Battery chemists at Argonne, the National Laboratory of the US Energy Department, have come up with a fluoride electrolyte that could guard the next generation of batteries against performance decline.
The first applications could be EVs beyond the present lithium-ion battery generation, equipped with lithium-metal batteries.
Non-lithium cathode batteries offer twice or more energy saved in each volume or weight unit compared to traditional lithium-ion batteries. The problem is that the new NMC (nickel, manganese and cobalt) electrode loses its properties after a while. But this problem can now be solved, they said.
The secret is the new fluorinated cation electrolyte, which replaces the lithium-salt electrolyte. The new electrolyte forms a robust protective layer on the anode and cathode surface of the battery, which allows a larger number of charge and discharge cycles before degradation of the material. The new electrolyte is less harmful to the environment and cheaper to produce since it can be purified in only one step. The electrolyte is also non-flammable.
John Zhang, group leader in the chemical sciences and engineering division at Argonne, said: “Lithium metal batteries with our fluorinated cation electrolyte could considerably boost the electric vehicle industry, and the usefulness of this electrolyte undoubtedly extends to other types of advanced battery systems beyond lithium ion.”
Fluorides have also been studied at Aalto University in Finland. The fluoride-ion battery can use a diversity of anode and cathode materials as well as solid and liquid electrolytes. The most promising experiments have been made with alkaline anodes, which could replace lithium-ion batteries in a number of applications thanks to the high energy density and long life cycle.
Fluorine is the most electronegative and reactive element in the periodic table. However, this toxic halogen gas can be very useful for many purposes – mainly in the form of a fluoride anion. Dentists have for more than 70 years used toothpaste containing harmless fluoride ions to reduce degradation of the tooth surface and to prevent tooth decay.
Image: Design of lithium metal battery with electrolyte containing a fluorinated cation. (Argonne National Laboratory)
