Flat Wound Electrode Assembly With Corner Gaps for Stress Relief
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Solution Overview
Problem
Existing secondary batteries with wound electrode assemblies face distortion and poor electrolyte infiltration due to unrelieved expanding stress between electrode plates, particularly in corner regions, leading to reduced cycle performance and risk of lithium precipitation.
Innovation Solution
The electrode assembly features a flat structure with a main region and corner regions, incorporating gaps between turns of the electrode plates, where the first gap in the corner regions is larger than the second gap in the main regions, allowing for stress release and improved electrolyte infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a wound electrode assembly is used, then the battery structure is compact and easy to manufacture, but expanding stress accumulates causing distortion and poor electrolyte infiltration
Solution Approach 1:
The electrode assembly is segmented into multiple regions with different gap dimensions. Corner regions have larger gaps while main regions have smaller gaps, allowing stress to be distributed and released at specific locations without compromising the overall compact structure
Solution Approach 2:
Different regions of the electrode assembly are given different local properties: corner regions have larger gaps to accommodate stress concentration, while main regions maintain smaller gaps for compactness. This local differentiation resolves the contradiction between compact structure and stress management
2Shape
If the electrode assembly is tightly wound, then the structure is compact, but expanding stress cannot be released leading to distortion
Solution Approach 1:
The compact wound structure is segmented into regions with different gap sizes, creating controlled release points for expanding stress while maintaining overall compactness
Solution Approach 2:
The gaps between electrode plate turns act as intermediary spaces that absorb and release expanding stress, preventing stress transmission that would cause distortion while maintaining the compact wound structure
3Ease of manufacture
If uniform gaps are provided between turns, then manufacturing is simple, but corner regions experience stress concentration and distortion
Solution Approach 1:
The gap dimension is varied locally: larger gaps in corner regions to reduce stress concentration, and smaller gaps in main regions for compactness. This local quality differentiation addresses stress concentration while remaining manufacturable
Solution Approach 2:
The gap structure transitions from uniform (symmetric) to asymmetric with different gap sizes in different regions. This asymmetry allows stress to be managed differently in corner regions versus main regions, preventing distortion
Data Source
AI summary
The present disclosure provides an electrode assembly and a secondary battery. The electrode assembly includes a first electrode plate, a second electrode plate and a separator. The first electrode plate, the second electrode plate and the separator are wound to a flat structure, and the flat structure comprises a main region and corner regions, the corner regions are provided at two ends of the main region along a width direction of the main region. The first electrode plate and the second electrode plate each are wound to turns. A gap is provided between two adjacent turns of the first electrode plate, the gap includes a first gap and a second gap. The first gap corresponds to the corner region in position, the second gap corresponds to the main region in position, and a dimension of the first gap is larger than a dimension of the second gap.