Positive Electrode Protective Layer for Separator Load Relief
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Solution Overview
Problem
Non-aqueous electrolyte rechargeable batteries face challenges in reducing the load on separators and other components during the joining and compression processes, leading to stress concentration and potential damage.
Innovation Solution
Incorporating an insulating protective layer on the positive electrode connection portion with specific yield stress and flexural strength settings to mitigate stress concentration and prevent contact with separators, thereby reducing the load on these components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If opposing parts of the connection portion are joined together with large bending angle, then the connection is achieved, but stress concentrates at the bent portion applying load to substrate and separators
Solution Approach 1:
The insulating protective layer is formed on the positive electrode connection portion before the joining process. This preliminary protective coating prevents stress concentration during the bending and joining operations, protecting both the substrate and separators from damage while allowing effective connection to be made.
2Strength
If the positive electrode connection portion is made more flexible to reduce bending stress, then stress concentration is reduced, but the structural integrity and electrical conductivity may be compromised
Solution Approach 1:
The insulating protective layer acts as an intermediary element between the positive electrode connection portion and the separators. It allows the connection portion to be bent and joined while protecting the electrical components from stress concentration, maintaining both mechanical flexibility and electrical reliability.
3Reliability
If thicker separators are used to withstand the load from bent connection portions, then separator durability is improved, but the battery energy density and compactness are reduced
Solution Approach 1:
The insulating protective layer extracts the protective function from the separator system. By placing the protection function on the positive electrode connection portion itself, the separator can be made thinner since it no longer needs to bear the full mechanical load from bending stresses, thus maintaining separator durability while improving energy density.
Data Source
AI summary
In an insulating protective layer formed on each of two opposite surfaces of a positive electrode connection portion, a yield stress X (N) of a positive electrode plate is set such that “X≤0.122 N” is satisfied. “MIN≥0.0372 N” is satisfied, where MIN (N) represents a flexural strength of the positive electrode plate including only an inner insulating protective layer formed on a surface of the positive electrode connection portion that is located toward a positive electrode current collector in a stacking direction of an electrode body.