All-solid-state battery

Abstract

This invention provides an all-solid-state battery that ensures sufficient electrical contact between the outer can and the power generation element, as well as between the sealed can and the power generation element, and prevents damage to the positive or negative electrode layer. The all-solid-state battery (1) comprises: an outer can (2) having a bottom (21) and a cylindrical sidewall portion (22); a negative electrode can (3) having a flat portion (31) and a peripheral wall portion (32); a power generation element (4) disposed between the outer can (2) and the sealed can (3); a gasket (6) disposed between the cylindrical sidewall portion (22) and the peripheral wall portion (32); and a restorative conductive sheet (5). An outwardly recessed portion (211) is formed in the bottom (21) of the outer can (2). Restorative conductive sheets (5) are disposed between the inner bottom surface of the power generation element (4) and the recess (211), and between the power generation element (4) and the flat portion (31) of the sealed can (3).

Description

Technical Field

[0001] This disclosure relates to all-solid-state batteries. Background Technology

[0002] Previously, Japanese Patent Application Publication No. 11-144761 disclosed a lithium-ion secondary battery in which the positive and negative electrodes are arranged opposite each other with a separator in between, and housed in a battery casing composed of a positive electrode can and a negative electrode can, which are riveted together with gaskets (Patent Document 1). The lithium-ion secondary battery has an elastomer covered by a conductive material disposed between the positive electrode and the positive electrode can, and between the negative electrode and the negative electrode can. Therefore, the lithium-ion secondary battery can sufficiently ensure the contact area between the positive electrode and the positive electrode can, and between the negative electrode and the negative electrode can, and can alleviate the stress during the riveting of the positive and negative electrode cans, thus preventing the positive and negative electrodes from cracking.

[0003] Japanese Patent Application Publication No. 2003-151511 discloses a flat non-aqueous electrolyte battery, which includes a positive electrode can and a negative electrode can, as well as positive electrode material, negative electrode material and separator housed in the two cans, and a gasket is disposed between the periphery of the positive electrode can and the periphery of the negative electrode can (Patent Document 2). The flat non-aqueous electrolyte battery has a sealing wall provided at the periphery of the bottom wall of the positive electrode can that abuts against the gasket, and the positive electrode material is housed in a recess located radially inward of the sealing wall. Therefore, the bottom wall of the recess expands and deforms under high temperature conditions, thereby preventing its influence from affecting the sealing wall. Furthermore, by setting the ratio of the inner diameter D1 of the housing portion on the upper wall side of the negative electrode can to the inner diameter D2 of the recess to D2 / D1 = 1.01 to 1.2, damage to the periphery of the positive electrode material from climbing up the opening edge of the recess during the assembly process is prevented.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 11-144761

[0007] Patent Document 2: Japanese Patent Application Publication No. 2003-151511 Summary of the Invention

[0008] However, the lithium-ion secondary battery in Patent Document 1 uses an elastomer whose surface is covered with a conductive material. That is, the conductive material is only disposed around the elastomer. Therefore, the elastomer in Patent Document 1 becomes a resistive component that hinders conductivity, thus increasing the internal resistance of the battery.

[0009] Patent Document 2's flat non-aqueous electrolyte battery improves sealing by providing a recess on the radially inner side of the sealing wall of the bottom wall of the positive electrode can. However, the flat non-aqueous electrolyte battery in Patent Document 2 is not an all-solid-state battery, and it does not envision housing a power generation element, which consists of a stacked positive electrode layer, a solid electrolyte layer, and a negative electrode layer, inside the battery. Therefore, no material is provided to mitigate the pressure generated when riveting the positive electrode can and the sealing can, and it is assumed that if the power generation element is housed inside the battery, the power generation element may be damaged, such as cracking.

[0010] Therefore, the subject of this disclosure is to provide an all-solid-state battery that can adequately ensure electrical contact between the outer can and the power generation element, as well as electrical contact between the sealed can and the power generation element, and can prevent damage to the positive or negative electrode layer.

