JP2021192354A - All-solid battery - Google Patents

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

The present invention relates to an all-solid-state battery.

In Patent Document 1, unevenness is provided on the outer periphery of the positive electrode to increase the peripheral length to form a relief allowance for deformation of the positive electrode, and by reducing the amount of elongation of the outer peripheral edge of the positive electrode, the outer peripheral edge of the positive electrode and the solid state are formed during press molding. An all-solid-state battery configured to reduce the stress generated in the contact portion of the electrolyte layer has been proposed.

Patent No. 5831442

Here, in recent years, an all-solid-state battery having a structure in which only lithium in the positive electrode active material is used as a lithium source (hereinafter, also referred to as “all-precipitation all-solid-state battery” in the present specification) is known. In this type of all-solid-state battery, the negative electrode does not contain lithium metal during discharge, and lithium metal precipitates on the negative electrode current collector during charging to form a lithium metal layer. In this case, since the precipitated lithium metal stretches toward the outside of the solid electrolyte layer, stress is applied to the solid electrolyte layer, which may cause cracks that cause a short circuit.

Therefore, the present invention is to provide an all-solid-state battery capable of suppressing the occurrence of cracks in the solid electrolyte layer, which causes a short circuit.

According to an aspect of the present invention, the negative electrode is laminated on the solid electrolyte layer and the negative electrode lithium metal layer is formed by precipitating metallic lithium between the solid electrolyte layer and the solid electrolyte layer during charging. All-solid-state batteries are provided, including. The negative electrode has a precipitation adjusting layer whose wettability with respect to metallic lithium is different from that of the solid electrolyte layer. Further, the precipitation adjusting layer is arranged so that the peripheral length of the outer periphery of the negative electrode lithium metal layer formed during charging is longer than the peripheral length of the outer circumference having a similar shape to the solid electrolyte layer.

According to the present invention, it is possible to suppress the occurrence of cracks in the solid electrolyte layer, which causes a short circuit.

FIG. 1 is a diagram illustrating a configuration of an all-solid-state battery according to the first embodiment of the present invention. FIG. 2 is a diagram illustrating each state of the negative electrode during discharge and charge. FIG. 3 is a diagram illustrating the configuration of the uneven portion of the highly wettable layer. FIG. 4 is a diagram illustrating the relationship between the outer peripheral shape of the negative electrode lithium metal layer and the outer peripheral shape of the solid electrolyte layer. FIG. 5 is a diagram illustrating a configuration of an all-solid-state battery according to the second embodiment. FIG. 6 is a diagram illustrating a configuration of an all-solid-state battery according to the third embodiment. FIG. 7 is a diagram illustrating a configuration of an all-solid-state battery according to the fourth embodiment. FIG. 8 is a diagram illustrating the inner peripheral shape of the low wetting layer. FIG. 9 is a diagram illustrating a configuration of an all-solid-state battery according to the fifth embodiment. FIG. 10 is a diagram illustrating a configuration of an all-solid-state battery according to the first modification. FIG. 11 is a diagram illustrating a configuration of an all-solid-state battery according to a second modification.

Hereinafter, each embodiment of the present invention will be described.

(First Embodiment)
The all-solid-state battery 10 according to the first embodiment of the present invention will be described.

FIG. 1 is a diagram illustrating the configuration of the all-solid-state battery 10 of the present embodiment. As shown in the figure, the all-solid-state battery 10 includes a cell unit 10A (one in FIG. 1) in which one or a plurality of cell units in which a solid electrolyte layer 15 is laminated between a positive electrode p and a negative electrode n are laminated. , An all-precipitation all-solid-state battery configured by sealing with a laminate 20. Further, electrical wiring (positive electrode lead, negative electrode lead, positive electrode current collector plate, negative electrode current collector plate, etc.) (such as a positive electrode lead, a negative electrode lead, and a negative electrode current collector plate) extending from the laminated material 20 are connected to the cell unit 10A.

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

The positive electrode p is mainly a positive electrode active material layer 17 laminated on one side surface (lower surface in the figure) in the stacking direction of the solid electrolyte layer 15, and a positive electrode current collector 18 connected to the positive electrode active material layer 17. And.

The negative electrode n is mainly a highly wettable layer 16 laminated on the other side surface (lower surface in the drawing) in the stacking direction of the solid electrolyte layer 15, and a negative electrode lithium metal layer 14 formed on the highly wettable layer 16. And a negative electrode current collector 12 connected to the negative electrode lithium metal layer 14. In this embodiment, the highly wettable layer 16 functions as a precipitation adjusting layer.

Here, the negative electrode lithium metal layer 14 is not generated in the discharged state, and metallic lithium is generated in the surface region (region of the highly wettable layer 16) of the solid electrolyte layer 15 and the negative electrode current collector 12 through the charging process. It is formed by precipitating.

