All-solid-state batteries

Abstract

To provide a metal-deposited all-solid battery capable of preventing excessive metal deposition at the ends.SOLUTION: In an all-solid battery, a negative electrode intermediate layer and a negative electrode current collector are bonded to each other in an adhesive region provided on an outer periphery of the negative electrode intermediate layer, and in a metal deposition region on the inner side of the adhesive region, metal deposits between the negative electrode intermediate layer and the negative electrode current collector during charging. A positive electrode layer includes a positive electrode layer central portion provided at a central part, and a low concentration region that is provided in the outer peripheral portion of the positive electrode layer, is continuous with the positive electrode layer central portion, and has a lower positive electrode active material concentration than that of the positive electrode layer central portion. The low concentration region at least partially overlaps the metal deposition region.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to all-solid-state batteries.

Background Art

[0002] An all-solid-state battery is a battery that uses a solid electrolyte as an electrolyte layer. As an all-solid-state battery, there is known a battery (hereinafter sometimes referred to as a metal deposition type all-solid-state battery etc.) configured such that an alkali metal such as lithium (hereinafter sometimes simply referred to as a metal) is deposited on the negative electrode side during charging.

[0003] An invention related to a metal deposition type all-solid-state battery is described in, for example, Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2021-192354). Patent Document 1 describes that since the deposited lithium metal extends toward the outside of the solid electrolyte layer, stress is applied to the solid electrolyte layer, which may cause cracks that are a factor in short circuit generation. As an all-solid-state battery capable of suppressing the generation of such cracks, an invention in which the configuration of the negative electrode is devised is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a metal deposition type all-solid-state battery, metal may be excessively deposited at the end. Excessive deposition of the metal can cause damage to the solid electrolyte layer etc. and short circuit between the negative electrode and the positive electrode.

[0006] Therefore, an object of the present invention is to provide a metal deposition type all-solid-state battery capable of preventing excessive deposition of metal at the end.

Means for Solving the Problems

[0007] The all-solid-state battery according to the present invention comprises a solid electrolyte layer, a positive electrode layer, a negative electrode intermediate layer, and a negative electrode current collector. The positive electrode layer and the negative electrode intermediate layer are provided so as to sandwich the solid electrolyte layer. The negative electrode current collector is provided on the negative electrode intermediate layer. The negative electrode intermediate layer and the negative electrode current collector are bonded together in an adhesive region provided on the outer periphery, and alkali metal is deposited between the negative electrode intermediate layer and the negative electrode current collector during charging in an alkali metal deposition region inside the adhesive region. The positive electrode layer has a central positive electrode layer portion provided in the middle and a low-concentration region provided on the outer periphery. The low-concentration region is continuous with the central positive electrode layer portion and has a lower positive electrode active material concentration than the central positive electrode layer portion. The low-concentration region overlaps with the alkali metal deposition region in at least a portion of it. [Effects of the Invention]

[0008] The present invention provides a metal deposition type all-solid-state battery that can prevent excessive metal deposition at the edges. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic cross-sectional view showing the configuration of an all-solid-state battery according to the first embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view showing the configuration of the all-solid-state battery of the first embodiment during charging. [Figure 3A] Figure 3A is a schematic cross-sectional view showing the end section of an all-solid-state battery according to a comparative example. [Figure 3B] Figure 3B is a schematic cross-sectional view showing the end section of the all-solid-state battery of the first embodiment. [Figure 4] Figure 4 is a schematic diagram showing a cross-sectional view of the end of an all-solid-state battery according to the second embodiment. [Figure 5] Figure 5 is a schematic diagram showing a cross-sectional view of the end of an all-solid-state battery according to the third embodiment. [Figure 6] Figure 6 is a schematic diagram showing a cross-sectional view of the end of an all-solid-state battery according to the fourth embodiment. [Figure 7]Figure 7 is a schematic diagram showing a cross-sectional view of the end of an all-solid-state battery according to the fifth embodiment. [Modes for carrying out the invention]

