Jelly-Roll Electrode Assembly Structure for Outer-Layer Crack Prevention
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Solution Overview
Problem
Cylindrical batteries with jelly-roll type electrode assemblies experience stress concentration and cracking at the negative electrode due to the thickness of the positive electrode, leading to deformation and potential cracks during charging and discharging.
Innovation Solution
A jelly-roll type electrode assembly design with a first electrode featuring a double-side coated portion on its outermost surface, matching the longitudinal end portion of the second electrode, to distribute stress evenly and prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a jelly-roll type electrode assembly with negative electrode-outermost structure is used, then the battery can be manufactured with standard processes, but stress concentration occurs on the outermost negative electrode during charging and discharging, causing cracks
Solution Approach 1:
The patent applies local quality by providing the outermost negative electrode with a specific structure at its longitudinal end portion, where the active material layer is positioned to cover the step portion formed by the positive electrode end. This localized structural modification addresses the stress concentration problem specifically at the vulnerable end region without changing the overall electrode assembly structure, maintaining manufacturing compatibility while improving crack resistance.
2Quantity of substance
If the positive electrode thickness is increased to improve capacity, then energy density is improved, but stress concentration on the outermost negative electrode increases, leading to cracking
Solution Approach 1:
The patent applies preliminary anti-action by pre-positioning the active material layer of the outermost negative electrode to cover the step portion before the battery undergoes charging and discharging cycles. This advance preparation creates a protective configuration that counteracts the stress concentration that will occur during operation, preventing crack formation before it can happen.
Data Source
AI summary
A jelly-roll type electrode assembly having an outer circumference tab structure. The jelly-roll type electrode assembly includes a first electrode double-side coated portion, whereby it is possible to prevent crack and deformation of the electrode assembly due to stress concentration on the outermost first electrode. A cylindrical secondary battery including the jelly-roll type electrode assembly is also provided.