[0011] To address the aforementioned issues, this disclosure comprises the following: The all-solid-state battery of this disclosure may include an outer can having a bottom portion including an outwardly recessed portion and a cylindrical sidewall portion. The all-solid-state battery may include a sealed can having a flat portion and a peripheral wall portion that covers the opening of the outer can. The all-solid-state battery may include a power generation element disposed between the inner bottom surface of the recess of the outer can and the flat portion of the sealed can, having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive and negative electrode layers. The all-solid-state battery may include a gasket riveted between the cylindrical sidewall portion of the outer can and the peripheral wall portion of the sealed can. The all-solid-state battery may include at least one of a first restorative conductive sheet disposed between the inner bottom surface of the recess and the power generation element, and a second restorative conductive sheet disposed between the flat portion of the sealed can and the power generation element.

[0012] According to the all-solid-state battery disclosed herein, sufficient electrical contact between the outer can and the power generation element, as well as between the sealed can and the power generation element, can be ensured, and damage to the positive or negative electrode layer can be prevented. Attached Figure Description

[0013] Figure 1 This is a cross-sectional view showing the structure of the all-solid-state battery according to this embodiment.

[0014] Figure 2 It is shown Figure 1 A cross-sectional view showing the manufacturing process of an all-solid-state battery.

[0015] Figure 3 It is shown Figure 1 A cross-sectional view showing the manufacturing process of an all-solid-state battery.

[0016] Figure 4 It is shown Figure 1 A cross-sectional view showing the manufacturing process of an all-solid-state battery.

[0017] Figure 5This is a cross-sectional view showing the structure of a modified solid-state battery. Detailed Implementation

[0018] The all-solid-state battery of this embodiment may include an outer can having a bottom including an outwardly recessed portion and a cylindrical sidewall portion. The all-solid-state battery may include a sealed can having a flat portion and a peripheral wall portion that covers the opening of the outer can. The all-solid-state battery may include a power generation element disposed between the inner bottom surface of the recess of the outer can and the flat portion of the sealed can, having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive and negative electrode layers. The all-solid-state battery may include a gasket riveted between the cylindrical sidewall portion of the outer can and the peripheral wall portion of the sealed can. The all-solid-state battery may include a restorative conductive sheet disposed between the power generation element and at least one of the inner bottom surface of the recess and the flat portion of the sealed can.

[0019] The resilient conductive sheet, through its resilience, effectively maintains the conductivity between the outer can and the power generation element, as well as between the sealed can and the power generation element. It also acts as a cushioning material, mitigating the pressure generated during the riveting of the outer can and the sealed can, thus preventing damage to the positive and negative electrode layers. Furthermore, when the resilient conductive sheet (the first resilient conductive sheet) is positioned between the inner bottom surface of the recess and the power generation element, its location within the recess prevents misalignment and trapping between the bottom of the outer can and the gasket during riveting. As a result, the reduction in the seal of the all-solid-state battery can be suppressed.

[0020] The first resilient conductive sheet can be disposed between the inner bottom surface of the recess and the power generation element. The depth of the recess can be greater than the thickness of the first resilient conductive sheet. That is, the first resilient conductive sheet has a thickness smaller than the depth of the recess. Therefore, when riveting the outer can and the sealing can, it is possible to more effectively prevent the first resilient conductive sheet from being sandwiched between the bottom of the outer can and the gasket.

[0021] A first restorative conductive sheet can be disposed between the inner bottom surface of the recess and the power generation element. The all-solid-state battery may also include a second restorative conductive sheet disposed between the flat portion of the sealing can and the power generation element. This ensures good conductivity between the outer can and the power generation element, as well as between the sealing can and the power generation element, and also functions as a cushioning material, thus mitigating the pressure generated during riveting the outer can and the sealing can and preventing damage to the positive and negative electrode layers. Furthermore, since the first restorative conductive sheet is disposed between the inner bottom surface of the recess and the power generation element, it prevents misalignment and being trapped between the bottom of the outer can and the gasket during riveting. As a result, the reduction in the seal of the all-solid-state battery can be suppressed.

[0022] The depth of the recess can be less than the height from the inner bottom surface of the recess to the upper end of the outer peripheral surface of the solid electrolyte layer. This prevents the bottom of the outer can from contacting the negative electrode layer and causing a short circuit.

[0023] The first and second restorative conductive sheets can be graphite sheets.

[0024] The following uses Figures 1-4 The embodiments of this disclosure will be described in detail. First, as Figure 1 As shown, the all-solid-state battery 1 comprises an outer can 2, a sealed can 3, a power generation element 4, a restorative conductive sheet 5 disposed between the outer can 2 and the power generation element 4, a restorative conductive sheet 5 disposed between the sealed can 3 and the power generation element 4, and a gasket 6. Furthermore, in this embodiment, the all-solid-state battery 1 is a flat battery.

