Battery Sealing Member Copolymer for Low Compression Set
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Solution Overview
Problem
Existing non-aqueous electrolyte battery members made from tetrafluoroethylene/fluoroalkyl vinyl ether copolymers face issues with high compression set at elevated temperatures and elution of fluorine ions into electrolytic solutions, affecting sealing and insulating properties.
Innovation Solution
A copolymer containing a tetrafluoroethylene unit and a fluoroalkyl vinyl ether unit with limited functional groups per 10^6 carbon atoms and a melt flow rate below 20 g/10 minutes, optimized for melt fabrication, is used to create members with improved resistance to compression set and reduced fluorine ion elution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tetrafluoroethylene/fluoroalkyl vinyl ether copolymer is used for insulating members, then insulating characteristics are improved, but compression set resistance at high temperatures deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the copolymer by controlling the ratio of tetrafluoroethylene units to fluoroalkyl vinyl ether units, and by controlling the number of functional groups per 10^6 carbon atoms. This parameter optimization achieves both good insulating characteristics and improved compression set resistance at high temperatures, resolving the contradiction between these two properties.
2Ease of manufacture
If copolymer with higher fluoroalkyl vinyl ether content is used, then processability is improved, but fluorine ion elution into electrolytic solution increases
Solution Approach 1:
The patent optimizes the functional group content parameter (number of functional groups per 10^6 carbon atoms) to a specific range. This parameter control reduces fluorine ion elution into the electrolytic solution while maintaining adequate processability, thus resolving the contradiction between ease of manufacture and harmful factor reduction.
3Strength
If copolymer with lower melt flow rate is used, then compression set resistance is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent carefully balances the melt flow rate parameter within a specific range. This controlled parameter optimization ensures that the copolymer has sufficient compression set resistance while maintaining adequate moldability and manufacturing precision, resolving the contradiction between these two competing requirements.
Data Source
AI summary
A member for a non-aqueous electrolyte battery containing a copolymer containing a tetrafluoroethylene unit and a fluoroalkyl vinyl ether unit, in which the number of functional groups per 106 carbon atoms of a main chain of the copolymer is 100 or less, and a melt flow rate of the copolymer is less than 20 g/10 minutes.