Variable-Thickness Battery Separator for Cylindrical Cell Impingement
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Solution Overview
Problem
Cylindrical batteries face issues with impingement of the separator due to electrode shrinkage and expansion during charging/discharging, leading to potential internal short circuits and reduced stability.
Innovation Solution
A separator design with a porous polymer substrate and coating layers containing inorganic particles and a binder polymer, featuring varying thickness distribution and asymmetrical/symmetrical interfaces, which enhances mechanical strength and resistance to electrode expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the separator has uniform thickness throughout, then the manufacturing process is simple, but the separator cannot effectively prevent impingement at the center during electrode expansion
Solution Approach 1:
The separator is designed with different thickness characteristics in different regions: the first region (including one end) has a first thickness while the second region (including the other end) has a second thickness different from the first. This local variation in thickness provides enhanced mechanical support at specific locations to prevent impingement during electrode expansion, while maintaining overall structural integrity.
Solution Approach 2:
The separator is divided into multiple regions (first region and second region) with distinct thickness characteristics. This segmentation allows each region to perform its specific function - the first region provides support at one end while the second region provides support at the other end, collectively preventing center impingement during electrode expansion.
2Strength
If the separator thickness is increased to prevent impingement, then the mechanical strength is improved, but the battery volume increases
Solution Approach 1:
Instead of uniformly increasing the separator thickness throughout, the invention applies thickness variation locally - the first region has a first thickness and the second region has a second thickness. This provides the necessary mechanical strength at specific locations to prevent impingement while minimizing the overall volume increase of the battery.
Data Source
AI summary
A separator according to one embodiment of the present disclosure includes a porous polymer substrate; and porous coating layers formed on both surfaces of the porous polymer substrate. The separator has one end A and the other end A′ in the longitudinal direction, and a point B is present between one end A and the other end A′. The thickness of the separator is constantly maintained from one end A to the other end A′. In a region AB from one end A to the point B, the thicknesses of the porous polymer substrate and the porous coating layers are constantly maintained. In a region BA′ from the point B to the other end A′, the thickness of the porous polymer substrate is decreased, and the thicknesses of the porous coating layers are increased.