All solid state battery

Abstract

To suppress the occurrence of cracks in a solid electrolyte layer which causes a short circuit.SOLUTION: An all-solid battery includes a solid electrolyte layer, and a negative electrode that is laminated on the solid electrolyte layer and in which a negative electrode lithium metal layer is formed by precipitating metallic lithium with the solid electrolyte layer during charging, and the negative electrode has a precipitation adjusting layer having wettability to metallic lithium different from that of the solid electrolyte layer, and the precipitation adjusting layer is arranged such that the circumference of the outer circumference of the negative electrode lithium metal layer formed during charging is longer than the circumference of the outer circumference having a similar shape to the solid electrolyte layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an all-solid-state battery. [Background technology]

[0002] Patent Document 1 proposes an all-solid-state battery that is configured to reduce stress generated at the contact portion between the outer periphery of the positive electrode and the solid electrolyte layer during press molding by providing irregularities on the outer periphery of the positive electrode to increase the circumferential length and form a clearance for deformation of the positive electrode and reducing the amount of elongation of the outer periphery of the positive electrode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5831442 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, all-solid-state batteries (hereinafter, also referred to as "all-precipitation type all-solid-state batteries" in this specification) have been known that use only lithium in the positive electrode active material as the lithium source. In this type of all-solid-state battery, no lithium metal is contained in the negative electrode during discharge, and lithium metal is precipitated on the negative electrode current collector during charge to form a lithium metal layer. In this case, the precipitated lithium metal extends toward the outside of the solid electrolyte layer, so that stress is applied to the solid electrolyte layer, which may cause cracks that may cause a short circuit.

[0005] Therefore, an object of the present invention is to provide an all-solid-state battery capable of suppressing the occurrence of cracks in the solid electrolyte layer, which are a cause of short circuits. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided an all-solid-state battery including a solid electrolyte layer and an anode that is laminated on the solid electrolyte layer and has a lithium metal layer formed between the solid electrolyte layer and the anode and that deposits lithium metal between the solid electrolyte layer and the anode during charging. The anode has a deposition adjustment layer that has a wettability with respect to lithium metal different from that of the solid electrolyte layer. The deposition adjustment layer is formed in a film shape. the high-wettability layer is applied to the solid electrolyte layer and has a higher wettability with respect to metallic lithium than the solid electrolyte layer; An uneven portion is formed on at least a part of the outer periphery. The protrusions in the concave-convex portion are formed in an inclined or curved shape that disperses stress that occurs in the solid electrolyte layer due to expansion of metallic lithium during charging. Effect of the Invention

[0007] According to the present invention, it is possible to suppress the occurrence of cracks in the solid electrolyte layer, which are a cause of short circuits. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating the configuration of an all-solid-state battery according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram illustrating the states of the negative electrode during discharging and charging. [Diagram 3] FIG. 3 is a diagram illustrating the structure of the concave-convex portion of the high-wettability layer. [Figure 4] FIG. 4 is a diagram illustrating the relationship between the peripheral shape of the negative electrode lithium metal layer and the peripheral shape of the solid electrolyte layer. [Diagram 5] FIG. 5 is a diagram illustrating the configuration of the all-solid-state battery according to the second embodiment. [Figure 6] FIG. 6 is a diagram illustrating the configuration of an all-solid-state battery according to the third embodiment. [Figure 7] FIG. 7 is a diagram illustrating the configuration of an all-solid-state battery according to the fourth embodiment. [Figure 8] FIG. 8 is a diagram illustrating the inner peripheral shape of the low wettability layer. [Figure 9] FIG. 9 is a diagram illustrating the configuration of an all-solid-state battery according to the fifth embodiment. [Figure 10] FIG. 10 is a diagram illustrating the configuration of an all-solid-state battery according to a first modified example. [Figure 11]FIG. 11 is a diagram illustrating the configuration of an all-solid-state battery according to a second modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Each embodiment of the present invention will be described below.

[0010] (First embodiment) An all-solid-state battery 10 according to a first embodiment of the present invention will be described.

[0011] 1 is a diagram for explaining the configuration of an all-solid-state battery 10 according to this embodiment. As shown in the figure, the all-solid-state battery 10 is a fully precipitated all-solid-state battery configured by sealing a cell unit 10A (one in FIG. 1) made by laminating one or more cell units each having a solid electrolyte layer 15 laminated between a positive electrode p and a negative electrode n, with a laminate material 20. In addition, electrical wiring (such as a positive electrode lead, a negative electrode lead, a positive electrode current collector, and a negative electrode current collector) (not shown) extending to the laminate material 20 is connected to the cell unit 10A.

[0012] The cell unit 10A of this embodiment is formed in a generally rectangular shape in plan view. That is, the positive electrode p, the negative electrode n, and the solid electrolyte layer 15 are formed in a generally rectangular shape in plan view.

[0013] The positive electrode p is mainly composed of a positive electrode active material layer 17 laminated on one surface in the lamination direction of the solid electrolyte layer 15 (the surface on the top or bottom in the figure), and a positive electrode current collector 18 connected to the positive electrode active material layer 17.

[0014] The negative electrode n is mainly composed of a high wettability layer 16 laminated on the other surface (the upper and lower surfaces in the figure) in the lamination direction of the solid electrolyte layer 15, a negative electrode lithium metal layer 14 formed on the high wettability layer 16, and a negative electrode current collector 12 connected to the negative electrode lithium metal layer 14. In this embodiment, the high wettability layer 16 functions as a precipitation adjustment layer.