The highly wettable 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 highly wettable layer 16 has a higher wettability to metallic lithium dissolved between the solid electrolyte layer 15 and the negative electrode current collector 12 during charging than the solid electrolyte layer 15, and is constant from the viewpoint of ensuring the conduction of lithium ions. It is formed of a material having ionic conductivity.

Hereinafter, the configuration and function of the highly wettable layer 16 will be described in more detail.

FIG. 2 is a diagram illustrating each state of the negative electrode n at the time of discharging and at the time of charging. In particular, FIGS. 2A and 2B are arrow views of the main parts AA of FIG. 1 in the discharged state and the charged state, respectively.

As shown in the figure, the negative electrode n at the time of discharge has a structure in which the highly wettable layer 16 is applied to the solid electrolyte layer 15 in the central surface region 15B excluding the outer peripheral edge portion 15A. Further, as described above, the uneven portion 16A is formed on the outer periphery of the highly wettability layer 16.

On the other hand, at the time of charging, lithium ions from the positive electrode active material layer 17 entered the solid electrolyte layer 15 or the highly wettable layer 16 and precipitated by alloying with the metal constituting the solid electrolyte layer 15 or the highly wettable layer 16. Form metallic lithium in the state. Then, the metallic lithium diffuses into the surface region of the solid electrolyte layer 15 or the highly wettable layer 16 to form the negative electrode lithium metal layer 14.

In particular, the negative electrode lithium metal layer 14 of the present embodiment is formed on the portion of the highly wettable layer 16 having a higher affinity for metallic lithium. More specifically, in the present embodiment, since the wettability of the highly wettable layer 16 to metallic lithium is higher than that of the solid electrolyte layer 15, metallic lithium gathers and precipitates on the highly wettable 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. Then, as described above, where the uneven portion 16A is formed on the outer periphery of the highly wettable layer 16, the outer peripheral 14A of the generated negative electrode lithium metal layer 14 also has an uneven shape having substantially the same shape as the uneven portion 16A. It will be formed. At the time of discharge, the negative electrode lithium metal layer 14 becomes smaller and almost disappears when the discharge progresses beyond a certain level.

FIG. 3 is a diagram illustrating a detailed structure of the uneven portion 16A of the highly wettability layer 16. Note that FIG. 3 shows the uneven shape of the negative electrode lithium metal layer 14 generated from the viewpoint of avoiding the complexity of the drawings. However, as described above, since the uneven shape is substantially the same as the shape of the uneven portion 16A of the high wettability layer 16, the uneven shape of the negative electrode lithium metal layer 14 shown in FIG. 3 is the uneven shape of the high wettability layer 16. The explanation will be given by equating with 16A.

As shown in the figure, uneven portions 16A are formed on the outer periphery of the highly wettable layer 16 of the present embodiment over the entire circumference thereof. In the present embodiment, the convex portion 16Aa of the concave-convex portion 16A is formed in a shape in which the opposite side portions are non-parallel to each other in a cross-sectional view, particularly in a trapezoidal shape. That is, the side surface of the convex portion 14Aa is formed as an inclined surface. Therefore, the outer peripheral surface 14A of the negative electrode lithium metal layer 14 is deposited with the same uneven shape as the uneven portion 16A. Therefore, the stress in the direction of causing cracks in the solid electrolyte layer 15 (see the white arrow) is dispersed in the direction corresponding 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 peripheral surface 14A of the negative electrode lithium metal layer 14 can be shaped to preferably disperse the stress that causes cracks.

Further, the width W of the concave portion 16Ab and the length L of the convex portion 16Aa in the uneven portion 16A are configured to have a maximum diameter r or more of one solid electrolyte particle P constituting the solid electrolyte layer 15.

Thereby, the shape of the concave portion 14Ab of the outer peripheral 14A of the negative electrode lithium metal layer 14 formed at the time of charging can be more preferably maintained. More specifically, since metallic lithium is likely to precipitate in one solid electrolyte particle P, when the size of the recess 16Ab of the highly wettable layer 16 is smaller than the size of one solid electrolyte particle P, the metallic lithium is recessed. It becomes easy to precipitate so as to fill 16Ab. On the other hand, since the size of the recess 16Ab is larger than the size of one solid electrolyte particle P, it is possible to prevent metallic lithium from being deposited in the recess 16Ab. The outer peripheral surface 14A will be more reliably formed into an uneven shape.

As described above, in the all-solid-state battery 10 of the present embodiment, the solid electrolyte layer 15 has a highly wettability layer 16 having a higher wettability to metallic lithium than the solid electrolyte layer 15 and having an uneven portion 16A formed on the outer periphery thereof. The shape of the outer peripheral surface 14A of the deposited negative electrode lithium metal layer 14 can be made into a shape capable of suppressing the amount of elongation that causes stress in the solid electrolyte layer 15.

