Battery Cell Electrode End Structure Against Lithium Precipitation
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Solution Overview
Problem
Battery cells are prone to lithium precipitation at the end portions of electrode plates during the cycling process due to continuous electrolyte consumption, leading to swelling and failure.
Innovation Solution
A battery cell design featuring a first electrode plate with a raised structure and transition section at the end portion of the active material layer, where the transition section is adjacent to the body portion and the raised structure, with a defined thickness ratio to prevent lithium precipitation, and a separator disposed between the electrode plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If active material is coated on current collectors to form active material layers, then battery capacity is improved, but end portions of active material layers are thinned which causes lithium precipitation
Solution Approach 1:
The patent applies local quality by creating a raised structure at the end portion of the active material layer with different thickness characteristics than the body portion. The raised structure has a specific thickness ratio (ha-hr)/ha≤2% compared to the body portion thickness ha, providing localized thickness enhancement where lithium precipitation risk is highest, while maintaining overall battery capacity.
2Productivity
If continuous cycling is performed to utilize battery capacity, then energy output is improved, but electrolyte is continuously consumed leading to end portion thinning and lithium precipitation
Solution Approach 1:
The raised structure at the end portion acts as a preemptive cushioning measure against electrolyte consumption effects. By providing additional active material thickness at the vulnerable end portions before cycling begins, the structure compensates for the gradual electrolyte depletion that occurs during continuous cycling, preventing lithium precipitation that would otherwise occur at thinned end portions.
3Duration of action of moving object
If end portions of active material layers are thinned during cycling, then battery operation is maintained, but lithium precipitation occurs causing swelling and battery failure
Solution Approach 1:
The raised structure implements preliminary anti-action by preemptively counteracting the thinning effect at end portions. The structure is designed with thickness ratio (ha-hr)/ha≤2% to provide sufficient active material reserve that opposes and prevents the harmful lithium precipitation process before it can occur during battery cycling operations.
Data Source
AI summary
A battery cell includes a first electrode plate and a second electrode plate that are alternately stacked. A separator is disposed between the first electrode plate and the second electrode plate. The first electrode plate includes a first current collector and a first active material layer disposed on the first current collector. The first active material layer includes a body portion and an end portion. The end portion is provided with a raised structure and a transition section. The transition section is adjacent to the body portion and the raised structure. In a thickness direction of the battery cell, a distance from a lowest point of a surface of the transition section to a surface of the first current collector is hr, and a thickness of the body portion of the first active material layer is ha, where (ha−hr)/ha≤2%.