Positive Electrode Plate Coating for High-Voltage Overcharge Control
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Solution Overview
Problem
Existing secondary batteries exhibit abnormally increased charging capacity under high-rate and high cut-off voltage charging conditions, leading to overcharging risks due to oxidative decomposition of the solvent in the electrolyte solution.
Innovation Solution
A positive electrode plate comprising a polymer and an organic solvent with an electrochemical oxidation window higher than 4 V is used, blocking direct contact between the positive electrode active material and the solvent to prevent oxidative decomposition and side reactions, thereby reducing the risk of overcharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-rate and high cut-off voltage charging is performed, then charging speed and charging capacity are improved, but oxidative decomposition of the solvent occurs causing overcharging risks
Solution Approach 1:
A polymer layer is introduced as an intermediary substance between the positive electrode active material and the electrolyte solvent. This polymer layer selectively blocks the solvent from contacting the active material while permitting ion transport, thereby preventing oxidative decomposition of the solvent during high-rate and high cut-off voltage charging without significantly impeding charging performance
Solution Approach 2:
A thin polymer film is formed on the surface of the positive electrode active material particles. This flexible thin film serves as a protective barrier that prevents direct contact between the solvent and active material, eliminating the harmful oxidative decomposition reaction while maintaining the electrode's structural integrity and ion conductivity
2Reliability
If polymer layer is added to block solvent contact, then overcharge risk is reduced, but electrode structure complexity increases
Solution Approach 1:
The protective polymer layer is applied locally only on the surface of the positive electrode active material particles rather than throughout the entire electrode structure. This localized treatment provides overcharge protection precisely where it is needed (at the particle-solvent interface) while minimizing the addition of structural complexity to the overall electrode system
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 polymer and organic solvent combination effectively prevents oxidative decomposition of the electrolyte solvent, reducing the risk of overcharge by blocking direct contact and preventing additional electrons from reaching the negative electrode, thus maintaining stable battery charging capacity.
Implementation Method 1
the polymer layer can block the direct contact between the positive electrode active material and the solvent in the electrolyte solution of the battery, thereby avoiding oxidative decomposition of the solvent of the electrolyte solution
Implementation Method 2
since the electrochemical oxidation window of the organic solvent is higher than 4 V, that is, the organic solvent will not undergo an oxidation reaction on the positive electrode side under the condition of charging at a high cut-off voltage (>4 V)
Data Source
AI summary
The present application discloses a positive electrode plate and a preparation method therefor, a positive electrode plate, a battery and an electrical apparatus. The positive electrode plate comprises a positive electrode current collector, and at least one side of the positive electrode plate away from the positive electrode current collector comprises a polymer and an organic solvent, wherein the organic solvent is located in the polymer, and the electrochemical oxidation window of the organic solvent is greater than 4 V.