Gel Polymer Electrolyte Composition for Dendrite-Resistant Li-Ion Cells
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Solution Overview
Problem
Existing gel polymer electrolytes for lithium-ion electrochemical cells face challenges in maintaining cycling stability and preventing the formation of dendritic lithium, while also lacking flame retardancy and self-extinguishing properties.
Innovation Solution
A gel polymer electrolyte comprising a polymer matrix of poly(vinylidene fluoride-co-hexafluoropropylene) infiltrated with a nonaqueous organic solvent mixture of propylene carbonate and fluoroethylene carbonate, and lithium salts such as lithium difluoro(oxalato)borate and lithium bis(trifluoromethanesulfonyl)imide, which promotes stable solid electrolyte interfaces and inhibits dendrite formation, and is self-extinguishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gel polymer electrolytes are used, then ionic conductivity is achieved, but cycling stability deteriorates and dendritic lithium forms
Solution Approach 1:
The patent employs a composite electrolyte system combining gel polymer matrix with specific lithium salt additives (lithium difluoro(oxalato)borate and lithium bis(trifluoromethanesulfonyl)imide) to create a multi-component system that simultaneously improves cycling stability and prevents dendrite formation through synergistic effects of different materials
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by introducing specific lithium salts with controlled concentrations, which alter the interfacial properties and electrochemical behavior to stabilize cycling performance and suppress dendritic growth
2Object-affected harmful factors
If conventional gel polymer electrolytes are used, then mechanical stability is provided, but flame retardancy and self-extinguishing properties are lacking
Solution Approach 1:
The patent converts the potential hazard of flammable organic solvents in gel polymer electrolytes into a safety feature by selecting solvents with inherent flame retardant properties and incorporating additives that promote self-extinguishing behavior, thereby transforming thermal instability into thermal safety
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 enhances cycling stability, prevents dendrite growth, and provides flame retardancy and self-extinguishing capabilities, improving the overall performance and safety of lithium-ion electrochemical cells.
Implementation Method 1
an ionically conductive electrolyte that provides a medium for the conduction of lithium ions between the negative and positive electrodes
Implementation Method 2
a liquid electrolyte solution, which generally comprises a lithium salt dissolved or dispersed in one or more nonaqueous aprotic organic solvents
Data Source
AI summary
A gel polymer electrolyte for an electrochemical cell that cycles lithium ions comprises a polymer matrix infiltrated with a liquid electrolyte solution. The polymer matrix comprises poly(vinylidene fluoride-co-hexafluoropropylene). The liquid electrolyte solution comprises a nonaqueous organic solvent, a first lithium salt in the nonaqueous organic solvent, and a second lithium salt in the nonaqueous organic solvent. The first lithium salt comprises lithium difluoro(oxalato)borate and the second lithium salt comprises lithium bis(trifluoromethanesulfonyl)imide.