Solid-state battery with case

Abstract

Provided is an all-solid-state battery with a case that can be reflow soldered and that makes it possible to suppress volume change during charging and discharging and stabilize electrical connection. This all-solid-state battery 1 with a case comprises a case 10, an all-solid-state battery 20, and a restorable conductive sheet 30. The case 10 includes a ceramic concave container 11, a connection terminal 13, and a connection terminal 14. The concave container 11 includes a conductor portion 113 of a bottom 111 and a conductor portion 114 of a side wall 112. An outer can 21 of the all-solid-state battery 20 is fixed so as to face the bottom 111. The outer can 21 is electrically connected to the connection terminal 13 by the conductor portion 113. The restorable conductive sheet 30 connects the upper surface of a sealing can 22 and the upper end of the side wall 112. The sealing can 22 is electrically connected to the connection terminal 14 by the restorable conductive sheet 30 and the conductor portion 114. The restorable conductive sheet 30 absorbs volume changes due to expansion of the all-solid-state battery 20 during charging and discharging. Therefore, when the all-solid-state battery 1 with a case is mounted on a circuit board, it is possible to prevent the surrounding parts from being pressed and damaged, and to stabilize the electrical connection.　

Description

[Technical Field]

[0001] This disclosure relates to a cased solid-state battery. [Background technology]

[0002] Compared to non-aqueous electrolyte batteries, which contain an electrolyte solution, all-solid-state batteries have a lower risk of ignition during reflow soldering and do not suffer from electrolyte leakage, allowing them to be mounted more safely on the surface of a circuit board.

[0003] Japanese Patent Publication No. 2009-211965 discloses a lithium-ion secondary battery (Patent Document 1). The lithium-ion secondary battery consists of a lithium-ion secondary battery element and a housing member. The lithium-ion secondary battery element comprises a solid electrolyte sandwiched between a first electrode and a second electrode. The housing member has a recess for housing the lithium-ion secondary battery element and comprises an insulating substrate made of ceramics and a metal lid member. The internal space of the housing member is filled with a flexible insulating material (epoxy resin, polyimide resin, etc.) so as to surround the lithium-ion secondary battery element.

[0004] Lithium-ion secondary batteries have an insulating substrate made of ceramics so that they can withstand the heating temperatures in a reflow oven. Furthermore, the lithium-ion battery element undergoes volume changes during charging and discharging. This volume change causes the battery voltage to become unstable. Lithium-ion secondary batteries address this problem by filling the lithium-ion battery element with a flexible insulating material such as resin.

[0005] Japanese Patent Publication No. 2012-185982 discloses an electrochemical cell package and an electrochemical cell (Patent Document 2). The electrochemical cell is constructed by housing a power generation element consisting of an active material used as a positive or negative electrode and an electrolyte using a non-aqueous solvent within a ceramic electrochemical cell package. The sealing plate of the electrochemical cell can also be made of a metal material. In that case, the central part of the sealing plate changes shape in response to the increase in internal pressure inside the concave container. This can suppress the destruction of the electrochemical cell. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2009-211965 [Patent Document 2] Japanese Patent Publication No. 2012-185982 [Overview of the Initiative]

[0007] In the lithium-ion secondary battery described in Patent Document 1, the volume expansion of the lithium-ion secondary battery element during charging and discharging could cause the insulating material filling around the lithium-ion secondary battery element to push up and deform the metal lid member outward.

[0008] Furthermore, in the electrochemical cell described in Patent Document 2, if the sealing plate is made of a metal material, as mentioned above, the central part of the sealing plate changes shape in response to the increase in internal pressure inside the concave container. Therefore, there was a risk that the sealing plate would deform outward due to the volume expansion of the electrodes during charging and discharging.

[0009] Therefore, the lithium-ion secondary battery described in Patent Document 1 and the electrochemical cell described in Patent Document 2 undergo a certain degree of volume expansion during charging and discharging. As a result, when mounted on a circuit board, these batteries have the potential to compress and damage surrounding components.

[0010] Furthermore, in the lithium-ion secondary battery described in Patent Document 1, the lithium-ion secondary battery element and the conductor are connected via metal wires embedded in insulating material filled in the internal space of the housing member. In this state, if the lithium-ion secondary battery element undergoes repeated volume changes, the metal wires deteriorate and break, particularly at the joints, leading to a problem of unstable electrical connection.

[0011] On the other hand, Patent Document 2 discloses electrically connecting the second electrode layer of the sealing plate and the second connection terminal on the side of the concave container via an electrically conductive material such as solder, or by seam welding. In the electrochemical cell of Patent Document 2, volume changes due to the expansion and contraction of the power generation element may result in insufficient contact with the electrically conductive material or welding material, potentially leading to an unstable electrical connection.

[0012] Therefore, the object of this disclosure is to provide a cased all-solid-state battery that can be reflow soldered, suppresses volume changes during charging and discharging, and stabilizes electrical connections.

[0013] To solve the above problems, this disclosure is configured as follows. That is, the case-equipped all-solid-state battery according to this disclosure may comprise a case, an all-solid-state battery housed in the case, and a resilient conductive sheet housed in the case. The case may include a ceramic concave container having a bottom and side walls, a lid covering the opening of the concave container, a first connection terminal disposed on the outer surface of the case, and a second connection terminal disposed on the outer surface of the case, spaced apart from the first connection terminal. The all-solid-state battery may include a first battery can having a first planar portion, a second battery can having a second planar portion, and a power generation element housed between the first and second battery cans, having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive and negative electrode layers. The first planar portion of the first battery can may be arranged in the internal space of the case so as to face the inner surface of the bottom of the concave container. The second planar portion of the second battery can may be arranged in the internal space of the case so as to face the inner surface of the lid. A first conductive path may be formed between the first battery can and the first connection terminal to electrically connect the first battery can and the first connection terminal. A second conductive path may be formed between the second battery can and the second connection terminal to electrically connect the second battery can and the second connection terminal. The resilient conductive sheet may be placed in at least one of the spaces between the inner surface of the bottom of the concave container and the first flat surface of the first battery can, and between the inner surface of the lid material and the second flat surface of the second battery can, and may constitute a part of the first conductive path or the second conductive path.