From the viewpoint of suppressing the amount of elongation of the negative electrode lithium metal layer 14 described above, the shape applied to the outer periphery of the highly wettable layer 16 is not limited to the uneven shape. That is, the highly wettable layer 16 can be adjusted to any shape as long as it functions to reduce the amount of elongation of the outer peripheral surface 14A of the negative electrode lithium metal layer 14 formed during charging. In particular, the highly wettable layer 16 takes an arbitrary form in which the peripheral length of the outer peripheral 14A of the negative electrode lithium metal layer 14 formed during charging can be made longer than the peripheral length of the outer circumference having a similar shape to the solid electrolyte layer 15. The details will be described below.

FIG. 4 is a diagram illustrating the relationship between the shape of the outer peripheral surface 14A of the negative electrode lithium metal layer 14 and the outer peripheral shape of the solid electrolyte layer 15. Here, the vertices s1 and the vertices e1 that define the outer peripheral line C1 on the rectangular outer circumference of the solid electrolyte layer 15 are set, and the vertices s2 that define the outer peripheral line C2 of the negative electrode lithium metal layer 14 facing the outer peripheral line C1 are set. And the vertex e2 are set. In this case, the solid electrolyte is determined by the similarity ratio determined by the ratio between the length of the outer peripheral line C1 of the solid electrolyte layer 15 and the linear distance between the apex s2 and the apex e2 defining the outer peripheral line C2 of the negative electrode lithium metal layer 14. The reduced shape of the layer 15 is set as a similar shape of the solid electrolyte layer 15. Then, in the example shown in FIG. 4, the length of the outer peripheral line C2 of the negative electrode lithium metal layer 14 (the partial peripheral length along the uneven line) is the outer circumference corresponding to the outer peripheral line C1 in the similar shape of the solid electrolyte layer 15. It is formed longer than the length of the line C'1 (which substantially corresponds to the linear distance between the vertices s2 and the vertices e2).

If the condition that the length of the outer peripheral line C2 of the negative electrode lithium metal layer 14 formed during charging is longer than the length of the outer peripheral line C'1 in the similar shape of the solid electrolyte layer 15, the negative electrode lithium is satisfied. Since the stress relief allowance at the time of deformation of the metal layer 14 is secured, the amount of elongation of the negative electrode lithium metal layer 14 is reduced. Therefore, in the highly wettable layer 16, the length of the outer peripheral line C2 of the negative electrode lithium metal layer 14 formed during charging is longer than the length of the outer peripheral line C'1 in the similar shape of the solid electrolyte layer 15. Any form can be taken as long as the shape of the outer peripheral surface 14A of the negative electrode lithium metal layer 14 can be adjusted.

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

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

(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 according to the present invention. For example, a metal or a resin having conductivity can be adopted.

Specifically, examples of the constituent 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, a clad material of copper and aluminum, and the like may be used. Further, the foil may be a metal surface coated with aluminum. Of these, aluminum, stainless steel, copper, or nickel is preferable from the viewpoints of electron conductivity, battery operating potential, adhesion of the negative electrode active material by sputtering to the current collector, and the like.

Examples of the conductive resin used as a constituent material of the current collector include a resin in which a conductive filler is added to a non-conductive polymer material as needed.

In particular, examples of the non-conductive polymer material include polyethylene (PE; high density polyethylene (HDPE), low density polyethylene (LDPE), etc.), polypropylene (PP), polyethylene terephthalate (PET), and polyether nitrile (PEN). ), Polyethylene (PI), Polyethyleneimide (PAI), Polyethylene (PA), Polytetrafluoroethylene (PTFE), Styrene-butadiene rubber (SBR), Polyacrylonitrile (PAN), Polymethylacrylate (PMA), Polymethylmethacrylate (PMMA), polyvinyl chloride (PVC), polyvinylidene fluoride (PVdF), polystyrene (PS) and the like.

(Highly wettable layer 16)
The highly wettable layer 16 can be made of any material that has higher wettability to metallic lithium than the solid electrolyte layer 15 and exhibits ionic conductivity of a certain level or higher. For example, as the material of the highly wettable layer 16, a simple substance selected from the group consisting of Au, Ag, copper, aluminum, magnesium, zinc, indium, gallium, tin, and bismuth, and two or more elemental metals. Examples include alloys, carbon materials, plastic crystals, or ionic liquids.

The thickness of the highly wettable layer 16 is not particularly limited, but there is a requirement that the thickness of the negative electrode lithium metal layer 14 should be a certain value or more from the viewpoint of properly precipitating metallic lithium and maintaining the energy density. It is preferable to set a suitable value in consideration of both. Further, the area of the highly wettable layer 16 is not particularly limited, but the requirement to maintain the shape (concave and convex shape) of the outer peripheral 14A of the negative electrode lithium metal layer 14 that contributes to the suppression of stress and the electrode area are secured as much as possible. It is preferable that the value is appropriately set in consideration of the balance between the demand for increasing the energy density and the demand for increasing the energy density.