[0010] [First Embodiment] Figure 1 is a schematic cross-sectional view showing the overall configuration of the all-solid-state battery 1 of the first embodiment. The all-solid-state battery 1 is a metal deposition type battery and has a solid electrolyte layer 2, a positive electrode layer 3, a negative electrode intermediate layer 4, a negative electrode current collector 5, and a positive electrode current collector 6. The positive electrode layer 3 and the negative electrode intermediate layer 4 are provided so as to sandwich the solid electrolyte layer 2. The negative electrode current collector 5 is provided on the negative electrode intermediate layer 4, and the positive electrode current collector 6 is provided on the positive electrode layer 3 (below the positive electrode layer 3 in the drawing). That is, in the all-solid-state battery 1, the positive electrode current collector 6, positive electrode layer 3, solid electrolyte layer 2, negative electrode intermediate layer 4, and negative electrode current collector 5 are stacked in this order.

[0011] Furthermore, an insulating layer 9 is provided on the outside of the positive electrode layer 3, surrounding the outer edge of the positive electrode layer. The insulating layer 9 prevents metal deposited on the negative electrode side from wrapping around the edge and causing a short circuit between the positive and negative electrodes.

[0012] The negative electrode intermediate layer 4 is bonded to the negative electrode current collector 5 in an adhesive region 7 provided on the outer periphery of the negative electrode intermediate layer 4. On the other hand, the region inside the adhesive region 7 is configured such that metal can be deposited between the negative electrode intermediate layer 4 and the negative electrode current collector 5 during charging. The region in which metal can be deposited is hereinafter referred to as the alkali metal deposition region 8x.

[0013] The positive electrode layer 3 is slightly smaller in area than the solid electrolyte layer 2. As a result, the end portion of the positive electrode layer 3 is located inside the end portion of the solid electrolyte layer 2. The positive electrode layer 3 has a central portion 3-1 of the positive electrode layer and a low-concentration region 3-2. The central portion 3-1 of the positive electrode layer is located at the center of the positive electrode layer 3 as the name implies. On the other hand, the low-concentration region 3-2 is provided at the outer peripheral portion of the positive electrode layer 3. The low-concentration region 3-2 is a region where the concentration of the positive electrode active material is lower than that of the central portion 3-1 of the positive electrode layer. Note that the concentration of the positive electrode active material in the low-concentration region 3-2 is constant from the inside to the outside. Also, the central portion 3-1 of the positive electrode layer and the low-concentration region 3-2 are continuous. That is, there is no gap between the central portion 3-1 of the positive electrode layer and the low-concentration region 3-2.

[0014] The central portion 3-1 of the positive electrode layer overlaps with the alkali metal deposition region 8x. Also, at least a part of the low-concentration region 3-2 also overlaps with the alkali metal deposition region 8x. The outer end portion of the low-concentration region 3-2 is located inside the inner end portion of the adhesion region 7.

[0015] Next, the schematic operation of the all-solid-state battery 1 according to this embodiment will be described. FIG. 2 is a schematic cross-sectional view showing the configuration of the all-solid-state battery 1 during charging. In the all-solid-state battery 1 according to this embodiment, the positive electrode active material contained in the positive electrode layer 3 serves as a supply source of alkali metal ions. During charging, alkali metal ions move from the positive electrode layer 3 to the negative electrode current collector 5 side through the solid electrolyte layer 2 and the negative electrode intermediate layer 4. The moved alkali metal ions are deposited in the alkali metal deposition region 8x to form the alkali metal layer 8. Specifically, metal is deposited in the region of the alkali metal deposition region 8x that generally overlaps with the positive electrode layer 3. In the adhesion region 7, there is no room for metal deposition, and the negative electrode intermediate layer 4 and the negative electrode current collector 5 remain adhered. The negative electrode intermediate layer 4 functions as a protective layer for the solid electrolyte layer 2 and prevents the deposited metal from directly contacting the solid electrolyte layer 2. Note that examples of the main component of the alkali metal include lithium metal, sodium metal, potassium metal, and the like.

