Gel Polymer Electrolyte High-Voltage Stability
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Solution Overview
Problem
Gel polymer electrolytes in lithium secondary batteries face limitations in high-voltage stability and mechanical properties, leading to lower lithium ion conductivity and safety concerns compared to liquid and solid polymer electrolytes.
Innovation Solution
A gel polymer electrolyte with a matrix polymer formed by polymerizing a first oligomer containing fluorine-substituted polyether units and acrylate units, which enhances lithium ion conductivity and mechanical strength, and includes inorganic particles to improve electrochemical stability and wettability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of gel polymer electrolyte is decreased to improve conductivity, then lithium ion conductivity improves, but mechanical strength decreases and short circuit occurs
Solution Approach 1:
The patent optimizes the PEO molecular weight to 200,000-400,000 and controls the gel polymer electrolyte thickness within 15-50 μm while maintaining adequate mechanical strength. This parameter optimization allows thin electrolyte films to provide both high ionic conductivity and sufficient mechanical integrity to prevent short circuits.
Solution Approach 2:
The composite structure of PEO polymer chains with cyclic carbonate solvents and LiPF6 salts creates a gel network that maintains mechanical strength even at reduced thickness, preventing electrode short circuiting while enabling high ion transport.
2Reliability
If high-voltage stability is improved through electrolyte composition, then battery safety improves, but battery performance decreases
Solution Approach 1:
The patent uses cyclic carbonates (EC, PC, DEC) with high dielectric constants and oxidation stability to achieve high-voltage stability up to 4.35 V, while optimizing LiPF6 concentration (0.5-2.0 M) and PEO molecular weight to maintain excellent charge-discharge performance and capacity retention.
Solution Approach 2:
The composite gel polymer electrolyte combines the high-voltage stability of cyclic carbonate solvents with the electrochemical activity of PEO-LiPF6 complex, achieving both high-voltage stability and excellent battery performance simultaneously through synergistic material combination.
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 increases high-temperature durability and high-voltage stability, improving lithium ion conductivity and mechanical properties, resulting in a lithium secondary battery with enhanced performance and safety.
Implementation Method 1
the matrix polymer is formed in a three-dimensional network structure by polymerizing a first oligomer
Implementation Method 2
an electrolyte solution impregnated in the matrix polymer
Implementation Method 3
lithium ion conductivity is lower than that of a liquid electrolyte composed only of an electrolyte solution
Data Source
AI summary
The present invention relates to a gel polymer electrolyte, which includes a matrix polymer and an electrolyte solution impregnated in the matrix polymer, wherein the matrix polymer is formed in a three-dimensional network structure by polymerizing a first oligomer which includes unit A represented by Formula 1 and unit B having a crosslinkable functional group derived from a compound including at least one copolymerizable acrylate group, and a lithium secondary battery including the same.