The negative electrode n of the present embodiment is produced by coating the negative electrode current collector 12 with the highly wettable layer 16 (including the uneven portion 16A). The coating of the highly wettable layer 16 on the negative electrode current collector 12 can be performed by a known coating method such as thin film deposition. Examples of such a coating method include an electroless plating method, a sputtering method, a vacuum vapor deposition method, and the like.

Further, an appropriate space height is secured between the negative electrode current collector 12 and the highly wettable layer 16 in consideration of precipitation of the negative electrode lithium metal layer 14.

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

The positive electrode active material layer 17 is configured as an active material capable of reversibly occluding 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, examples of the lithium metal composite oxide include _{layered rock salt compounds such as LiCoO 2} , LiMnO ₂ , LiNiO ₂ , LiVO ₂ , or Li (Ni—Mn—Co) O2, LiMn ₂ O ₄ , or LiNi _0.5. Examples thereof include spinnel-type compounds such as Mn _1.5 O ₄ , olivine-type compounds such as _{LiFePO 4} or LiMnPO ₄ , and Si-containing compounds such as _{Li 2} FeSiO ₄ or Li _{2 MnSiO 4.} Examples of the lithium metal composite oxide other than the above include Li ₄ Ti ₅ O ₁₂ .

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

[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 a sulfide solid electrolyte is preferable.

In particular, examples of the sulfide solid electrolyte include LiI-Li ₂ S-SiS ₂ , LiI-Li ₂ S-P2O ₅ , LiI-Li ₃ PO _4- P ₂ S _{5 , Li 2} SP 2 S 5, and Li _{2 SP 2} S ₅ . _{LiI-Li 3 PS 4, LiI} -LiBr-Li 3 PS 4, Li 3 PS 4, Li 2 S-P 2 S 5, Li 2 S-P 2 S 5 -LiI, Li 2 S-P 2 S 5 - Li ₂ O, Li ₂ S-P ₂ S _{5 -Li 2} OLiI, Li ₂ S-SiS ₂ , Li ₂ S-SiS _2- LiI, Li ₂ S-SiS _2- LiBr, Li ₂ S-SiS _2- LiC _l , Li ₂ S-SiS _2- B ₂ S _3- LiI, Li ₂ S-SiS _2- P ₂ S _5- LiI, Li _{2 SB 2} S ₃ , Li _{2 SP 2} S _5- Z _m S _n (where _m and _n are positive numbers and Z is one of Ge, Zn or Ga), Li ₂ S-GeS ₂ , Li ₂ S-SiS _{2 -Li 3} PO ₄ or Examples thereof include Li ₂ S-SiS _{2 -Li x} MO _y (where _x and _y are positive numbers, and M is any of P, Si, Ge, B, Al, Ga, and In). .. The description of "Li ₂ SP ₂ S ₅ " means a sulfide solid electrolyte using a raw material composition containing _{Li 2} S and P ₂ S _{5, and the same applies to other descriptions.}

Further, the sulfide solid electrolyte may be sulfide glass, crystallized sulfide glass, or a crystalline material obtained by a solid phase method. The sulfide glass can be obtained, for example, by performing mechanical milling (ball mill or the like) on the raw material composition.

[Action effect]
The configuration of the all-solid-state battery 10 of the present embodiment described above and its action and effect will be collectively described.

As described above, the all-solid-state battery 10 of the present embodiment, the solid electrolyte layer 15, and the solid electrolyte layer 15 are laminated, and metallic lithium is deposited between the solid electrolyte layer 15 during charging to cause negative electrode lithium. Includes a negative electrode on which the metal layer 14 is formed. The negative electrode has a precipitation adjusting layer (highly wettability layer 16) whose wettability with respect to metallic lithium is different from that of the solid electrolyte layer 15. Further, the precipitation adjusting layer is arranged so that the circumference of the outer circumference 14A of the negative electrode lithium metal layer 14 formed during charging is longer than the circumference of the outer circumference of the solid electrolyte layer 15 having a similar shape.

Thereby, by the function of the precipitation adjusting layer, the outer peripheral surface 14A of the negative electrode lithium metal layer 14 formed at the time of charging can be adjusted to a shape having a small elongation amount (stretching amount) per peripheral length. Therefore, the stress acting on the solid electrolyte layer 15 due to the stretching of the outer peripheral 14A of the negative electrode lithium metal layer 14 is reduced, and the generation of cracks in the solid electrolyte layer 15 can be prevented.