[0016] The thickness of the deposited metal is thick at the central part overlapping with the central part 3-1 of the positive electrode layer and thin at the part overlapping with the low-concentration region 3-2. This is because the amount of metal ion movement is small in the part overlapping with the low-concentration region 3-2. Furthermore, in the adhesion region 7, no metal is deposited. As a result, the outer peripheral part of the alkali metal layer 8 has a shape in which the thickness gradually decreases toward the outside.

[0017] On the other hand, during discharge, contrary to the charging process, alkali metal ions move from the alkali metal layer 8 to the positive electrode layer 3 side, and the alkali metal ions are occluded in the positive electrode layer 3.

[0018] By adopting the above-described configuration, excessive deposition of metal at the end during charging is prevented. This point will be described in detail below while comparing with a comparative example.

[0019] FIG. 3A is a cross-sectional view schematically showing an end cross-section of the all-solid-state battery 1 according to the comparative example. In FIG. 3A, the active material concentration in the positive electrode layer 3 (hereinafter, may be simply referred to as the active material concentration) and the magnitude of the stress generated in the solid electrolyte layer 2 (hereinafter, may be simply referred to as the stress) are shown together.

[0020] As shown in FIG. 3A, in the all-solid-state battery according to the comparative example, the active material concentration in the positive electrode layer 3 is constant. That is, the low-concentration region 3- (2) is not provided. Also, a gap is generated between the positive electrode layer 3 and the insulating layer 9. Furthermore, the adhesion region 7 is not provided between the negative electrode intermediate layer 4 and the negative electrode current collector 5. Other points have the same configuration as the all-solid-state battery 1 according to the first embodiment.

[0021] In the all-solid-state battery 1 of the comparative example, during charging, metal is deposited in the region overlapping with the positive electrode layer 3. Since the low-concentration region 3-2 does not exist, a relatively high step is generated at the end of the alkali metal layer 8. Also, since the adhesion region 7 does not exist, a gap is generated between the negative electrode current collector 5 and the negative electrode intermediate layer 4 outside the alkali metal layer 8. <,

[0022] In a solid-state battery 1, loads are typically applied from above and below in the thickness direction, sandwiching the battery for purposes such as retention. The load applied from the negative electrode current collector 5 side is concentrated at the edge of the alkali metal layer 8 where a step is formed. As a result, the load is also concentrated on the solid electrolyte layer 2 at a position corresponding to the edge of the alkali metal layer 8 (i.e., a position overlapping the edge of the positive electrode layer 3), generating concentrated stress. In the solid electrolyte layer 2, current tends to concentrate in the area where stress is concentrated, making it easier for excess metal deposition to occur.

[0023] On the other hand, Figure 3B shows the end cross-section of the all-solid-state battery according to the first embodiment, along with the active material concentration and stress. As shown in Figure 3B, in the all-solid-state battery 1 according to the first embodiment, the outer periphery of the alkali metal layer 8 is stepped, with a shape in which the thickness changes gradually. Even if steps occur, their height is smaller than that of the comparative example shown in Figure 3A. Also, because an adhesive region 7 is provided, almost no gap is formed under the negative electrode current collector 5, and the negative electrode current collector 5 is in close contact with the alkali metal layer 8. As a result, the load applied to the alkali metal layer 8 is dispersed in the region overlapping with the low-concentration region 3-2, and unlike the comparative example, it does not concentrate in one place. There is a possibility that some stress may concentrate at the boundary between the central part 3-1 of the positive electrode layer and the low-concentration region 3-2, but its magnitude is smaller than that of the comparative example shown in Figure 3A. Therefore, excessive deposition of metal is suppressed.