[0015] Here, the negative electrode lithium metal layer 14 is not formed in a discharged state, but is formed by the precipitation of metallic lithium on the surface region of the solid electrolyte layer 15 (the region of the high wettability layer 16) and the negative electrode current collector 12 through the charging process.

[0016] The high wettability layer 16 is applied to the central surface region 15B excluding the outer peripheral edge portion of the solid electrolyte layer 15. In particular, the high wettability layer 16 has higher wettability than the solid electrolyte layer 15 with respect to metallic lithium that dissolves between the solid electrolyte layer 15 and the negative electrode current collector 12 during charging, and is formed from a material having a certain level of ion conductivity from the viewpoint of ensuring the conduction of lithium ions.

[0017] The structure and function of the high-wettability layer 16 will be described in more detail below.

[0018] Fig. 2 is a diagram for explaining the states of the negative electrode n during discharge and during charge, in particular Fig. 2(a) and Fig. 2(b) are views of the main part of Fig. 1 taken along the line A-A in the discharged and charged states, respectively.

[0019] As shown in the figure, the negative electrode n during discharge has a structure in which the high wettability layer 16 is applied to the central surface region 15B of the solid electrolyte layer 15 except for the outer peripheral edge portion 15A. Also, as described above, the uneven portion 16A is formed on the outer periphery of the high wettability layer 16.

[0020] On the other hand, during charging, lithium ions from the positive electrode active material layer 17 enter the solid electrolyte layer 15 or the high wettability layer 16 and form a precipitated metallic lithium by alloying with the metal constituting the solid electrolyte layer 15 or the high wettability layer 16. Then, this metallic lithium diffuses into the surface region of the solid electrolyte layer 15 or the high wettability layer 16, thereby forming the negative electrode lithium metal layer 14.

[0021] In particular, the negative electrode lithium metal layer 14 of this embodiment is formed in the high wettability layer 16, which has a higher affinity for metallic lithium. More specifically, in this embodiment, the high wettability layer 16 is configured to have a higher wettability to metallic lithium than the solid electrolyte layer 15, so that metallic lithium gathers and precipitates in the high wettability layer 16 during charging. Therefore, the negative electrode lithium metal layer 14 is mainly formed in the central surface region 15B of the solid electrolyte layer 15. As described above, the uneven portion 16A is formed on the outer periphery of the high wettability layer 16, and the outer periphery 14A of the generated negative electrode lithium metal layer 14 is also formed in an uneven shape having substantially the same shape as the uneven portion 16A. During discharge, the negative electrode lithium metal layer 14 becomes smaller, and when discharge proceeds beyond a certain level, it almost disappears.

[0022] 3 is a diagram illustrating the detailed structure of the uneven portion 16A of the high wettability layer 16. In FIG. 3, the uneven shape of the negative electrode lithium metal layer 14 is shown in order to avoid complicating the drawing. However, as described above, the uneven shape is substantially the same as the shape of the uneven portion 16A of the high wettability layer 16, and therefore the uneven shape of the negative electrode lithium metal layer 14 shown in FIG. 3 will be described by regarding it as the same as the uneven portion 16A of the high wettability layer 16.

[0023] As shown in the figure, the high wettability layer 16 of this embodiment has an uneven portion 16A formed over its entire circumference. In this embodiment, the convex portion 16Aa of the uneven portion 16A is formed in a shape in which the opposing sides are non-parallel to each other in a cross-sectional view, particularly in a trapezoid shape. That is, the side surface of the convex portion 14Aa is formed as an inclined surface. Therefore, the negative electrode lithium metal layer 14 is deposited with the outer periphery 14A having the same uneven shape as the uneven portion 16A. Therefore, the stress in the direction that causes cracks in the solid electrolyte layer 15 (see the white arrow) is dispersed in a direction according to the inclined surface of the convex portion 14Aa of the negative electrode lithium metal layer 14 (see the black arrow). That is, the outer periphery 14A of the negative electrode lithium metal layer 14 can be shaped to suitably disperse the stress that causes cracks.

[0024] Furthermore, the width W of the recesses 16Ab and the length L of the protrusions 16Aa in the uneven portion 16A are configured to be equal to or greater than the maximum diameter r of one solid electrolyte particle P that constitutes the solid electrolyte layer 15.

[0025] This makes it possible to more suitably maintain the shape of the recesses 14Ab in the outer periphery 14A of the negative electrode lithium metal layer 14 formed during charging. More specifically, since metallic lithium is likely to precipitate in one solid electrolyte particle P, if the size of the recesses 16Ab in the high wettability layer 16 is smaller than the size of one solid electrolyte particle P, metallic lithium is likely to precipitate so as to fill the recesses 16Ab. In contrast, by configuring the size of the recesses 16Ab to be larger than the size of one solid electrolyte particle P, metallic lithium is prevented from being precipitated in the recesses 16Ab, and the outer periphery 14A of the negative electrode lithium metal layer 14 is more reliably formed in an uneven shape.