[0014] The cased solid-state battery described herein allows for reflow soldering and enables suppression of volume changes during charging and discharging, as well as stabilization of electrical connections. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a cross-sectional view of the all-solid-state battery with a case according to this embodiment. [Figure 2] Figure 2 is an enlarged cross-sectional view of the all-solid-state battery shown in Figure 1. [Figure 3] Figure 3 is a plan view of the cased all-solid-state battery shown in Figure 1. [Figure 4] Figure 4 is a plan view of a modified example of a solid-state battery with a case. [Figure 5] Figure 5 is a cross-sectional view of a modified all-solid-state battery with a case. [Modes for carrying out the invention]

[0016] A cased solid-state battery according to the embodiment of this disclosure may comprise a case, a solid-state battery housed in the case, and a resilient conductive sheet housed in the case. The case may include a ceramic concave container having a bottom and side walls, a lid covering the opening of the concave container, a first connection terminal disposed on the outer surface of the case, and a second connection terminal disposed on the outer surface of the case, spaced apart from the first connection terminal. The solid-state battery may include a first battery can having a first planar portion, a second battery can having a second planar portion, and a power generation element housed between the first and second battery cans, having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive and negative electrode layers. The first planar portion of the first battery can may be arranged in the internal space of the case so as to face the inner surface of the bottom of the concave container. The second planar portion of the second battery can may be arranged in the internal space of the case so as to face the inner surface of the lid. A first conductive path may be formed between the first battery can and the first connection terminal to electrically connect the first battery can and the first connection terminal. A second conductive path may be formed between the second battery can and the second connection terminal to electrically connect the second battery can and the second connection terminal. The resilient conductive sheet may be placed in at least one of the spaces between the inner surface of the bottom of the concave container and the first flat surface of the first battery can, and between the inner surface of the lid material and the second flat surface of the second battery can, and may constitute a part of the first conductive path or the second conductive path.

[0017] The all-solid-state battery with a case houses the all-solid-state battery, in which the power generation element is housed inside the first battery can and the second battery can, inside the case. Therefore, it is less susceptible to the influence of volume changes of the power generation element than when the power generation element is directly housed inside the case, and it is possible to prevent the lid material from being pressed and deformed outward during charge and discharge. Also, since the electrical connection between the first battery can and the first connection terminal and the electrical connection between the second battery can and the second connection terminal are less susceptible to the influence of volume changes of the power generation element, the electrical connection can be stabilized. Furthermore, even when the all-solid-state battery expands and the lid material is pressed, the deformability of the lid material can be prevented by compressing the restorative conductive sheet to relieve the pressing force. In this case, the restorative conductive sheet can maintain contact with the all-solid-state battery with a certain force by its restoring force and can maintain the electrical connection. Note that by providing the first conduction path and the second conduction path, the all-solid-state battery inside the case can be electrically connected to a circuit board or the like outside the case.

[0018] A gasket is disposed between the first battery can and the second battery can, and the gasket may be sealed by caulking. By housing the all-solid-state battery in a case having excellent heat resistance and completely sealing it, it is possible to suppress a decrease in the sealing performance of the gasket due to the influence of heat during reflow soldering. Also, even when the sealing performance of the gasket deteriorates, it is possible to prevent moisture from entering the all-solid-state battery. In particular, when the solid electrolyte layer is a sulfide-based solid electrolyte, it is possible to prevent corrosion by corrosive hydrogen sulfide gas in an electronic circuit in which the all-solid-state battery with a case is mounted.

[0019] The first conductor part may be formed to penetrate inside the bottom of the concave container and may be part of the first conduction path. The second conductor part may be formed to penetrate inside the side wall part of the concave container and may be part of the second conduction path. The first connection terminal may be disposed on the outer surface of the bottom of the concave container. The second connection terminal may be disposed on the outer surface of the bottom of the concave container, separated from the first connection terminal. Thereby, the first connection terminal and the second connection terminal can be disposed on the outer surface of the bottom of the concave container, and mounting on the surface of the circuit board can be facilitated.

[0020] A restorative conductive sheet may be disposed between the inner surface of the lid member and the second flat portion of the second battery can. The end portion on the second battery can side of the restorative conductive sheet disposed on the lid member side may be chamfered in a plan view. Thereby, it is possible to prevent the corner portion of the restorative conductive sheet from contacting the first battery can and causing a short circuit.

[0021] A restorative conductive sheet may be disposed between the inner surface of the lid member and the second flat portion of the second battery can. The restorative conductive sheet disposed on the lid member side and the second conductor portion may have electrical connections at two or more locations. Thereby, the restorative conductive sheet is more firmly connected to the second conductor portion. As a result, even when the restorative conductive sheet is displaced due to the expansion and contraction of the all-solid-state battery, it is possible to achieve stabilization of the electrical connection.

[0022] The first battery can may be an exterior can. The second battery can may be a sealed can.

[0023] The restorative conductive sheet disposed between the inner surface of the lid member and the flat portion of the sealed can may have a width larger than the diameter of the flat portion of the sealed can. Thereby, the restorative conductive sheet can be stably brought into contact with the flat portion of the sealed can, and the stabilization of the electrical connection can be achieved.

