There are a few things we should demand from a decent power supply. Not least, it shouldn't require oven-like temperatures to function. That's just a given.
"Fluoride batteries can have a higher energy density, which means that they may last longer – up to eight times longer than batteries in use today," says Caltech researcher Robert Grubbs, famous for winning a Nobel Prize in Chemistry in 2005.
The type of electrochemical technology supplying power to your smart devices makes use of positively charged lithium 'Li2+' cations as a kind of chemical 'piston' to draw an electrical charge through a circuit.
At full charge, a supply of cations occupy the battery's anode. Once the circuit is closed, ions surge into the cathode, producing a current that does the all-important work. To reset the cell, all that's required is a voltage to 'push' the lithium piston back again.
"For a battery that lasts longer, you need to move a greater number of charges," says Simon Jones, a researcher at NASA's Jet Propulsion Laboratory.
"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."
"But fluoride can be challenging to work with, in particular because it's so corrosive and reactive," says Grubbs.
This isn't to say nobody has successfully made a functional fluoride ion battery. But the ions are part of a solid structure, which as you can imagine doesn't let them slip around too easily. Not at room temperature at least.
On finding the solvent did a fairly suitable job of allowing fluoride's anions to shuffle between electrodes at room temperature, the team ran models to find ways to tweak its performance with additives.
"We are still in the early stages of development, but this is the first rechargeable fluoride battery that works at room temperature," says Jones.
So, we might need to wait a bit longer for weekly phone recharges, but this is an exciting step - an we can hardly wait for this exciting technology to come into the market.