surrounding the recess on the first surface, and a lid portion closing the frame portion. The battery module is composed of the battery package and a battery housed inside it. A conductive metal sheet is placed between the lid of the battery package and the battery to maintain an electrical connection with the battery while pressing it. The conductive sheet is joined to a second electrode provided on the first surface via a conductive bonding material made of a conductive adhesive, and the second external electrode, which is an external terminal, is electrically connected to one electrode of the battery. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2012-69508 [Patent Document 2] Japanese Patent Publication No. 2006-12792 [Patent Document 3] International Publication No. 2022 / 030424 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, the V-shaped leaf spring in the electrochemical cell described in Patent Document 1 may not make stable contact with the electrochemical element and may be displaced due to vibration, etc. Furthermore, a diaphragm-shaped spring formed in a concave curved surface may also be displaced due to vibration, etc., and the area of ​​the central part that contacts the electrochemical element is small, which may result in unstable electrical connection.

[0008] Furthermore, in the battery case described in Patent Document 2, when joining the lid to the base, it is necessary to press the battery elements that are in contact with the lid with the lid during joining, making it difficult to achieve uniform joining around the entire circumference. This can result in areas with insufficient joining and a decrease in sealing performance. In addition, the lid may deform due to the volume change of the battery elements caused by charging and discharging.

[0009] Furthermore, while solder and conductive adhesives are exemplified as conductive bonding materials in the battery module described in Patent Document 3, using solder requires a soldering process, and it is difficult to control the amount of solder present between the conductive sheet and the second electrode. This can lead to insufficient bonding or failure of the flat surface of the conductive sheet and the flat surface of the battery to make complete contact, potentially resulting in increased electrical resistance. Additionally, when using conductive adhesives, attempting to increase conductivity weakens the bonding strength, and vibrations or changes in the battery's volume can alter the bonding state, potentially leading to problems such as increased electrical resistance.

[0010] Therefore, the object of this disclosure is to provide an electrochemical element that can maintain good electrical connections and has excellent sealing properties. [Means for solving the problem]

[0011] To solve the above problems, this disclosure is configured as follows. Specifically, the electrochemical element according to this disclosure comprises a case having a concave container having a bottom and side walls and a lid covering the opening of the concave container; a power generation element sealed inside 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 and second electrode layers; and a conductive plate disposed between the power generation element and the lid. The concave container or lid of the case has a first conductive path corresponding to the first electrode layer that leads from the inside to the outside, and a conductive path corresponding to the second electrode layer that leads from the inside to the outside. The first electrode layer is electrically connected to the first conductive path. The second electrode layer is electrically connected to the second conductive path via the conductive plate. The edge of the conductive plate is fixed to the side wall of the concave container. The power generation element is pressed towards the bottom of the concave container by the conductive plate. [Effects of the Invention]

[0012] The electrochemical element relating to this disclosure can maintain good electrical connections and achieve excellent sealing performance. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a cross-sectional view showing an electrochemical element according to the first embodiment. [Figure 2] Figure 2 is an external perspective view showing the concave container of the electrochemical element shown in Figure 1. [Figure 3] Figure 3 is an external perspective view showing another concave container of an electrochemical element. [Figure 4] Figure 4 is a plan view showing the electrochemical element (excluding the cover material and conductive plate) shown in Figure 1. [Figure 5] Figure 5 is a plan view showing the conductive plate of the electrochemical element shown in Figure 1. [Figure 6] Figure 6 is a cross-sectional view showing an electrochemical element according to the second embodiment. [Figure 7] Figure 7 is a cross-sectional view showing an electrochemical element according to the third embodiment. [Figure 8]FIG. 8 is an external perspective view showing another concave container of the electrochemical device.

Embodiment for Carrying Out the Invention

[0014] (Configuration 1) The electrochemical device according to an embodiment of the present disclosure includes a case having a concave container with a bottom portion and a side wall portion and a lid member covering an opening of the concave container, a power generation element sealed in the case and having a first electrode layer disposed on the bottom side, a second electrode layer disposed on the lid member side, and a separation layer disposed between the first electrode layer and the second electrode layer, and a conductive plate disposed between the power generation element and the lid member.

[0015] Here, the power generation element refers to a component capable of supplying power to the outside by the first electrode layer and the second electrode layer. Examples of the power generation element include batteries such as lithium ion secondary batteries or all solid state batteries, and capacitors such as electric double layer capacitors or lithium ion capacitors.

[0016] The first electrode layer and the second electrode layer of the power generation element are electrically isolated by the separation layer. As the separation layer, a solid electrolyte layer or a separator used in a normal battery or capacitor can be used.

[0017] The concave container or the lid member of the case has a first conduction path that communicates from the inside to the outside corresponding to the first electrode layer and a conduction path that communicates from the inside to the outside corresponding to the second electrode layer. The first electrode layer is electrically connected to the first conduction path. The second electrode layer is electrically connected to the second conduction path via the conductive plate.

[0018] Further, an edge end of the conductive plate is fixed to the side wall portion of the concave container. The power generation element is pressed toward the bottom portion of the concave container by the conductive plate.

[0019] In this way, the conductive plate presses the power generation element toward the bottom of the concave container, allowing the conductive plate to make more stable contact with the power generation element even due to changes in the element's volume. Furthermore, because the edge of the conductive plate is fixed to the side wall of the concave container, the sealed battery can maintain a good electrical connection without the conductive plate shifting due to vibration or other factors. In addition, since the lid does not come into contact with the power generation element, the thickness variation of the power generation element does not affect the lid when it is joined to the upper end surface of the side wall of the concave container, thereby improving the sealing performance of the case.