[0024] The restorative conductive sheet may be a graphite sheet. The graphite sheet has excellent conductivity and restorability. Therefore, even when the volume of the all-solid-state battery changes, due to the excellent restorability of the graphite sheet, it is possible to further achieve stabilization of the electrical connection.

[0025] Hereinafter, embodiments of the present disclosure will be specifically described with reference to FIGS. 1 to 5. First, as shown in FIG. 1, the all-solid-state battery 1 with a case includes a case 10, an all-solid-state battery 20 housed in the case 10, and a restorative conductive sheet 30 housed in the case 10. In this embodiment, the all-solid-state battery 20 is a flat battery.

[0026] Case 10 includes a concave container 11, a lid 12, and connection terminals 13 and 14.

[0027] The concave container 11 is made of ceramic. The concave container 11 includes a square-shaped bottom 111 and a square 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 all-solid-state battery 20. In a longitudinal cross-sectional view, the side wall 112 is provided so as to extend substantially perpendicular to the bottom 111. A conductive part 113 is formed inside the bottom 111. A conductive part 114 is formed inside the side wall 112. The manufacturing method of the concave container 11 will be described later. Note that the concave container 11 is not limited to being made of ceramic, and may be a container that can withstand the heating temperature during reflow. Note that the concave container 11 is not limited to being square in plan view, and may be circular, elliptical, or polygonal. Note that the internal space for housing the all-solid-state battery 20 is not limited to being cylindrical, and may be formed in a polygonal cylindrical shape such as a square cylindrical shape. 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 also be made electrically connected to the connection terminal 14 by penetrating the inside of the bottom portion 111. In this case, it is desirable to form an insulating layer between the cylindrical side wall portion 212 and the conductor portion 114, for example, on the inner surface of the conductor portion 114, so that the cylindrical side wall portion 212 of the outer can 21 and the conductor portion 114 do not come into contact.

[0028] The lid 12 is a rectangular metal plate that covers the opening of the concave container 11. The lid 12 is joined (seam-welded) to the concave container 11 by a rectangular frame-shaped sealing ring (manufactured by Hitachi Metals, Ltd.) 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 lid 12 is not limited to a metal plate, as long as it can cover the opening of the concave container 11 and withstand the heating temperature during reflow. 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. Furthermore, the lid 12 may be in a shape other than a flat plate.

[0029] The connection terminal 13 is located on the outer surface of the bottom 111 of the concave container 11. The connection terminal 13 is electrically connected to the outer container 21, which will be described later, via the conductor portion 113 and the conductive adhesive 16. The outer container 21 functions as a positive electrode container, as will be described later. Therefore, the conductor portion 113 and the conductive adhesive 16 form a conductive path that connects the connection terminal 13 to the positive electrode container, and the connection terminal 13 functions as a positive electrode terminal.

[0030] The connection terminal 14 is positioned on the outer surface of the bottom 111 of the concave container 11, away from the connection terminal 13. The connection terminal 14 is electrically connected to the side wall portion 112 of the resilient conductive sheet 30, which will be described later, via the conductor portion 114 and the conductive adhesive 18. As will be described later, the resilient conductive sheet 30 is electrically connected to the sealing can 22, which functions as a negative electrode can, via the conductive adhesive 17. Therefore, the conductor portion 114, the conductive adhesive 18, the resilient conductive sheet 30, and the conductive adhesive 17 form a conductive path that connects the connection terminal 14 to the negative electrode can, and the connection terminal 14 functions as a negative electrode terminal. Note that the arrangement of the connection 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 conductor portion 114 and the connection terminal 14 may be formed on the outer surface of the lid material 12. However, by arranging these two terminals on the outer surface of the bottom 111 of the concave container 11 with a certain distance between them, mounting them onto the surface of the circuit board becomes easier.

[0031] 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. This makes it possible to manufacture a concave container 11 having conductive parts 113 and 114 inside. Note that the conductive part 113 is not limited to being formed by this method as long as it can electrically connect the outer can 21 and the connecting terminal 13. The conductive part 114 is not limited to being formed by this method as long as it can electrically connect the resilient conductive sheet 30 and the connecting terminal 14. In addition, the connecting terminals 13 and 14 can also be formed by the printed patterns of this metal paste.

[0032] The all-solid-state battery 20 will be explained in detail using Figure 2. As shown in Figure 2, the all-solid-state battery 20 includes an outer casing (battery casing) 21, a sealing casing (battery casing) 22, a power generation element 23, a gasket 24, and a current collector sheet 25.

[0033] The outer container 21 comprises a circular flat portion 211 and a cylindrical side wall portion 212 that is continuously formed from the outer circumference of the flat portion 211. The cylindrical side wall portion 212 is provided so as to extend substantially perpendicular to the flat portion 211 in a longitudinal cross-sectional view. The outer container 21 is made of a metal material such as stainless steel.

[0034] The sealed can 22 comprises a circular flat portion 221 and a cylindrical peripheral wall portion 222 that is continuously formed from the outer circumference of the flat portion 221. The opening of the sealed can 22 faces the opening of the outer can 21. The sealed can 22 is made of a metal material such as stainless steel.

[0035] The outer casing 21 and the sealing casing 22 are crimped together via a gasket 24 between the cylindrical side wall 212 of the outer casing 21 and the peripheral wall 222 of the sealing casing 22 after the power generation element 23 has been housed in the internal space. Specifically, the outer casing 21 and the sealing casing 22 are positioned with their openings facing each other, the peripheral wall 222 of the sealing casing 22 is inserted inside the cylindrical side wall 212 of the outer casing 21, and then crimped together via a gasket 24 between the cylindrical side wall 212 and the peripheral wall 222. As a result, the internal space formed by the outer casing 21 and the sealing casing 22 becomes airtight. Note that the outer casing 21 and the sealing casing 22 are not limited to a circular shape in plan view, but can be changed to various shapes such as elliptical or polygonal shapes depending on the shape of the all-solid-state battery 20.

