The Honda team wroked with researchers at the California Institute of Technology (Caltech) and NASA's Jet Propulsion Laboratory to overcome the current temperature limitations of fluoride-based battery (FIB) technology and demonstrate the room-temperature operation of fluoride-ion based energy cells.
"Fluoride-ion batteries offer a promising new battery chemistry with up to ten times more energy density than currently available Lithium batteries," said Dr. Christopher Brooks, Chief Scientist, Honda Research Institute. "Unlike Li-ion batteries, FIBs do not pose a safety risk due to overheating, and obtaining the source materials for FIBs creates considerably less environmental impact than the extraction process for lithium and cobalt."
The low atomic weight of fluorine means rechargeable batteries based on the element could offer very high energy densities–up to 10 times greater than the theoretical values for lithium-ion technologies. However, while FIBs are considered a strong contender for the "next-generation" of high-density energy storage devices, they are limited by the temperature requirements. Solid-state fluoride ion-conducting batteries operate at temperatures above 150ºC to make the electrolyte fluoride-conducting, which is a significant challenge for an everyday cell.
So the team used a chemically stable liquid fluoride-conducting electrolyte with high ionic conductivity and a wide operating voltage at room temperature. The electrolyte uses dry tetraalkylammonium fluoride salts dissolved in an organic, fluorinated ether solvent and paired with a composite cathode featuring a core-shell nanostructure of copper, lanthanum and fluorine, showed reversible electrochemical cycling at room temperature.
In the future, FIBs could power battery-electric vehicles and other power procuts says the team.