[0020] Furthermore, a gap is formed between the conductive plate and the lid material. This prevents the conductive plate from coming into contact with the lid material, even if the conductive plate is pushed toward the lid material due to a volume change of the power generation element, thereby suppressing deformation of the lid material. The lid material and the concave container may be bonded together with an adhesive, or they may be fixed by welding via a sealing ring. By providing a gap between the lid material and the conductive plate, when welding the lid material and the concave container, the impact of the welding heat on the power generation element can be suppressed. In addition, since the lid material and the conductive plate do not come into contact, it is not necessary to press the battery element or conductive plate with the lid material when joining the lid material to the upper end surface of the concave container, thereby further improving the sealing performance of the case. Also, even if the conductive plate deforms toward the lid material due to the volume expansion of the power generation element, the lid material is not pressed by the conductive plate, thus preventing deformation of the lid material during charging and discharging.

[0021] (Configuration 2) In the electrochemical element of configuration 1, the conductive plate may have an edge fixed to the side wall of the concave container, a bottom surface facing the power generation element and having a plane that presses the power generation element toward the bottom of the concave container, and a stepped portion displaced in the thickness direction from the bottom surface. The thickness direction of the conductive plate can also be said to be the direction perpendicular to the bottom surface. The edge of the conductive plate is configured to be fixed to the side wall of the concave container. By fixing the edge of the conductive plate to the side wall of the concave container, the bottom surface of the conductive plate can press the power generation element toward the bottom of the concave container. In this state, as described above, the conductive plate electrically connects the second electrode layer and the second conductive path.

[0022] Here, the flat bottom surface of the conductive plate presses the power generation element toward the bottom of the concave container over a wider area, ensuring that the conductive plate makes more stable contact with the power generation element even if the power generation element undergoes a volume change. Furthermore, damage to the electrode layer during expansion of the power generation element can be suppressed, and a good electrical connection can be maintained. In addition, since the lid material does not come into contact with the conductive plate or the power generation element, a uniform bond can be made around the entire circumference when joining the lid material to the upper end surface of the side wall of the concave container, thereby improving the sealing performance of the case.

[0023] A stepped portion is formed around the bottom surface of the conductive plate, displaced in the thickness direction. This makes the conductive plate more likely to function as a spring, and the elasticity makes it easier for the bottom surface to press against the power generation element. In addition, the overall thickness can be reduced compared to a conductive plate formed in a diaphragm shape. Furthermore, the position of the edge of the conductive plate, i.e., the supported portion as described later, can be freely set in the height direction (thickness direction of the conductive plate). For example, the position at the edge of the conductive plate that is fixed to the inner circumferential surface of the side wall of the concave container can be set closer to the bottom of the concave container than to the bottom surface of the conductive plate. Therefore, even if a gap is formed between the lid material and the conductive plate, the distance between the lid material and the bottom surface of the conductive plate does not become large, and thus the gap between the lid material and the power generation element can be limited, preventing it from becoming an obstacle to increasing capacity.

[0024] (Composition 3) In the electrochemical element of configuration 1 or 2, the concave container may have a plurality of support parts on its side wall. The edge of the conductive plate may have a plurality of supported parts corresponding to each of the support parts. Each supported part may be fixed to the support part.

[0025] The edges of the conductive plate can be fixed to the side wall of the concave container, for example, as follows. Support portions are provided on the inner circumferential surface of the side wall of the concave container for engaging the edges of the conductive plate. Supported portions are also provided on the edge of the conductive plate for engaging with the support portions. To securely fix the conductive plate, it is preferable to provide multiple support portions on the inner circumferential surface of the side wall of the concave container, and it is preferable to provide multiple supported portions on the edge of the conductive plate corresponding to the positions of each support portion. As each supported portion is engaged with and supported by the support portion, the edges of the conductive plate are fixed to the side wall, and the bottom surface of the conductive plate can press the power generation element toward the bottom of the concave container. This allows for the maintenance of a better electrical connection.

[0026] (Composition 4) In the electrochemical element of configuration 3, the support portion of the concave container can be a protruding portion formed on the inner circumferential surface of the side wall. The supported portion of the conductive plate can be a locking piece that extends from the edge of the conductive plate and can be locked to the lower surface of the protruding portion.

[0027] (Composition 5) In any of the electrochemical elements of configurations 1 to 4, the isolation layer may be a solid electrolyte layer having a sulfide-based solid electrolyte.

[0028] (Composition 6) In any of the electrochemical elements of configurations 1 to 5, the electrochemical element may further have a conductive sheet between the bottom surface of the conductive plate and the power generation element. The electrochemical element may have a conductive sheet, such as a metal foil or porous material, or a carbon sheet or nonwoven fabric, or a conductive film, such as a coating or vapor-deposited film containing a conductive material such as metal or carbon, placed between the bottom surface of the conductive plate and the power generation element. This reduces contact resistance compared to the case where the conductive plate and the power generation element are in direct contact, and enables even better electrical connection. In order to easily reduce contact resistance, it is preferable to use a conductive sheet or conductive film that is more flexible and easier to deform than the conductive plate.