[0036] The gasket 24 is made of a resin material such as a polyamide resin, polypropylene resin, or polyphenylene sulfide resin. Therefore, the crimping stress of the gasket 24 may be relaxed due to the heat generated during reflow soldering, which can reduce its sealing performance. This reduction in sealing performance can cause moisture to enter the internal space of the all-solid-state battery 20. When moisture enters the all-solid-state battery 20, especially when the solid electrolyte layer 233 is a sulfide-based solid electrolyte as described later, the moisture reacts with the sulfide-based solid electrolyte to generate corrosive hydrogen sulfide gas. Therefore, the all-solid-state battery 20 has the problem of potentially corroding the electronic circuit during reflow soldering. The cased all-solid-state battery 1 of this disclosure houses the all-solid-state battery 20 in a case 10 that can withstand the heating temperature during reflow. The ceramic concave container 11 that constitutes the case 10 has excellent heat resistance. The lid material 12 is also made of a material that can sufficiently withstand the heating temperature during reflow, such as a thin metal plate. The concave container 11 and the lid material 12 are joined by a seal ring 15 to achieve complete airtightness. As a result, the solid-state battery 20 housed in the case-equipped solid-state battery 1 will not experience a decrease in the sealing performance of the gasket 24, or even if the sealing performance does decrease, moisture will not enter the case 10, thus preventing the generation of hydrogen sulfide gas and preventing corrosion of the electronic circuit on which the case-equipped solid-state battery 1 is mounted. Therefore, the case-equipped solid-state battery 1 of this disclosure is particularly suitable for solid-state batteries that contain a sulfide-based solid electrolyte as a constituent material and are sealed by crimping. Note that the method for sealing the internal space formed by the outer can 21 and the sealing can 22 is not limited to crimping via the gasket 24, but may be done by other methods. For example, the cylindrical side wall portion 212 of the outer can 21 and the peripheral wall portion 222 of the sealing can 22 may be joined and sealed by interposing a heat-meltable resin or adhesive.

[0037] The power generation element 23 includes a positive electrode layer 231, a negative electrode layer 232, and a solid electrolyte layer 233. The solid electrolyte layer 233 is positioned between the positive electrode layer 231 and the negative electrode layer 232. The power generation element 23 is formed in a cylindrical shape. The power generation element 23 is stacked in the order of positive electrode layer 231, solid electrolyte layer 233, and negative electrode layer 232 from the flat portion 211 side (bottom in the figure) of the outer casing 21. Therefore, the outer casing 21 functions as a positive electrode casing. The sealing casing 22 functions as a negative electrode casing. Note that the power generation element 4 is not limited to a cylindrical shape, but can be changed to various shapes such as a rectangular parallelepiped or polygonal prism, depending on the shape of the all-solid-state battery 20.

[0038] The positive electrode layer 231 is a positive electrode active material used in lithium-ion secondary batteries, with an average particle size of 3 μm (LiNi). 0.6 Co 0.2 Mn 0.2 The positive electrode pellet is formed into a cylindrical shape by placing 180 mg of a positive electrode mixture containing O2, a sulfide solid electrolyte (Li6PS5Cl), and a conductive additive carbon nanotube in a mass ratio of 55:40:5 into a 10 mm diameter mold. The positive electrode layer 231 is not particularly limited as long as it can function as the positive electrode layer of the power generation element 23, and may be, for example, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese composite oxide, olivine type composite oxide, etc., or a mixture of these as appropriate. Furthermore, the size and shape of the positive 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 all-solid-state battery 20.

[0039] The negative electrode layer 232 is made of LTO (Li4Ti5O) as the negative electrode active material used in lithium-ion secondary batteries. 12 The negative electrode pellet is formed into a cylindrical shape from 300 mg of a negative electrode mixture containing lithium titanate, a sulfide solid electrolyte (Li6PS5Cl), and carbon nanotubes in a weight ratio of 50:45:5. The negative electrode layer 232 is not particularly limited as long as it can function as the negative electrode layer of the power generation element 23, and can be made of carbon materials such as metallic lithium, lithium alloy, graphite, or low-crystallinity carbon, or SiO2, LTO (Li4Ti5O2).12 It may also be lithium titanate, etc., or a mixture of these as appropriate. Furthermore, the size and shape of the negative electrode layer 232 are not limited to a cylindrical shape, but can be changed in various ways depending on the size and shape of the all-solid-state battery 20.

[0040] The solid electrolyte layer 233 is formed by molding 60 mg of sulfide solid electrolyte (Li6PS5Cl) into a cylindrical shape. While the solid electrolyte layer 233 is not particularly limited, other sulfur-based solid electrolytes such as argyrodites may be used from the viewpoint of ionic conductivity. When using a sulfur-based solid electrolyte, it is preferable to coat the surface of the positive electrode active material with niobium oxide to prevent reaction with the positive electrode active material. Furthermore, the solid electrolyte layer 233 may also be a hydride-based solid electrolyte or an oxide-based solid electrolyte. The size and shape of the solid electrolyte layer 233 are not limited to a cylindrical shape and can be varied according to the size and shape of the all-solid-state battery 20.