[0025] The outer container 2 has a circular bottom 21 and a cylindrical sidewall 22 continuously formed from the outer periphery of the bottom 21. The cylindrical sidewall 22 is configured to extend substantially perpendicular to the bottom 21 in longitudinal section. The outer container 2 is made of a metal material such as stainless steel.

[0026] The bottom 21 of the outer can 2 has a recess 211. The recess 211 is integrally formed with the outer can 2 by stamping. The recess 211 is recessed axially further outward (lower in the figure) than the bottom 21 towards the all-solid-state battery 1. The recess 211 accommodates the restorative conductive sheet 5. The recess 211 has a depth d. Figure 1 As shown, the depth d of the recess 211 is the depth from the inner surface of the bottom 21 to the inner bottom surface of the recess 211. The depth d and inner diameter d1 of the recess 211 will be described in detail later.

[0027] The sealing can 3 has a circular flat portion 31 and a cylindrical peripheral wall portion 32 continuously formed from the outer periphery of the flat portion 31. The opening of the sealing can 3 is opposite to the opening of the outer can 2. The sealing can 3 is made of a metal material such as stainless steel.

[0028] After the power generation element 4 and the restorative conductive sheet 5 are housed within the internal space, the outer can 2 and the sealed can 3 are riveted together with a gasket 6 between the cylindrical sidewall 22 of the outer can 2 and the peripheral wall 32 of the sealed can 3. Specifically, the openings of the outer can 2 and the sealed can 3 are positioned opposite each other. After the peripheral wall 32 of the sealed can 3 is inserted into the inner side of the cylindrical sidewall 22 of the outer can 2, the cylindrical sidewall 22 and the peripheral wall 32 are riveted together with a gasket 6 between them. Thus, the internal space formed by the outer can 2 and the sealed can 3 becomes sealed. It should be noted that there are no particular limitations on the structure, raw materials, shape, etc. of the outer can 2, the sealed can 3, and the gasket 6.

[0029] The power generation element 4 includes a positive electrode layer 41, a negative electrode layer 42, and a solid electrolyte layer 43. The solid electrolyte layer 43 is disposed between the positive electrode layer 41 and the negative electrode layer 42. The power generation element 4 is formed by sequentially stacking the positive electrode layer 41, the solid electrolyte layer 43, and the negative electrode layer 42 from the bottom 21 side of the outer can 2 (lower part of the figure). The power generation element 4 is formed in a cylindrical shape. The power generation element 4 is disposed on the inner bottom surface of the recess 211 of the outer can 2 via a restorative conductive sheet 5. Therefore, the outer can 2 functions as a positive electrode can. In addition, the power generation element 4 is in contact with the inner surface of the flat portion 31 of the sealing can 3 via the restorative conductive sheet 5. Therefore, the sealing can 3 functions as a negative electrode can. It should be noted that the power generation element 4 is not limited to a cylindrical shape and can be modified in various ways according to the shape of the all-solid-state battery 1, such as a cuboid shape, a polygonal prism shape, etc.

[0030] The positive electrode layer 41 is composed of LiNi with an average particle size of 3 μm in a mass ratio of 55:40:5. 0.6 Co 0.2 Mn 0.2 O2, a sulfide solid electrolyte (Li6PS5Cl), and carbon nanotubes as a conductive additive, forming 180 mg of the positive electrode active material used in lithium-ion secondary batteries, are placed in a mold with a diameter of 10 mm to form cylindrical positive electrode particles. It should be noted that the positive electrode layer 41 is not particularly limited as long as it can function as the positive electrode layer of the power generation element 4. For example, it can be lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese composite oxide, olivine-type composite oxide, or a mixture thereof. Furthermore, the size and shape of the positive electrode layer 41 are not limited to a cylindrical shape and can be varied according to the size and shape of the all-solid-state battery 1.

[0031] The negative electrode layer 42 is made of LTO (Li4Ti5O) in a weight ratio of 50:45:5. 12 The negative electrode mixture, consisting of lithium titanate, sulfide solid electrolyte (Li6PS5Cl), and carbon nanotubes, is formed into cylindrical negative electrode particles using 300 mg of these materials as the negative electrode active material in lithium-ion secondary batteries. It should be noted that the negative electrode layer 42 only needs to function as the negative electrode layer of the power generation element 4; there are no particular limitations. For example, it can be metallic lithium, lithium alloys, graphite, low-crystallinity carbon and other carbon materials, SiO2, LTO (Li4Ti5O2), etc. 12 The material can be lithium titanate, etc., or it can be a mixture of these materials. In addition, the size and shape of the negative electrode layer 42 are not limited to a cylindrical shape, and can be varied according to the size and shape of the all-solid-state battery 1.

