Gel Polymer Electrolyte Urethane Coating for Battery Swelling
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Solution Overview
Problem
Lithium secondary batteries face issues with liquid electrolyte leakage, flammability, and side reactions that lead to capacity degradation and swelling due to the use of non-aqueous solvents, which are not adequately addressed by conventional gel polymer electrolytes despite their improved electrochemical stability.
Innovation Solution
A composition for a gel polymer electrolyte is developed that includes an isocyanate-containing monomer to induce a urethane reaction with LiOH on the surface of lithium transition metal oxide, forming a urethane bond-containing oligomer coating layer, enhancing adhesion and minimizing side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gel polymer electrolyte is used, then safety is improved, but battery performance deteriorates due to lower conductivity
Solution Approach 1:
The patent optimizes the ratio of cyclic carbonate to chain carbonate solvents (1:4 to 4:1), adjusts polyethylene glycol content (5-50 wt%), and controls LiPF6 concentration to achieve maximum ionic conductivity (1.2×10^-3 S/cm at 20°C) while maintaining gel structure and safety properties, thereby improving battery performance without sacrificing safety.
Solution Approach 2:
Polyethylene glycol acts as a plasticizer intermediary that enhances ionic conductivity of the gel polymer electrolyte by facilitating lithium ion transport through its ether oxygen atoms, while maintaining the gel structure and not causing leakage, thus bridging the gap between safety and 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
This solution improves capacity characteristics and adhesion between electrodes, reducing swelling and side reactions, while maintaining electrochemical stability and mechanical strength.
Implementation Method 1
an isocyanate-containing monomer is introduced to a composition for a gel polymer electrolyte to induce a urethane reaction with LiOH on a surface of a lithium transition metal oxide to form a coating layer including a urethane bond-containing oligomer on the surface of the lithium transition metal oxide
Data Source
AI summary
The present invention relates to a composition for a gel polymer electrolyte and a lithium secondary battery including the same, and more specifically, an objective of the present invention is to provide a secondary battery in which, since an isocyanate-containing monomer is introduced to a composition for a gel polymer electrolyte to induce a urethane reaction with LiOH on a surface of a lithium transition metal oxide to form a coating layer including a urethane bond-containing oligomer on the surface of the lithium transition metal oxide, and thereby side reactions caused by HF in the battery are minimized, capacity characteristics are improved, and adhesion between a positive electrode and a separator is enhanced to minimize the swelling phenomenon of the battery.