US-12626950-B2 - All-solid-state battery

US12626950B2US 12626950 B2US12626950 B2US 12626950B2US-12626950-B2

Abstract

An 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 and a plurality of carbon materials therein, and 8% or more of the plurality of voids are in contact with any of the plurality of carbon materials.

Inventors

Teiichi TANAKA
Takeo Tsukada

Assignees

TDK CORPORATION

Dates

Publication Date: 20260512
Application Date: 20200929
Priority Date: 20191023

Claims (9)

1 . An all-solid-state battery comprising: a positive electrode layer, a negative electrode layer, a solid electrolyte layer positioned between the positive electrode layer and the negative electrode layer, and side margin layers disposed on an outer periphery thereof along each of the positive electrode layer and the negative 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, each of the positive electrode active material layer and the negative electrode active material layer has a plurality of voids and a plurality of carbon materials therein, 8% or more of the plurality of voids are in contact with any of the plurality of carbon materials each of the side margin layers is a region which a plurality of voids are formed, 8% or more of the plurality of voids in the side margin layers are in contact with any of the plurality of carbon materials, an area ratio of the plurality of carbon materials in the layer which includes the plurality of carbon materials and voids of the positive electrode active material layer and the negative electrode active material layer is 3% or more and 12% or less, the plurality of voids in the positive active material layer are surrounded by the positive active material, the plurality of voids in the negative active material layer are surrounded by the negative active material, in the plurality of voids of each of the positive electrode active material layer and the negative electrode active material, only the carbon materials are included, each of the side margin layers is a solid electrolyte; each of the side margin layers entirely surrounds either the positive electrode layer or the negative electrode layer on at least three sides of the respective positive electrode layer or negative electrode layer, and the plurality of voids in the side margin layers are surrounded by the solid electrolyte.
2 . The all-solid-state battery according to claim 1 , wherein each of the plurality of carbon materials has shape anisotropy, and the major axis direction of each of the carbon materials is oriented in an in-plane direction in which the positive electrode active material layer or the negative electrode active material layer spreads.
3 . The all-solid-state battery according to claim 1 , wherein an average major axis length of the plurality of carbon materials is 0.2 μm or more and 40 μm or less, and the average minor axis length of the plurality of carbon materials is 0.1 μm or more and 5 μm or less.
4 . The all-solid-state battery according to claim 1 , porosity calculated by dividing a difference between theoretical mass and measured mass by measured mass in the layer which includes the plurality of carbon materials and voids of the positive electrode active material layer and the negative electrode active material layer is 2% or more and 15% or less.
5 . The all-solid-state battery according to claim 1 , wherein a ratio of length of a cross-section outer perimeter of the carbon materials which is in contact with any of the voids in the cross-section crossing the positive electrode and the negative electrode is 10% or more and 70% or less.
6 . The all-solid-state battery according to claim 1 , 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 has a plurality of voids, and a ratio of the plurality of voids in the intermediate layer is 0.1% or more and 8% or less.
7 . The all-solid-state battery according to claim 1 , wherein each of the side margin layers include a solid electrolyte.
8 . The all-solid-state battery according to claim 1 , wherein the side margin layers are disposed along the positive electrode layer or the negative electrode layer.
9 . The all-solid-state battery according to claim 1 , wherein the average major axis length of the plurality of carbon materials is 0.5 μm or more and 20 μm or less.

Description

TECHNICAL FIELD The present invention relates to an all-solid-state battery. Priority is claimed on Japanese Patent Application No. 2019-192584, 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 20131175993 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 arranging a plurality of voids and a plurality of carbon materials in contact with each other 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 reduced 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 and a plurality of carbon materials therein, and 8% or more of the plurality of voids are in contact with any of the plurality of carbon materials. (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. (3) 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 and a plurality of carbon materials therein, and 8% or more of the plurality of voids may be in contact with any of the plurality of carbon materials. (4) In the all-solid-state battery according to the above-described aspect, each of the plurality of carbon materials may have shape anisotropy, and the major axis direction of each of the carbon materials may be oriented in 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 major axis length of the plurality of carbon materials may be 0.2 μm or more and 40 μm or less, and the average minor axis length of the plurality of carbon materials may b