Dual-Salt Fluorosulfonyl Electrolyte for Durable Lithium Metal Batteries
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Solution Overview
Problem
Existing lithium metal batteries face issues with battery durability due to the depletion of LiFSI salt and oxidative degradation of the FSA solvent, leading to reduced ionic conductivity and performance.
Innovation Solution
A complex electrolyte system is developed, comprising a first lithium salt with a fluorosulfonyl group, a second lithium salt with a trifluoromethanesulfonyl group, and a solvent with a fluorosulfonyl group, in specific molar ratios, to enhance ionic conductivity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiFSI salt and FSA solvent are used in existing electrolytes, then lithium deposition-stripping reversibility is improved, but battery durability deteriorates due to salt depletion and solvent oxidative degradation
Solution Approach 1:
The patent uses a composite electrolyte system combining LiFSI salt, LiTFSI salt, and FSA solvent in specific molar ratios (0.6:0.4 to 0.8:0.2 for salts, 0.3:0.7 to 0.7:0.3 for salt-to-solvent). This composite approach allows the electrolyte to maintain lithium reversibility while improving durability through the synergistic effects of multiple components, where LiTFSI compensates for LiFSI depletion and the specific ratio optimization prevents solvent oxidative degradation.
Solution Approach 2:
The patent optimizes the molar ratios of LiFSI to LiTFSI (0.6:0.4 to 0.8:0.2) and electrolyte components (0.3:0.7 to 0.7:0.3 salt-to-solvent ratio). By adjusting these parameters, the electrolyte achieves both high lithium deposition-stripping reversibility and improved battery durability, preventing salt depletion and solvent degradation that occur in single-ratio systems.
2Quantity of substance
If higher energy density batteries are developed, then driving range is improved, but battery durability and stability may deteriorate
Solution Approach 1:
The patent employs a composite electrolyte system with LiFSI and LiTFSI salts in optimized ratios that enables high energy density lithium metal batteries to achieve both improved driving range and enhanced durability. The composite nature of the electrolyte provides stability that prevents degradation even at high energy densities.
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 complex electrolyte system improves lithium metal battery durability and ionic conductivity, maintaining capacity retention and suppressing dendritic lithium growth, suitable for use in portable devices and electric vehicles.
Implementation Method 1
the electrolyte for a lithium metal battery having advantages of improving battery durability and ionic conductivity
Implementation Method 2
deposition-stripping reversibility of lithium
Data Source
AI summary
Described are an electrolyte for a lithium metal battery, and a lithium metal battery including the same, the electrolyte containing a first lithium salt containing a fluorosulfonyl group, a second lithium salt containing a trifluoromethanesulfonyl group, and a solvent containing a fluorosulfonyl group, wherein a molar ratio of the first lithium salt to the second lithium salt is 0.65:0.35 to 0.75:0.25.