Fluorinated Electrolyte Composition for Stable Lithium Metal Batteries
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Solution Overview
Problem
Lithium metal secondary batteries face issues with high reactivity of lithium metal, leading to volume expansion, surface non-uniformity, and rapid electrolyte decomposition, which deteriorate battery life and performance.
Innovation Solution
A non-aqueous electrolyte comprising lithium bis(fluorosulfonyl)imide, 1,2-(1,1,2,2-tetrafluoroethoxy)ethane, cyclic fluorinated carbonate, and chain carbonate/ester/ether solvents, optimized in specific volume ratios, to enhance stability and reduce side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal is used as negative electrode active material to obtain highest energy density, then energy density is improved, but high reactivity of lithium metal causes volume expansion, surface non-uniformity, and continuous electrolyte decomposition leading to poor battery life
Solution Approach 1:
The patent introduces a specific electrolyte composition as an intermediary between lithium metal and conventional electrolytes. This electrolyte contains 1,3-propanesultone (0.01-5 wt%) combined with cyclic carbonate and chain carbonate/ester solvents, along with lithium bis(fluorosulfonyl)imide salt. The 1,3-propanesultone acts as a mediator that forms stable protective films on lithium metal surface, preventing direct contact between lithium and conventional electrolyte components, thereby suppressing decomposition reactions while maintaining high energy density benefits
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by incorporating 1,3-propanesultone at specific concentrations (0.01-5 wt%) alongside traditional carbonate solvents. This parameter change transforms the electrolyte's interaction with lithium metal, enabling formation of stable solid electrolyte interphase (SEI) layers that prevent further decomposition. The specific concentration range of 1,3-propanesultone is critical to achieving both high energy density and extended battery life
2Device complexity
If conventional electrolyte composition is used with lithium metal electrode, then battery assembly is simple, but continuous decomposition reaction of electrolyte occurs rapidly increasing battery resistance and depleting electrolyte and available lithium
Solution Approach 1:
The patent modifies the electrolyte composition parameters by adding 1,3-propanesultone (0.01-5 wt%) to conventional carbonate-based electrolytes. This parameter change maintains the simple liquid electrolyte format and assembly process while fundamentally improving battery life by suppressing continuous decomposition reactions. The modified electrolyte composition enables stable operation without complicating the battery assembly process
Solution Approach 2:
The patent creates a composite electrolyte system combining 1,3-propanesultone with conventional cyclic carbonate and chain carbonate/ester solvents, along with lithium bis(fluorosulfonyl)imide salt. This composite electrolyte material integrates the beneficial properties of traditional electrolytes (simplicity, conductivity) with the protective functions of sultone compounds, achieving both assembly simplicity and extended battery life
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 significantly improves battery life, high-rate charging performance, and high-temperature performance by suppressing side reactions and maintaining electrolyte stability.
Implementation Method 1
wherein the lithium salt includes lithium bis(fluorosulfonyl)imide
Implementation Method 2
the non-aqueous solvent includes 1,2-(1,1,2,2-tetrafluoroethoxy)ethane; a cyclic fluorinated carbonate; and a solvent containing at least one selected from the group consisting of a chain carbonate, a chain ester, and a chain ether
Data Source
AI summary
An electrolyte for a lithium metal secondary battery, the electrolyte comprising a lithium salt including lithium bis(fluorosulfonyl)imide, and a non-aqueous solvent including 1,2-(1,1,2,2-tetrafluoroethoxy)ethane; a cyclic fluorinated carbonate; and a solvent containing at least one selected from the group consisting of a chain carbonate, a chain ester, and a chain ether, wherein the 1,2-(1,1,2,2-tetrafluoroethoxy)ethane is contained in an amount of 5% to 30% by volume based on the total volume of the non-aqueous solvent.