Cathode Material Coating to Inhibit Solid Electrolyte Oxidation
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Solution Overview
Problem
Batteries containing solid electrolytes face issues with capacity degradation due to oxygen generation from the cathode active material, leading to increased internal resistance and reduced cycle characteristics.
Innovation Solution
A cathode material is designed with a coating layer containing a first solid electrolyte composed of Li, Al, and a halogen (F, Cl, or I) that covers the cathode active material, maintaining a volume ratio between 5.6% to 8.1%, inhibiting oxidation of a second solid electrolyte and improving cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cathode active material is used in a battery with solid electrolyte, then the battery can operate with solid electrolyte benefits, but oxygen generation from the cathode active material oxidizes the solid electrolyte leading to increased internal resistance and capacity degradation
Solution Approach 1:
A coating layer containing a first solid electrolyte (Li-Al-X type without Ti) is introduced as an intermediary between the cathode active material and the second solid electrolyte. This coating layer acts as a protective barrier that prevents direct contact and chemical reaction between the cathode active material and the second solid electrolyte, thereby inhibiting oxidation and improving cycle characteristics while maintaining battery operation benefits
2Reliability
If the volume ratio of the first solid electrolyte to the total volume of the first solid electrolyte and cathode active material is controlled within 5.6-8.1%, then the deterioration resistance is improved, but the coating layer thickness and composition must be precisely controlled
Solution Approach 1:
The patent specifies a precise volume ratio range (5.6-8.1%) of the first solid electrolyte to the total volume of the first solid electrolyte and cathode active material. This parameter control ensures optimal protective effect while preventing excessive coating that would reduce battery capacity. The defined range provides clear manufacturing guidance for achieving improved deterioration resistance
3Object-affected harmful factors
If the first solid electrolyte contains Li, Al, and halogen (F, Cl, Br, or I) but does not contain Ti, then the oxidation resistance is improved, but the material composition is restricted
Solution Approach 1:
The patent specifies particular compositional requirements for the first solid electrolyte (Li-Al-X type without Ti) to achieve optimal oxidation resistance. By defining specific elemental composition (Li, Al, and halogen) and excluding Ti, the coating layer gains enhanced protective properties against oxidation from the cathode active material, demonstrating localized quality optimization for the coating function
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 solution enhances the battery's durability and charge-discharge efficiency by preventing oxidation of the second solid electrolyte, ensuring both initial performance and resistance to cycling degradation.
Implementation Method 1
inhibiting oxidation of a second solid electrolyte and improving cycle characteristics
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 cathode active material is greater than or equal to 5.6% and less than or equal to 8.1%.