Negative Electrode Roughness Zoning for Precise Battery Coating
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Solution Overview
Problem
In non-aqueous electrolyte secondary batteries, the hydrophilic surface of the negative electrode core can lead to sagging of the negative electrode mixture, resulting in uneven thickness and potential lithium precipitation, while reducing the hydrophilicity to prevent sagging may compromise the adherence of the negative electrode mixture layer.
Innovation Solution
The battery design incorporates a negative electrode plate with a negative electrode core that has a higher arithmetic mean roughness on the first area (planned coating portion) and a lower arithmetic mean roughness on the second area (planned non-coating portion), ensuring proper adhesion and preventing sagging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the negative electrode core surface is made hydrophilic to improve ease of coating, then the negative electrode mixture slurry spreads readily on the surface, but this causes sagging of the negative electrode mixture beyond the planned coating area
Solution Approach 1:
The negative electrode core surface is divided into different regions with different hydrophilicities: the first area (opposite the positive electrode) has high hydrophilicity for good mixture adhesion, while the second area (edge portion) has low hydrophilicity to prevent sagging. This local differentiation resolves the contradiction between ease of coating and coating area control.
Solution Approach 2:
The negative electrode core surface is segmented into functionally distinct zones: a first area for mixture attachment and a second area for preventing mixture overflow. This segmentation allows each zone to perform its specific function optimally, addressing both coating ease and precision requirements.
2Manufacturing precision
If the hydrophilicity of the entire negative electrode core surface is reduced to prevent sagging, then the negative electrode mixture does not spread beyond the planned area, but this reduces the adherence between the negative electrode mixture layer and the negative electrode core
Solution Approach 1:
Different regions of the negative electrode core surface are assigned different hydrophilic properties: the first area maintains high hydrophilicity to ensure strong adherence between the mixture layer and core, while the second area has reduced hydrophilicity to prevent sagging. This local quality differentiation simultaneously achieves both good adhesion and precise coating control.
Solution Approach 2:
The negative electrode core surface is divided into functional segments where the first area provides strong mixture attachment through high hydrophilicity, and the second area prevents overflow through low hydrophilicity. This segmentation resolves the contradiction between adherence and coating area control.
3Manufacturing precision
If the negative electrode mixture layer thickness is reduced at the end portion to prevent sagging, then the mixture does not protrude beyond the planned area, but this creates a thin portion that causes lithium precipitation due to excessive positive electrode mixture
Solution Approach 1:
The negative electrode core surface exhibits local quality differences in hydrophilicity: the first area has high hydrophilicity to ensure proper mixture thickness and prevent lithium precipitation, while the second area has low hydrophilicity to contain the mixture within the planned coating area. This resolves the contradiction between coating precision and battery reliability.
Solution Approach 2:
The negative electrode core is segmented into a first area that ensures adequate mixture thickness for preventing lithium precipitation and a second area that prevents mixture overflow. This functional segmentation simultaneously achieves coating area control and prevents lithium precipitation issues.
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
This configuration effectively prevents sagging of the negative electrode mixture and enhances the peeling strength of the negative electrode mixture layer with respect to the negative electrode core, maintaining optimal battery performance.
Implementation Method 1
Ra1 represents an arithmetic mean roughness of the first area, and Ra2 represents an arithmetic mean roughness of the second area, and Ra1>Ra2 is satisfied
Data Source
AI summary
A non-aqueous electrolyte secondary battery including a negative electrode plate with a negative electrode core body, and a negative electrode mixture layer formed on the surface of the negative electrode core body. At an end portion of the negative electrode core body on one side in an electrode plate width direction there is formed a core body exposed portion along the longitudinal direction of the electrode plate, the core body exposed portion being electrically connected to an outer package can. The surface of the negative electrode core body includes a first region other than the end portion on the one side in the electrode plate width direction, and a second region that is the end portion on the one side. The relationship Ra1>Ra2 holds, where Ra1 represents the arithmetic average roughness of the first region, and Ra2 represents the arithmetic average roughness of the second region.