[0032] The solid electrolyte layer 43 is formed by molding 60 mg of a sulfide solid electrolyte (Li6PS5Cl) into a cylindrical shape. It should be noted that the solid electrolyte layer 43 is not particularly limited, but from the viewpoint of ion conductivity, it can also be other sulfide-based solid electrolytes such as bauxite. When using a sulfide-based solid electrolyte, to prevent reaction with the positive electrode active material, it is preferable to coat the surface of the positive electrode active material with niobium oxide (LiNbO3, etc.). Alternatively, the solid electrolyte layer 43 can also be a hydride-based solid electrolyte, an oxide-based solid electrolyte, etc. Furthermore, the size and shape of the solid electrolyte layer 43 are not limited to a cylindrical shape and can be varied according to the size and shape of the all-solid-state battery 1.

[0033] The resilient conductive sheet 5 is a sheet made of a conductive material that exhibits a certain degree of resilience in restoring its shape when compressed and its thickness reduced. Besides elastically deformable materials such as conductive rubber, which is made by uniformly mixing carbon black, metal powder, and rubber, the sheet constituting the resilient conductive sheet 5 is preferably made of a material such as graphite sheets, which does not completely recover its shape when compression stops, but partially recovers its thickness at a predetermined recovery rate. The resilient conductive sheets 5 are respectively disposed between the recess 211 of the outer can 2 and the positive electrode layer 41 of the power generation element 4, and between the flat portion 31 of the sealed can 3 and the negative electrode layer 42 of the power generation element 4. That is, the resilient conductive sheets 5 are disposed on both the upper and lower surfaces of the power generation element 4. The top view shape of the resilient conductive sheet 5 is formed to be approximately similar to the top view shape of the internal space of the all-solid-state battery 1. Therefore, the resilient conductive sheet 5 is formed to be approximately circular in top view. The area of ​​the upper surface of the restorative conductive sheet 5 on the outer can 2 side can be the same as the area of ​​the lower surface of the positive electrode layer 41 of the power generation element 4, or it can be slightly different from the area of ​​the lower surface of the positive electrode layer 41 of the power generation element 4. Similarly, the area of ​​the lower surface of the restorative conductive sheet 5 on the sealing can 3 side can be the same as the area of ​​the upper surface of the negative electrode layer 42 of the power generation element 4, or it can be slightly different from the area of ​​the upper surface of the negative electrode layer 42 of the power generation element 4. It should be noted that the upper surface of the restorative conductive sheet 5 on the outer can 2 side preferably covers the lower surface of the positive electrode layer 41, and the lower surface of the restorative conductive sheet 5 on the sealing can 3 side preferably covers the upper surface of the negative electrode layer 42. The restorative conductive sheet 5 is pressed together with the power generation element 4 by riveting during battery assembly, and the restorative conductive sheet 5 is pressed along the thickness direction (…). Figure 1The battery is assembled while under compressed conditions (vertical direction), functioning as a current collector. When the assembled solid-state battery 1 is charged and discharged, the power generation element 4 repeatedly expands and contracts. However, because the restorative conductive sheet 5 remains compressed, the continuous pressing of the power generation element 4 with its rebound force effectively maintains the conductivity between the outer can 2 and the power generation element 4, as well as between the sealed can 3 and the power generation element 4. Furthermore, by placing the restorative conductive sheet 5 between the recess 211 of the outer can 2 and the positive electrode layer 41 of the power generation element 4, when the outer can 2 and the sealed can 3 are riveted together, the restorative conductive sheet 5 will not be misaligned and will be sandwiched between the bottom 21 of the outer can 2 and the gasket 6, thus suppressing any reduction in sealing performance. Additionally, it prevents contact between the positive electrode layer 41 and the periphery of the inner bottom surface of the recess 211, preventing damage to the positive electrode layer 41.