[0029] The electrochemical element can be configured such that the power generation element is sealed inside the case in an outer material separate from the case, such as a metal container, and the power generation element is double-sealed by both the case and the outer material. In other words, the electrochemical element may be configured to seal a flattened element, in which the power generation element is sealed inside an outer material, within the case.

[0030] (Composition 7) Therefore, another embodiment of the electrochemical element comprises a case having a concave container with a bottom and side walls and a lid covering the opening of the concave container; an outer casing sealed inside the case and including a first electrode terminal located on the bottom side and a second electrode terminal located on the lid side; a flattened element enclosed inside the outer casing and including a power generation element with a first electrode layer, a second electrode layer, and an isolation layer disposed between the first and second electrode layers; and a conductive plate disposed between the flattened element and the lid. The first electrode terminal is electrically connected to a first conductive path leading from the inside to the outside of the case. The second electrode terminal is electrically connected to a second conductive path leading from the inside to the outside of the case via the conductive plate. The edge of the conductive plate is fixed to the side wall of the concave container. The flattened element is pressed towards the bottom of the concave container by the conductive plate. A gap is formed between the conductive plate and the lid. In this way, good electrical connection can be maintained even when the flattened element is housed in the internal space of the case.

[0031] (Composition 8) In the electrochemical element of configuration 7, the conductive plate may have an edge fixed to the side wall of the concave container, a flat bottom surface facing the flat element and pressing the flat element toward the bottom of the concave container, and a stepped portion displaced in the thickness direction from the bottom surface. As a result, the electrochemical element of configuration 8 can obtain the same effect as the electrochemical element of configuration 2.

[0032] (Composition 9) In the electrochemical elements of configurations 7 and 8, the concave container has a plurality of support parts on its side wall. The edge of the conductive plate has a plurality of supported parts corresponding to each of the support parts. Each supported part is fixed to the support part. As a result, the electrochemical element of configuration 9 can obtain the same effect as the electrochemical element of configuration 3.

[0033] (Composition 10) In the electrochemical element of configuration 9, the support portion of the concave container can be a protruding portion formed on the inner circumferential surface of the side wall. The supported portion of the conductive plate can be a locking piece that extends from the edge of the conductive plate and can be locked to the lower surface of the protruding portion.

[0034] (Composition 11) In any of the electrochemical elements of configurations 7 to 10, the isolation layer is a solid electrolyte layer having a sulfide-based solid electrolyte. The flattened element is an all-solid-state battery.

[0035] (Composition 12) In any of the electrochemical elements of configurations 7 to 11, the electrochemical element further includes a conductive sheet between the bottom surface of the conductive plate and the flattened element. As a result, the electrochemical element of configuration 12 can obtain the same effect as the electrochemical element of configuration 6.

[0036] The material of the concave container is not particularly limited, and various materials such as resin, glass (borosilicate glass, glass ceramics, etc.), metal, and ceramic can be used as examples. It may also be a composite material in which ceramic or glass powder is dispersed in resin. When the concave container is made of a metal material, it is desirable to cover the inner surface of the bottom of the concave container and the inner circumferential surface of the side walls with an insulating material such as resin or glass in order to ensure insulation between the concave container and the power generation element, or between the concave container and the flattened element.

[0037] (First Embodiment) Hereinafter, the first embodiment of this disclosure will be specifically described using Figures 1 to 5, with the example of the case in which the electrochemical element is an all-solid-state battery. First, as shown in Figure 1, the electrochemical element 1 consists of a case 10, a power generation element 20 housed in the case 10, and a conductive plate 30 housed in the case 10.

[0038] Case 10 includes a concave container 11, a lid material 12, external terminals 13 and 14.

[0039] The concave container 11 is made of ceramic. The concave container 11 includes a rectangular bottom 111 and a rectangular cylindrical side wall 112 that is formed continuously from the outer circumference of the bottom 111 and has a cylindrical space inside for housing the power generation element 20. In a longitudinal cross-sectional view, the side wall 112 is provided so as to extend substantially perpendicular to the bottom 111. A conductor portion 113 is formed inside the bottom 111. The conductor portion 113 extends between the power generation element 20 and the bottom 111 so as to be electrically connected to the power generation element 20, and forms a conductive path corresponding to the electrode layer 21. A conductor portion 114 is formed inside the side wall 112. As shown in Figure 1, a part of the conductor portion 114 is formed on the inner circumferential surface of the side wall 112, exposed to the lower surface and side surface of the support portion 115, which will be described later, and forms a conductive path corresponding to the electrode layer 22. The manufacturing method of the concave container 11 will be described later. The concave container 11 is not limited to ceramic, but may be made of an insulating material such as synthetic resin. The concave container 11 is not limited to a rectangular shape in plan view, but may be circular, elliptical, or polygonal. The internal space for housing the power generation element 20 is not limited to a cylindrical shape, but may be formed in a polygonal cylindrical shape such as a rectangular cylinder depending on the shape of the power generation element 20. 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 also penetrate the inside of the bottom portion 111 to make electrical contact with the external terminal 14. In this case, it is desirable to form an insulating layer between the outer surface of the power generation element 20 and the conductor portion 114, for example, on the inner surface of the conductor portion 114, so that the outer surface of the power generation element 20 and the conductor portion 114 do not come into contact.

