The rechargeable fluoride-based batteries rely on a tetraalkylammonium salt-fluorinated ether electrolyte, and a copper-lanthanum trifluoride core-shell cathode to function without building up heat. (Image credit: Honda)


Move over lithium; fluoride is set to become the medium for more efficient, higher-density rechargeable batteries, according to researchers from Honda’s Research Institute, Caltech, and NASA’s JPL, who developed a new chemistry with a more favorable environmental footprint. Fluoride-based batteries have been around since the 1970s, but because of their high operating temperatures, they are only used in solid-state batteries.


According to Honda Chief Scientist Dr. Christopher Brooks- “Fluoride-ion batteries (FIBs) offer a promising new battery chemistry with up to ten times more energy density than currently available Lithium batteries. 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 secret to the FIB’s larger density lies in fluorine’s low atomic weight, which is up to ten times greater than that of lithium, but is again, encumbered by high temperatures when used as an electrolyte- over 1500 C to make it conductive.


To get around the issue of heat, and to operate at room temperatures, the researchers utilized a tetraalkylammonium salt-fluorinated ether electrolyte with high ionic conductivity and paired it with a composite copper-lanthanum trifluoride core-shell cathode- thus creating reversible electrochemical recycling at much lower heat levels.


The researchers state that obtaining source material for fluoride-based rechargeable batteries offers less of an environmental footprint over the extraction process of lithium and cobalt, and is more plentiful in resource over rare earth metals. As far as applications are concerned, the researchers feel FIBs could be used power electric vehicles, consumer gadgets and mobile devices at some point in the near future.


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