[0041] The current collector sheet 25 can be a conductive sheet made of expanded graphite, as described later. The conductive sheet has excellent restorative force against pressure. Therefore, it can absorb the expansion and contraction of the power generation element 23 during charging and discharging. Thus, the electrical connection can be stabilized. The current collector sheet 25 is not limited to the conductive sheet, but can be any current collector that functions in the all-solid-state battery 20. Alternatively, without providing the current collector sheet 25, the positive electrode layer 231 may be arranged in contact with the inner surface of the flat portion 211 of the outer casing 21, and the negative electrode layer 232 may be arranged in contact with the inner surface of the flat portion 221 of the sealing casing 22.

[0042] As shown in Figure 1, the flat portion 211 of the outer casing 21 is positioned opposite the inner surface of the bottom portion 111 of the concave container 11. That is, the outer casing 21 is positioned on the inner surface side (lower in the figure) of the bottom portion 111 of the concave container 11. A conductive adhesive 16 is placed between the bottom surface of the flat portion 211 of the outer casing 21 and the inner surface of the bottom portion 111 of the concave container 11. The outer casing 21 is fixed to the inner surface of the bottom portion 111 of the concave container 11 by the conductive adhesive 16. As a result, the outer casing 21 is electrically connected to the connection terminal 13 via a conductive path consisting of the conductive adhesive 16 and the conductor portion 113. Note that the bottom surface of the flat portion 211 of the outer casing 21 has a larger surface area than the top surface of the flat portion 221. Therefore, the outer casing 21 can be fixed to the bottom portion 111 of the concave container 11 over a larger area. This allows the all-solid-state battery 20 to be fixed to the concave container 11 more stably.

[0043] The flat portion 221 of the sealing can 22 is positioned to face the inner surface of the lid material 12. That is, the sealing can 22 is positioned on the inner side (upper side in the figure) of the lid material 12. Conductive adhesive 17 is placed between the upper surface of the flat portion 221 of the sealing can 22 and the resilient conductive sheet 30, which will be described later. The sealing can 22 is fixed to the resilient conductive sheet 30 by the conductive adhesive 17. As a result, the sealing can 22 is electrically connected to the connection terminal 14 via a conductive path consisting of the conductive adhesive 17, the resilient conductive sheet 30, the conductive adhesive 18 (described later), and the conductor portion 114.

[0044] As shown in Figure 1, the resilient conductive sheet 30 connects the upper surface of the flat portion 221 of the sealing can 22 and the upper end of the side wall portion 112 of the concave container 11 via conductive adhesives 17 and 18. One end of the resilient conductive sheet 30 (the left end in the figure) is fixed to the upper surface of the flat portion 221 of the sealing can 22 by conductive adhesive 17. The other end of the resilient conductive sheet 30 (the right end in the figure) is fixed to the upper end of the side wall portion 112 of the concave container 11 by conductive adhesive 18. In this way, by connecting the upper surface of the flat portion 221 of the sealing can 22 and the upper end of the side wall portion 112 of the concave container 11 with the resilient conductive sheet 30, even if the thickness of the all-solid-state battery 20 changes, the resilient conductive sheet 30 is compressed, easing the pressing force applied to the lid material, thereby preventing the lid material from deforming outward. Furthermore, the resilient conductive sheet 30 comes into contact with the conductive adhesives 17 and 18 with a certain amount of pressure. As a result, the electrical connection can be stabilized. In addition, to further enhance the effect of preventing the lid material from deforming outward when the thickness of the all-solid-state battery 20 changes, a small gap may be created between the resilient conductive sheet 30 and the lid material 12 when assembling the all-solid-state battery 1 with case.

[0045] As shown in Figure 3, the resilient conductive sheet 30 has a length L1 from the upper surface of the flat portion 221 of the sealing can 22 to the upper end of the side wall portion 112 of the concave container 11. Note that Figure 3 is a plan view with the lid material 12 removed to clearly explain the internal space of the concave container 11. The length L1 of the resilient conductive sheet 30 is longer than the length L2 from the center C of the flat portion 221 to the upper end of the side wall portion 112 of the concave container 11 on the resilient conductive sheet 30. This increases the area on which the flat portion 221 and the resilient conductive sheet 30 are fixed together, thereby stabilizing the electrical connection. Also, the length L1 of the resilient conductive sheet 30 is shorter than the length L3 from the upper end of the side wall portion 112 of the concave container 11 on the resilient conductive sheet 30 to the end of the cylindrical side wall portion 212 of the outer can 21 passing through the center C. This prevents the excess resilient conductive sheet 30 from coming into contact with the outer can 21 and causing a short circuit, on the side opposite to the upper end of the side wall portion 112 of the resilient conductive sheet 30, with the center C as the reference point.

[0046] As shown in Figure 3, the resilient conductive sheet 30 has a width w that is larger than the diameter of the flat portion 221 of the sealing can 22. The width w of the resilient conductive sheet 30 is the width in the direction perpendicular to the length L1 of the resilient conductive sheet 30. This allows the resilient conductive sheet 30 to be stably fixed to the flat portion 221 of the sealing can 22, further stabilizing the electrical connection. On the other hand, the width w is the same as or smaller than the inner diameter of the end of the cylindrical side wall portion 212 of the outer can 21 after crimping with the sealing can 22. This prevents short circuits caused by contact between the resilient conductive sheet 30 and the outer can 21.

[0047] As shown in Figure 3, the end of the resilient conductive sheet 30 on the sealing can 22 side, i.e., the corner, is beveled by being cut at an angle. In a plan view, the diameter of the flat portion 221 of the sealing can 22 is smaller than the inner diameter of the cylindrical side wall portion 212 of the outer can 21. Therefore, if the corner of the resilient conductive sheet 30 is not beveled, the corner may come into contact with the outer can 21 and cause a short circuit. By beveling the corner of the resilient conductive sheet 30 on the sealing can 22 side, such a short circuit can be prevented.

