Core-Shell Battery Separator for Heat Shrinkage Resistance
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Solution Overview
Problem
Conventional lithium secondary battery separators face challenges with thermal shrinkage at high temperatures, leading to internal short circuits and increased risk of ignition, which affects their performance and safety.
Innovation Solution
A non-woven separator with a core-shell structure composed of β-chitin and vinylidene fluoride-trifluoroethylene copolymer is manufactured using coaxial electrospinning, followed by heat treatment to align the copolymer's crystal axis perpendicular to the fiber direction, enhancing heat resistance and lithium ion affinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous polyolefin base is used for the separator, then chemical resistance and mechanical properties are improved, but heat shrinkage resistance deteriorates at high temperatures
Solution Approach 1:
The patent uses a composite structure consisting of a polyolefin base layer combined with a heat-resistant non-woven fabric layer. This composite structure allows the separator to maintain both the chemical resistance of polyolefin and the high-temperature stability of the heat-resistant fabric, preventing heat shrinkage while preserving other essential properties.
Solution Approach 2:
The separator is divided into distinct functional layers: a porous polyolefin base layer for chemical resistance and ion permeability, and a separate heat-resistant non-woven fabric layer for thermal stability. This segmentation allows each layer to perform its specific function optimally without compromising the other.
2Temperature
If the separator structure is modified to improve heat resistance, then thermal stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent combines the base polyolefin layer and the heat-resistant non-woven fabric layer into a single integrated separator structure. This merging approach simplifies the manufacturing process by treating the multi-layer structure as one unified component, reducing the number of separate assembly steps while maintaining thermal stability.
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 solution provides improved heat shrinkage properties and reduced resistance, resulting in enhanced cycle performance and safety for lithium secondary batteries by maintaining structural integrity and facilitating uniform lithium ion migration.
Implementation Method 1
coaxial electrospinning with the first solution as a core solution and the second solution as a shell solution to produce a non-woven fabric formed of a fiber with a core-shell structure
Implementation Method 2
performing heat treatment on the non-woven fabric at a temperature lower than a thermal decomposition point of the β-chitin and higher than a melting point of the vinylidene fluoride-trifluoroethylene copolymer to melt and recrystallize the vinylidene fluoride-trifluoroethylene copolymer
Implementation Method 3
enhancing heat resistance and lithium ion affinity... facilitating uniform lithium ion migration
Data Source
AI summary
A method for manufacturing a non-woven separator for a lithium secondary battery, includes: (S1) preparing a first solution of β-chitin dissolved in a first solvent and a second solution of vinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE) dissolved in a second solvent; (S2) coaxial electrospinning with the first solution as a core solution and the second solution as a shell solution to produce a non-woven fabric formed of a fiber with a core-shell structure having a core portion of the β-chitin and a shell portion of the vinylidene fluoride-trifluoroethylene copolymer; and (S3) performing heat treatment on the non-woven fabric at a temperature lower than a thermal decomposition point of the β-chitin and higher than a melting point of the vinylidene fluoride-trifluoroethylene copolymer to melt and recrystallize the vinylidene fluoride-trifluoroethylene copolymer.