[0040] The side wall portion 112 has a plurality of support portions 115 that support the conductive plate 30. In this embodiment, the support portions 115 are protruding portions formed at the upper end of the inner circumferential surface of the side wall portion 112 and extending radially inward. More specifically, as shown in Figure 2, the support portions 115 are the top walls of a plurality of recesses formed radially outward on the inner circumferential surface of the side wall portion 112. As a result, the support portions 115 are formed to protrude radially inward. The lower surface of each support portion 115, that is, the lower surface of each top wall, can engage with and support the supported portion 31 of the conductive plate 30, which will be described later. In addition, although four support portions 115 are provided in this embodiment, the number is not limited. For example, if the supported portion 31 of the conductive plate 30, which will be described later, is made up of two, then two support portions 115 should be provided at positions corresponding to the supported portion 31, as shown in Figure 3.

[0041] The lid 12 is a rectangular metal plate that covers the opening of the concave container 11. As shown in Figures 1 and 4, the lid 12 is joined (seam welded) to the concave container 11 by a rectangular frame-shaped sealing ring 15 positioned between the lower surface of its outer circumference 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 preferably a vacuum atmosphere or an inert gas atmosphere such as nitrogen, considering the influence on the power generation element 20. The lid 12 is not limited to a metal plate as long as it can cover the opening of the concave container 11. The lid 12 is not limited to a rectangular shape and can be changed to various shapes such as circular, elliptical, and polygonal depending on the shape of the concave container 11 in plan view. The lid 12 may also be in a shape other than a flat plate. The lid 12 may also be bonded to the concave container 11 with an adhesive, and the method of joining the lid 12 to the concave container 11 is not particularly limited.

[0042] The external terminal 13 is located on the outer surface of the bottom 111 of the concave container 11. The external terminal 13 is electrically connected to the electrode layer 21, which will be described later, via the conductive portion 113. The electrode layer 21 functions as a positive electrode layer, as will be described later. Therefore, the conductive 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.

[0043] The external terminal 14 is positioned 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 conductive 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 conductive portion 114 becomes a conductive path that connects the external terminal 14 and the negative electrode layer, and the conductive plate 30 becomes a connecting terminal that connects this conductive path and the electrode layer 22, so the external terminal 14 functions as a negative electrode terminal. Note that the arrangement of the external terminals 13 and 14 is not limited to the above, and they may be positioned on the outer surface of the side wall portion 112 of the concave container 11, or the lid material 12 may function as the conductive portion 114 and the external terminal 14 may be formed on the outer surface of the lid material 12. However, by positioning both of these terminals on the outer surface of the bottom 111 of the concave container 11 with a certain distance between them, mounting to the surface of the circuit board becomes easier.

[0044] Here, the manufacturing method for the concave container 11 will be described. First, a metal paste is printed onto a ceramic green sheet to form printed patterns that will become the conductive parts 113 and 114. Next, multiple green sheets with these printed patterns are stacked and fired. By stacking multiple green sheets of different shapes, the support portion 115 described above is formed. This makes it possible to manufacture a concave container 11 having conductive parts 113 and 114 inside, and the support portion 115 described above 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. External terminals 13 and 14 can also be formed by the printed patterns of this metal paste.

[0045] The power generation element 20 includes a laminate formed by stacking an electrode layer (positive electrode layer) 21, an electrode layer (negative electrode layer) 22, and a solid electrolyte layer 23. The solid electrolyte layer 23 is positioned between the electrode layers 21 and 22 as an isolation layer. In other words, in this embodiment, the isolation layer is the solid electrolyte layer 23. The power generation element 20 is formed in a cylindrical shape. The power generation element 20 is stacked in the order of electrode layer 21, solid electrolyte layer 23, and electrode layer 22 from the bottom 111 side (bottom in the figure) of the concave container 11. That is, the power generation element 20 is positioned so that one end, electrode layer 21, faces the bottom 111 side of the concave container 11, and the other end, electrode layer 22, faces the lid material 12 side, and is housed in the internal space of the case 10. Note that the power generation element 20 is not limited to a cylindrical shape and can be changed to various shapes such as a rectangular parallelepiped or polygonal prism. Also, the power generation element 20 may have multiple laminates. Multiple stacked structures may be stacked so as to be connected in series.

[0046] The electrode layer 21 is a positive electrode pellet formed into a cylindrical shape by placing 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 into a mold with a diameter of 7.45 mm. 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, etc., or a mixture of these as appropriate. Other components and their proportions are also not particularly limited. Furthermore, the size and shape of the electrode layer 231 are not limited to a cylindrical shape and can be changed in various ways depending on the size and shape of the electrochemical element 1.

[0047] The electrode layer 22 is made of LTO (Li4Ti5O) as the negative electrode active material used in lithium-ion secondary batteries. 12The negative electrode pellet is formed into a cylindrical shape from a negative electrode mixture containing 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. For example, it may be metallic lithium, lithium alloy, carbon materials such as graphite and low-crystallinity carbon, or oxides such as SiO, or a mixture of these as appropriate. Other components and their proportions are also not particularly limited. Furthermore, the size and shape of the electrode layer 22 are not limited to a cylindrical shape and can be changed in various ways depending on the size and shape of the electrochemical element 1.

