Positive Electrode Coating Adhesion Against Penetration Short Circuits
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Solution Overview
Problem
Lithium-ion batteries are prone to short circuits and safety hazards due to penetration by foreign objects, which can lead to fires or explosions, as the current collector can connect conductively with other electrodes, causing heat generation.
Innovation Solution
A positive electrode with a coating on the current collector, where the adhesion between the coating and the current collector is greater than or equal to 5 N/m, improving structural stability and reducing short circuit occurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating is applied to the current collector to improve safety, then adhesion between coating and current collector must be increased, but this increases manufacturing complexity and cost
Solution Approach 1:
A primer layer is introduced as an intermediary between the current collector and the topcoat. This primer layer serves as a bonding bridge that enhances adhesion between the metal current collector surface and the protective topcoat, resolving the contradiction by improving safety performance through better coating attachment without requiring direct complex coating formulations
Solution Approach 2:
The coating system is designed as a composite structure with multiple layers (primer layer and topcoat) having different functions. The primer layer provides adhesion to the current collector, while the topcoat provides protective functions. This composite approach allows optimization of each layer for its specific purpose, improving overall safety performance while managing manufacturing complexity through functional specialization
2Strength
If the coating adhesion is increased to prevent short circuits during penetration, then the coating must withstand higher mechanical stress, but this requires more robust coating materials and processes
Solution Approach 1:
The primer layer acts as a mechanical intermediary that distributes and absorbs stress between the rigid topcoat and the metal current collector. This stress distribution mechanism allows the coating system to withstand higher mechanical stresses during penetration events without requiring excessively robust or complex coating materials and application processes
Solution Approach 2:
The coating system parameters are optimized to achieve adequate adhesion strength. The primer layer composition and thickness are specifically controlled to provide sufficient bonding without over-engineering the system. This parameter optimization approach balances coating strength requirements with manufacturing ease by avoiding unnecessarily robust or complex material and process requirements
Data Source
AI summary
A positive electrode, including a positive electrode current collector, a positive electrode active material layer, and a coating, where the positive electrode active material layer and the coating are provided on a surface of the positive electrode current collector, and adhesion between the coating and the positive electrode current collector is greater than or equal to 5 N/m. The coating is provided, the coating and the positive electrode current collector are designed, and the adhesion of the coating to the positive electrode current collector is improved so that the safety performance of electrode assemblies containing such positive electrode can be effectively improved. When the electrochemical apparatus is impacted or penetrated by an external force, the coating with high adhesion can improve the structural stability of the electrode assembly containing the coating and reduce the occurrence of short circuits between electrode plates, thereby improving safety performance of the electrochemical apparatus.