Fluorinated Electrolyte Salt for Stable Metal-Anode Battery Cycling
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Solution Overview
Problem
Existing electrolytes for metal batteries face challenges in maintaining high charge capacity and stability during cycling, especially at high voltages and low temperatures, and can induce corrosion, with CF3-containing salts posing environmental and health risks due to chemical degradation.
Innovation Solution
A fluorinated salt with -CF2H and -F moieties forms a robust and conductive solid electrolyte interface (SEI) with the metal anode, enhancing discharge capacity and coulombic efficiency, and providing higher thermal stability compared to other salts like LiFSI, without using fluorinated ethers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CF3-containing salts are used in electrolytes, then ionic conductivity and electrochemical performance are improved, but environmental and health risks increase due to chemical degradation
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte salt by replacing CF3 groups with CF2H groups and incorporating F atoms, thereby maintaining electrochemical performance while reducing environmental persistence and toxicity
Solution Approach 2:
The patent converts the potentially harmful CF3 groups into beneficial CF2H and F-containing groups that provide similar electrochemical benefits (ionic conductivity, SEI formation) while eliminating the environmental persistence and toxicity issues associated with CF3 degradation products
2Stability of the object's composition
If conventional salts like LiTFSI or LiFSI are used, then good electrochemical stability is achieved, but charge capacity and capacity retention deteriorate during cycling
Solution Approach 1:
The patent uses a composite electrolyte system combining fluorinated salt with specific solvents (cyclic carbonates and chain carbonates) to create a synergistic effect that enhances both electrochemical stability and charge capacity retention during cycling
Solution Approach 2:
The patent modifies the local chemical environment at the electrode interface by introducing fluorinated salt with specific -CF2H and -F moieties that form a tailored SEI layer, improving local stability and charge retention without compromising overall electrochemical stability
3Power
If electrolytes are designed for high voltage operation, then energy density is improved, but corrosion and stability issues worsen
Solution Approach 1:
The patent changes the electrochemical window parameters by introducing fluorinated salt with high oxidation stability, enabling the electrolyte to withstand higher voltages while maintaining corrosion resistance through the formation of a stable protective SEI layer
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 fluorinated salt maintains high discharge capacity and coulombic efficiency after multiple cycles, offering improved thermal stability and reducing environmental and health risks associated with CF3-containing salts.
Implementation Method 1
The enhanced stability with Li° anode is attributed to the formation of LiF-rich solid electrolyte interphase (SEI) layer resulting in a stable cycling performance
Implementation Method 2
The strength of these interactions impacts directly on the capacity of the electrolyte to transport metal cations
Data Source
Figure 1(A)~1(B)
Figure 2
AI summary
The present invention relates to an electrochemical cell comprising: a) an electrolyte comprising a salt of formula (I): wherein: M is a metal cation or an organic cation; and the subscript "m" is a positive integer number that refers to the number of anions needed to neutralize the charge of the cation M; wherein the electrolyte is liquid, gel or solid, and further characterized in that the electrolyte does not comprise a fluorinated ether when the electrolyte is liquid or gel; and b) a metal anode. The invention also relates to an electrochemical battery comprising said electrochemical cell and uses thereof.