[0048] The solid electrolyte layer 23 contains a sulfide-based solid electrolyte. The solid electrolyte layer 23 is molded into a cylindrical shape. The solid electrolyte contained in the electrode layer 21, electrode layer 22, and solid electrolyte layer 23 is not particularly limited, but from the viewpoint of ionic conductivity, a sulfide-based solid electrolyte, particularly an argyrodite-type sulfide-based solid electrolyte, is preferably used. When using a sulfide-based solid electrolyte, it is preferable to coat the surface of the positive electrode active material with a lithium-ion conductive material such as niobium oxide to prevent reaction with the positive electrode active material. Furthermore, the solid electrolyte contained in the solid electrolyte layer 23, electrode layer 21, and electrode layer 22 may be a hydride-based solid electrolyte or an oxide-based solid electrolyte, etc. Also, the size and shape of the solid electrolyte layer 23 are not limited to a cylindrical shape and can be changed in various ways depending on the size and shape of the electrochemical element 1.

[0049] As shown in Figures 1 and 5, the conductive plate 30 is a metal plate material that is rectangular in plan view and installed in the opening of the concave container 11 of the case 10. The conductive plate 30 has a plurality of supported portions 31 corresponding to the positions of each of the support portions 115 described above. In this embodiment, the supported portions 31 are hook-shaped locking pieces that engage with the support portions 115, i.e., the lower surface of the top wall. More specifically, the supported portions 31 extend from the edge of the conductive plate 30 toward the support portions 115 (downward in Figure 1). The supported portions 31 have a tip that is folded back toward the support portion 115, i.e., the lower surface of the top wall. The tip of the supported portion 31 is in contact with the conductor portion 114 exposed on the lower surface and side surface of the top wall. As a result, the conductive plate 30 functions as a current collector and as a connecting 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 circumferential surface of the concave container 11, and covers a portion of the opening of the concave container 11. The area of ​​the conductive plate 30 in plan view is smaller than the opening area of ​​the concave container 11.

[0050] As shown in Figure 1, the conductive plate 30 is fixed to the side wall portion 112 of the concave container 11 and presses the power generation element 20 toward the bottom portion 111 of the concave container 11. The conductive plate 30 has a recess that is recessed toward the electrode layer 22 at the contact position with the upper surface of the electrode layer 22, which is the other end of the power generation element 20. The bottom surface 32 of the recess is formed flat so that the power generation element 20 can be pressed over a wider area. In addition, the area around the bottom surface 32 of the recess is a stepped portion 33 that is displaced in the thickness direction. The stepped portion 33 is the peripheral wall of a frustocone whose diameter gradually decreases toward the power generation element 20. As shown in Figure 1, the bottom surface 32 of the recess faces the electrode layer 22 and is in contact with the upper surface of the electrode layer 22. In this way, the flat bottom surface 32 presses the electrode layer 22 over a wide area, which can suppress damage to the electrode layer 22 when the power generation element 20 expands. Furthermore, by ensuring a wider contact area between the conductive plate 30 and the power generation element 20, and by making the conductive connection between the conductive plate 30 and the power generation element 20 over a wider area, a good electrical connection can be maintained. In addition, by providing the stepped portion 33, the overall thickness of the conductive plate 30 can be reduced. Moreover, since the position of the edge of the conductive plate 30, i.e., the supported portion, can be freely set in the height direction (thickness direction of the conductive plate), even if a gap is formed between the cover material 12 and the conductive plate 30, the distance between the cover material 12 and the bottom surface 32 of the conductive plate 30 does not increase. As a result, the increase in the air gap between the cover material 12 and the power generation element 20 can be suppressed, thereby increasing the capacitance of the electrochemical element 1. Note that the thickness direction is the vertical direction in Figure 1 (height direction of the electrochemical element 1), and can also be said to be the direction perpendicular to the bottom surface 32 in the illustration. Note that the entire bottom surface 32 does not need to be flat; a part of it may have a shape other than flat. However, it is preferable that the larger the proportion of the bottom surface 32 occupied by a flat surface, the larger the contact area with the electrode layer 22, which can reduce the contact resistance, and it is even more preferable that the entire bottom surface 32 be made of a flat surface.

[0051] Examples of metals that make up the conductive plate 30 include nickel, iron, copper, chromium, cobalt, titanium, aluminum, and alloys thereof. To facilitate its function as a leaf spring, spring stainless steels such as SUS301-CSP, SUS304-CSP, SUS316-CSP, SUS420J2-CSP, SUS631-CSP, and SUS632J1-CSP are preferably used.

[0052] Furthermore, the thickness 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 that the pressing force on the power generation element 20 is above a certain level. On the other hand, in order to prevent the volume of the case from increasing due to the thickness of the conductive plate 30 becoming too thick, and in order to make the conductive plate 30 easily deformable so that it can be easily locked to 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.

[0053] To reduce contact resistance, the area of ​​the bottom surface of the conductive plate is preferably 10% or more of the area of ​​the electrode 22 of the opposing power generation element in a plan view, more preferably 30% or more, particularly preferably 50% or more, and most preferably 60% or more. On the other hand, in order to reduce the radial void around the power generation element 20, the area of ​​the bottom surface 32 of the conductive plate 30 is preferably 100% or less of the area of ​​the electrode layer 22 of the opposing power generation element 20 in a plan view, more preferably 95% or less, particularly preferably 90% or less, and most preferably 85% or less. Furthermore, the shape of the bottom surface 32 of the conductive plate 30 does not have to be a perfectly flat surface; it may have irregularities, such as embossing, to reduce contact resistance with the power generation element 20.