[0034] It should be noted that the restorative conductive sheet 5 is not limited to a roughly circular shape when viewed from above. It can be modified in various ways according to the top view shape of the all-solid-state battery 1, such as an elliptical shape or a roughly polygonal shape when viewed from above. In addition, the restorative conductive sheet 5 may not be disposed between the power generation element 4 and the inner bottom surface of the recess 211 of the outer can 2 and the flat surface 31 of the sealed can 3. It may be disposed only between the power generation element 4 and the inner bottom surface of the recess 211 of the outer can 2, or only between the power generation element 4 and the flat surface 31 of the sealed can 3. By continuously pressing the power generation element 4 with the rebound force, the conductivity between the outer can 2 and the power generation element 4, as well as between the sealed can 3 and the power generation element 4, can be well maintained. On the other hand, the periphery of the flat surface 31 of the sealed can 3 is easily deformed by stress during riveting. Therefore, if the restorative conductive sheet 5 is disposed at least on the side of the flat surface 31 of the sealed can 3, it will function as a buffer material and can prevent damage to the negative electrode layer 42.

[0035] As described above, the resilient conductive sheet 5 can also be a graphite sheet. The graphite sheet is formed by rolling expanded graphite, and more specifically, it is manufactured as follows: First, acid-treated graphite particles that have undergone acid treatment on natural graphite are heated. The acid-treated graphite expands by foaming due to the acid vaporization located between its layers. This expanded graphite (expanded graphite) is shaped into a felt-like form and then rolled using a rolling mill to form a sheet. The graphite sheet is manufactured by shaping the expanded graphite sheet into a round shape. As described above, the expanded graphite is formed by foaming the acid-treated graphite through acid vaporization. Therefore, the graphite sheet is formed as a porous sheet. Thus, the graphite sheet not only possesses the conductivity inherent in graphite itself but also exhibits excellent flexibility and resilience due to its porous nature. Therefore, the graphite sheet functions as a current collector and can suppress damage to the power generation element 4 and the reduction in conductivity during charging and discharging due to its expansion and contraction. It should be noted that the method of manufacturing the graphite sheet is not limited to this; the graphite sheet can be manufactured by any method. In addition, the restorative conductive sheet 5 is not limited to graphite sheets, but can also be composed of conductive strips.

[0036] Here, the depth d and inner diameter d1 of the recess 211 are described in detail. Figure 1 As shown, the depth d of the recess 211 is greater than the thickness t of the restorative conductive sheet 5. Furthermore, the inner diameter of the recess 211 is greater than the outer diameter of the restorative conductive sheet 5. That is, the entire restorative conductive sheet 5 is housed within the internal space of the recess 211. Therefore, when riveting the outer can 2 to the sealing can 3, it is possible to prevent the restorative conductive sheet 5 from being trapped between the bottom 21 of the outer can 2 and the gasket 6. As a result, the current collection efficiency of the restorative conductive sheet 5 can be improved.

[0037] If the thickness t of the restorative conductive sheet 5 is too thick, the proportion of the power generation element 4 in the internal space of the all-solid-state battery 1 will decrease, thus reducing the battery capacity. Therefore, the ratio A(t / d) of the depth d of the recess 211 to the restorative conductive sheet 5 can be set to less than 1.0, preferably 0.9 or less, and more preferably 0.8 or less. On the other hand, if the restorative conductive sheet 5 is too thin, the effect of preventing damage to the power generation element 4 during expansion and contraction and reducing conductivity will be reduced. Therefore, the ratio A(t / d) of the depth d of the recess 211 to the restorative conductive sheet 5 can be 0.5 or more, preferably 0.6 or more, and more preferably 0.7 or more.

[0038] More specifically, when the restorative conductive sheet 5 is a graphite sheet, from the viewpoint of increasing the proportion of the power generation element 4 in the internal space of the all-solid-state battery 1, i.e., increasing the battery capacity of the power generation element 4, and preventing damage and reduced conductivity of the power generation element 4 during expansion and contraction, the thickness t of the restorative conductive sheet 5 (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. Furthermore, the thickness t of the restorative conductive sheet 5 (graphite sheet) is not limited to graphite sheets, and can also be applied to restorative conductive sheets 5 formed of other materials such as conductive strips.

