Polyether Modified Silicone Oil Coating for Lithium Battery Stability
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Solution Overview
Problem
Conventional rechargeable lithium batteries with high-capacity negative active materials, such as Si, face challenges in maintaining electrochemical stability and safety due to volume expansion and electrolyte decomposition, leading to poor cycle characteristics and safety issues.
Innovation Solution
A positive active material for rechargeable lithium batteries is developed, incorporating a polyether modified silicone oil that is supported on the active material, allowing for reversible lithium intercalation and deintercalation, and is used in conjunction with a negative active material primarily composed of Si, enhancing electrochemical stability and preventing deterioration during charge and discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If LiCoO2 is used as the positive active material to achieve high capacity, then the charge and discharge capacity is improved, but the positive active material becomes electrochemically unstable and Co is eluted during charging, deteriorating cycle characteristic and safety
Solution Approach 1:
A silane-modified polyether compound is introduced as an intermediary substance between the LiCoO2 positive active material and the electrolyte. This compound forms a protective film on the surface of the positive active material, preventing direct contact between the electrolyte and LiCoO2, thereby suppressing Co elution and electrochemical instability while maintaining high capacity
Solution Approach 2:
The invention uses a composite structure where silane-modified polyether compound (containing both silane groups and polyether chains) is combined with the LiCoO2 positive active material. The silane groups form a stable protective layer while the polyether chains provide lithium ion conductivity, creating a composite material that simultaneously achieves high capacity and excellent cycle characteristic
2Quantity of substance
If Si is used as the negative active material to achieve 10 times the charge and discharge capacity of graphite, then the capacity is improved, but volume expansion and electrolyte decomposition occur, leading to poor cycle characteristics
Solution Approach 1:
The silane-modified polyether compound acts as an intermediary protective layer on the Si negative active material surface. This layer prevents direct contact between Si and the electrolyte, suppressing electrolyte decomposition while allowing lithium ion transport, thereby maintaining high capacity and improving cycle characteristic
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 results in a rechargeable lithium battery with improved cycle characteristics, safety, and stability, as the polyether modified silicone oil prevents the deterioration of the positive active material, maintaining high capacity and efficiency over repeated charge and discharge cycles.
Implementation Method 1
a polyether modified silicone oil supported on the active material
Implementation Method 2
an active material that can reversibly intercalate and deintercalate lithium
Data Source
AI summary
A positive active material for rechargeable lithium battery includes an active material that can reversibly intercalate and deintercalate lithium; and polyether modified silicone oil supported on the active material. The positive active material is not deteriorated during charge and discharge, and has high-capacity, an excellent cycle characteristic and good safety.