[0024] The above is a general overview of the all-solid-state battery 1. Next, the details of the all-solid-state battery 1 will be explained below.

[0025] The overall shape of the all-solid-state battery 1 is not particularly limited, but is, for example, sheet-like. That is, the solid electrolyte layer 2, positive electrode layer 3, negative electrode intermediate layer 4, negative electrode current collector 5, and positive electrode current collector 6 are each sheet-like, and the all-solid-state battery 1, which is a laminate of these, is also sheet-like. The all-solid-state battery 1 may be provided by winding the sheet-like laminate and housing it in a cylindrical container.

[0026] The solid electrolyte layer 2 is a solid and can function as an electrolyte in the battery; its material is not particularly limited. For example, the solid electrolyte layer 2 can be formed from a sulfide or oxide. Preferably, the solid electrolyte layer 2 is a sulfide solid electrolyte. Examples of sulfide solid electrolytes include LPS-based (e.g., argyrodite (Li6PS5Cl)) and LGPS-based (e.g., Li 10 GeP2S 12 Examples of materials include the following. The thickness of the solid electrolyte layer 2 is not particularly limited, but is, for example, 10 to 100 μm.

[0027] The negative electrode current collector 5 and the positive electrode current collector 6 are formed from, for example, a conductive thin film. For the negative electrode current collector 5, for example, a thin film made of a metal such as stainless steel (SUS) or copper (Cu) can be used. For the positive electrode current collector 6, for example, aluminum foil can be used. The thickness of the negative electrode current collector 5 is not particularly limited, but is for example 5 to 30 μm. The thickness of the positive electrode current collector 6 is not particularly limited, but is for example 5 to 30 μm.

[0028] The thickness of the negative electrode intermediate layer 4 is not particularly limited, but is, for example, 1 to 100 μm. The negative electrode intermediate layer 4 is provided between the solid electrolyte layer 2 and the alkali metal layer 8. This negative electrode intermediate layer 4 is a layer that assists in the smooth deposition of alkali metals and / or prevents the alkali metal layer 8 from directly contacting the solid electrolyte layer. The negative electrode intermediate layer 4 contains a material capable of intercalating and releasing alkali metal ions, or a material having electronic insulating properties and lithium ion conductivity. The material capable of intercalating and releasing alkali metal ions contains one or more materials selected from the group consisting of carbon materials such as graphite and metallic materials such as silver. Furthermore, the material having electronic insulating properties and lithium ion conductivity is a material that is more stable against reductive decomposition by contact with lithium metal than the solid electrolyte contained in the solid electrolyte layer 2. Examples of such materials include at least one selected from the group consisting of lithium halides (lithium fluoride (LiF), lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI)), lithium ion conductive polymers, composite metal oxides represented as Li-MO (where M is one or more metal elements selected from the group consisting of Mg, Au, Al, Sn, and Zn), and Li-Ba-TiO3 composite oxides. All of these materials are particularly stable against reductive decomposition upon contact with lithium metal. The negative electrode intermediate layer 4 may also contain, for example, a resin binder.

[0029] The positive electrode layer 3 is a layer containing a positive electrode active material. The positive electrode layer 3 includes, for example, a resin binder and a positive electrode active material dispersed in the resin binder. The positive electrode active material can be any material that can release alkali metal ions during charging and absorb alkali metal ions during discharging by utilizing an oxidation-reduction reaction. The positive electrode active material is also a source of alkali metal ions. Examples of positive electrode active materials include lithium metal composite oxides. Examples of lithium metal composite oxides include layered rock salt type compounds such as LiCoO2, LiMnO2, LiNiO2, LiVO2, or Li(Ni-Mn-Co)O2, LiMn2O4, or LiNi 0.5 Mn 1.5Examples include spinel-type compounds such as O4, olivine-type compounds such as LiFePO4 or LiMnPO4, or Si-containing compounds such as Li2FeSiO4 or Li2MnSiO4. Other lithium metal composite oxides include, for example, Li4Ti5O 12 These are some examples.

