Fluorinated Electrolyte Composition for Dendrite-Safe Li-Ion Batteries
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Solution Overview
Problem
Existing lithium-ion batteries face challenges in achieving a balance between various performance metrics such as energy density, safety, output performance, and cycling performance, especially at high working voltages.
Innovation Solution
The development of an electrolyte solution comprising a fluorinated solvent, a fluorine-containing sulfonylimide lithium salt, and a lithium halide salt, which improves conductivity, flame retardancy, and inhibits lithium dendrite growth, thereby enhancing the comprehensive performance of lithium-ion batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional electrolyte solutions are used to achieve high energy density, then the battery capacity increases, but safety performance deteriorates due to poor flame retardancy and lithium dendrite growth
Solution Approach 1:
The patent uses a composite electrolyte system combining fluorinated cyclic carbonate (FCC) as the main solvent with fluorinated chain carbonate (FEC) and lithium halide salt (LiX) additives. This composite approach creates synergistic effects where FCC provides high voltage stability and energy density, while FEC and LiX work together to suppress lithium dendrite growth and enhance flame retardancy, thus achieving both high energy density and improved safety performance simultaneously
Solution Approach 2:
The patent optimizes specific parameter ranges: FCC content at 80-99.5 wt%, FEC at 0.5-20 wt%, and LiX at 0.01-5 wt%. These parameter adjustments are critical - the fluorinated solvent structure changes provide high electrochemical stability for energy density, while the specific concentration ranges of additives ensure effective dendrite suppression and flame retardancy without compromising performance
2Speed
If electrolyte composition is optimized for high conductivity, then charge-discharge rate improves, but flame retardancy deteriorates
Solution Approach 1:
The patent achieves optimal balance by controlling the concentration parameters: high FCC content (80-99.5 wt%) ensures high ionic conductivity for fast charge-discharge rates, while the presence of FEC (0.5-20 wt%) and LiX (0.01-5 wt%) at specific levels maintains flame retardancy. The fluorinated molecular structure inherently provides both high ion mobility and fire resistance
Solution Approach 2:
The lithium halide salt (LiX) acts as an intermediary substance that mediates between conductivity and flame retardancy requirements. It forms protective interfaces that facilitate ion transport (improving conductivity) while the halide ions enhance the electrolyte's fire resistance properties, thus reconciling the contradiction between fast charge-discharge rates and flame retardancy
3Reliability
If lithium halide salt content is increased to inhibit dendrite growth, then safety improves, but conductivity deteriorates due to increased viscosity
Solution Approach 1:
The patent precisely controls the LiX concentration parameter within 0.01-5 wt%, with optimal ranges identified. This parameter optimization ensures sufficient dendrite inhibition through lithium halide crystal formation on the electrode surface, while maintaining low enough concentration to avoid excessive viscosity increase that would compromise ionic conductivity and charge-discharge 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
The proposed electrolyte solution achieves improved energy density, first-cycle efficiency, cycling performance, and safety by inhibiting lithium dendrite growth and enhancing flame retardancy, thus addressing the limitations of existing lithium-ion batteries.
Implementation Method 1
the electrolyte solution has improved conductivity
Implementation Method 2
the electrolyte solution has improved conductivity and flame retardancy
Implementation Method 3
inhibit the growth of lithium dendrites
Data Source
AI summary
Provided are an electrolyte solution, comprising an organic solvent, an electrolyte lithium salt, and an additive; wherein the organic solvent comprises a fluorinated solvent; the electrolyte lithium salt comprises a fluorine-containing sulfonylimide lithium salt; and the additive comprises a lithium halide salt. The electrolyte solution of the present application has good conductivity and flame retardancy, and a lithium-ion battery comprising the electrolyte solution has at least one of improved energy density, safety performance, output performance, and cycling performance.