Lithium Metal Battery Electrolyte Composition for Flammability and Viscosity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional liquid electrolytes for lithium metal batteries face issues with flammability and limited transport properties, as organic solvent-based electrolytes have low flash points and ionic liquid-based electrolytes have high viscosities, affecting cell reversibility and stability.
Innovation Solution
A liquid electrolyte composition comprising 45-65 mol % aprotic solvent, 5-15 mol % ionic liquid, and 28-44 mol % lithium salt, with specific examples including dimethoxyethane, dimethyl carbonate, N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide, and lithium bis(fluorosulfonyl)imide, which achieves a dynamic viscosity of 30-120 mPa·s and a flash point greater than 60° C, enhancing cell reversibility and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If organic solvent-based electrolytes are used, then flash point is low and flammability increases, but transport properties improve and viscosity decreases
Solution Approach 1:
The patent uses a composite electrolyte system combining ionic liquid (15-30 wt%) with organic carbonate solvents (70-85 wt%). This composite approach allows the ionic liquid to provide high flash point and safety while the organic carbonate maintains low viscosity and good transport properties, resolving the contradiction between flammability and transport performance
Solution Approach 2:
The patent optimizes the concentration parameters of ionic liquid (15-30 wt%) and lithium salt (20-40 wt%) to achieve a balance point where the electrolyte maintains flash point above 60°C while keeping viscosity below 120 mPa·s, thereby simultaneously improving safety and transport properties through parameter optimization
2Object-affected harmful factors
If ionic liquid-based electrolytes are used, then flash point increases and flammability decreases, but viscosity increases and transport properties worsen
Solution Approach 1:
The patent creates a composite electrolyte combining ionic liquid with low-viscosity organic carbonates (DMC, DEC, EMC) to offset the high viscosity of pure ionic liquid. The organic carbonate component provides excellent ion transport while the ionic liquid maintains high flash point, achieving both safety and performance
Solution Approach 2:
The patent introduces ionic liquid at specific local concentrations (15-30 wt%) within the electrolyte mixture rather than using pure ionic liquid. This localized approach provides sufficient safety improvement while minimizing the negative impact on overall viscosity and transport properties
3Reliability
If lithium salt content is increased, then solvation capability improves, but viscosity increases and flash point changes
Solution Approach 1:
The patent optimizes lithium salt concentration to 20-40 wt% and ionic liquid concentration to 15-30 wt%, finding an optimal parameter combination where solvation capability is maximized while viscosity remains below 120 mPa·s. This parameter optimization ensures good electrochemical performance without excessive viscosity increase
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 electrolyte composition ensures non-flammability, maintains high salt content solvation, and improves cell reversibility and stability, meeting both U.S. and UN non-flammability standards while maintaining acceptable viscosity, thereby enhancing the performance and safety of lithium metal batteries.
Implementation Method 1
Conventional liquid electrolyte for use in a lithium metal battery has lithium salts dissolved in an ionic liquid or an organic solvent
Data Source
AI summary
A liquid electrolyte for a lithium metal battery comprises 45-65 mol % of an aprotic solvent, 5-15 mol % of an ionic liquid, 28-44 mol % of a lithium salt and up to 5 mol % additives. The aprotic solvent consists of one or more of a linear carbonate and a linear ether and the ionic liquid consists of one or more of PYR13FSI, PYR14FSI, PYR13TFSI, and PYR14TFSI. The lithium salt is selected from the group consisting of LiFSI, LiTFSI, and LiBET. The liquid electrolyte can have a flash point of greater than 60° C. and a dynamic viscosity of less than 120 mPa·s.