Cross-Linked Separator Coating for Thin High-Heat Battery Separators
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Solution Overview
Problem
Conventional olefin-based separators for lithium batteries suffer from low heat resistance and thermal contraction at high temperatures, leading to potential short circuits and reduced battery stability.
Innovation Solution
A separator coating composition comprising an aqueous crosslinking reactive poly(vinylamide)-based copolymer, a multifunctional crosslinking agent, inorganic particles, and water, which forms a cross-linked network structure on a porous substrate to enhance heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyethylene wax is used to add shutdown function to separator, then shutdown function is improved, but coating layer retention deteriorates at high temperature
Solution Approach 1:
The patent changes the chemical parameters of the coating material from polyethylene wax to poly(vinylidene fluoride-co-hexafluoropropylene) copolymer. This material parameter change enables the coating to maintain both shutdown function and high-temperature retention, as the copolymer's chemical structure provides thermal stability while maintaining porosity for shutdown capability.
Solution Approach 2:
The patent creates a composite coating structure by combining poly(vinylidene fluoride-co-hexafluoropropylene) copolymer with inorganic particles. This composite material approach enhances both the thermal stability and mechanical properties of the coating layer, allowing it to retain its structure at high temperatures while providing shutdown function.
2Ease of operation
If olefin-based polymer is used as separator, then flexibility is improved, but heat resistance deteriorates at high temperature
Solution Approach 1:
The patent changes the material parameter from olefin-based polymer to poly(vinylidene fluoride-co-hexafluoropropylene) copolymer for the coating layer. This chemical composition change provides superior heat resistance while maintaining flexibility, as the copolymer structure offers both thermal stability and mechanical flexibility required for separator operation.
Solution Approach 2:
The patent forms a composite structure with the copolymer coating layer on the olefin-based separator substrate. This composite approach allows the base olefin separator to provide flexibility while the copolymer coating provides enhanced heat resistance, achieving both properties simultaneously.
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
The composition provides a separator with high heat resistance and improved lifespan characteristics, reducing the risk of short circuits and enhancing the stability of lithium batteries.
Implementation Method 1
a binder including an aqueous crosslinking reactive poly(vinylamide)-based copolymer; a multifunctional crosslinking agent having at least bifunctionality
Implementation Method 2
drying, with hot air, the porous substrate coated with the composition thereon
Data Source
AI summary
Provided are a separator coating composition, a method of manufacturing a separator using the same, and a separator and a lithium battery using the same. The separator coating composition includes a binder containing an aqueous crosslinking reactive poly(vinylamide)-based copolymer, a crosslinking agent having at least bifunctionality, inorganic particles, and water, wherein the poly(vinylamide)-based copolymer includes a repeating unit derived from a vinylamide monomer and a repeating unit derived from a crosslinking reactive group-containing monomer. The separator coating composition may be used to prepare a separator capable of exhibiting high heat resistance even at a thinner coating thickness.