Electrode Sheet Insulator Coating for Uniform Winding Pressure
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Solution Overview
Problem
Existing electrode sheet manufacturing methods face challenges in forming insulator layers that properly cover the active material layer edges, leading to issues with uniform contact pressure and risk of short-circuits due to conductive foreign substances, especially when the insulator layer is either too high or overlaps excessively, causing misalignment and uneven pressure during battery assembly.
Innovation Solution
A strip-shaped electrode sheet design with an insulator layer positioned lower than the active material layer, featuring a slant coating portion that covers the thinner edge portions and a foil coating portion extending to cover the insulator layer support, preventing gaps and ensuring uniform contact pressure and reducing the risk of short-circuits by maintaining insulation even at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insulator layer is formed to cover the active material layer edge, then insulation reliability is improved, but the insulator layer becomes higher than the active material layer causing misalignment and uneven contact pressure
Solution Approach 1:
The insulator layer is designed with different heights at different locations: at the active material layer edge portion, the insulator layer height is controlled to be lower than the active material layer height, while at other portions it can extend higher. This local differentiation ensures insulation where needed without causing misalignment issues.
2Reliability
If the insulator layer is formed to cover the active material layer edge, then short-circuit prevention is improved, but contact pressure uniformity deteriorates due to excessive height
Solution Approach 1:
The insulator layer height is locally optimized: at the active material layer edge where short-circuit risk is highest, the insulator layer is kept lower than the active material layer to maintain uniform contact pressure, while insulation is still provided through the slant coating portion.
3Reliability
If the insulator layer is formed higher than the active material layer, then insulation coverage is improved, but winding appropriateness deteriorates
Solution Approach 1:
The insulator layer height is locally controlled to be lower than the active material layer at the edge portions critical for winding, while maintaining sufficient insulation coverage through the slant coating portion that extends along the active material layer.
4Device complexity
If gaps are left between insulator layer and active material layer, then manufacturing complexity is reduced, but insulation reliability deteriorates due to exposed edges
Solution Approach 1:
The insulator layer is designed to extend in advance along the active material layer edge portion, with the slant coating portion covering the edge from the insulation layer support side, ensuring continuous insulation coverage before potential short-circuit risks arise.
Data Source
AI summary
A strip-shaped electrode sheet includes an electrode foil including a strip-shaped foil exposed portion in which the electrode foil is exposed, a strip-shaped active material layer extending in a longitudinal direction, and a strip-shaped insulator layer containing insulating resin and formed on an insulator-layer support portion along a one-side layer edge portion of the active material layer and between the foil exposed portion of the electrode foil and an active-material-layer support portion. The insulator layer is located lower than a top face of the active material layer toward the electrode foil and includes a slant coating portion covering at least a lower portion of a one-side slant portion of the active material layer and a foil coating portion extending from the slant coating portion in a width-direction one side and covering the insulator-layer support portion of the electrode foil.