Fluorinated Gel Polymer Electrolyte for Stable Lithium-Ion Transfer
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Solution Overview
Problem
Existing lithium polymer batteries face challenges in securing mechanical strength, ion transfer capability, and safety against external impacts due to issues with conventional separators and electrolyte injection methods, leading to potential short circuits and reduced stability.
Innovation Solution
A copolymer for polymer electrolytes is developed, comprising a fluorine-based polymer main chain grafted with an acrylate-based monomer or polymer containing an ion conductive functional group, which improves solubility and electrode wetting, forming a stable solid electrolyte interface (SEI) and enhancing high-temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a polyethylene separator is used in conventional lithium polymer batteries, then the battery structure is simple and easy to manufacture, but the separator has high thermal shrinkage rate causing short circuit between electrodes at high temperature
Solution Approach 1:
The patent uses a fluorinated polymer main chain (such as polyvinylidene fluoride or polytetrafluoroethylene) as the base material, which provides inherent thermal stability and low shrinkage characteristics. This fluorinated polymer is then grafted with acrylate-based side chains containing ion conductive functional groups (such as carboxyl, hydroxyl, or ether groups). The composite structure combines the thermal stability of the fluorinated backbone with the ion conductivity and flexibility of the acrylate side chains, creating a separator that maintains dimensional stability at high temperatures while enabling reliable ion transport.
2Ease of operation
If an oligomer or monomer polymerizable with a polymerization initiator is mixed in a liquid electrolyte solution, then the electrolyte composition can be injected into the battery, but the high viscosity and surface tension cause poor wetting in the cell and mechanical strength is not easily secured
Solution Approach 1:
The patent carefully controls the molecular weight, viscosity, and functional group density of the acrylate-based monomers or oligomers used in the electrolyte composition. By adjusting these parameters, the patent achieves an optimal balance between fluidity (for easy injection and wetting) and mechanical strength (after gelation). The fluorinated polymer backbone provides structural integrity while the acrylate side chains ensure adequate solubility and reactivity for crosslinking, resulting in a gel polymer electrolyte that is both easy to operate with and mechanically strong.
3Ease of manufacture
If one surface of an electrode or separator is coated with electrolyte composition and cured by heat or UV light to form gel polymer electrolyte, then the gel-coated separator can be used to prepare battery, but the gel-coated separator absorbs moisture to degrade performance and stability
Solution Approach 1:
The fluorinated polymer main chain creates a chemically inert and hydrophobic environment that resists moisture absorption. The fluorinated backbone (such as polyvinylidene fluoride or polytetrafluoroethylene) has low surface energy and high chemical stability, forming a barrier against water molecules. This inert fluorinated structure protects the gel polymer electrolyte from moisture degradation, maintaining battery performance and stability even in humid conditions, while still allowing the acrylate side chains to provide necessary ion conductivity.
4Reliability
If a copolymer with fluorine-based polymer main chain and acrylate-based grafted units is used, then solubility and electrode wetting are improved, but the polymer structure becomes more complex
Solution Approach 1:
The patent divides the polymer structure into two distinct segments: a fluorinated polymer main chain and acrylate-based grafted side chains. The fluorinated backbone (such as polyvinylidene fluoride or polytetrafluoroethylene) provides the structural framework with inherent thermal stability and low shrinkage, while the acrylate side chains (containing functional groups like carboxyl, hydroxyl, or ether groups) are grafted onto this backbone. This segmentation allows each component to perform its specialized function independently - the fluorinated backbone ensures dimensional stability and thermal resistance, while the acrylate side chains provide ion conductivity, solubility, and electrode wetting capability, thereby achieving high reliability without excessive overall complexity.
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 copolymer enhances mechanical strength, lithium ion transfer capability, and high-temperature stability in lithium secondary batteries by improving solubility and forming a stable SEI, while maintaining low internal resistance.
Implementation Method 1
a unit derived from an acrylate-based monomer or an acrylate-based polymer containing an ion conductive functional group grafted to the fluorine-based polymer main chain
Implementation Method 2
forming a stable solid electrolyte interface (SEI) and enhancing high-temperature stability
Data Source
AI summary
The present invention discloses a copolymer for a polymer electrolyte, and a gel polymer electrolyte and a lithium secondary battery which include the same. Specifically, the present invention discloses a copolymer for a polymer electrolyte, which includes a fluorine-based polymer main chain and a unit derived from an acrylate-based monomer or an acrylate-based polymer containing an ion conductive functional group grafted to the fluorine-based polymer main chain, and a gel polymer electrolyte in which lithium ion transfer capability is improved by including the same. Also, the present invention may prepare a lithium secondary battery with enhanced high-temperature safety by including the gel polymer electrolyte.