Fluoro Ether Electrolyte for Lithium Battery Safety and Cycle Life
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in achieving both high safety and long-term charge-discharge cycle-life characteristics due to the limitations of existing electrolytes, particularly those using organic fluoro ether compounds which provide high safety but deteriorate cycle-life characteristics due to high viscosity.
Innovation Solution
An electrolyte for rechargeable lithium batteries is developed, comprising a lithium salt and a non-aqueous organic solvent with a fluoro-based solvent having a controlled fluoro substitution ratio, along with a flame retardant such as a phosphazene compound, to enhance safety, rate capability, and cycle-life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an organic fluoro ether compound is used in the electrolyte to improve safety against oxidation decomposition, then safety is improved, but cycle-life characteristics deteriorate due to high viscosity
Solution Approach 1:
The patent applies parameter changes by controlling the fluoro substitution ratio within a specific range (5-50%) and using a mixture of fluoro-based solvents with different substitution ratios. This optimization balances the viscosity and safety properties, resolving the contradiction between improved safety and maintained cycle-life characteristics
Solution Approach 2:
The patent uses a composite electrolyte system comprising multiple fluoro-based solvents with different fluoro substitution ratios (5-50%), combined with specific additives. This composite approach allows the electrolyte to achieve both high safety and good cycle-life characteristics by combining the advantages of different solvent compositions
2Reliability
If a high amount of fluoro is included in the organic fluoro ether compound to enhance safety, then safety is improved, but rate capability deteriorates due to increased viscosity
Solution Approach 1:
The patent optimizes the fluoro substitution ratio parameter within the range of 5-50% and controls the content of different fluoro-based solvents to balance safety and rate capability. By adjusting these parameters, the electrolyte achieves both high safety and acceptable rate capability despite the inherent viscosity increase from fluoro content
3Duration of action of stationary object
If conventional electrolyte compositions are used to achieve long-term charge-discharge cycle-life characteristics, then cycle-life is improved, but safety characteristics deteriorate
Solution Approach 1:
The patent employs a composite electrolyte formulation combining multiple fluoro-based solvents with different substitution ratios (5-50%), along with specific additives. This composite structure maintains long-term charge-discharge cycle-life characteristics while simultaneously achieving high safety performance, overcoming the limitations of conventional single-component electrolytes
Data Source
AI summary
An electrolyte for a rechargeable lithium battery that includes a lithium salt and a non-aqueous organic solvent, wherein the non-aqueous organic solvent includes a fluoro-based solvent represented by the following Chemical Formula 1, and a rechargeable lithium battery including the same.R—O—R′ Chemical Formula 1In Chemical Formula 1, R and R′ are independently a substituted or unsubstituted C1 to C6 alkyl group, or a substituted or unsubstituted C1 to C6 fluoroalkyl group, wherein at least one of R and R′ is the substituted or unsubstituted C1 to C6 fluoroalkyl group, and a substitution ratio of fluoro in the fluoro-based solvent represented by the Chemical Formula 1 may range from more than about 0% to less than or equal to about 50%.