Sulfone Solid Electrolyte for High-Temperature Secondary Batteries
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Solution Overview
Problem
Conventional lithium secondary batteries are vulnerable to external shocks and have issues such as explosions or leaks due to low ion conductivity, narrow electrochemical potential window, and low wettability with electrodes, and existing solid electrolytes have melting points below the operating temperature limit, leading to stability deterioration.
Innovation Solution
A sulfone solvent and bis(fluorosulfonyl)imide alkali metal salt combination forms a solid electrolyte with a melting point of 50 to 170°C, enhancing ion conductivity and stability, and a crystalline organic electrolyte with a cocrystal structure for improved interfacial resistance and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a succinonitrile-based organic solid electrolyte is used, then the electrolyte can be formed, but its melting point is 50°C or lower which is lower than the upper limit of common secondary battery operating temperature (60°C), causing stability deterioration
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by replacing succinonitrile with sulfone-based solvents (such as dimethyl sulfone, diethyl sulfone, ethyl methyl sulfone) and adjusting the salt-to-solvent ratio to achieve a melting point above 60°C while maintaining ion conductivity. This parameter change resolves the contradiction between melting point and stability.
2Reliability
If conventional liquid electrolytes are used, then ion conductivity can be maintained, but the battery is vulnerable to external shocks and has problems such as explosion or leak
Solution Approach 1:
The patent utilizes the phase transition from liquid to solid state by employing solid electrolytes with melting points above the operating temperature range. This phase transition eliminates the safety issues of liquid electrolytes (explosion, leakage) while maintaining ionic conductivity through the solid matrix, thereby improving safety without significantly complicating manufacturing.
3Reliability
If sulfide-based solid electrolyte, oxide-based solid electrolyte, or polymer-based solid electrolyte are used, then safety can be improved, but there are problems such as low ion conductivity, narrow electrochemical potential window, and low wettability with electrode
Solution Approach 1:
The patent creates a composite electrolyte system combining sulfone-based solvents with lithium salts (such as LiFSO3, LiBF4, LiPF6) to achieve a material that simultaneously provides high ion conductivity, wide electrochemical stability window, and good electrode wettability. This composite approach overcomes the limitations of individual solid electrolyte types.
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 maintains a solid state at high temperatures, ensuring high ion conductivity and safety, thereby improving battery capacity and life characteristics.
Implementation Method 1
The electrolyte for a secondary battery according to the present invention shows a high ion conductivity
Implementation Method 2
The electrolyte may have a melting point of 50 to 170°C. The electrolyte maintains a solid state at high temperatures
Data Source
AI summary
Provided is an electrolyte for a secondary battery including: a sulfone solvent represented by the following Chemical Formula 1; and a bis(fluorosulfonyl)imide alkali metal salt (MFSI):R1R2SO2 [Chemical Formula 1]wherein R1 and R2 are independently of each other alkyl having 1 to 10 carbon atoms, alkoxy having 1 to 10 carbon atoms, aryl having 6 to 12 carbon atoms, or a combination thereof, and the alkyl, alkoxy, and aryl of R1 and R2 are independently of one another unsubstituted or substituted with halogen, amino, or nitro.