[0039] Furthermore, the apparent density of the restorative conductive sheet 5 (graphite sheet) is preferably 0.3 g / cm³. 3 The above, more preferably 0.7 g / cm³ 3 The above, preferably 1.5 g / cm³ 3 The preferred value is 1.3 g / cm³. 3 The following is because when the apparent density is too low, the resilient conductive sheet 5 (graphite sheet) is easily damaged, and when the apparent density is too high, the flexibility decreases. It should be noted that the apparent density of the resilient conductive sheet 5 (graphite sheet) is not limited to graphite sheets, but can also be applied to resilient conductive sheets 5 formed from other materials such as conductive strips.

[0040] Furthermore, the resilience of the resilient conductive sheet 5 (graphite sheet) can be set to 7% or more. By giving the resilient conductive sheet 5 (graphite sheet) such moderate resilience, the resilient conductive sheet 5 (graphite sheet) moderately presses the power generation element 4. As a result, the inner bottom surface of the recess 211 of the outer can 2 and the power generation element 4 can be well maintained, and the inner surface of the flat portion 31 of the sealed can 3 and the power generation element 4 can be well maintained. From the viewpoint of maintaining good conductivity, the resilience is more preferably 10% or more. On the other hand, from the viewpoint of mitigating the pressing pressure on the power generation element 4 generated when riveting the outer can 2 and the sealed can 3, the resilience is preferably 80% or less, more preferably 50% or less, and particularly preferably 30% or less. It should be noted that the recovery rate refers to the value expressed by the following formula when the thickness of the recoverable conductive sheet 5 (graphite sheet) is set as t, the thickness of the recoverable conductive sheet 5 (graphite sheet) when compressed with a predetermined pressure is set as t1, and the thickness of the recoverable conductive sheet 5 (graphite sheet) when the pressure is removed is set as t2. Furthermore, the recoverable conductive sheet 5 (graphite sheet) possesses recoverability when its recovery rate is above a certain level.

[0041] (t2-t1) / (t-t1)×100(%)

[0042] The recovery rate can be measured using the method described in Japanese Industrial Standard JIS R3453 2001 (bonded sheet). Furthermore, the recovery rate of the recoverable conductive sheet 5 (graphite sheet) is not limited to graphite sheets, but can also be applied to recoverable conductive sheets 5 formed from other materials such as conductive strips.

[0043] Therefore, considering flexibility, resilience, and the space required for effective use of the internal space, it is preferable to determine the apparent density or thickness of the resilient conductive sheet 5 (graphite sheet) in a balanced manner.

[0044] As described above, the resilient conductive sheet 5 (graphite sheet) possesses excellent conductivity and flexibility. Therefore, the resilient conductive sheet 5 (graphite sheet) can function as a current collector and can absorb the expansion and contraction caused by the charging and discharging of the power generation element 4, or the pressure applied when riveting the outer can 2 to the sealing can 3. Thus, the all-solid-state battery 1 can suppress the degradation of battery performance caused by damage to the power generation element 4 and the formation of gaps.

[0045] Furthermore, the highly flexible and resilient conductive sheet 5 (graphite sheet) exhibits moderate resilience relative to the expansion caused by charging of the power generation element 4, or the compression caused by the pressing pressure when riveting the outer can 2 and the sealing can 3, as described above. Therefore, the all-solid-state battery 1 can effectively maintain the conductivity between the inner surface of the bottom 21 of the outer can 2 and the power generation element 4, and can effectively maintain the conductivity between the inner surface of the flat portion 31 of the sealing can 3 and the power generation element 4, thus maintaining battery performance.

[0046] like Figure 1 As shown, the depth d of the recess 211 is less than its height h. Height h is the height from the inner bottom surface of the recess 211 to the upper end of the outer peripheral surface of the solid electrolyte layer 43. In other words, height h is the combined height of the positive electrode layer 41 and the solid electrolyte layer 43. This prevents the bottom 21 of the outer can 2 from contacting the negative electrode layer 42 and causing a short circuit. Furthermore, even when the positions of the positive electrode layer 41 and the negative electrode layer 42 are interchanged, height h is still the combined height of the negative electrode layer 42 and the solid electrolyte layer 43.