[0026] As described above, in the all-solid-state battery 10 of the present embodiment, by providing the high wettability layer 16, which has higher wettability to metallic lithium than the solid electrolyte layer 15 and has the uneven portion 16A formed on the outer periphery, in the solid electrolyte layer 15, the shape of the outer periphery 14A of the precipitated negative electrode lithium metal layer 14 can be made to be a shape that can suppress the amount of elongation that causes stress in the solid electrolyte layer 15.

[0027] In addition, from the viewpoint of suppressing the amount of expansion of the negative electrode lithium metal layer 14, the shape applied to the outer periphery of the high wettability layer 16 is not limited to an uneven shape. That is, the high wettability layer 16 can be adjusted to any shape as long as it functions to make the shape of the outer periphery 14A of the negative electrode lithium metal layer 14 formed during charging into a shape that reduces the amount of expansion. In particular, the high wettability layer 16 can take any shape that can form the periphery of the outer periphery 14A of the negative electrode lithium metal layer 14 formed during charging to be longer than the periphery of the similar shape of the solid electrolyte layer 15. The details will be described below.

[0028] FIG. 4 is a diagram for explaining the relationship between the shape of the outer periphery 14A of the negative electrode lithium metal layer 14 and the outer periphery shape of the solid electrolyte layer 15. Here, vertices s1 and e1 are set to define a certain outer periphery line C1 on the rectangular outer periphery of the solid electrolyte layer 15, and vertices s2 and e2 are set to define the outer periphery line C2 of the negative electrode lithium metal layer 14 facing the outer periphery line C1. In this case, the shape of the solid electrolyte layer 15 reduced in size is set as the similar shape of the solid electrolyte layer 15 according to a similarity ratio determined by the ratio between the length of the outer periphery line C1 of the solid electrolyte layer 15 and the straight-line distance between the vertices s2 and e2 that define the outer periphery line C2 of the negative electrode lithium metal layer 14. In the example shown in FIG. 4, the length of the outer periphery line C2 of the negative electrode lithium metal layer 14 (partial periphery along the uneven line) is formed longer than the length of the outer periphery line C'1 corresponding to the outer periphery line C1 in the similar shape of the solid electrolyte layer 15 (approximately equal to the straight-line distance between the vertices s2 and e2).

[0029] Thus, if the condition is satisfied that the length of the peripheral line C2 of the negative electrode lithium metal layer 14 formed during charging is longer than the length of the peripheral line C'1 in the similar shape of the solid electrolyte layer 15, a relief for stress during deformation of the negative electrode lithium metal layer 14 is ensured, and the amount of elongation of the negative electrode lithium metal layer 14 is reduced. Therefore, the high wettability layer 16 can take any shape as long as the shape of the peripheral line 14A of the negative electrode lithium metal layer 14 can be adjusted so that the length of the peripheral line C2 of the negative electrode lithium metal layer 14 formed during charging is longer than the length of the peripheral line C'1 in the similar shape of the solid electrolyte layer 15.

[0030] Next, materials constituting each element (negative electrode n, positive electrode p, and solid electrolyte layer 15) constituting the all-solid-state battery 10 according to this embodiment will be described.

[0031] [Negative electrode] The negative electrode n of this embodiment includes a negative electrode current collector 12 and a highly wettable layer 16.

[0032] (Negative electrode current collector 12) The material constituting the negative electrode current collector 12 is not particularly limited as long as it functions as a current collector applicable to the all-solid-state battery 10 in the technical field related to the present invention. For example, a metal or a resin having electrical conductivity can be used.

[0033] Specifically, examples of the material of the negative electrode current collector 12 include aluminum, nickel, iron, stainless steel, titanium, and copper. In addition to these, a clad material of nickel and aluminum, or a clad material of copper and aluminum may be used. Also, a foil in which a metal surface is coated with aluminum may be used. Among these, aluminum, stainless steel, copper, and nickel are preferred from the viewpoints of electronic conductivity, battery operating potential, and adhesion of the negative electrode active material to the current collector by sputtering.

[0034] The conductive resin used as the constituent material of the current collector may be a resin obtained by adding a conductive filler to a non-conductive polymeric material as required.

[0035] In particular, examples of non-conductive polymeric materials include polyethylene (PE; high density polyethylene (HDPE) or low density polyethylene (LDPE), etc.), polypropylene (PP), polyethylene terephthalate (PET), polyethernitrile (PEN), polyimide (PI), polyamideimide (PAI), polyamide (PA), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyvinylidene fluoride (PVdF), and polystyrene (PS).

[0036] (High wettability layer 16) The high-wettability layer 16 can be made of any material that has higher wettability with respect to metallic lithium than the solid electrolyte layer 15 and exhibits a certain level of ion conductivity. For example, the material of the high-wettability layer 16 can be an elemental metal selected from the group consisting of Au, Ag, copper, aluminum, magnesium, zinc, indium, gallium, tin, and bismuth, an alloy of two or more of the elemental metals, a carbon material, a plastic crystal, or an ionic liquid.

[0037] The thickness of the high wettability layer 16 is not particularly limited, but is preferably set to a suitable value in consideration of both the requirement for appropriate deposition of metallic lithium and the requirement for the thickness of the negative electrode lithium metal layer 14 to be at least a certain value in terms of maintaining the energy density. The area of ​​the high wettability layer 16 is also not particularly limited, but is preferably set to a suitable value in consideration of the balance between the requirement for maintaining the shape (uneven shape) of the outer periphery 14A of the negative electrode lithium metal layer 14 that contributes to suppressing stress and the requirement for increasing the energy density by securing the electrode area as much as possible.