[0030] As previously described, the positive electrode layer 3 has a central portion 3-1 and a low-concentration region 3-2. The low-concentration region 3-2 only needs to have a lower active material concentration than the central portion 3-1 of the positive electrode layer. For example, the low-concentration region 3-2 can be formed by a mixture of the material constituting the central portion 3-1 of the positive electrode layer and the material constituting the insulating layer 9.

[0031] The width of the low-concentration region 3-2 is, for example, 0.1 to 100 mm.

[0032] As previously described, the insulating layer 9 is provided to protect the edges of the positive electrode layer 3. By providing the insulating layer 9, metal deposition around the edges prevents short circuits between the negative electrode and the positive electrode. The material constituting the insulating layer 9 is not particularly limited, as long as it has insulating properties. For example, the insulating layer 9 can be formed from an insulating resin. Examples of such resins include ultraviolet curing resins such as Aronics® and Aronoxetane®. Alternatively, thermosetting resins (polyethylene terephthalate (PET), epoxy resin, etc.) can also be used. Kapton®, polypropylene (PP), polytetrafluoroethylene (PTFE), rubber (natural rubber, synthetic rubber), etc. can also be used as materials constituting the insulating layer 9. The width of the insulating layer 9 is, for example, 1 to 100 mm.

[0033] Note that the insulating layer 9 is not necessarily an essential component and can be omitted.

[0034] As previously described, the bonding region 7 is the region where the negative electrode current collector 5 is bonded to the negative electrode intermediate layer 4. In the bonding region 7, the negative electrode current collector 5 is bonded to the negative electrode intermediate layer 4 via an adhesive. As the adhesive, for example, a resin-based adhesive can be used. For example, if the negative electrode intermediate layer 4 contains a resin binder, the adhesive can be made of the same components as that resin binder. The width of the bonding region 7 is, for example, 1 to 100 mm.

[0035] Next, a method for manufacturing the all-solid-state battery 1 according to this embodiment will be described with an example.

[0036] First, a material for forming the positive electrode current collector 6 (e.g., aluminum foil) is prepared. On top of this material, the material for forming the positive electrode layer 3 and the material for forming the insulating layer 9 are placed. The material for forming the insulating layer 9 is frame-shaped and is positioned so that a portion of its inner surface overlaps with the material for forming the positive electrode layer 3. Furthermore, the materials for forming the solid electrolyte layer 2, the negative electrode intermediate layer 4, and the negative electrode current collector 5 are laminated on top of these, respectively. An adhesive is provided between the negative electrode intermediate layer 4 and the negative electrode current collector 5 to form an adhesive region 7. The resulting laminate is then pressed and integrated. This yields the all-solid-state battery 1 according to this embodiment. Here, during pressing, in the region where the material for forming the positive electrode layer 3 and the material for forming the insulating layer 9 overlap, the two are mixed, forming a low-concentration region 3-2. When the all-solid-state battery 1 is made in this way, the central part 3-1 of the positive electrode layer, the low-concentration region 3-2, and the insulating layer 9 are formed continuously. In other words, no gap is formed between the central part 3-1 of the positive electrode layer and the low-concentration region 3-2, nor between the low-concentration region 3-2 and the insulating layer 9. Because no gaps are formed, stress concentration in the solid electrolyte layer 2 is more easily suppressed, and excess metal deposition is more easily suppressed.

