Cathode Coating Composition for Oxidation-Resistant Solid-State Batteries
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Solution Overview
Problem
Batteries containing solid electrolytes suffer from decreased capacity due to oxygen generation and increased internal resistance during charge-discharge cycles, leading to deterioration in cycle characteristics.
Innovation Solution
A cathode material is developed with a coating layer containing a first solid electrolyte composed of Li, Al, and a halogen (F, Cl, Br, or I) that inhibits oxidation of a second solid electrolyte, maintaining a volume ratio between the first and second electrolytes between 5.1% and 12.0%, enhancing oxidation resistance and ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sulfur-containing solid electrolyte is used to enhance ionic conductivity, then the battery achieves better performance, but the sulfur-containing solid electrolyte is easily oxidized by oxygen generated from the cathode active material, leading to increased internal resistance
Solution Approach 1:
The aluminum-containing solid electrolyte coating serves as a protective intermediary layer that shields the sulfur-containing solid electrolyte from oxidation by oxygen generated during cathode active material decomposition. This allows the sulfur-containing solid electrolyte to maintain its high ionic conductivity benefits while preventing the harmful oxidation reactions that would otherwise increase internal resistance
Solution Approach 2:
A composite electrolyte structure is created by combining an aluminum-containing solid electrolyte coating with a sulfur-containing solid electrolyte. The composite structure leverages the oxidation resistance of the aluminum-containing layer while utilizing the high ionic conductivity of the sulfur-containing layer, achieving both improved performance and stability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The cathode material improves battery durability and charge-discharge efficiency by inhibiting oxidation reactions, ensuring both initial performance and long-term stability.
Implementation Method 1
oxygen may be generated from a cathode active material in the last stage of a charge. The generated oxygen oxidizes the solid electrolyte to increase the internal resistance of the battery
Data Source
AI summary
A cathode material of the present disclosure includes a cathode active material, a coating layer containing a first solid electrolyte, and coating at least part of a surface of the cathode active material, and a second solid electrolyte. The first solid electrolyte contains Li, Al, and X, and does not contain Ti. X is at least one selected from the group consisting of F, Cl, Br, and I. The ratio of the volume of the first solid electrolyte to the total volume of the first solid electrolyte and the second solid electrolyte is greater than or equal to 5.1% and less than or equal to 12.0%.