US-12620630-B2 - All-solid-state battery

US12620630B2US 12620630 B2US12620630 B2US 12620630B2US-12620630-B2

Abstract

This all-solid-state battery includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer positioned between the positive electrode layer and the negative electrode layer, the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer which is in contact with the positive electrode current collector, the negative electrode layer includes a negative electrode current collector and a negative electrode active material layer which is in contact with the negative electrode current collector, at least one of the positive electrode active material layer and the negative electrode active material layer has a plurality of voids therein, and the plurality of voids include an anisotropic void in which an aspect ratio obtained by dividing a length in a major axis direction by a length in a minor axis direction is 2 or more and 29 or less.

Inventors

Teiichi TANAKA
Takeo Tsukada

Assignees

TDK CORPORATION

Dates

Publication Date: 20260505
Application Date: 20200929
Priority Date: 20191023

Claims (7)

1 . An all-solid-state battery comprising: a positive electrode layer, a negative electrode layer, and a solid electrolyte layer positioned between the positive electrode layer and the negative electrode layer, and a plurality of side margin layers disposed on the outer periphery along the positive electrode layer and thenegative electrode layer, wherein the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer which is in contact with the positive electrode current collector, the negative electrode layer includes a negative electrode current collector and a negative electrode active material layer which is in contact with the negative electrode current collector, at least one of the positive electrode active material layer and the negative electrode active material layer is a layer in which a plurality of voids are formed, and the plurality of voids in the at least one of the positive electrode active layer and the negative electrode active material layer include anisotropic voids in which an aspect ratio obtained by dividing a length in a major axis direction by a length in a minor axis direction is 2 or more and 29 or less, wherein the side margin layer contains a solid electrolyte, and wherein the plurality of the side margin layers is a regin in which a plurality of voids are formed, and the plurality of voids in the plurality of side margin layers include an antisotropic void in which the aspect ration obtained by dividing the length in the major axis direction by the length in the minor axis direction is 2 or more and 29 or less, wherein an intermediate layer having ionic conductivity is provided between at least one of the positive and negative electrode layers and the solid electrolyte layer, the intermediate layer is a layer in which a plurality of voids are formed and which has a composition between the active material that forms the positive electrode active material layer or the negative electrode active material layer and the solid electrolyte that forms the solid electrolyte layer, and a ratio of the plurality of voids in the intermediate layer is 0.1% or more and 8% or less.
2 . The all-solid-state battery according to claim 1 , wherein 30% or more of the plurality of voids are the anisotropic voids.
3 . The all-solid-state battery according to claim 1 , wherein the major axis direction of the anisotropic void substantially coincides with an in-plane direction in which the positive electrode active material layer or the negative electrode active material layer spreads.
4 . The all-solid-state battery according to claim 1 , wherein an average length of the anisotropic void in the major axis direction is 0.2 μm or more and 40 μm or less, and the average length of the anisotropic void in the minor axis direction is 0.1 μm or more and 5 μm or less.
5 . The all-solid-state battery according to claim 1 , wherein a ratio of the plurality of voids in the positive electrode active material layer or the negative electrode active material layer is 3% or more and 30% or less.
6 . The all-solid-state battery according to claim 1 , wherein the positive electrode active material layer and the negative electrode active material layer is lithium vanadium phosphate, the solid electrolyte is lithium zirconium phosphate, and the intermediate layer is lithium zirconium phosphate containing vanadium or lithium vanadium phosphate containing zirconium.
7 . The all-solid-state battery according to claim 1 , wherein a ratio of the plurality of voids in the intermediate layer is 4% or more and 8% or less.

Description

TECHNICAL FIELD The present invention relates to an all-solid-state battery. Priority is claimed on Japanese Patent Application No. 2019-192583, filed Oct. 23, 2019, the content of which is incorporated herein by reference. BACKGROUND ART In recent years, batteries have been used for various purposes. Batteries are also used, for example, in portable batteries, and are required to be smaller, lighter, thinner, and more reliable. Batteries using an electrolytic solution have problems such as liquid leakage and liquid depletion. Therefore, attention is focused on all-solid-state batteries using solid electrolytes. An all-solid-state battery includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer. The positive electrode or the negative electrode expands and contracts when the all-solid-state battery is charged and discharged. The strain generated by the expansion and contraction of the positive electrode or the negative electrode is one of the causes of occurrence of cracks and one of the causes of peeling at the laminated interface of each layer. For example, Patent Literature 1 discloses an all-solid-state battery having three solid electrolyte layers having different porosities between a positive electrode layer and a negative electrode layer. The three solid electrolyte layers having different porosities absorb the internal stress and suppress the occurrence of cracks. CITATION LIST Patent Literature [Patent Literature 1] PCT International Publication No. WO 2013/175993 SUMMARY OF INVENTION Technical Problem Cracks and interfacial peeling are one of the causes of increase in internal resistance and one of the causes of deterioration of cycle characteristics. Patent Literature 1 discloses a method for suppressing cracks. However, the structure of the all-solid-state battery is complicated and manufacturing is difficult. In addition, the thickness in the lamination direction increases, and the thickness of the entire all-solid-state battery increases. The present invention has been made in view of the above-described problems, and an object thereof is to provide an all-solid-state battery capable of suppressing the occurrence of cracks and peeling at a laminated interface. Solution to Problem The inventors have found that, by providing a void having a predetermined shape in the negative electrode layer or the positive electrode layer, which is the source origin of internal stress, the internal stress generated in the all-solid-state battery can be relaxed and the occurrence of cracks or interfacial peeling can be absorbed. That is, in order to solve the above-described problems, the following means are provided. (1) According to a first aspect, there is provided an all-solid-state battery including: a positive electrode layer, a negative electrode layer, and a solid electrolyte layer positioned between the positive electrode layer and the negative electrode layer, in which the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer which is in contact with the positive electrode current collector, the negative electrode layer includes a negative electrode current collector and a negative electrode active material layer which is in contact with the negative electrode current collector, at least one of the positive electrode active material layer and the negative electrode active material layer has a plurality of voids therein, and the plurality of voids include anisotropic voids in which an aspect ratio obtained by dividing a length in a major axis direction by a length in a minor axis direction is 2 or more and 29 or less. (2) In the all-solid-state battery according to the above-described aspect, at least a part of a side margin layer, which is disposed on an outer periphery thereof along each of the positive electrode layer and the negative electrode layer, may have a plurality of voids therein, and the plurality of voids may include an anisotropic void in which the aspect ratio obtained by dividing the length in the major axis direction by the length in the minor axis direction is 2 or more and 29 or less. (3) In the all-solid-state battery according to the above-described aspect, 30% or more of the plurality of voids may be the anisotropic voids. (4) In the all-solid-state battery according to the above-described aspect, the major axis direction of the anisotropic void may substantially coincide with an in-plane direction in which the positive electrode active material layer or the negative electrode active material layer spreads. (5) In the all-solid-state battery according to the above-described aspect, an average length of the anisotropic void in the major axis direction may be 0.2 μm or more and 40 μm or less, and the average length of the anisotropic void in the minor axis direction may be 0.1 μm or more and 5 μm or less. (6) In the all-solid-state battery according to the above-described aspect, a