Fluoride ion batteries operate essentially in the opposite direction of lithium-ion cells, attracting electrons instead of removing them. Flouride (an ionized version of fluorine) is an interesting battery pack because it has a low atomic mass and a very high storage capacity for electrons. However, you have to dissolve fluoride ions in the electrolyte and scientists have found that they only work with solid high-temperature electrolytes.
To do this, the Honda / NASA / Caltech team has created a liquid electrolyte called BTFE that allows fluoride to dissolve at room temperature. With two positively charged areas, he uses the "opposites" principle and heavily reacts to the negatively charged fluoride.
Researchers combined the copper, lanthanum and fluorine electrolyte to create a prototype battery capable of reversible chemical reactions (such as recharging) at room temperature. Batteries have the potential for ten times the energy density of lithium-ion batteries and have a "more favorable environmental footprint".
However, we have heard such a thing many times before, so the usual caution and warning is common. For example, the team still has to figure out how to stabilize anodes and cathodes that tend to dissolve completely in the electrolyte. They are making some headway, even if there are further tests – and hopefully we will not be disappointed with batteries that work great in laboratories but not in the car.