[0037] As described above, in the all-solid-state battery 1 according to this embodiment, the negative electrode intermediate layer 4 and the negative electrode current collector 5 are bonded in an adhesive region 7 provided on the outer periphery of the negative electrode intermediate layer 4, and in the alkali metal deposition region 8x inside the adhesive region 7, metal can be deposited between the negative electrode intermediate layer 4 and the negative electrode current collector 5 during charging. The positive electrode layer 3 has a central positive electrode layer portion 3-1 provided in the center, and a low-concentration region 3-2 provided on the outer periphery of the positive electrode layer 3, which is continuous with the central positive electrode layer portion 3-1 and has a lower positive electrode active material concentration than the central positive electrode layer portion 3-1. The low-concentration region 3-2 overlaps with the alkali metal deposition region 8x in at least a part of it. By adopting such a configuration, it is possible to prevent the formation of a large step at the edge of the metal deposited during charging, and to prevent stress concentration in the solid electrolyte layer 2. This prevents excessive metal deposition and prevents damage to the solid electrolyte layer 2 and short circuits between the positive and negative electrodes.

[0038] Furthermore, in the all-solid-state battery 1 according to this embodiment, an insulating layer 9 is provided so as to surround the outer edge of the positive electrode layer 3. This prevents metal deposited on the negative electrode side from wrapping around the edge and causing a short circuit between the positive and negative electrodes.

[0039] In this embodiment, as shown in Figure 1, the case described is one in which there is a single stacked structural unit (hereinafter referred to as a unit) consisting of a solid electrolyte layer 2, a positive electrode layer 3, a negative electrode intermediate layer 4, a negative electrode current collector 5, and a positive electrode current collector 6. However, the number of units in the all-solid-state battery 1 may be multiple. Multiple units can be connected in series or parallel as needed to form an all-solid-state battery 1 as a whole.

[0040] [Second Embodiment] Next, a second embodiment will be described. Figure 4 is a schematic diagram showing an end cross-section of the all-solid-state battery 1 of the second embodiment. Figure 4 also shows the active material concentration of the positive electrode layer 3 and the stress generated in the solid electrolyte layer 2.

[0041] In this embodiment, the position of the adhesive region 7 has been modified. Regarding other aspects, the same configuration as in the first embodiment can be adopted, so a detailed explanation will be omitted.

[0042] As shown in Figure 4, in this embodiment, the inner edge of the adhesive region 7 is located inside the insulating layer 9. Specifically, the inner edge of the adhesive region 7 overlaps with the low-concentration region 3-2. Furthermore, the outer edge of the adhesive region 7 is located outside the outer edge of the low-concentration region 3-2 and overlaps with the insulating layer 9.

[0043] According to this embodiment, during charging, no metal is deposited at the position opposite the insulating layer 9. If the inner end of the adhesive region 7 is located outside the inner end of the insulating layer 9, there is a possibility that metal may be deposited at the position opposite the insulating layer 9. Metal deposited at such a position does not move towards the positive electrode layer 3 during discharge and does not contribute to the charging and discharging operation of the battery. Therefore, it reduces the efficiency of the battery. In contrast, according to this embodiment, metal is deposited only at the position opposite the positive electrode layer 3 and not at the position opposite the insulating layer 9, thus improving the efficiency of the battery.

[0044] [Third Embodiment] Next, a third embodiment will be described. Figure 5 is a schematic diagram showing a cross-section of the end of the all-solid-state battery 1 of the third embodiment. The active material concentration and stress are also shown in Figure 5.

[0045] In this embodiment, the active material concentration in the low-concentration region 3-2 has been carefully designed. Regarding other aspects, the same configuration as in the previously described embodiments, particularly the second embodiment, can be adopted, so a detailed explanation will be omitted.

[0046] In this embodiment, the concentration of the positive electrode active material in the low-concentration region 3-2 decreases continuously from the inside to the outside.

[0047] According to this embodiment, the thickness of the metal deposited during charging decreases continuously from the inside to the outside, corresponding to the positive electrode active material concentration in the low-concentration region 3-2. In other words, no step is created at the edge of the alkali metal layer 8. As a result, the load applied to the alkali metal layer 8 from the negative electrode current collector 5 side is more easily dispersed, and the stress generated in the solid electrolyte layer 2 is more easily dispersed. Therefore, excessive metal deposition can be prevented more reliably.

