Sodium Thiosulfate-Coated Cathode Material for Solid-State Battery Cycling
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Solution Overview
Problem
All-solid-state lithium secondary batteries face degradation in cycling performance due to high electrochemical activity of positive electrode active materials, especially in solid-phase contact with electrolytes, leading to rapid capacity decline.
Innovation Solution
A positive electrode active material with a sodium thiosulfate coating layer is developed, which isolates substances causing side reactions, improving cycling performance and capacity retention by forming a physical amorphous membrane that enhances lithium ion conductivity without affecting electronic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high electrochemical activity positive electrode active materials are used, then battery capacity and power performance are improved, but side reactions on contact interfaces between electrodes and electrolyte increase, causing rapid capacity decline and poor cycling performance
Solution Approach 1:
A sodium thiosulfate coating layer is applied as an intermediary substance between the positive electrode active material and the solid-state electrolyte. This coating layer acts as a mediator that prevents direct harmful interactions while allowing beneficial ionic conduction, thereby resolving the contradiction between high capacity and good cycling performance.
Solution Approach 2:
A thin film coating of sodium thiosulfate is formed on the surface of the positive electrode active material particles. This thin film serves as a protective shell that isolates the active material from the electrolyte, preventing side reactions while maintaining electrochemical functionality, thus improving cycling performance without sacrificing capacity.
2Reliability
If a coating layer is applied to reduce side reactions, then cycling performance is improved, but initial capacity and efficiency may be affected
Solution Approach 1:
The concentration and composition of the sodium thiosulfate coating layer are optimized to achieve the right balance. By controlling the coating parameters, the layer is made thin enough to allow sufficient ionic conduction for high initial capacity, while still providing adequate protection for improved cycling performance.
Solution Approach 2:
The coating layer is applied selectively on the surface of the positive electrode active material particles, creating a localized protective zone. This local modification allows the bulk material to retain its high electrochemical activity for good initial capacity, while the surface layer provides protection for enhanced cycling performance.
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 sodium thiosulfate coating significantly improves cycling performance and capacity retention rates of all-solid-state lithium secondary batteries, maintaining high performance over extended cycles while minimizing initial capacity and efficiency impacts.
Implementation Method 1
The sodium thiosulfate coating layer isolates a substance causing side reactions from the positive electrode active substance
Implementation Method 2
sulfur atoms on a surface of the positive electrode active material are easy to attract sulfur atoms in the solid-state electrolyte
Data Source
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AI summary
Provided are a positive electrode active material and a positive electrode plate for an all-solid lithium secondary battery, an all-solid lithium secondary battery (5), and a device. The provided positive electrode active material comprises a positive electrode active substance and a sodium thiosulfate coating layer forming a surface coating on the positive electrode active material. Applying the provided positive electrode active material to a positive electrode plate of an all-state lithium secondary battery can remarkably improve the cycle performance and capacity retention rate of the battery.