[0048] The resilient conductive sheet 30 has three electrical connections formed by three conductive adhesives 18. By forming multiple electrical connections in this way, the resilient conductive sheet 30 is more firmly fixed to the upper end of the side wall 112. In other words, displacement of the resilient conductive sheet 30 due to the expansion and contraction of the all-solid-state battery 20 can be prevented, and the stability of the electrical connections can be further improved. The conductive adhesives 18 are not limited to three; displacement of the resilient conductive sheet 30 can be prevented by providing two or more. In particular, if conductive adhesives 18 are provided at each corner of the upper end of the side wall 112 side of the resilient conductive sheet 30, displacement of the resilient conductive sheet 30 can be sufficiently prevented.

[0049] The restorative conductive sheet 30 is a conductive sheet composed of expanded graphite, that is, a graphite sheet. The graphite sheet is manufactured as follows. First, the particles of acid-treated graphite obtained by subjecting natural graphite to acid treatment are heated. Then, the acid-treated graphite expands due to the acid existing between its layers vaporizing and foaming. The expanded graphite (expanded graphite) is formed into a felt shape, and further, a sheet body is formed by rolling using a roll rolling machine. The restorative conductive sheet 30 is manufactured by punching out the sheet body of this expanded graphite into a circular shape. As described above, expanded graphite is formed by the acid vaporizing and the acid-treated graphite foaming. Therefore, the graphite sheet is formed in a porous shape. Thus, the graphite sheet has flexibility and compression restorability that conventional graphite products do not have, along with the conductivity inherent to graphite itself. Note that the manufacturing method of 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.

[0050] The apparent density of only the graphite sheet is preferably 0.3 g / cm 3 or more, more preferably 0.7 g / cm 3 or more, and preferably 1.5 g / cm 3 or less, more preferably 1.3 g / cm 3 or less. This is because if the apparent density of the graphite sheet is too low, the graphite sheet is likely to be damaged, and if the apparent density is too high, the restorability decreases. Note that the apparent density is not limited to the graphite sheet, and is also applicable to the restorative conductive sheet 30 formed of other materials such as conductive tape.

[0051] 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 all-solid-state battery 20, reducing the volume (thickness) of the all-solid-state battery 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 resilient conductive sheets 30 formed from other materials such as conductive tape.

[0052] The recovery rate of the resilient conductive sheet (graphite sheet) should preferably be 7% or higher. This moderate resilience of the graphite sheet allows it to absorb volume changes due to the expansion of the all-solid-state battery 20, thereby suppressing deformation of the lid material and stabilizing electrical connections. From the viewpoint of stabilizing electrical connections, a recovery rate of 10% or higher is more preferable. On the other hand, to enhance the effect of absorbing volume changes of the all-solid-state battery, a recovery rate of 80% or less is preferable, 50% or less is more preferable, and 30% or less is particularly preferable. The recovery rate is expressed by the following formula, where t is the thickness of the graphite sheet, t1 is the thickness when the graphite sheet is compressed with a predetermined pressing force, and t2 is the thickness of the graphite sheet when the pressing force is removed. Furthermore, a graphite sheet is considered to have resilience when its recovery rate is above a certain level. (t2-t1) / (t-t1)×100(%) The recovery rate can be measured using the method described in Japanese Industrial Standard JIS R3453 2001 (Joint Sheet). Note that the recovery rate is not limited to graphite sheets, but is also applicable to resilient conductive sheets 30 formed from other materials such as conductive tape.

[0053] Therefore, it is preferable that the apparent density or thickness of the graphite sheet be determined in a balanced manner, taking into consideration resilience, strength, and effective use of internal space.

[0054] Furthermore, when the graphite sheet is used as the current collector sheet 25 of the all-solid-state battery 20 shown in Figure 2, it can absorb the volume changes due to the expansion and contraction of the power generation element 23 during charging and discharging, or the pressing force when crimping the outer casing 21 and the sealing casing 22, and maintain contact with the power generation element 23 due to its appropriate resilience. As a result, the all-solid-state battery 20 can suppress the deterioration of battery performance due to damage to the power generation element 23 or the formation of gaps.

[0055] Here, the discharge capacity of a cased all-solid-state battery 1 using a graphite sheet as the resilient conductive sheet 30 was tested. Thickness: 0.1 mm, apparent density: 1.2 g / cm³ 3 The discharge capacity after charge-discharge cycles was compared between a case-mounted all-solid-state battery 1 assembled by placing an expanded graphite sheet (resilient conductive sheet 30) with a recovery rate of 12% between the upper surface of the flat portion 221 of the sealing can 22 and the inner surface of the lid material 12, as shown in Figure 1, and a case-mounted all-solid-state battery assembled by placing an aluminum foam substrate with a thickness of 1 mm and a porosity of 97% between the upper surface of the flat portion 221 of the sealing can 22 and the inner surface of the lid material 12 instead of the graphite sheet. After 100 charge-discharge cycles, the former was able to maintain more than 95% of its initial discharge capacity. This is because the electrical connection was stable due to the resilience of the graphite sheet. On the other hand, in the latter case, since the foam substrate is a current collector that does not substantially possess resilience, the electrical connection was unstable, resulting in a decrease to about 10% of the initial discharge capacity.