[0047] In order to accommodate the resilient conductive sheet 5 within the recess 211, the outer diameter d2 of the resilient conductive sheet 5 is smaller than the inner diameter d1 of the recess 211. If the outer diameter d2 of the resilient conductive sheet 5 is too large relative to the inner diameter d1 of the recess 211, it will be difficult to accommodate the resilient conductive sheet 5 within the recess 211. Therefore, the ratio C(d1 / d2) of the inner diameter d1 of the recess 211 to the outer diameter d2 of the resilient conductive sheet 5 can be set to 1.02 or more, preferably 1.05 or more, and more preferably 1.08 or more. On the other hand, if the outer diameter d2 of the resilient conductive sheet 5 is too small relative to the inner diameter d1 of the recess 211, the contact area between the outer diameter d2 of the resilient conductive sheet 5 and the power generation element 4 will become smaller, and the current collection efficiency of the resilient conductive sheet 5 will decrease. Therefore, the ratio C(d1 / d2) can also be set to 1.15 or less, preferably 1.12 or less, and more preferably 1.09 or less. Furthermore, the inner diameter d1 of the recess 211 is smaller than the outer diameter of the positive electrode layer 41 of the power generation element 4. For example... Figure 1 As shown, this is to house the end of the positive electrode layer 41 side of the power generation element 4 within the recess 211.

[0048] Next, the manufacturing method of the all-solid-state battery 1 will be described. For example... Figure 2 As shown, a restorative conductive sheet 5 is housed in the recess 211 of the outer can 2. Then, after the power generation element 4 is placed on the upper surface of the restorative conductive sheet 5, a restorative conductive sheet 5 is further placed on the upper surface of the power generation element 4.

[0049] Next, as Figure 3 As shown, a gasket 6 is formed at the peripheral end of the peripheral wall portion 32 of the sealed can 3. The gasket 6 is formed from the inner surface of the peripheral wall portion 32 through the peripheral end of the peripheral wall portion 32 to the outer surface of the peripheral wall portion 32. The method of forming the gasket 6 is not particularly limited, and injection molding or other methods can be used.

[0050] Next, as Figure 4 As shown, the sealed can 3 is placed to cover the opening of the outer can 2. At this time, the gasket 6 contacts the inner surface of the bottom 21 of the outer can 2, thus preventing it from penetrating the interior of the recess 211. On the other hand, since the restorative conductive sheet 5 is housed in the recess 211 of the outer can 2, it is prevented from being trapped between the inner surface of the bottom 21 of the outer can 2 and the gasket 6. Finally, the front end of the gasket 6, formed on the outer side of the peripheral wall portion 32, is pressed together with the cylindrical sidewall portion 22 of the outer can 2 towards the outer peripheral surface of the peripheral wall portion 32 of the sealed can 3. Thus, the outer can 2 and the sealed can 3 are riveted together, completing the process. Figure 1 The all-solid-state battery 1 shown.

[0051] Assembled using graphite sheets (resilient conductive sheet 5) Figure 1The all-solid-state battery 1 shown prevents damage to the positive electrode layer 41 and the negative electrode layer 42 through the resilience of the graphite sheets. Furthermore, this all-solid-state battery 1 prevents graphite sheets from being trapped between the inner surface of the bottom 21 of the outer casing 2 and the gasket 6, thus providing excellent sealing. Therefore, when the all-solid-state battery 1 is charged and discharged, a predetermined discharge capacity can be obtained.

[0052] Here, regarding the use of graphite sheets as restorative conductive sheets 5 Figure 1 The all-solid-state battery 1 shown has the following characteristics, except that the bottom of the outer can can be a flat surface without a recess. Figure 1 All-solid-state batteries with the same structure as the all-solid-state battery 1 shown were subjected to cycle tests. The restorative conductive sheet 5 used had a thickness of 0.1 mm and an apparent density of 1.2 g / cm³. 3 And the graphite sheet with a recovery rate of 12%. The former all-solid-state battery 1 can maintain the conductivity between the outer canister 2 and the sealed canister 3 and the power generation element 4 well under repeated charge and discharge cycles. Therefore, even after 100 cycles, it can maintain more than 95% of the discharge capacity relative to the time before repeated charge and discharge cycles.

[0053] On the other hand, the latter all-solid-state battery exhibited reduced sealing due to graphite sheet misalignment in a portion of multiple test subjects, resulting in decreased battery performance due to the introduction of moisture from the air. Therefore, it was confirmed that some cells in the latter all-solid-state battery did not reach the predetermined discharge capacity.

