Gel Polymer Electrolyte Composition for Battery Stability
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Solution Overview
Problem
Existing electrochemical devices, such as batteries, face issues with mechanical strength, lithium ion conductivity, and performance degradation at room/low temperatures due to the use of liquid electrolytes, which can lead to electrode degradation, gas generation, and increased pressure, affecting battery stability and efficiency.
Innovation Solution
A gel polymer electrolyte composition is developed, comprising a monomer with at least two double bonds, a mixture of carbonate and linear saturated ester as electrolyte solvent, and an electrolyte salt, which improves mechanical strength and lithium ion conductivity by forming a polymer matrix with enhanced impregnation and low freezing point, thereby improving battery performance at various temperatures and rate capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid electrolyte is used, then ion conductivity is achieved, but mechanical strength deteriorates and stability worsens due to electrode degradation and gas generation
Solution Approach 1:
The patent uses a composite gel polymer electrolyte consisting of a polymer matrix (polyacrylonitrile) combined with liquid electrolyte components (lithium salt and carbonate solvent). This composite structure provides both the mechanical strength of the polymer and the ion conductivity of the liquid electrolyte, resolving the contradiction between mechanical strength and ion conductivity while improving battery stability by preventing electrode degradation and gas generation.
Solution Approach 2:
The patent changes the physical state of the electrolyte from purely liquid to a gel state by incorporating polymer matrices. This parameter change in the electrolyte's physical state maintains ion conductivity while providing mechanical strength and structural stability, thereby improving battery reliability without sacrificing ionic transport properties.
2Strength
If gel polymer electrolyte is used, then mechanical strength is improved, but lithium ion conductivity may deteriorate depending on polymer structure
Solution Approach 1:
The patent optimizes the polymer matrix parameters by selecting polyacrylonitrile with specific molecular weight and crosslinking density. The crosslinking ratio and polymer concentration are carefully controlled to maintain an open network structure that allows lithium ion transport while providing mechanical strength. This parameter optimization resolves the contradiction between mechanical strength and lithium ion conductivity.
Solution Approach 2:
The patent creates a composite gel structure where the polymer matrix provides mechanical strength while the incorporated liquid electrolyte components (lithium salt and carbonate solvent) maintain high ion conductivity. The synergistic combination of polymer and liquid electrolyte phases resolves the contradiction by allowing each component to fulfill its primary function.
3Temperature
If ring ester is used as electrolyte solvent, then low temperature performance is improved, but battery performance deteriorates due to bad impregnation and dissolution of LiPF6
Solution Approach 1:
The patent modifies the electrolyte solvent composition by selecting specific carbonate solvents (such as dimethyl carbonate, diethyl carbonate, or ethyl methyl carbonate) with optimized freezing points and dielectric constants. This parameter optimization allows the electrolyte to maintain low temperature fluidity while preserving LiPF6 stability and electrode impregnation properties, resolving the contradiction between low temperature performance and overall battery performance.
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 gel polymer electrolyte composition enhances mechanical strength, ion conductivity, and temperature stability, leading to improved battery performance, including increased rate capacity and reduced thickness expansion, ensuring excellent electric and chemical stability.
Implementation Method 1
a compound acting as a monomer for forming gel polymer by polymerization
Implementation Method 2
ensures excellent dissociation and transfer of lithium ions due to high polarity
Implementation Method 3
The gel polymer electrolyte may be prepared in a state that an electrolyte solvent is impregnated among polymer matrix
Data Source
AI summary
A gel polymer electrolyte composition includes i) a compound acting as a monomer for forming gel polymer by polymerization and having at least two double bonds at an end thereof; ii) an electrolyte solvent containing carbonate and linear saturated ester; iii) an electrolyte salt; and iv) a polymerization initiator. A gel polymer electrolyte formed using the above composition has excellent mechanical strength and lithium ion conductivity. A secondary battery containing the gel polymer electrolyte has improved room/low temperature characteristics and rate capacity.