[0056] As described above, in the cased solid-state battery 1, the resilient conductive sheet 30 compresses in accordance with the change in thickness of the solid-state battery 20, mitigating the force pressing on the lid material 12, thus preventing the lid material 12 from deforming outward due to the expansion of the solid-state battery 20. On the other hand, the resilience of the resilient conductive sheet 30 allows the solid-state battery 20 to be continuously pressed with a certain amount of force, thereby stabilizing the electrical connection. Furthermore, by housing the solid-state battery 20 in the case 10, which has excellent heat resistance, and completely sealing it, even if the sealing performance of the gasket 24 deteriorates due to the heat during reflow soldering, moisture can be prevented from entering the inside of the solid-state battery 20. As a result, especially when the solid electrolyte layer 233 is a sulfide-based solid electrolyte, corrosion by corrosive hydrogen sulfide gas in the electronic circuit on which the cased solid-state battery 1 is mounted can be prevented. Furthermore, since the power generation element 23 is housed within the case 10 and the upper surface of the flat portion 221 of the sealed can 22 and the upper end of the side wall portion 112 of the concave container 11 are connected with a resilient conductive sheet 30, manufacturing is easy.

[0057] The placement of the resilient conductive sheet 30 is not limited to the space between the upper surface of the flat portion 221 of the sealing can 22 and the inner surface of the lid material 12. The resilient conductive sheet 30 may be placed between the flat portion 211 of the outer casing 21 and the inner surface of the bottom portion 111 of the concave container 11, although this is not shown in the figures. Alternatively, it may be placed both between the upper surface of the flat portion 221 of the sealing can 22 and the inner surface of the lid material 12, and between the flat portion 211 of the outer casing 21 and the inner surface of the bottom portion 111 of the concave container 11. This ensures good contact between the all-solid-state battery 20 and each conductive path, thereby stabilizing the electrical connection. If the resilient conductive sheet 30 is not placed between the upper surface of the flat portion 221 of the sealing can 22 and the inner surface of the lid material 12, leads can be formed on the inner surface of the lid material 12 and the inner surface of the sealing ring 15 using conductive adhesive or non-adhesive conductive paint, and the upper surface of the flat portion 221 of the sealing can 22 and the conductor portion 114 of the sealing can 22 can be brought into contact with the leads, thereby forming an electrical path between the leads and the conductor portion 114, and electrically connecting the flat portion 221 of the sealing can 22 and the connection terminal 14. In this case, it is desirable to form an insulating layer between the cylindrical side wall portion 212 and the leads, for example, on a part of the inner surface of the leads, so that the cylindrical side wall portion 212 of the outer can 21 and the leads do not come into contact.

[0058] (modified version) As shown in Figure 4, in a plan view, the resilient conductive sheet 30 can also be chamfered with an R-shape to round its corners. This prevents short circuits that could occur if the corners of the resilient conductive sheet 30 come into contact with the outer can 21. The shape of the chamfer is not limited; it is sufficient if the chamfer prevents the corners of the resilient conductive sheet 30 from coming into contact with the outer can 21.

[0059] Furthermore, as shown in Figure 5, the flat portion 221 of the sealing can 22 may be positioned to face the inner surface of the bottom 111 of the concave container 11. That is, the sealing can 22 may be positioned on the inner surface side (downward in the figure) of the bottom 111 of the concave container 11. A conductive adhesive 16 is placed between the flat portion 221 of the sealing can 22 and the inner surface of the bottom 111 of the concave container 11. The sealing can 22 may be fixed to the inner surface of the bottom 111 of the concave container 11 by the conductive adhesive 16. As a result, the sealing can 22 is electrically connected to the connection terminal 13 via a conductive path consisting of the conductive adhesive 16 and the conductor portion 113. Also, the flat portion 211 of the outer can 21 may be positioned to face the inner surface of the lid material 12. That is, the outer can 21 may be positioned on the inner surface side (upward in the figure) of the lid material 12. A conductive adhesive 17 is placed between the upper surface of the flat portion 211 of the outer can 21 and the resilient conductive sheet 30. The outer can 21 is fixed to the resilient conductive sheet 30 by the conductive adhesive 17. As a result, the outer can 21 is electrically connected to the connection terminal 14 via a conductive path consisting of the conductive adhesive 17, the resilient conductive sheet 30, the conductive adhesive 18, and the conductor portion 114. In this case, the connection terminal 13 functions as the negative terminal, and the connection terminal 14 functions as the positive terminal.

[0060] In the above embodiment, the outer can 21 was used as the positive electrode can and the sealed can 22 was used as the negative electrode can. However, by providing a negative electrode layer 232 on the outer can 21 side and a positive electrode layer 231 on the sealed can 22 side, the outer can 21 can function as the negative electrode can and the sealed can 22 can function as the positive electrode can.

[0061] 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. [Explanation of Symbols]

[0062] 1 Solid-state battery with case 10 Case, 11 Concave container, 12 Lid material, 13 Connector terminal, 14 Connector terminal, 15 Seal ring, 16 Conductive adhesive, 17 Conductive adhesive, 18 Conductive adhesive 111 Bottom, 112 Side wall, 113 Conductor section, 114 Conductor section 20 All-solid-state battery, 21 Exterior can, 211 Planar part, 22 Sealed can, 221 Planar part, 23 Power generation element 24 Gasket, 25 Current collector sheet 30 Resilient conductive sheet