In particular, the precipitation adjusting layer is composed of a highly wettability layer 16 having a higher wettability to metallic lithium than the solid electrolyte layer 15. Then, the uneven portion 16A is formed on at least a part of the outer circumference of the highly wettability layer 16 (in the present embodiment, the entire outer circumference).

As a result, the metallic lithium that dissolves during charging is deposited at the portion of the highly wettable layer 16 that has a higher wettability (affinity) with respect to the metallic lithium than the solid electrolyte layer 15. Therefore, the outer peripheral surface 14A of the negative electrode lithium metal layer 14 is formed on the outer peripheral surface 14A of the high wettability layer 16 in a concavo-convex shape substantially the same as the concavo-convex portion 16A. Therefore, since the peripheral length of the outer peripheral 14A of the negative electrode lithium metal layer 14 is further increased, a relief allowance for deformation of the negative electrode lithium metal layer 14 is secured, and the outer circumference in a direction in which stress is generated in the solid electrolyte layer 15. The amount of elongation of 14A can be reduced. As a result, the effect of suppressing the stress generated in the solid electrolyte layer 15 can be further enhanced.

Further, the convex portion 16Aa in the uneven portion 16A of the highly wettable layer 16 is formed with an inclined shape that disperses the stress generated in the solid electrolyte layer 15 due to the stretching of metallic lithium during charging.

As a result, the concentration of stress generated in the solid electrolyte layer 15 in a specific direction is suppressed, so that the generation of cracks in the solid electrolyte layer 15 can be more reliably prevented.

Further, in the present embodiment, the width W of the concave portion 16Ab and the length L of the convex portion 16Aa in the uneven portion 16A of the highly wettable layer 16 are configured to be equal to or larger than the maximum diameter r of the solid electrolyte particles P constituting the solid electrolyte layer 15. Will be done.

Thereby, the uneven shape of the outer peripheral surface 14A of the negative electrode lithium metal layer 14 formed at the time of charging can be more preferably maintained. More specifically, since metallic lithium is likely to precipitate in one solid electrolyte particle P, when the size of the recess 16Ab of the highly wettable layer 16 is smaller than the size of one solid electrolyte particle P, the metallic lithium is recessed. It becomes easy to precipitate so as to fill 16Ab. On the other hand, since the size of the recess 16Ab is larger than the size of one solid electrolyte particle P, it is suppressed that metallic lithium is deposited in the recess 16Ab, and the outer periphery 14A of the negative electrode lithium metal layer 14 is suppressed. Will be more reliably formed into a concavo-convex shape.

In particular, when it is applied to applications where both miniaturization and operation at a high current density are required (that is, applications where a high energy density is required for the all-solid-state battery 10) such as mounting the all-solid-state battery 10 in a vehicle. In, the electrode area (area of the negative electrode lithium metal layer 14) is kept above a certain level while realizing the ratio of the width W and 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. It is desired to make the unevenness of the outer peripheral surface 14A of the negative electrode lithium metal layer 14 as small as possible so that it can be secured. Therefore, it is assumed that the recess 16Ab of the highly wettable layer 16 is configured to have a size on the order equivalent to the size of one solid electrolyte particle P.

Even in such an application, if the size of the uneven portion 16A of the highly wettable layer 16 exceeds the size of one solid electrolyte particle P as described above, the uneven shape of the outer peripheral portion 14A of the negative electrode lithium metal layer 14 Will be suitably secured.

Further, in the present embodiment, the all-solid-state battery 10 in a charged state including the solid electrolyte layer 15 and the negative electrode laminated on the solid electrolyte layer 15 is provided. In the all-solid-state battery 10 in the charged state, the negative electrode has a precipitation adjusting layer (highly wettable layer 16) applied to the solid electrolyte layer 15 and a negative electrode lithium metal layer 14 formed on the precipitation adjusting layer. The precipitation adjusting layer is configured so that the wettability with respect to metallic lithium is 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 substantially matches the shape of the outer periphery (concave and convex portion 16A) of the precipitation adjusting layer. It is formed to do.

Further, in the present embodiment, an all-solid-state battery 10 in a discharged state including a solid electrolyte layer 15 and a negative electrode laminated on the solid electrolyte layer 15 is provided. In the all-solid-state battery 10 in this discharged state, the negative electrodes are a precipitation adjusting layer (highly wettable layer 16) applied to the solid electrolyte layer 15 and a negative electrode current collector 12 arranged to face the precipitation adjusting layer. , Have. The precipitation adjusting layer is configured so that the wettability with respect to metallic lithium is different from that of the solid electrolyte layer 15, and the peripheral length of the outer peripheral 14A of the negative electrode lithium metal layer 14 formed during charging is similar to that of the outer peripheral of the solid electrolyte layer 15. It is arranged so as to be longer than the circumference of the shape.