[0048] In the example shown in Figure 5, the active material concentration decreases "continuously" in the low-concentration region 3-2, but the active material concentration in the low-concentration region 3-2 may decrease "gradually". In such a case, a step corresponding to the active material concentration in the low-concentration region 3-2 may occur in the alkali metal layer 8. Compared to the case where the active material concentration decreases "continuously", the load tends to concentrate at the step portion. However, compared to the case where the active material concentration in the low-concentration region 3-2 is constant, as in the embodiment described above, the height of each step is smaller, so the load applied to the edge of the alkali metal layer 8 is more easily distributed. Therefore, from this viewpoint, it becomes easier to prevent excessive deposition of metal.

[0049] In this embodiment, the low-concentration region 3-2 can be formed, for example, by preparing a number of sheets with different active material concentrations in advance and pressing them together while overlapping them. Specifically, the sheet with the highest active material concentration is placed in the center. Then, a frame-shaped sheet with the next highest active material concentration is placed outside of it, partially overlapping with the central sheet. Further outside of that, a frame-shaped sheet with the next highest active material concentration is placed, partially overlapping with the inner sheet. In this way, multiple frame-shaped sheets with different active material concentrations are arranged, partially overlapping, so that the active material concentration decreases from the inside to the outside. Finally, a sheet for forming the insulating layer 9 is placed on the outermost side. These are then pressed together. This makes it possible to obtain a configuration in which the active material concentration decreases continuously or stepwise from the inside to the outside.

[0050] [Fourth Embodiment] Next, the fourth embodiment will be described. Figure 6 is a schematic diagram showing a cross-section of the end of the all-solid-state battery 1 of the fourth embodiment. In this embodiment, the configuration of the adhesive region 7 has been improved. As other points can be adopted in the same way as in the embodiments described above, particularly the second embodiment, a detailed explanation will be omitted.

[0051] In this embodiment, the adhesive permeates the negative electrode intermediate layer 4 in the bonding region 7. When the negative electrode intermediate layer 4 is composed of a resin binder or the like, pores (voids) may occur in the negative electrode intermediate layer 4. If pores exist, metal may permeate the negative electrode intermediate layer 4 through the pores during deposition and seep out to the outside. In contrast, according to this embodiment, the adhesive permeates the negative electrode intermediate layer 4. That is, the pores are filled with the adhesive. Therefore, metal does not seep into the negative electrode intermediate layer 4. Thus, it is possible to prevent metal from seeping out to the outside through the negative electrode intermediate layer 4. This makes it possible to more reliably prevent short circuits between the positive electrode side and the negative electrode side.

[0052] The adhesive region 7 having the configuration described in this embodiment can be realized, for example, by using a material with a viscosity low enough to penetrate the negative electrode intermediate layer 4 as the adhesive during manufacturing. Alternatively, the adhesive may be heated during bonding to lower its viscosity, thereby allowing the adhesive to permeate the negative electrode intermediate layer 4.

[0053] [Fifth Embodiment] Next, the fifth embodiment will be described. Figure 7 is a schematic diagram showing a cross-section of the end of the all-solid-state battery 1 of the fifth embodiment. In this embodiment, the sizes of the negative electrode intermediate layer 4 and the solid electrolyte layer 2 have been modified. As other points can be adopted in the same way as in the embodiments described above, particularly the second embodiment, a detailed explanation will be omitted.

[0054] As shown in Figure 7, in this embodiment, the solid electrolyte layer 2 is larger than the negative electrode intermediate layer 4. The edges of the solid electrolyte layer 2 are located outside the edges of the negative electrode intermediate layer 4. The edges of the negative electrode intermediate layer 4 are located in the portion that overlaps with the insulating layer 9.

[0055] According to this embodiment, since the end of the solid electrolyte layer 2 is located outside the end of the negative electrode intermediate layer 4, the path from the end of the alkali metal layer 8, around the ends of the negative electrode intermediate layer 4 and the solid electrolyte layer 2, to the positive electrode layer 3 becomes longer. As a result, metal is deposited around the ends of the all-solid-state battery 1, preventing a short circuit between the positive electrode and the negative electrode.