[0038] The negative electrode n of this embodiment is produced by coating the high wettability layer 16 (including the uneven portion 16A) on the negative electrode current collector 12. The high wettability layer 16 can be coated on the negative electrode current collector 12 by a known coating method such as vapor deposition. Examples of such coating methods include electroless plating, sputtering, and vacuum deposition.

[0039] Furthermore, an appropriate space height is ensured between the negative electrode current collector 12 and the high wettability layer 16 in consideration of the deposition of the negative electrode lithium metal layer 14 .

[0040] [Positive electrode] The positive electrode p is composed of a positive electrode active material layer 17 and a positive electrode current collector 18 .

[0041] The positive electrode active material layer 17 is configured as an active material capable of reversibly absorbing and releasing lithium ions. For example, the material constituting the positive electrode active material layer 17 is, for example, a lithium metal composite oxide. More specifically, the lithium metal composite oxide may be a layered rock salt compound such as LiCoO2, LiMnO2, LiNiO2, LiVO2, or Li(Ni-Mn-Co)O2, LiMn2O4, or LiNi 0.5 Mn 1.5 Examples of lithium metal composite oxides other than those mentioned above include spinel-type compounds such as LiFePO4 and LiMnPO4, olivine-type compounds such as Li2FeSiO4 and Li2MnSiO4, and Si-containing compounds such as Li4Ti5O 12 Examples include:

[0042] The positive electrode current collector 18 can be made of the same material as the negative electrode current collector 12 .

[0043] [Solid electrolyte layer] The solid electrolyte layer 15 is a layer containing a solid electrolyte as a main component. Examples of the solid electrolyte include a sulfide solid electrolyte and an oxide solid electrolyte, and the sulfide solid electrolyte is preferable.

[0044] In particular, examples of sulfide solid electrolytes include LiI-Li2S-SiS2, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li2S-P2S5, LiI-Li3PS4, LiI-LiBr-Li3PS4, Li3PS4, Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-Li2O, Li2S-P2S5-Li2OLiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, and Li2S-SiS2-LiC. l , Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (however, m , nis a positive number, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, or Li2S-SiS2-Li x MO y (however, x , y is a positive number, and M is any of P, Si, Ge, B, Al, Ga, and In. The description "Li2S-P2S5" means a sulfide solid electrolyte obtained by using a raw material composition containing Li2S and P2S5, and the same applies to other descriptions.

[0045] The sulfide solid electrolyte may be a sulfide glass, a crystallized sulfide glass, or a crystalline material obtained by a solid phase method. The sulfide glass may be obtained, for example, by subjecting a raw material composition to mechanical milling (such as a ball mill).

[0046] [Effects] The configuration and the effects of the all-solid-state battery 10 of the present embodiment described above will be described together.

[0047] As described above, the all-solid-state battery 10 of this embodiment includes a solid electrolyte layer 15 and a negative electrode that is laminated on the solid electrolyte layer 15 and in which metallic lithium is precipitated between the solid electrolyte layer 15 and the negative electrode to form the negative electrode lithium metal layer 14 during charging. The negative electrode has a precipitation adjustment layer (high wettability layer 16) that has a wettability with respect to metallic lithium different from that of the solid electrolyte layer 15. Furthermore, the precipitation adjustment layer is disposed so that the perimeter of the outer periphery 14A of the negative electrode lithium metal layer 14 formed during charging is longer than the periphery of a similar shape to the outer periphery of the solid electrolyte layer 15.

[0048] This allows the precipitation adjustment layer to adjust the outer periphery 14A of the negative electrode lithium metal layer 14 formed during charging to a shape with less elongation (stretching amount) per periphery. This reduces the stress acting on the solid electrolyte layer 15 due to the stretching of the outer periphery 14A of the negative electrode lithium metal layer 14, making it possible to prevent the occurrence of cracks in the solid electrolyte layer 15.

[0049] In particular, the precipitation adjustment layer is constituted by a high wettability layer 16 having higher wettability with respect to metallic lithium than the solid electrolyte layer 15. Then, the high wettability layer 16 has an uneven portion 16A formed on at least a part of its outer periphery (the entire outer periphery in this embodiment).

[0050] As a result, metallic lithium that dissolves during charging is deposited in the portion of the high wettability layer 16 that has a higher wettability (affinity) to metallic lithium than the solid electrolyte layer 15. Therefore, the outer periphery 14A of the negative electrode lithium metal layer 14 is formed in an uneven shape that is substantially the same as the uneven portion 16A on the outer periphery 14A of the high wettability layer 16. Therefore, the circumferential length of the outer periphery 14A of the negative electrode lithium metal layer 14 is further increased, so that a clearance for deformation of the negative electrode lithium metal layer 14 is secured, and the amount of elongation of the outer periphery 14A in the direction that generates stress in the solid electrolyte layer 15 can be reduced. As a result, the effect of suppressing the stress generated in the solid electrolyte layer 15 can be further enhanced.

[0051] Furthermore, the protrusions 16Aa in the concave-convex portion 16A of the high wettability layer 16 are formed with an inclined shape that disperses the stress generated in the solid electrolyte layer 15 due to the expansion of metallic lithium during charging.

[0052] This suppresses the concentration of stress generated in solid electrolyte layer 15 in a specific direction, so that the occurrence of cracks in solid electrolyte layer 15 can be more reliably prevented.

