Wound Battery Electrode Stress Management via Local Density Variation
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Solution Overview
Problem
Wound type batteries face issues with cracking and breaking at the winding-back portions of the positive and negative electrode current collectors due to increased area density of active material layers, leading to potential battery failure.
Innovation Solution
Incorporating a second region with a lower area density in the winding-back portions of the positive electrode active material layer, specifically as a recess, to distribute stress and prevent cracking, while maintaining a higher area density in the first region for increased capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the area density of the active material layer is improved to increase battery capacity, then the battery capacity increases, but cracks and breaks are easily generated in the current collector at winding-back portions
Solution Approach 1:
The patent applies local quality by creating a second region with lower area density specifically at the winding-back portions of the active material layer, while maintaining higher area density in the first region. This localized variation in density allows the electrode to accommodate stress at critical winding-back areas without compromising overall battery capacity, thereby preventing cracks while preserving energy storage capability.
2Quantity of substance
If the area density of the active material layer is increased, then more active material is packed in the electrode, but stress concentration occurs at winding-back portions causing cracks
Solution Approach 1:
The patent changes the area density parameter of the active material layer by introducing a second region with lower area density at the winding-back portions. This parameter modification redistributes stress throughout the electrode structure, preventing stress concentration at critical locations while maintaining high active material content in the first region for adequate capacity.
Data Source
AI summary
The battery is provided. The battery includes an electrode. The electrode includes a current collector and an active material layer provided on an inside surface of the current collector. The active material layer includes a first region and a second region, where the second region includes an area density lower than the first region, and the second region is provided in a winding-back portion of the active material layer.