[0054] In addition, instead of the restorative conductive sheet 5 (graphite sheet), a metal foam substrate with a thickness of 1 mm and a porosity of 97% is used (outer can side: aluminum, sealing can side: copper). Furthermore, for materials with... Figure 1 The all-solid-state battery 1 shown has the same configuration and was subjected to the same cycle test as described above. The foamed substrate of this all-solid-state battery is a current collector that is essentially non-resilient, and therefore cannot consistently maintain good conductivity between the outer can and the sealed can and the power generation element. Consequently, the discharge capacity of this all-solid-state battery decreases to approximately 10% after 100 cycles compared to before the repeated charge-discharge cycles.

[0055] (Modified Example)

[0056] In the all-solid-state battery 1 of the above embodiment, a restorative conductive sheet 5 is provided between the power generation element 4 and the inner bottom surface of the recess 211 of the outer can 2, and a restorative conductive sheet 5 is provided between the power generation element 4 and the inner surface of the flat part 31 of the sealed can 3. However, the restorative conductive sheet 5 may also be provided only between the power generation element 4 and the inner surface of the flat part 31 of the sealed can 3.

[0057] In addition, such as Figure 5As shown, the peripheral wall portion 32 of the sealed can 3 can also be composed of a base end portion 32a, an enlarged diameter portion 32b, and a stepped portion 32c. In the longitudinal sectional view, the base end portion 32a is configured to extend approximately perpendicularly to the flat portion 31. The enlarged diameter portion 32b is provided in a stepped shape via the stepped portion 32c, with a diameter larger than that of the base end portion 32a. That is, the stepped portion 32c is provided between the base end portion 32a and the enlarged diameter portion 32b. The open end of the cylindrical side wall portion 22 of the outer can 2 is bent toward the stepped portion 22c and riveted. Therefore, the outer can 2 and the sealed can 3 can be sufficiently riveted together, and the diameter of the flat portion 31 of the sealed can 3 can be larger than that of the all-solid-state battery 1 of the above embodiment. As a result, Figure 5 The solid-state battery 1 shown, with the same diameter as the solid-state battery 1 of the above embodiment, can effectively utilize the internal space of the solid-state battery 1; or, by housing the power generation element 4 with the same diameter as the solid-state battery 1 of the above embodiment within the internal space, the solid-state battery 1 can be miniaturized. It should be noted that... Figure 5 In the solid-state battery 1 shown, the peripheral wall 32 of the sealed can 3 is bent at the open end, and the diameter expansion portion 32b has a double wall. However, it can also be formed by a straight wall without bending the diameter expansion portion 32b. That is, the front end of the peripheral wall 32 is formed in a manner opposite to the bottom 21 of the outer can 2.

[0058] The implementation methods have been described above, but this disclosure is not limited to the above implementation methods. Various changes can be made as long as they do not depart from the spirit of the document.

[0059] Symbol Explanation

[0060] 1—All-solid-state battery, 2—Outer can, 21—Bottom, 211—Recess, 22—Cylindrical sidewall, 3—Sealed can, 31—Flat surface, 32—Peripheral wall, 4—Power generation element, 41—Positive electrode layer, 42—Negative electrode layer, 43—Solid electrolyte layer, 5—Resilient conductive sheet, 6—Gasket.

Claims

1. An all-solid-state battery, characterized in that, have: An outer can having a bottom including an outwardly recessed portion and a cylindrical sidewall portion; A sealed can having a flat portion and a peripheral wall portion that covers the opening of the outer can; A power generation element is disposed between the inner bottom surface of the recess of the outer can and the flat surface of the sealed can, and has a positive electrode layer, a negative electrode layer and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer; A gasket, which is riveted between the cylindrical sidewall of the outer can and the peripheral wall of the sealed can; and A resilient conductive sheet is disposed between the power generation element and at least one of the inner bottom surface of the recess and the flat surface of the sealed can. The resilient conductive sheet is a graphite sheet, which is a porous sheet formed by expanded graphite generated by foaming.

2. The all-solid-state battery according to claim 1, characterized in that, The resilient conductive sheet is disposed between the inner bottom surface of the recess and the power generation element. The depth of the recess is greater than the thickness of the restorative conductive sheet.

3. The all-solid-state battery according to claim 1 or 2, characterized in that, The first resilient conductive sheet is disposed between the inner bottom surface of the recess and the power generation element. The all-solid-state battery also includes a second restorative conductive sheet disposed between the flat portion of the sealed can and the power generation element.

4. The all-solid-state battery according to claim 1 or 2, characterized in that, The depth of the recess is smaller than the height from the inner bottom surface of the recess to the upper end of the outer peripheral surface of the solid electrolyte layer.

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