[0053] Furthermore, in this embodiment, the width W of the recesses 16Ab and the length L of the protrusions 16Aa in the uneven portion 16A of the high wettability layer 16 are configured to be equal to or larger than the maximum diameter r of the solid electrolyte particles P that compose the solid electrolyte layer 15.

[0054] This makes it possible to more suitably maintain the uneven shape of the outer periphery 14A of the negative electrode lithium metal layer 14 formed during charging. More specifically, since metallic lithium is likely to precipitate within one solid electrolyte particle P, if the size of the recesses 16Ab of the high wettability layer 16 is smaller than the size of one solid electrolyte particle P, metallic lithium is likely to precipitate so as to fill the recesses 16Ab. In contrast, by configuring the size of the recesses 16Ab to be larger than the size of one solid electrolyte particle P, metallic lithium is prevented from being precipitated in the recesses 16Ab, and the outer periphery 14A of the negative electrode lithium metal layer 14 is more reliably formed into an uneven shape.

[0055] In particular, when the all-solid-state battery 10 is applied to an application requiring both miniaturization and operation at a high current density, such as mounting the battery on a vehicle (i.e., an application requiring high energy density for the all-solid-state battery 10), it is desirable to make the irregularities on the outer periphery 14A of the negative electrode lithium metal layer 14 as small as possible so as to ensure a certain or greater electrode area (area of ​​the negative electrode lithium metal layer 14) while realizing a ratio of the width W to the length L of the recess 16Ab that effectively reduces the amount of elongation due to the stretching of the negative electrode lithium metal layer 14. For this reason, it is also envisioned that the recess 16Ab of the high wettability layer 16 is configured to have a size on the same order as the size of one solid electrolyte particle P.

[0056] Even in such applications, as described above, by configuring the size of the uneven portion 16A of the high wettability layer 16 to exceed the size of a single solid electrolyte particle P, the uneven shape of the outer periphery 14A of the negative electrode lithium metal layer 14 can be suitably secured.

[0057] Moreover, in this embodiment, there is provided an all-solid-state battery 10 in a charged state, which includes a solid electrolyte layer 15 and a negative electrode laminated on the solid electrolyte layer 15. In this all-solid-state battery 10 in a charged state, the negative electrode has a precipitation adjustment layer (high wettability layer 16) applied to the solid electrolyte layer 15, and a negative electrode lithium metal layer 14 formed on the precipitation adjustment layer. The precipitation adjustment layer is configured so as to have wettability with respect to metallic lithium different from that of the solid electrolyte layer 15, and the shape of the outer periphery 14A of the negative electrode lithium metal layer 14 is formed so as to substantially match the shape of the outer periphery (uneven portion 16A) of the precipitation adjustment layer.

[0058] Furthermore, in this embodiment, there is provided an all-solid-state battery 10 in a discharged state, which includes a solid electrolyte layer 15 and a negative electrode laminated on the solid electrolyte layer 15. In this all-solid-state battery 10 in a discharged state, the negative electrode has a precipitation adjustment layer (high wettability layer 16) applied to the solid electrolyte layer 15, and a negative electrode current collector 12 arranged opposite the precipitation adjustment layer. The precipitation adjustment layer is configured so that its wettability with respect to metallic lithium is different from that of the solid electrolyte layer 15, and is arranged so that the perimeter of the outer periphery 14A of the negative electrode lithium metal layer 14 formed during charging is longer than the periphery of a similar shape to the outer periphery of the solid electrolyte layer 15.

[0059] Second embodiment The all-solid-state battery 10 according to the second embodiment will be described below. Note that the same elements as those in the first embodiment are given the same reference numerals, and the description thereof will be omitted.

[0060] Fig. 5 is a diagram illustrating the configuration of the all-solid-state battery 10 according to this embodiment. In particular, Fig. 5(a) shows a schematic cross-sectional structure of the negative electrode lithium metal layer 14 of the negative electrode n, and Fig. 5(b) shows the entire laminated structure of the cell unit 10A.

[0061] As shown in the figure, in the all-solid-state battery 10 of this embodiment, the area of ​​the positive electrode active material layer 17 is configured to be smaller than the area of ​​the negative electrode n (particularly, the area of ​​the high wettability layer 16). More specifically, the area of ​​the positive electrode active material layer 17 in the planar direction (hereinafter also referred to as the "positive electrode area pa") is contained within a planar region inside the outer periphery 14A (uneven portion) of the negative electrode lithium metal layer 14. That is, the positive electrode area pa is contained within the planar region of the high wettability layer 16.

[0062] If necessary, support members may be disposed on both sides of the positive electrode active material layer 17 (space portions not facing the negative electrode lithium metal layer 14) to stabilize the structure of the cell unit 10A.

[0063] In the all-solid-state battery 10 of this embodiment described above, the positive electrode presence range pa is configured to be contained inside the recesses 16Ab in the concave-convex portion 16A of the high wettability layer 16.

[0064] This allows the entire surface of the positive electrode active material layer 17 to face only the surface region (i.e., the portion other than the outer periphery 14A of the uneven shape) of the negative electrode lithium metal layer 14 that functions as the negative electrode active material. In other words, since the positive electrode active material layer 17 is configured not to face the uneven portion 16A of the high wettability layer 16, deposition of metallic lithium in the uneven portion 16A is suppressed, and the uneven shape of the outer periphery 14A of the negative electrode lithium metal layer 14 can be more reliably maintained.

