Battery Separator Covering Layer for Short-Circuit Resistance
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Solution Overview
Problem
Current secondary battery configurations do not adequately achieve superior battery characteristics, such as preventing short circuits and maintaining discharge capacity during repeated charging and discharging.
Innovation Solution
Incorporating a separator with a porous layer and a covering layer containing insulating particles between the positive and negative electrodes, where the insulating particles have a specific size range and aspect ratio, ensuring the covering layer effectively adheres to the electrodes even under thermal contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator is disposed between the positive electrode and the negative electrode to prevent short circuits, then safety is improved, but the battery characteristic (discharge capacity) is insufficient
Solution Approach 1:
The separator is designed with non-uniform thickness, featuring 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 allows the separator to provide enhanced protection in specific areas while maintaining better electrode contact and ion transport in other regions, thus preventing short circuits without compromising discharge capacity
Solution Approach 2:
The separator is pre-formed with specific thickness variations before battery assembly. The non-uniform thickness profile is established in advance to anticipate and address potential short circuit risks in specific regions while ensuring optimal performance characteristics are maintained in other areas
2Temperature
If the separator thickness is increased to improve heat resistance and prevent short circuits, then safety is improved, but the discharge capacity deteriorates
Solution Approach 1:
The separator features a non-uniform thickness profile where the first thickness and second thickness are different, allowing regions of enhanced heat resistance where needed while maintaining thinner sections that preserve ion transport efficiency and discharge capacity
Solution Approach 2:
The separator's thickness parameter is varied spatially across different regions. By changing the thickness parameter from a uniform value to a non-uniform distribution, the separator achieves optimized heat resistance in critical areas while maintaining overall battery performance
Data Source
AI summary
A secondary battery includes a positive electrode, a negative electrode, a separator, and an electrolytic solution. The separator is disposed between the positive electrode and the negative electrode. The positive electrode includes primary particles as a positive electrode active material. The separator includes a porous layer and a covering layer. The covering layer is disposed between the porous layer and the positive electrode. The covering layer includes insulating particles. The insulating particles each have a major axis and a minor axis. An average particle size of the primary particles is greater than or equal to 100 nm and less than or equal to 2120 nm. A ratio of an average length of the respective minor axes of the insulating particles to the average particle size is greater than or equal to 0.22 and less than or equal to 1.00.