Claims

1. The case and The all-solid-state battery housed in the aforementioned case, The case comprises a resilient conductive sheet housed in the aforementioned case, The case includes a ceramic concave container having a bottom and side walls, a lid covering the opening of the concave container, a first connection terminal disposed on the outer surface of the case, and a second connection terminal disposed on the outer surface of the case, separated from the first connection terminal. The aforementioned all-solid-state battery is The power generation element comprises a first battery can having a first flat portion, a second battery can having a second flat portion, and a power generation element housed between the first and second battery cans, having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein the first flat portion of the first battery can faces the inner surface of the bottom of the concave container, and the second flat portion of the second battery can faces the inner surface of the lid material, A first conductive path is formed between the first battery can and the first connection terminal, which electrically connects the first battery can and the first connection terminal. A second conductive path is formed between the second battery can and the second connection terminal, which electrically connects the second battery can and the second connection terminal. The resilient conductive sheet is positioned between the inner surface of the bottom of the concave container and the first flat surface of the first battery can, and between the inner surface of the lid material and the second flat surface of the second battery can, and constitutes a part of the first conductive path or the second conductive path. A first conductor portion is formed that penetrates the interior of the bottom of the concave container and constitutes a part of the first conductive path, It has a second conductor portion that is formed penetrating the interior of the side wall portion of the concave container and constitutes a part of the second conductive path, The first connection terminal is positioned on the outer surface of the bottom of the concave container. The second connection terminal is positioned on the outer surface of the bottom of the concave container, separated from the first connection terminal. The resilient conductive sheet is placed between the inner surface of the lid material and the second flat portion of the second battery can. A cased solid-state battery in which the resilient conductive sheet disposed on the lid side and the second conductor portion have two or more electrical connections.

2. A case-equipped all-solid-state battery according to claim 1, A cased solid-state battery in which a gasket is placed between the first battery case and the second battery case and sealed by crimping.

3. The case and The all-solid-state battery housed in the aforementioned case, The case comprises a resilient conductive sheet housed in the aforementioned case, The case includes a ceramic concave container having a bottom and side walls, a lid covering the opening of the concave container, a first connection terminal disposed on the outer surface of the case, and a second connection terminal disposed on the outer surface of the case, separated from the first connection terminal. The aforementioned all-solid-state battery is The power generation element comprises a first battery can having a first flat portion, a second battery can having a second flat portion, and a power generation element housed between the first and second battery cans, having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein the first flat portion of the first battery can faces the inner surface of the bottom of the concave container, and the second flat portion of the second battery can faces the inner surface of the lid material, A first conductive path is formed between the first battery can and the first connection terminal, which electrically connects the first battery can and the first connection terminal. A second conductive path is formed between the second battery can and the second connection terminal, which electrically connects the second battery can and the second connection terminal. The resilient conductive sheet is positioned between the inner surface of the bottom of the concave container and the first flat surface of the first battery can, and between the inner surface of the lid material and the second flat surface of the second battery can, and constitutes a part of the first conductive path or the second conductive path. The resilient conductive sheet is placed between the inner surface of the lid material and the second flat portion of the second battery can. The end of the resilient conductive sheet positioned on the lid side, on the side of the second battery can, is chamfered in a plan view, in a cased all-solid-state battery.

4. A case-equipped all-solid-state battery according to any one of claims 1 to 3, The aforementioned first battery can is an outer casing, The second battery casing is a sealed casing, a case-enclosed solid-state battery.

5. A case-equipped all-solid-state battery according to claim 4, The resilient conductive sheet is placed between the inner surface of the lid material and the flat portion of the sealing can. A cased solid-state battery comprising a resilient conductive sheet positioned on the lid side having a width greater than the diameter of the flat portion of the sealing can.

6. The case and The all-solid-state battery housed in the aforementioned case, The case comprises a resilient conductive sheet housed in the aforementioned case, The case includes a ceramic concave container having a bottom and side walls, a lid covering the opening of the concave container, a first connection terminal disposed on the outer surface of the case, and a second connection terminal disposed on the outer surface of the case, separated from the first connection terminal. The aforementioned all-solid-state battery is The power generation element comprises a first battery can having a first flat portion, a second battery can having a second flat portion, and a power generation element housed between the first and second battery cans, having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein the first flat portion of the first battery can faces the inner surface of the bottom of the concave container, and the second flat portion of the second battery can faces the inner surface of the lid material, A first conductive path is formed between the first battery can and the first connection terminal, which electrically connects the first battery can and the first connection terminal. A second conductive path is formed between the second battery can and the second connection terminal, which electrically connects the second battery can and the second connection terminal. The resilient conductive sheet is positioned between the inner surface of the bottom of the concave container and the first flat surface of the first battery can, and between the inner surface of the lid material and the second flat surface of the second battery can, and constitutes a part of the first conductive path or the second conductive path. The aforementioned first battery can is an outer casing, The second battery can is a sealed can, The resilient conductive sheet is placed between the inner surface of the lid material and the flat portion of the sealing can. A cased solid-state battery comprising a resilient conductive sheet positioned on the lid side having a width greater than the diameter of the flat portion of the sealing can.

7. A case-equipped solid-state battery according to any one of claims 1 to 6, The aforementioned resilient conductive sheet is a graphite sheet, in a cased all-solid-state battery.

8. The case and The all-solid-state battery housed in the aforementioned case, The case comprises a resilient conductive sheet housed in the aforementioned case, The case includes a ceramic concave container having a bottom and side walls, a lid covering the opening of the concave container, a first connection terminal disposed on the outer surface of the case, and a second connection terminal disposed on the outer surface of the case, separated from the first connection terminal. The aforementioned all-solid-state battery is The power generation element comprises a first battery can having a first flat portion, a second battery can having a second flat portion, and a power generation element housed between the first and second battery cans, having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein the first flat portion of the first battery can faces the inner surface of the bottom of the concave container, and the second flat portion of the second battery can faces the inner surface of the lid material, A first conductive path is formed between the first battery can and the first connection terminal, which electrically connects the first battery can and the first connection terminal. A second conductive path is formed between the second battery can and the second connection terminal, which electrically connects the second battery can and the second connection terminal. The resilient conductive sheet is positioned between the inner surface of the bottom of the concave container and the first flat surface of the first battery can, and between the inner surface of the lid material and the second flat surface of the second battery can, and constitutes a part of the first conductive path or the second conductive path. The aforementioned resilient conductive sheet is a graphite sheet, in a cased all-solid-state battery.

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