[0054] The conductive plate 30 is placed on the upper surface of the power generation element 20 after the power generation element 20 is housed inside the concave container 11. With the conductive plate 30 placed on the upper surface of the power generation element 20, the tip of the supported portion 31 is positioned between the upper surface of the power generation element 20 and the support portion 115, i.e., the lower surface of the top wall, in the axial direction of the power generation element 20 (up and down direction in Figure 1). Then, the supported portion 31 of the conductive plate 30 is pushed toward the bottom 111 of the concave container 11, and the supported portion 31 is supported by the support portion 115. More specifically, the tip of the supported portion 31 is locked to the support portion 115, i.e., the lower surface of the top wall. As the supported portion 31 is pushed downward, the conductive plate 30 bends in the opposite direction to the electrode layer 22 while in contact with the power generation element 20. The conductive plate 30 presses the power generation element 20 toward the bottom 111 of the concave container 11 by its elastic force. As a result, the conductive plate 30 can make more stable contact with the power generation element 20 without being displaced by vibrations, and a good electrical connection can be maintained without displacement due to vibrations. At this time, by forming the recess described above, the effect of deflection on the flat bottom surface 32 is reduced, so that an even better electrical connection can be maintained. Thus, the configuration of the conductive plate 30 is not particularly limited as long as its elastic force can press the power generation element 20 toward the bottom 111 side of the concave container 11 while its edge is supported on the inner circumferential surface of the side wall portion 112.

[0055] A gap is formed between the conductive plate 30 and the lid material 12. In other words, the conductive plate 30 and the lid material 12 do not come into contact. This suppresses deformation of the lid material 12 even if the conductive plate 30 is pushed toward the lid material 12 due to a change in the volume of the power generation element 20. Furthermore, the lid material 12 and the concave container 11 are welded together via the seal ring 15 as described above. By providing a gap between the conductive plate 30 and the lid material 12, the effect of welding heat on the power generation element 20 can be suppressed. In addition, since the conductive plate 30 and the lid material 12 do not come into contact, the volume change of the power generation element 20 does not affect the joining of the lid material 12 to the upper end surface of the side wall portion 112 of the concave container 11, thereby further improving the sealing performance of the case 10.

[0056] (Second Embodiment) Next, the electrochemical element 1 of the second embodiment will be described in detail with reference to Figure 6. In the electrochemical element 1 of this embodiment, the same configuration as the electrochemical element 1 of the first embodiment will be omitted from the explanation, and only the configuration that differs from the electrochemical element 1 of the first embodiment will be described.

[0057] 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, i.e., a graphite sheet. The graphite sheet is manufactured as follows. First, particles of acid-treated graphite, which is natural graphite treated with acid, are heated. When this is done, the acid-treated graphite expands as the acid between its layers vaporizes and foams. This expanded graphite (expanded graphite) is molded into a felt shape and then rolled using a roll rolling mill to form a sheet. The conductive sheet 40 is manufactured by cutting out a circular shape from this expanded graphite sheet. As described above, expanded graphite is formed when acid vaporizes and the acid-treated graphite foams. Therefore, the graphite sheet is formed in a porous shape. Consequently, the graphite sheet has the conductivity inherent in graphite itself, as well as flexibility not found in conventional graphite products. Furthermore, the method for manufacturing the graphite sheet is not limited to this, and it may be composed of materials other than expanded graphite, and the graphite sheet may be manufactured by any method.

[0058] The apparent density of the graphite sheet is 0.3 g / cm³. 3 The above is preferable, and more preferably 0.7 g / cm³. 3 The above is 1.5 g / cm³. 3 The following is preferred, and more preferably, 1.3 g / cm³. 3 The following is preferable: 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, its flexibility decreases. Note that apparent density is not limited to graphite sheets, but can also be applied to conductive sheets 40 formed from other materials such as conductive tape.

[0059] The thickness of the graphite sheet is preferably 0.05 mm or more, more preferably 0.07 mm or more, preferably 0.5 mm or less, and more preferably 0.2 mm or less. If the thickness of the graphite sheet is too small, it becomes easily damaged, and if the thickness is too large, the graphite sheet narrows the internal space of the case 10 that houses the power generation element 20, reducing the volume (thickness) of the power generation element 20 that can be housed. Note that the thickness of the graphite sheet is not limited to graphite sheets, and can also be applied to conductive sheets 40 formed from other materials such as conductive tape or metal.

[0060] As described above, by providing a conductive sheet 40 that is more flexible than the conductive plate, i.e., easily deformable, the pressing force of the conductive plate 30 is transmitted more uniformly to the power generation element 20, thereby suppressing damage to the power generation element 20 and stabilizing the electrical connection. The conductive sheet 40 may also be placed between the electrode layer 21 and the bottom 111 of the concave container 11, as shown in Figure 6. This further suppresses damage to the power generation element 20 and stabilizes the electrical connection.

[0061] (Third embodiment) Next, the electrochemical element 1 of the third embodiment will be described in detail with reference to Figure 7. In the electrochemical element 1 of this embodiment, the same configuration as the electrochemical element 1 of the first and second embodiments will be omitted from the explanation, and only the configuration that differs from the electrochemical element 1 of the first and second embodiments will be described.

[0062] In this embodiment, the electrochemical element 1 houses a flattened element 50 in the internal space of the case 10. As shown in Figure 7, the flattened element 50 has an outer casing (electrode terminals) 51, a sealing casing (electrode terminals) 52, the aforementioned power generation element 20, and a gasket 53.

