Jelly-roll electrode assembly with varying thickness to reduce stress
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The conventional jelly-roll electrode assembly experiences stress concentration and deformation due to its step structure, leading to potential cracks and short circuits during repeated charge/discharge cycles, compromising the safety of secondary batteries.
Innovation Solution
The electrode assembly is designed with a first portion having a thinner thickness than the second portion, where the first electrode is wound closer to the center, and a third portion with gradually decreasing thickness is introduced to minimize the step structure, reducing bending stress and preventing cracks and disconnections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional jelly-roll electrode assembly is used with uniform electrode thickness, then the manufacturing process is simple, but stress concentration and deformation occur during repeated charge/discharge cycles due to the step structure
Solution Approach 1:
The electrode assembly employs varying electrode thicknesses at different locations. Specifically, the first electrode has a first thickness in a first region and a second thickness different from the first thickness in a second region. This local variation in thickness eliminates the step structure that causes stress concentration, while maintaining manufacturing feasibility through controlled deposition or lamination processes.
2Quantity of substance
If electrodes are wound to form a jelly-roll structure, then the battery energy density is improved, but bending stress and potential cracks develop at the step structure during charge/discharge cycles
Solution Approach 1:
By implementing different electrode thicknesses at different locations, the invention eliminates the step structure that serves as a stress concentration point. The varying thickness design ensures that the electrode assembly can withstand bending stresses during winding and charge/discharge cycles, preventing cracks while maintaining the compact jelly-roll configuration for high energy density.
3Ease of manufacture
If a step structure is formed in the electrode assembly, then the winding process is simplified, but deformation and short circuits occur due to stress concentration at the step
Solution Approach 1:
The invention achieves structural uniformity by eliminating the step structure through varying electrode thicknesses. The first electrode has different thicknesses in different regions, which prevents the formation of steps during winding. This approach maintains manufacturing simplicity while achieving precise structural uniformity, preventing deformation and short circuits.
Data Source
AI summary
An electrode assembly includes a first electrode; a second electrode; and a first separator interposed between the first electrode and the second electrode. The first electrode, the second electrode and the first separator are wound together to form a jelly-roll structure. The first electrode includes a first portion including an innermost edge of the first electrode near a center portion of the jelly-roll structure and a second portion extending from the first portion away from the center portion of the jelly-roll structure. A thickness of the first portion is thinner than a thickness of the second portion.