Wound Battery Cell Electrode Layout for Inner Ring Fracture Control
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Solution Overview
Problem
Lithium-ion batteries experience rapid lithium intercalation and subsequent fracture at positions with large curvature in the negative electrode inner ring, leading to premature failure during charging and discharging cycles.
Innovation Solution
The battery cell design features a positive electrode plate and negative electrode plate with inner and outer rings, where the surface density of the inner rings is less than that of the outer rings, and the areic capacity ratios between the rings are controlled between 1.1 to 1.5, preventing excessive lithium intercalation and reducing the expansion rate of the negative electrode plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the negative electrode inner ring has high areic capacity to increase battery energy density, then the battery energy density improves, but the negative electrode plate expands rapidly and fractures at positions with large curvature
Solution Approach 1:
The patent applies local quality by creating different areic capacity values at different locations of the electrode plates. Specifically, the positive electrode inner ring has a different areic capacity than the positive electrode outer ring, and similarly for the negative electrode. This local differentiation allows the inner ring regions (which have larger curvature) to have lower areic capacity, reducing lithium intercalation stress and preventing fracture, while the outer ring regions maintain higher areic capacity to contribute to overall battery energy density.
2Productivity
If the areic capacity ratio of negative electrode inner ring to positive electrode outer ring is increased to improve capacity utilization, then the capacity utilization improves, but the negative electrode plate expansion rate increases leading to fracture
Solution Approach 1:
The patent applies parameter changes by optimizing the areic capacity ratios within specific ranges (1.05-1.30 for the first ratio and 1.10-1.25 for the second ratio). These parameter adjustments balance capacity utilization with structural integrity. By controlling the areic capacity distribution and maintaining ratios within these optimized ranges, the patent achieves good capacity utilization while preventing excessive expansion and fracture of the negative electrode plate.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively prolongs the service life of the battery by reducing the likelihood of fracture and lithium precipitation, maintaining the battery's performance and capacity utilization during long-term cycling.
Implementation Method 1
the amount of lithium intercalation in the negative electrode plate in a short time at the position where the curvature of the inner ring of the negative electrode is large
Data Source
AI summary
A battery cell, a battery, and an electric device relating to the field of battery. The battery cell comprises a positive electrode plate, wherein the positive electrode plate comprises a positive electrode inner ring, a positive electrode current collector, and a positive electrode outer ring arranged sequentially from inside to outside; a negative electrode plate, wherein the negative electrode plate comprises a negative electrode inner ring, a negative electrode current collector, and a negative electrode outer ring arranged sequentially from inside to outside; and a separator, wherein the separator is located between the positive electrode plate and the negative electrode plate, and the positive electrode plate, the separator, and the negative electrode plate together form the battery cell; wherein, a surface density of the positive electrode inner ring is less than that of the positive electrode outer ring, and/or a surface density of the negative electrode inner ring is less than that of the negative electrode outer ring. This can reduce the expansion rate of the negative electrode plate, making it difficult for the negative electrode inner ring to fracture and fail at the position with large curvature, thereby improving the service life of the wound battery during the (high rate) charging and discharging process.