[0065] The all-solid-state battery 10 of this embodiment is configured so that the outer edge of the positive electrode presence range pa is approximately aligned with the bottom surface of the recess 16Ab in the uneven portion 16A. That is, the area of ​​the positive electrode active material layer 17 is configured to be as large as possible within a range that does not overlap with the uneven portion 16A of the high wettability layer 16. This allows the energy density to be maintained by making the opposing area between the negative electrode lithium metal layer 14 and the positive electrode active material layer 17 as large as possible while maintaining the uneven shape of the outer periphery 14A of the negative electrode lithium metal layer 14.

[0066] Third embodiment The all-solid-state battery 10 according to the third embodiment will be described below. Note that the same elements as those in the first or second embodiment are given the same reference numerals, and the description thereof will be omitted.

[0067] Fig. 6 is a diagram illustrating the configuration of the all-solid-state battery 10 of this embodiment. In particular, Fig. 6(a) shows a schematic cross-sectional structure of the all-solid-state battery 10, and Fig. 5(b) shows the entire layered structure of the cell unit 10A.

[0068] As shown in the figure, the all-solid-state battery 10 of this embodiment is further provided with a restraining mechanism C. The restraining mechanism C is configured with a bolt mechanism that presses the end plates 40, 40 arranged at both ends in the stacking direction of the cell unit 10A in a direction toward each other. In particular, the restraining mechanisms C of this embodiment are provided in multiple numbers (four each in FIG. 6) along the extension directions of a pair of opposing sides 10Aa, 10Aa on the outer periphery of the cell unit 10A.

[0069] By providing such a restraint mechanism C, a load can be applied to the cell unit 10A to ensure good contact between the positive electrode active material layer 17 and the negative electrode lithium metal layer 14 functioning as the negative electrode active material, and the solid electrolyte layer 15 or the highly wettable layer 16.

[0070] In this embodiment, the uneven shape of the outer periphery 14A of the negative electrode lithium metal layer 14 is formed along the sides 10Aa, 10Aa where the constraint mechanism C is provided, while the sides where the constraint mechanism C is not provided are formed in a straight line. That is, the uneven portion 16A on the outer periphery of the high wettability layer 16 in this embodiment is provided only in the region facing the sides 10Aa, 10Aa where the constraint force (pressure in the stacking direction) by the constraint mechanism C acts relatively strongly.

[0071] The all-solid-state battery 10 of this embodiment described above further includes a restraining mechanism C that restrains the cell unit 10A as a cell stack including the solid electrolyte layer 15 and the negative electrode n in the stacking direction. The restraining mechanism C is disposed along a restrained region (sides 10Aa, 10Aa) that is a part of the outer periphery of the cell unit 10A. Furthermore, the uneven portion 16A is formed on the outer periphery of the high wettability layer 16 so as to face the sides 10Aa, 10Aa.

[0072] As a result, unevenness 16A that reduces the amount of elongation of negative electrode lithium metal layer 14 is formed in a portion of the outer periphery of high wettability layer 16 where the pressing force in the stacking direction by constraining mechanism C promotes the extension of negative electrode lithium metal layer 14, which generates stress in solid electrolyte layer 15, and the stress suppression effect of unevenness 16A can be more suitably exerted. On the other hand, by forming the outer periphery of high wettability layer 16, where the constraining force of constraining mechanism C does not directly act, into a linear shape, the electrode area can be enlarged while maintaining the stress suppression effect, thereby improving the energy density.

[0073] (Fourth embodiment) Hereinafter, the all-solid-state battery 10 of the fourth embodiment will be described. The same elements as those of the first embodiment will be denoted by the same reference numerals, and the description thereof will be omitted. In this embodiment, an example will be described in which a low-wettability layer 30 is provided as a precipitation adjustment layer instead of the high-wettability layer 16 described in the first to third embodiments.

[0074] FIG. 7 is a diagram for explaining the configuration of the all-solid-state battery 10 of this embodiment. FIG. 8 is a diagram for explaining the inner peripheral shape of the low wettability layer. As shown in the figure, in the all-solid-state battery 10 of this embodiment, a low wettability layer 30 as a precipitation adjustment layer is provided along the outer peripheral edge portion 15A of the solid electrolyte layer 15. In particular, the low wettability layer 30 is applied over the entire outer peripheral edge portion 15A except for the central surface region 15B of the solid electrolyte layer 15. In addition, an uneven portion 30A is formed on the inner peripheral portion of the low wettability layer 30.

[0075] The low-wettability layer 30 can be made of a material having lower wettability to metallic lithium than the solid electrolyte layer 15. Examples of materials for the low-wettability layer 30 include lithium nitride (Li3N) and lithium carbonate (Li2CO3). Similarly to the high-wettability layer 16, the low-wettability layer 30 is formed by coating the solid electrolyte layer 15 in the above-mentioned shape using a known method such as vapor deposition.

[0076] In the all-solid-state battery 10 of the present embodiment described above, the precipitation adjustment layer is configured as a low-wettability layer 30 having lower wettability with respect to metallic lithium than the solid electrolyte layer 15. The low-wettability layer 30 is provided along the outer peripheral edge portion 15A in the central surface region 15B of the solid electrolyte layer. Furthermore, an uneven portion 30A is formed on at least a part of the inner circumference of the low-wettability layer 30.