(Second Embodiment)
Hereinafter, the all-solid-state battery 10 of the second embodiment will be described. The same elements as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 5 is a diagram illustrating the configuration of the all-solid-state battery 10 according to the present embodiment. In particular, FIG. 5A shows a schematic cross-sectional structure of a portion of the negative electrode lithium metal layer 14 of the negative electrode n, and FIG. 5B shows the entire laminated structure of the cell unit 10A.

As shown in the figure, in the all-solid-state battery 10 of the present embodiment, the area of the positive electrode active material layer 17 is smaller than the area of the negative electrode n (particularly, the area of the highly wettable layer 16). More specifically, the presence range of the positive electrode active material layer 17 in the surface direction (hereinafter, also referred to as “positive electrode existence range pa”) is contained within the surface region inside the outer peripheral surface 14A (concave and convex portion) of the negative electrode lithium metal layer 14. ing. That is, the positive electrode presence range pa is contained within the surface region of the high wettability layer 16.

If necessary, support members may be arranged on both sides of the positive electrode active material layer 17 (the space portion where the negative electrode lithium metal layer 14 does not face) to stabilize the structure of the cell unit 10A.

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

As a result, the entire surface of the positive electrode active material layer 17 can be opposed only to the surface region of the negative electrode lithium metal layer 14 that functions as the negative electrode active material (that is, the portion other than the outer peripheral surface 14A of the uneven shape). That is, since the positive electrode active material layer 17 does not face the uneven portion 16A of the highly wettable layer 16, precipitation of metallic lithium in the uneven portion 16A is suppressed, and the uneven shape of the outer peripheral 14A of the negative electrode lithium metal layer 14 is formed. It can be maintained more reliably.

The all-solid-state battery 10 of the present embodiment is configured such that the outer edge of the positive electrode presence range pa substantially coincides with the bottom surface of the recess 16Ab in the concave-convex 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. As a result, the energy density can be maintained by making the facing area between the negative electrode lithium metal layer 14 and the positive electrode active material layer 17 as wide as possible while maintaining the uneven shape of the outer peripheral surface 14A of the negative electrode lithium metal layer 14.

(Third Embodiment)
Hereinafter, the all-solid-state battery 10 of the third embodiment will be described. The same elements as those in the first or second embodiment are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 6 is a diagram illustrating the configuration of the all-solid-state battery 10 of the present embodiment. In particular, FIG. 6A shows a schematic cross-sectional structure of the all-solid-state battery 10, and FIG. 5B shows the entire laminated structure of the cell unit 10A.

As shown in the figure, the all-solid-state battery 10 of the present embodiment is further provided with a restraint mechanism C. The restraint mechanism C is configured by a bolt mechanism that presses the end plates 40, 40 arranged at both ends of the cell unit 10A in the stacking direction in a direction approaching each other. In particular, a plurality of restraint mechanisms C of the present embodiment are provided (four each in FIG. 6) along the extending directions of the pair of facing sides 10Aa and 10Aa on the outer periphery of the cell unit 10A.

By arranging such a restraining mechanism C, 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 are arranged in the cell unit 10A. A load can be applied to ensure a good contact condition.

In the present embodiment, the uneven shape of the outer peripheral surface 14A of the negative electrode lithium metal layer 14 is formed along the sides 10Aa and 10Aa provided with the restraining mechanism C, while the side not provided with the restraining mechanism C is formed. It is formed in a linear shape. That is, the uneven portion 16A on the outer periphery of the highly wettable layer 16 of the present embodiment is provided only in the region facing the sides 10Aa and 10Aa on which the restraining force (pressing pressure in the stacking direction) by the restraining mechanism C acts relatively strongly. Be done.

The all-solid-state battery 10 of the present embodiment described above further has a restraint mechanism C that restrains the cell unit 10A as a cell laminate including the solid electrolyte layer 15 and the negative electrode n in the stacking direction. Then, the restraint mechanism C is arranged along the restrained region (sides 10Aa, 10Aa) which is a part of the outer circumference of the cell unit 10A. Further, the uneven portion 16A is formed on the outer periphery of the highly wettability layer 16 so as to face the sides 10Aa and 10Aa.

As a result, the negative electrode lithium is located on the outer periphery of the highly wettable layer 16 where the stretching of the negative electrode lithium metal layer 14 that causes stress in the solid electrolyte layer 15 is further promoted by the pressing force in the stacking direction by the restraint mechanism C. By forming the uneven portion 16A that reduces the amount of elongation of the metal layer 14, the stress suppressing effect of the uneven portion 16A can be more preferably exhibited. On the other hand, by forming the outer peripheral portion of the highly wettability layer 16 in which the restraining force by the restraining mechanism C does not act directly into a linear shape, the electrode area is expanded and the energy density is increased while maintaining the stress suppressing effect. Can be improved.

