Fluoride used in toothpaste could be key to longer battery life

Researchers have found a new way of making batteries last longer than the usual lithium ions by using fluoride present in toothpaste. A team of chemists from California Institute of Technology (Caltech), Jet Propulsion Laboratory or JPL, as well as Honda Research Institute and Lawrence Berkeley National Laboratory, experimented on the anion or the negatively charged form of fluoride to make batteries.
Robert Grubbs, Victor and Elizabeth Atkins Professor of Chemistry at Caltech, said that fluoride batteries can last up to eight times longer than the typical lithium-ion batteries used today. Fluoride’s higher density contributes to the battery’s better lifespan.
“Fluoride-based battery electrodes can store more ions per site than typical lithium-ion electrodes, which means that this technology has the capability to be much more energy dense,” said Brett Savoie, a professor of chemical engineering at Purdue University.
The researchers said that manufacturing this type of battery is challenging since fluoride is naturally corrosive and reactive. Instead of producing rechargeable fluoride batteries on solid components, the team used liquid components. The result is the first of its kind to work at room temperature.
To do this, fluoride ions are dissolved into a liquid electrolyte similar to the process of making lithium-ion batteries. The molecule responsible in dissolving fluoride ions
is called bis(2,2,2-trifluoroethyl)ether or BTFE.
“For a battery that lasts longer, you need to move a greater number of charges,” said Simon Jones, co-author and a chemist at JPL. “Moving multiply charged metal cations is difficult, but a similar result can be achieved by moving several singly charged anions, which travel with comparative ease.”
Another challenge is figuring out how to make the batteries work at varying voltages. They found that fluoride’s anion is compatible with high-voltage power.
The study was published on December 7 in the journal Science.
Researchers are doing more tests to determine the stability of these batteries under high energy. If successful, it is possible that fluoride-based batteries can be used to power small electronic devices like mobile phones and computers.