[0077] As a result, metallic lithium that dissolves during charging is collected in a portion (i.e., central surface region 15) other than outer peripheral edge portion 15A of solid electrolyte layer 15 where low wettability layer 30 is formed. That is, the region where negative electrode lithium metal layer 14 is formed can be adjusted within a surface region excluding outer peripheral edge portion 15A of solid electrolyte layer 15. In particular, since uneven portion 30A is formed on the inner circumference of low wettability layer 30, the shape of outer circumference 14A of negative electrode lithium metal layer 14 can be suitably maintained as an uneven shape that can suppress the amount of elongation of negative electrode lithium metal layer 14.

[0078] Fifth embodiment Hereinafter, the all-solid-state battery 10 according to the fifth embodiment will be described. Note that the same elements as those in the fourth embodiment are given the same reference numerals, and the description thereof will be omitted.

[0079] Fig. 9 is a diagram illustrating the configuration of the all-solid-state battery 10 of this embodiment. In particular, Fig. 9(a) shows a schematic cross-sectional structure of the negative electrode lithium metal layer 14 of the negative electrode n, and Fig. 9(b) shows the entire laminated structure of the cell unit 10A.

[0080] As shown in the figure, in the all-solid-state battery 10 of this embodiment, the area of ​​the positive electrode active material layer 17 is configured to be smaller than the area of ​​the negative electrode n. More specifically, the positive electrode presence range pa, which is the presence range of the positive electrode active material layer 17 in the planar direction, extends to the bottom surface of the recess in the uneven portion 30A of the low wettability layer 30.

[0081] This allows the opposing area between negative electrode lithium metal layer 14 and positive electrode active material layer 17 to be as large as possible, while maintaining the uneven shape of outer periphery 14A of negative electrode lithium metal layer 14, thereby maintaining the energy density.

[0082] (Modification) The configuration of the all-solid-state battery 10 according to the modified example will be described below.

[0083] Fig. 10 is a diagram for explaining the configuration of an all-solid-state battery 10 according to a first modified example. Fig. 11 is a diagram for explaining the configuration of an all-solid-state battery 10 according to a second modified example. In both of the modified examples shown in Fig. 10 and Fig. 11, the shape of the concave-convex portion 16A (particularly the shape of the convex portion 16Aa) formed on the outer periphery of the high wettability layer 16 is formed into a shape different from the shape (trapezoid) explained in Fig. 3.

[0084] Specifically, in a first modified example shown in Fig. 10, the side surface of the protrusion 16Aa is configured to have a plurality of inclined shapes with different angles (two in Fig. 10), and in a second modified example shown in Fig. 11, the side surface of the protrusion 16Aa is formed in a curved shape.

[0085] This allows the shape of the projections and recesses 16A of the high wettability layer 16 to be varied in order to suitably distribute the direction of stress depending on the direction of stress concentration that may occur in the solid electrolyte layer.

[0086] Incidentally, the uneven portion 16A of the high wettability layer 16 may be configured in a shape other than that shown in the above embodiment and each modified example, so long as the outer periphery 14A of the negative electrode lithium metal layer 14 formed during charging can be made to have a function of reducing the amount of elongation of the outer periphery 14A. For example, although the effect of dispersing stress is reduced, the protruding portion 16Aa of the uneven portion 16A may be formed in a simple rectangular shape (a shape having no inclination or curvature on the side) to simplify the manufacturing process of the high wettability layer 16.

[0087] Moreover, the shape of the concave-convex portion 30A on the inner periphery of the low-wettability layer 30 described in the fourth embodiment can also be changed in the same manner as the concave-convex portion 16A of the high-wettability layer 16.

[0088] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and the technical scope of the present invention is not limited to the specific configurations of the above-mentioned embodiments. In addition, the above-mentioned embodiments can be appropriately combined.

[0089] For example, the all-solid-state battery 10 of the present embodiment can be configured as a stacked battery in which a plurality of stacked cell units 10A are sealed with an exterior material depending on the application. In addition, the appearance of the all-solid-state battery 10 of the present embodiment and the internal electrical connection state (electrode structure) are not particularly limited. The appearance of the all-solid-state battery 10 may be, for example, a flattened rectangular shape, or a circular or elliptical shape. Alternatively, the all-solid-state battery 10 may be configured as a cylindrical type in which one or more cell units 10A are wound and housed. In addition, the electrode structure of the all-solid-state battery 10 may be either a so-called non-bipolar type (internal parallel connection type) or a bipolar type (internal series connection type). [Explanation of symbols]

[0090] 10 All-solid-state battery 10A cell unit 10Aa side 12 Negative electrode current collector 14 Negative electrode lithium metal layer 14A Outer circumference 14Aa Convex part 14Ab Recess 15 Solid electrolyte layer 15A Outer edge 15B Central plane area 16 Highly wettable layer 16A Uneven part 16Aa Convex part 16Ab Recess 17 Cathode active material layer 18 Positive electrode current collector 20 Laminate material 30 Low wettability layer 30A uneven part 40 End Plate

Claims

1. 1. An all-solid-state battery comprising: a solid electrolyte layer; and an anode laminated on the solid electrolyte layer, the anode having a lithium metal layer formed between the solid electrolyte layer and the anode and having metallic lithium deposited between the solid electrolyte layer and the anode during charging, the negative electrode has a precipitation adjustment layer having a wettability with respect to the metallic lithium different from that of the solid electrolyte layer, The precipitation adjustment layer is a high-wettability layer that is formed in a film shape and applied to the solid electrolyte layer, the high-wettability layer having a higher wettability with respect to the metallic lithium than the solid electrolyte layer; An uneven portion is formed on at least a part of the outer periphery, The convex portions of the concave-convex portion are formed in an inclined or curved shape that disperses stress generated in the solid electrolyte layer due to expansion of the metallic lithium during charging. All-solid-state battery.