[0056] [Sixth Embodiment] Next, a sixth embodiment will be described. In this embodiment, the composition of the solid electrolyte layer 2 has been modified. As other points can be adopted in the same way as in the previously described embodiments, particularly the second embodiment, a detailed explanation will be omitted.

[0057] In this embodiment, the negative electrode intermediate layer 4 contains a flexibility-imparting substance that provides flexibility. In other words, the negative electrode intermediate layer 4 is made flexible. Because the negative electrode intermediate layer 4 is flexible, it can deform to follow the shape of the alkali metal layer 8 during metal deposition. As a result, the negative electrode intermediate layer 4 becomes less prone to damage, and the metal is deposited more uniformly.

[0058] The material used to impart flexibility is not particularly limited, but for example, rubber components can be used. Examples of rubber components include SBR (styrene-butadiene rubber) and HNBR (hydrogenated nitrile rubber). [Explanation of Symbols]

[0059] 1 All-solid-state battery 2 Solid electrolyte layer 3. Positive electrode layer 3-1 Central part of the positive electrode layer 3-2 Low concentration area 4. Negative electrode intermediate layer 5 Negative electrode current collector 6 Positive electrode current collector 7 Adhesive area 8. Alkali metal layer 8x alkali metal deposition region 9. Insulating layer

Claims

1. A solid electrolyte layer, A positive electrode layer and a negative electrode intermediate layer are provided so as to sandwich the solid electrolyte layer, A negative electrode current collector provided on the negative electrode intermediate layer, It has, The negative electrode intermediate layer and the negative electrode current collector are bonded together in an adhesive region provided on the outer periphery of the negative electrode intermediate layer, and in the alkali metal deposition region inside the adhesive region, alkali metals can be deposited between the negative electrode intermediate layer and the negative electrode current collector during charging. The positive electrode layer is The central part of the positive electrode layer located in the center, It has a low-concentration region provided on the outer periphery of the positive electrode layer, which is continuous with the central part of the positive electrode layer and has a lower positive electrode active material concentration than the central part of the positive electrode layer, The low-concentration region overlaps with the alkali metal deposition region in at least a portion of it. All-solid-state battery.

2. The all-solid-state battery according to claim 1, In the aforementioned low-concentration region, the concentration of the positive electrode active material is constant from the inside outwards. All-solid-state battery.

3. The all-solid-state battery according to claim 1, In the aforementioned low-concentration region, the concentration of the positive electrode active material decreases stepwise or continuously from the inside out. All-solid-state battery.

4. A solid-state battery according to claim 1 or 2, Furthermore, it has an insulating layer provided so as to surround the outer edge of the positive electrode layer, All-solid-state battery.

5. The all-solid-state battery according to claim 4, The inner end of the adhesive region is located inside the insulating layer. All-solid-state battery.

6. The all-solid-state battery according to claim 5, The outer edge of the low-concentration region is located inward from the outer edge of the adhesive region. All-solid-state battery.

7. The all-solid-state battery according to claim 4, The low-concentration region is formed by a mixture of the material constituting the central part of the positive electrode layer and the material constituting the insulating layer. All-solid-state battery.

8. A solid-state battery according to claim 1 or 2, In the aforementioned bonding region, the negative electrode current collector is bonded to the negative electrode intermediate layer by an adhesive. The adhesive is impregnated into the negative electrode intermediate layer. All-solid-state battery.

9. A solid-state battery according to claim 1 or 2, The end of the solid electrolyte layer is located outside the end of the negative electrode intermediate layer. All-solid-state battery.

10. A solid-state battery according to claim 1 or 2, The negative electrode intermediate layer contains a flexibility-imparting substance that provides flexibility. All-solid-state battery.

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