Sulfone-based electrolyte and secondary battery containing the same

Low-viscosity flame-retardant electrolyte with improved fluorinated ether compatibility using sulfone co-solvents with 2 or more carbon atoms

This technology is an electrolyte system that improves miscibility with hydrofluoroether (HFE) solvents, reduces electrolyte viscosity, and enhances separator wettability by incorporating sulfone solvents with 2 or more carbon atoms into a dimethyl sulfone (DMS)-based electrolyte.

Sulfone-based electrolytes have historically suffered from poor compatibility with graphite anodes, and the use of high-concentration salts increases viscosity, leading to reduced ionic conductivity and poor separator wettability. Meanwhile, carbonate-based electrolytes pose significant fire risks and generate flammable gases.

This technology features a multi-component electrolyte containing dimethyl sulfone, a sulfone solvent with an alkyl group of 2 or more carbon atoms, and a hydrofluoroether solvent. The sulfone solvent acts as a mediator for the dissolution of dimethyl sulfone and HFE, maintaining ionic conductivity while lowering viscosity to the 20–70 mPa·s range and inducing the release of non-flammable gases during high-temperature storage. Applicable to energy storage systems, densely packed electric vehicle cells, and lithium/sodium-ion batteries, it can replace carbonate solvents and reduce the risk of fire propagation during thermal runaway.

‍

‍

Key Features:

• Sulfone-based electrolyte containing a metal salt, dimethyl sulfone, a sulfone solvent with the chemical formula R1R2SO2, and a hydrofluoroether solvent
• Sulfone solvent where at least one of R1 or R2 has 2 or more carbon atoms, facilitating the dissolution of dimethyl sulfone and hydrofluoroether
• Hydrofluoroether solvent that provides wettability to the separator and reduces room-temperature viscosity to 20–70 mPa·s
• Metal salt selected from LiFSI, NaFSI, KFSI, LiTFSI, LiBF4, or LiDFOB, included at a molar ratio of 2:1 to 5:1 relative to the sulfone-based solvent

‍