2. The all-solid-state battery according to claim 1 , a width of a concave portion and a length of a convex portion in the concave-convex portion are configured to be equal to or greater than a diameter of a solid electrolyte particle constituting the solid electrolyte layer. All-solid-state battery.

3. The all-solid-state battery according to claim 1 or 2, the positive electrode surface is located within a region inside the concave portions of the concave-convex portion of the high wettability layer; All-solid-state battery.

4. The all-solid-state battery according to any one of claims 1 to 3, a restraining mechanism for restraining a cell stack including the solid electrolyte layer and the negative electrode in a stacking direction; The restraining mechanism is disposed along a restrained region that is a part of an outer periphery of the cell stack, the concave-convex portion is formed on the outer periphery of the high wettability layer so as to face the constrained region; All-solid-state battery.

5. An all-solid-state battery including a solid electrolyte layer and an anode laminated on the solid electrolyte layer, the anode having a lithium metal layer formed between the solid electrolyte layer and the anode by deposition of metallic lithium between the solid electrolyte layer and the anode during charging, the negative electrode has a precipitation adjustment layer having a wettability with respect to the metallic lithium different from that of the solid electrolyte layer, the precipitation adjustment layer is applied to the solid electrolyte layer and is configured as a low-wettability layer having a lower wettability with respect to the metallic lithium than the solid electrolyte layer; the low wettability layer is provided along an outer peripheral edge portion of the solid electrolyte layer excluding a central surface region, An uneven portion is formed on at least a part of the inner periphery of the low wettability layer. All-solid-state battery.

6. The all-solid-state battery according to claim 5 , The positive electrode surface is configured to extend to at least the bottom surface of the recess in the uneven portion of the low wettability layer. All-solid-state battery.

7. The all-solid-state battery according to any one of claims 1 to 6, The precipitation adjustment layer is disposed on a surface of the solid electrolyte layer. All-solid-state battery.

8. An all-solid-state battery including a solid electrolyte layer and a negative electrode laminated on the solid electrolyte layer, The negative electrode has a precipitation adjustment layer applied to the solid electrolyte layer and a negative electrode lithium metal layer formed on the precipitation adjustment layer, The precipitation adjustment layer is a high wettability layer having a higher wettability with respect to metallic lithium than the solid electrolyte layer; It is structured like a membrane, An uneven portion is formed on at least a part of the outer periphery, The negative electrode lithium metal layer is formed so that its outer periphery shape coincides with that of the precipitation adjustment layer, The convex portions of the concave-convex portion are formed in an inclined or curved shape that disperses stress generated in the solid electrolyte layer due to expansion of the metallic lithium during charging. All-solid-state battery.

9. An all-solid-state battery including a solid electrolyte layer and a negative electrode laminated on the solid electrolyte layer, The negative electrode has a precipitation adjustment layer applied to the solid electrolyte layer and a negative electrode current collector disposed opposite the precipitation adjustment layer, The precipitation adjustment layer is a high wettability layer having a higher wettability with respect to metallic lithium than the solid electrolyte layer; It is structured like a membrane, An uneven portion is formed on at least a part of the outer periphery, The convex portions of the concave-convex portion are formed in an inclined or curved shape that disperses stress generated in the solid electrolyte layer due to expansion of the metallic lithium during charging. All-solid-state battery.

10. An all-solid-state battery comprising a solid electrolyte layer and a negative electrode laminated on the solid electrolyte layer, The negative electrode has a precipitation adjustment layer applied to the solid electrolyte layer and a negative electrode lithium metal layer formed on the precipitation adjustment layer, the precipitation adjustment layer is applied to the solid electrolyte layer and is configured as a low-wettability layer having a lower wettability with respect to metallic lithium than the solid electrolyte layer; the low wettability layer is provided along an outer peripheral edge portion of the solid electrolyte layer excluding a central surface region, an uneven portion is formed on at least a part of the inner periphery of the low wettability layer; The negative electrode lithium metal layer is formed so that its outer periphery shape coincides with the inner periphery shape of the low wettability layer. All-solid-state battery.

11. An all-solid-state battery comprising a solid electrolyte layer and a negative electrode laminated on the solid electrolyte layer, The negative electrode has a precipitation adjustment layer applied to the solid electrolyte layer and a negative electrode current collector disposed opposite the precipitation adjustment layer, the precipitation adjustment layer is applied to the solid electrolyte layer and is configured as a low-wettability layer having a lower wettability with respect to metallic lithium than the solid electrolyte layer; the low wettability layer is provided along an outer peripheral edge portion of the solid electrolyte layer excluding a central surface region, An uneven portion is formed on at least a part of the inner periphery of the low wettability layer. All-solid-state battery.

Images