[0063] The outer container 51 comprises a circular flat portion 511 and a cylindrical side wall portion 512 that is continuously formed from the outer circumference of the flat portion 511. The cylindrical side wall portion 512 is provided so as to extend substantially perpendicular to the flat portion 511 in a longitudinal cross-sectional view. The outer container 51 is made of a metal material such as stainless steel. The outer container 51 is positioned on the bottom 111 side of the concave container 11.

[0064] The sealing can 52 comprises a circular flat portion 521 and a cylindrical peripheral wall portion 522 that is continuously formed from the outer circumference of the flat portion 521. The opening of the sealing can 52 faces the opening of the outer can 51. The sealing can 52 is made of a metal material such as stainless steel. The sealing can 52 is positioned on the lid material 12 side. The power generation element 20 is housed between the outer can 51 and the sealing can 52. Therefore, the outer can 51 functions as an electrode terminal connected to the conductor portion 113, and the sealing can 52 functions as the other electrode terminal connected to the conductive plate 30.

[0065] The outer can 51 and the sealing can 52 are crimped together via a gasket 53 between the cylindrical side wall 512 of the outer can 51 and the peripheral wall 522 of the sealing can 52 after the power generation element 20 has been housed in the internal space. More specifically, the outer can 51 and the sealing can 52 are crimped together via a gasket 53 after the openings of the outer can 51 and the sealing can 52 are facing each other and the peripheral wall 522 of the sealing can 52 is inserted inside the cylindrical side wall 512 of the outer can 51, and then the cylindrical side wall 512 and the peripheral wall 522 are crimped together via a gasket 53. As a result, the internal space formed by the outer can 51 and the sealing can 52 becomes airtight. Note that the outer can 51 and the sealing can 52 are not limited to a circular shape in plan view, but can be changed to various shapes such as an ellipse or polygon.

[0066] The gasket 53 is made of a resin material such as a polyamide resin, polypropylene resin, or polyphenylene sulfide resin. The method for sealing the internal space formed by the outer can 51 and the sealing can 52 is not limited to crimping via the gasket 53, but may be done by other methods. For example, the cylindrical side wall portion 512 of the outer can 51 and the peripheral wall portion 522 of the sealing can 52 may be joined and sealed by interposing a heat-meltable resin or adhesive.

[0067] After the flat element 50 is housed inside the concave container 11, the conductive plate 30 is placed on the upper surface of the flat element 50, and the supported portion 31 is locked to the support portion 115 for support. At this time, the conductive plate 30 bends in the opposite direction to the flat element 50 while in contact with the flat portion 521 of the sealing can 52. The conductive plate 30 presses the flat element 50 toward the bottom portion 111 of the concave container 11 due to its elastic force. As a result, the conductive plate 30 makes more stable contact with the flat element 50 without being displaced by vibration, etc., and, similar to the electrochemical element 1 of the first embodiment described above, a good electrical connection can be maintained without displacement due to vibration, etc.

[0068] In the electrochemical element 1 of this embodiment, although not specifically shown, the conductive sheet 40 or conductive film described above may be placed between the flat element 50 and the conductive plate 30. Alternatively, the conductive sheet 40 or conductive film may be placed between the flat element 0 and the bottom 111 of the concave container 11.

[0069] The flattened element 50 is not limited to all-solid-state batteries having a solid electrolyte layer, but may also be non-aqueous electrolyte batteries such as lithium-ion secondary batteries, other batteries having a flattened shape, or capacitors such as lithium-ion capacitors.

[0070] (Variation 1) In the first embodiment described above, the support portion 115 was formed to protrude radially inward. However, as shown in Figure 8, the support portion 115 may be formed to protrude along the circumferential direction of the inner surface of the side wall portion 112 at the upper end of the inner surface of the side wall portion 112. That is, the support portion 115 may be a top wall formed radially outward on the inner surface of the side wall portion 112. The top wall has an opening for inserting the supported portion (locking piece) 31 of the conductive plate 30 from the upper end surface of the concave container 11. The supported portion 31 is inserted into the recess through the opening in the top wall. At this time, by rotating the conductive plate 30 horizontally, the folded tip of the supported portion 31 comes into contact with the lower surface of the top plate. In this way, the supported portion 31 can also be supported by the support portion 115. In this case, the orientation of the supported portion 31 of the conductive plate 30 should be changed so that it can be locked against the support portion 115 that protrudes in the circumferential direction. For example, the angle of the supported portion 31 in a plan view, as shown in Figure 5, can be shifted by 90 degrees. As shown in Figure 8, the concave container 11 has two support portions 115, but the number of support portions 115 may be two or more. The supported portion 31 should be formed according to the number of support portions 115.

[0071] (Modification 2) Furthermore, the support portion 115 may be provided on the upper end surface of the side wall portion 112, rather than on the inner circumferential surface of the side wall portion 112. For example, although not specifically shown, the support portion 115 may be a protruding portion that extends radially inward in a recess having an opening on the upper end surface of the side wall portion 112. In this case, the conductive plate 30 can be fixed by inserting the supported portion 31 into the recess provided on the upper end surface of the side wall portion 112. The tip of the supported portion 31 may be supported by the lower surface of the support portion 115 (protruding portion) that extends radially inward or circumferentially, or the recess itself may be used as the support portion 115, and the conductive plate 30 may be fixed by pressing the supported portion 31 against the inner surface of the recess. In this way, the configuration of the conductive plate 30 is not particularly limited as long as its elastic force can press the power generation element 20 toward the bottom 111 side of the concave container 11 while its edge is fixed to the side wall portion 112.

