Inorganic-Coated Battery Separator for Low Resistance Under Pressure
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Solution Overview
Problem
Conventional separators for electrochemical devices with high porosity suffer from poor mechanical strength and vulnerability to external pressure, leading to increased resistance and stability issues during long-term operation.
Innovation Solution
A separator comprising a porous polymer substrate with a low melt index and a coating layer containing inorganic particles, which maintains high porosity and mechanical strength, minimizing pore closure and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the porosity of the separator is increased to reduce resistance, then the electrical resistance decreases, but the mechanical strength deteriorates
Solution Approach 1:
The separator is constructed as a composite material consisting of a porous polymer substrate combined with a coating layer containing inorganic particles. This composite structure allows the porous substrate to provide low electrical resistance through high porosity (50-65 vol%), while the coating layer with inorganic particles (such as alumina, boehmite, or silica) reinforces the mechanical strength and provides thermal stability, thus resolving the contradiction between electrical resistance and mechanical strength
Solution Approach 2:
Different regions of the separator have different properties optimized for their specific functions. The porous polymer substrate region is optimized for high porosity to facilitate ion transport and reduce resistance, while the coating layer region is optimized for mechanical reinforcement and thermal stability. This local differentiation allows each region to excel at its primary function without compromising the overall separator performance
2Productivity
If the porosity of the separator is increased to improve ion transport, then the output increases, but the stability under external pressure deteriorates
Solution Approach 1:
The composite structure of porous substrate plus coating layer enables the separator to maintain high porosity (50-65 vol%) for excellent ion transport and high output, while the coating layer containing inorganic particles provides structural rigidity and resistance to external pressure, preventing pore collapse and maintaining stability during battery operation
Solution Approach 2:
The coating layer acts as a protective cushion that is applied beforehand to the porous substrate. This coating layer anticipates and counteracts the effects of external pressure that may occur during battery assembly and operation, preventing the porous structure from collapsing and maintaining both porosity and stability simultaneously
Data Source
AI summary
A separator for an electrochemical device includes a porous polymer substrate; and a coating layer disposed on at least one surface of the porous polymer substrate and including inorganic particles. The porous polymer substrate has a porosity of about 50 vol % or more and 65 vol % or less, the porous polymer substrate includes a polymer having a melt index of about 0.0001 g/10 min or more and 0.01 g/10 min or less, and the coating layer has a porosity of about 40 vol % or more and 70 vol % or less.