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 larger first gaps in corner regions and smaller second gaps in main regions between adjacent turns of the electrode plates, allowing for stress release and improved electrolyte infiltration, thereby reducing deformation and enhancing cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a wound electrode assembly is used with uniform gaps between turns, then the structure is simple and easy to manufacture, but expanding stress accumulates in corner regions causing distortion and poor electrolyte infiltration
Solution Approach 1:
The patent applies local quality by differentiating the gap dimensions in different regions of the wound electrode assembly. Specifically, the corner regions have larger gaps (first gaps) while the main regions have smaller gaps (second gaps). This local differentiation allows the corner regions to better accommodate expanding stress during charge-discharge cycles, preventing distortion and improving electrolyte infiltration, while maintaining overall structural integrity and manufacturability
2Stability of the object's composition
If the gap dimension is increased to release expanding stress, then distortion is reduced, but the energy density and compactness of the battery decreases
Solution Approach 1:
The patent implements local quality by strategically placing larger gaps only in corner regions where expanding stress concentrates, while maintaining smaller gaps in the main regions. This localized approach minimizes the overall gap volume and maximizes the quantity of active materials and electrolyte that can be accommodated, thereby preserving energy density while effectively releasing expanding stress where needed
Solution Approach 2:
The patent applies asymmetry by creating non-uniform gap distribution throughout the wound electrode assembly. The gap dimensions vary asymmetrically based on position, with corner regions having larger gaps and main regions having smaller gaps. This asymmetric design optimizes stress release in critical areas while maintaining compactness and maximizing active material content in non-critical areas
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.