Positive Electrode Current Collector With Ultra-Thin Protective Layer
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Solution Overview
Problem
Existing current collectors for lithium ion batteries face issues with simultaneous coating of ceramic protective layers, leading to reduced active coating capacity and potential wrinkling during winding, affecting production quality and efficiency.
Innovation Solution
A positive electrode current collector with an ultra-thin protective layer having a thickness ratio of 0.05-0.7 to the foil, allowing for a step-by-step coating process, reducing wrinkling and improving production quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ceramic protective layer is coated simultaneously with the active coating on the current collector, then the safety performance and processability of the electrode sheet are improved, but the gram capacity of the active coating is reduced due to fusion between ceramic and active slurry
Solution Approach 1:
The patent divides the coating process into two separate stages: first coating the active material layer, then coating the ceramic protective layer. This segmentation prevents the fusion problem that occurs with simultaneous coating, allowing both the active coating to maintain its full gram capacity and the ceramic layer to provide safety protection without interference between the two materials.
Solution Approach 2:
The active coating is applied first as a preliminary step before applying the ceramic protective layer. This preliminary action ensures that the active coating is already in place and can be fully utilized for capacity, while the subsequent ceramic coating provides protection without causing fusion issues.
2Reliability
If a thick protective layer is used on the current collector, then the safety performance is improved, but the electrode sheet forms wrinkles during winding and causes bulging, reducing production quality
Solution Approach 1:
The patent optimizes the thickness parameter of the ceramic protective layer, specifying it should be 1-10 μm. This parameter change balances the safety performance provided by the ceramic layer with the mechanical flexibility needed to prevent wrinkles and bulging during winding, thereby maintaining high production quality.
3Reliability
If the protective layer thickness is increased to ensure safety, then the safety performance is improved, but the electrode sheet is more likely to form wrinkles and bulges during winding
Solution Approach 1:
The patent specifies the ceramic protective layer thickness should be 1-10 μm, which is sufficient to provide safety protection while remaining thin enough to prevent wrinkling and bulging during the winding process. This parameter optimization resolves the contradiction between safety and shape integrity.
Data Source
AI summary
A positive electrode current collector and a preparation method therefor, a positive electrode sheet and a preparation method therefor, and a battery are provided. The positive electrode current collector includes a foil and a protective layer provided on a surface of the foil. The protective layer includes inorganic particles. The ratio of a thickness of the protective layer to a thickness of the foil is 0.05-0.7. In the present disclosure, by controlling the thickness of the protective layer containing inorganic particles, the ratio of the thickness of the protective layer to the thickness of the foil is ensured, thereby obtaining a current collector having an ultra-thin protective layer.