(Fourth Embodiment)
Hereinafter, the all-solid-state battery 10 of the fourth embodiment will be described. The same elements as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. In the present embodiment, an example in which the low-wetting layer 30 is provided in place of the high-wetting layer 16 described in the first to third embodiments as the precipitation adjusting layer will be described.

FIG. 7 is a diagram illustrating the configuration of the all-solid-state battery 10 of the present embodiment. FIG. 8 is a diagram illustrating the inner peripheral shape of the low wetting layer. As shown in the figure, in the all-solid-state battery 10 of the present embodiment, the low-wetting layer 30 as the precipitation adjusting layer is provided along the outer peripheral edge portion 15A of the solid electrolyte layer 15. In particular, the low wetting 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. Further, the uneven portion 30A is formed on the inner circumference of the low wetting layer 30.

The low wetting layer 30 can be made of a material having a lower wettability to metallic lithium than the solid electrolyte layer 15. For example, examples of the material of the low wetting layer 30 include lithium nitride (Li ₃ N) and lithium carbonate (Li ₂ CO ₃ ). The low-wetting layer 30 is formed by coating the solid electrolyte layer 15 in the above-mentioned shape by using a known method such as thin-film deposition as in the high-wetting layer 16.

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

As a result, the metallic lithium that dissolves during charging gathers in the portion (that is, the central surface region 15) other than the outer peripheral edge portion 15A of the solid electrolyte layer 15 in which the low wetting layer 30 is formed. That is, the region where the negative electrode lithium metal layer 14 is formed can be adjusted within the surface region excluding the outer peripheral edge portion 15A of the solid electrolyte layer 15. In particular, since the uneven portion 30A is formed on the inner circumference of the low wetting layer 30, the shape of the outer peripheral surface 14A of the negative electrode lithium metal layer 14 is suitable for the uneven shape capable of suppressing the elongation amount of the negative electrode lithium metal layer 14. Can be maintained.

(Fifth Embodiment)
Hereinafter, the all-solid-state battery 10 of the fifth embodiment will be described. The same elements as those in the fourth embodiment are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 9 is a diagram illustrating the configuration of the all-solid-state battery 10 of the present embodiment. In particular, FIG. 9A shows a schematic cross-sectional structure of a portion of the negative electrode lithium metal layer 14 of the negative electrode n, and FIG. 9B shows the entire laminated structure of the cell unit 10A.

As shown in the figure, in the all-solid-state battery 10 of the present embodiment, the area of the positive electrode active material layer 17 is smaller than the area of the negative electrode n. More specifically, the positive electrode existing range pa, which is the present range of the positive electrode active material layer 17 in the plane direction, extends to the bottom surface of the concave portion in the uneven portion 30A of the low wetting layer 30.

As a result, the energy density can be maintained by making the facing area between the negative electrode lithium metal layer 14 and the positive electrode active material layer 17 as wide as possible while maintaining the uneven shape of the outer peripheral surface 14A of the negative electrode lithium metal layer 14.

(Modification example)
Hereinafter, the configuration of the all-solid-state battery 10 according to the modified example will be described.

FIG. 10 is a diagram illustrating the configuration of the all-solid-state battery 10 according to the first modification. Further, FIG. 11 is a diagram illustrating the configuration of the all-solid-state battery 10 according to the second modification. In any of the modified examples shown in FIGS. 10 and 11, the shape of the uneven portion 16A formed on the outer periphery of the high wettability layer 16 (particularly the shape of the convex portion 16Aa) is different from the shape (trapezoidal shape) described in FIG. It is formed in a shape.

Specifically, in the first modification shown in FIG. 10, the side surface of the convex portion 16Aa is configured to have a plurality of (two in FIG. 10) inclined shapes having different angles. Further, in the second modification shown in FIG. 11, the side surface of the convex portion 16Aa is formed in a curved shape.

Thereby, from the viewpoint of appropriately dispersing the stress direction according to the stress concentration direction that can occur in the solid electrolyte layer, the shape of the uneven portion 16A of the high wettability layer 16 can be varied.

Regarding the uneven portion 16A of the highly wettable layer 16, the above-described embodiment and each of the above-described embodiments can be used as long as the outer peripheral 14A of the negative electrode lithium metal layer 14 formed during charging can be provided with a function of reducing the amount of elongation of the outer peripheral 14A. It may be configured in a shape other than the shape shown in the modified example. For example, although the effect of dispersing stress is reduced, the convex portion 16Aa of the uneven portion 16A is formed into a simple rectangular shape (a shape having no inclination or curvature on the side surface) to simplify the manufacturing process of the highly wettable layer 16. You may try.