[0072] In the first to third embodiments described above, electrode layer 21 functions as the positive electrode layer and electrode layer 22 functions as the negative electrode layer. However, electrode layer 21 may function as the negative electrode layer and electrode layer 22 may function as the negative electrode layer. In this case, external terminal 13 functions as the negative electrode terminal and external terminal 14 functions as the positive electrode terminal.

[0073] In the third embodiment described above, the flattened element 50 was housed in the internal space of the case 10 such that the outer can 51 was positioned on the bottom 111 side of the concave container 11. However, it may also be housed so that the sealing can 52 is positioned on the bottom 111 side of the concave container 11. That is, the flattened element 50 may be housed in the internal space of the case 10 with the top and bottom of the flattened element 50 shown in Figure 6 inverted.

[0074] (Variation 3) In the first and second embodiments described above, the power generation element 20 was constructed as a laminate formed by stacking an electrode layer 21, an electrode layer 22, and a solid electrolyte layer 23. However, by providing a separator (not shown) instead of the solid electrolyte layer 23 as an isolation layer, and housing the electrolyte together with the power generation 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, etc. In this case, the separator and electrolyte are those commonly used in lithium-ion secondary batteries, lithium-ion capacitors, or electric double-layer capacitors. Furthermore, the electrode layers 21 and 22 can be replaced with composite layers of positive and negative electrodes commonly used in various electrochemical elements 1.

[0075] Although embodiments have been described above, this disclosure is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the disclosure. [Examples]

[0076] [Evaluation of vibration resistance] An electrochemical element (all-solid-state battery) shown in Figure 1 was fabricated using a conductive plate made of SUS304-CSP with a thickness of 0.1 mm. The vibration resistance of this electrochemical element was evaluated by conducting vibration tests as follows.

[0077] A test was conducted in which sinusoidal vibrations were sequentially applied to the three directions (length, width, and height) of the electrochemical element of the example. The sinusoidal sweep was performed as a logarithmic sweep, moving back and forth over 15 minutes in the range of 7 Hz to 200 Hz while varying the frequency, and this 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. From 18 Hz onward, the sweep was performed up to the frequency (approximately 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.

[0078] The AC impedance of the electrochemical element in the example in which the vibration test was performed was measured at 1kHz with an applied voltage of 10mV and compared with the AC impedance value measured before the vibration test. No change was observed, confirming that the electrical connection was well maintained by the conductive plate attached to the side wall of the concave container.

[0079] On the other hand, for comparison, a comparative electrochemical element was fabricated in which the conductive plate was not fixed to the side wall of the concave container, but instead fixed to a conductive path formed on the side wall of the concave container using a conductive adhesive, thereby creating electrical contact with the conductive path. The same evaluation as in the above-described example was performed, but an increase in impedance (more than 60%) was observed in the comparative electrochemical element after the vibration test, and it was not possible to maintain good electrical connection. [Explanation of symbols]

[0080] 1 Electrochemical element, 10 Case, 11 Concave container, 12 Lid material, 13 External terminal, 14 External terminal, 15 Seal ring, 111 Bottom, 112 Side wall, 113 Conductor part, 114 Conductor part, 115 Support part, 20 Power generation element, 30 Conductive plate, 31 Supported part, 32 Recess, 33 Stepped part, 40 Conductive sheet, 50 Flat element, 51 Outer can, 511 Flat part, 52 Sealing can, 521 Flat part, 53 Gasket

Claims

1. A case having a concave container with a bottom and side walls, and a lid material that covers the opening of the concave container, A power generation element sealed within the case, having a first electrode layer located on the bottom side, a second electrode layer located on the lid side, and a isolation layer located between the first electrode layer and the second electrode layer, The system comprises a conductive plate disposed between the power generation element and the cover material, The first electrode layer is electrically connected to a first conductive path that extends from the inside to the outside of the case. The second electrode layer is electrically connected to a second conductive path that extends from the inside to the outside of the case via the conductive plate. The conductive plate has its edge fixed to the side wall of the concave container. The power generation element is pressed by the conductive plate toward the bottom of the concave container. A gap is formed between the conductive plate and the cover material. The isolation layer is a solid electrolyte layer, forming an electrochemical element.

2. The electrochemical element according to claim 1, The conductive plate is an electrochemical element having an edge fixed to the side wall of the concave container, a bottom surface facing the power generation element and having a plane that presses the power generation element toward the bottom of the concave container, and a stepped portion displaced in the thickness direction from the bottom surface.

3. The electrochemical element according to claim 1, The concave container has a plurality of support parts on its side wall, The edge of the conductive plate has a plurality of supported portions corresponding to each of the support portions, Each of the aforementioned supported parts is an electrochemical element fixed to the support part.

4. The electrochemical element according to claim 1, The solid electrolyte contained in the solid electrolyte layer is a sulfide-based solid electrolyte, in this electrochemical element.

5. An electrochemical element according to claim 4, The aforementioned sulfide-based solid electrolyte is of the argyrodite type, and is used in electrochemical devices.

6. An electrochemical element according to Claim 1, An electrochemical element in which either the first electrode layer or the second electrode layer contains a solid electrolyte.

7. An electrochemical element according to claim 6, An electrochemical element in which the solid electrolyte contained in either the first electrode layer or the second electrode layer is a sulfide-based solid electrolyte.

8. An electrochemical element according to any one of claims 1 to 7, An electrochemical element further comprising a conductive sheet between the bottom surface of the conductive plate and the power generation element.

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