Poly(siloxane-g-ethylene oxide) Electrolyte for Safe Lithium Batteries
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Solution Overview
Problem
Current electrochemical storage devices face challenges in achieving high ionic conductivity, safety, and thermal stability, particularly in lithium secondary batteries, due to the use of volatile and combustible solvents, which are a concern for applications in portable electronics, vehicles, and medical devices.
Innovation Solution
The development of a nonaqueous and nonvolatile polymeric electrolyte based on poly(siloxane-g-ethylene oxide) with a Si—O backbone, which exhibits high room temperature ionic conductivity, flame resistance, and thermal stability, making it suitable for lithium secondary batteries and other electrochemical storage devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional volatile and combustible solvents are used in electrochemical storage devices, then high ionic conductivity can be achieved, but safety and thermal stability deteriorate due to combustion risk
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by using poly(siloxane-g-ethylene oxide) copolymer instead of conventional volatile solvents. This parameter change maintains ionic conductivity while eliminating combustion risk, directly resolving the contradiction between safety and harmful factors
Solution Approach 2:
The patent employs a composite polymer structure combining siloxane backbone with ethylene oxide side chains. This composite material approach creates a electrolyte that integrates the thermal stability of siloxane with the ionic conductivity of ethylene oxide units, resolving the contradiction between safety and performance
2Reliability
If poly(ethylene oxide) is used as electrolyte, then ionic conductivity is achieved, but thermal stability and flame resistance are insufficient
Solution Approach 1:
The patent creates a composite polymer structure where siloxane units provide thermal stability and flame resistance, while ethylene oxide units provide ionic conductivity. This composite approach resolves the contradiction between ionic conductivity and thermal stability that limits pure PEO electrolytes
Solution Approach 2:
The patent applies local quality by assigning different functional properties to different parts of the polymer chain: siloxane backbone segments provide thermal stability locally, while ethylene oxide side chains provide ionic conductivity locally, achieving both properties simultaneously in the overall electrolyte system
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 poly(siloxane-g-ethylene oxide) electrolyte provides enhanced safety and performance by offering high ionic conductivity, low viscosity, and improved thermal stability, reducing the risk of combustion and toxicity, thus making it suitable for medical and high-energy applications.
Implementation Method 1
high room temperature ionic conductivity
Implementation Method 2
The Si—O backbone of these polymers is highly flexible, yet retains its chemical and thermal integrity
Implementation Method 3
when substituted with oligoethylene oxide groups, solvate lithium salts
Data Source
AI summary
Disclosed is a nonaqueous liquid electrolyte comprising poly(siloxane-g-3 ethylene oxide) and its synthesis. This electrolyte provides significant safety, improved electrochemical stability, improved conductivity, lower impedance, and lower manufacturing costs.