Further, the shape of the uneven portion 30A on the inner circumference of the low wettability layer 30 described in the fourth embodiment can be changed in the same manner as the uneven portion 16A of the high wettability layer 16.

Although the embodiments of the present invention have been described above, the above embodiments are only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiments. No. In addition, the above embodiments can be combined as appropriate.

For example, the all-solid-state battery 10 of the present embodiment can be configured as a laminated battery in which a plurality of laminated cell units 10A are sealed with an exterior material, depending on the intended use. Further, the appearance of the all-solid-state battery 10 of the present embodiment and the electrical connection state (electrode structure) inside are not particularly limited. The appearance of the all-solid-state battery 10 may be, for example, a rectangular flat square shape, a circular shape, or an elliptical shape. Alternatively, the all-solid-state battery 10 may be configured in a cylindrical shape in which one or more cell units 10A are wound and accommodated. Further, as the electrode structure of the all-solid-state battery 10, either a so-called non-bipolar type (internal parallel connection type) or a bipolar type (internal series connection type) may be adopted.

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 Concave part 15 Solid electrolyte layer 15A Outer peripheral edge part 15B Central surface area 16 High wettability layer 16A Concavo-convex part 16Aa Convex part 16Ab Recess 17 Positive electrode active material layer 18 Positive electrode current collector 20 Laminating material 30 Low wettability layer 30A Concavo-convex part 40 End plate

Claims (10)

It is an all-solid-state battery including a solid electrolyte layer and a negative electrode which is laminated on the solid electrolyte layer and a negative electrode lithium metal layer is formed by precipitating metallic lithium between the solid electrolyte layer during charging. hand,
The negative electrode has a precipitation adjusting layer whose wettability with respect to metallic lithium is different from that of the solid electrolyte layer.
The precipitation adjusting layer is arranged so that the peripheral length of the outer periphery of the negative electrode lithium metal layer formed during charging is longer than the peripheral length of the outer circumference having a similar shape to the solid electrolyte layer.
All-solid-state battery. The all-solid-state battery according to claim 1.
The precipitation adjusting layer is applied to the solid electrolyte layer, and is composed of a highly wettable layer having a higher wettability with respect to the metallic lithium than the solid electrolyte layer.
Concavo-convex portions are formed on at least a part of the outer periphery of the highly wettable layer.
All-solid-state battery. The all-solid-state battery according to claim 2.
The convex portion in the uneven portion is formed in an inclined shape or a curved shape that disperses the stress generated in the solid electrolyte layer due to the stretching of the metallic lithium during charging.
All-solid-state battery. The all-solid-state battery according to claim 2 or 3.
The width of the concave portion and the length of the convex portion in the uneven portion are formed to be equal to or larger than the diameter of the solid electrolyte particles constituting the solid electrolyte layer.
All-solid-state battery. The all-solid-state battery according to any one of claims 2 to 4.
The range of existence of the positive electrode surface is contained inside the recess in the uneven portion of the highly wettable layer.
All-solid-state battery. The all-solid-state battery according to any one of claims 2 to 4.
Further having a restraining mechanism for restraining the cell laminate including the solid electrolyte layer and the negative electrode in the stacking direction.
The restraint mechanism is arranged along a constrained region that is a part of the outer circumference of the cell laminate.
The uneven portion is formed on the outer periphery of the highly wettable layer so as to face the restrained region.
All-solid-state battery. The all-solid-state battery according to claim 1.
The precipitation adjusting layer is applied to the solid electrolyte layer, and is configured as a low wettability layer having a wettability to the metallic lithium lower than that of the solid electrolyte layer.
The low wetting layer is provided along the outer peripheral edge portion excluding the central surface region of the solid electrolyte layer.
An all-solid-state battery in which uneven portions are formed on at least a part of the inner circumference of the low-wetting layer. The all-solid-state battery according to claim 7.
The range of existence of the positive electrode surface is configured to extend to at least the bottom surface of the concave portion in the uneven portion of the low wetting layer.
All-solid-state battery. 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 adjusting layer applied to the solid electrolyte layer and a negative electrode lithium metal layer formed on the precipitation adjusting layer.
The precipitation adjusting layer is configured so that the wettability to metallic lithium is different from that of the solid electrolyte layer.
The shape of the outer circumference of the negative electrode lithium metal layer is formed so as to substantially match the shape of the outer circumference of the precipitation adjusting layer.
All-solid-state battery. 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 adjusting layer applied to the solid electrolyte layer and a negative electrode current collector arranged to face the precipitation adjusting layer.
The precipitation adjusting layer is
The wettability to metallic lithium is configured to be different from that of the solid electrolyte layer.
The circumference of the outer circumference of the negative electrode lithium metal layer formed during charging is arranged to be longer than the circumference of the outer circumference of the solid electrolyte layer having a similar shape.
All-solid-state battery.

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