US20250300232
2025-09-25
Electricity
H01M10/0569
The patent application details a new family of fluorinated acetal molecules used as solvents in electrolytes for lithium metal batteries. These electrolytes, composed of one or more fluorinated acetal molecules and soluble salts, can be formulated with or without additional solvents, diluents, or additives. The molecular structure is characterized by the formula R1-O-CH2-O-R2, where R1 and R2 are hydrocarbon, fluorocarbon, or hydrofluorocarbon chains. Notable products include di(2-fluoroethoxy)methane (F1DEM) and bis(2,2-difluoroethoxy)methane (F2DEM), which improve battery performance metrics such as Coulombic efficiency and ion transport.
This research was supported by the Department of Energy under contract number DE-AC02-76SF00515. As a result, the government holds certain rights to this invention.
Previous advancements in electrolyte compatibility with lithium metal batteries have been made by the applicants in earlier patent applications. However, challenges remain with existing electrolytes, including slow initial Coulombic efficiencies, high cell impedance, incompatibility with high-voltage cathodes, and expensive manufacturing processes. The newly developed fluorinated acetal molecules address these issues by enhancing electrode stabilization and compatibility with high-voltage cathodes while maintaining economic viability.
The invention introduces two new organic molecules: F1DEM and F2DEM. These molecules are synthesized through straightforward reactions from common chemical feedstocks. When combined with standard LiFSI salt at appropriate concentrations, they exhibit fast stabilization of lithium metal, improved compatibility with high-voltage cathodes, rapid ion transport, and reduced cell impedance. The unique —O—C—O— backbone in these molecules provides better electrode stability compared to traditional structures.
The synthesis process involves reactions using 2-fluoroethanol or 2,2-difluoroethanol with dibromomethane and NaOH in tetraglyme. The resulting products undergo distillation to ensure purity. These solvents can be integrated into electrolyte formulations for lithium metal batteries, targeting existing battery manufacturers and startups. Compared to current advanced electrolytes, these new solvents offer faster lithium metal cycling stabilization, improved cathode compatibility, lower cell impedance, and scalability.