Fluoride ion batteries essentially work in the opposite direction of lithium-ion cells, attracting electrons instead of eliminating them. Flouride (the ionized version of fluorine) is an interesting material for the battery because it has a low atomic weight and a very high capacity to store electrons. However, to do that, you have to dissolve the fluoride ions in an electrolyte, and the researchers found that it only works with solid electrolytes heated to high temperatures.
To circumvent the problem, the Honda / NASA / Caltech team has created a liquid electrolyte called BTFE that allows the fluoride to dissolve at room temperature. With two positively charged regions, it exploits the principle "opposites attract", reacting strongly to the negatively charged fluoride.
Scientists have coupled the electrolyte with a copper, a lanthanum and fluorine to create a battery prototype capable of reversible chemical reactions (eg, refill ) at room temperature. All in all, the batteries have the potential to ten times the energy density of lithium-ion batteries, and they would have a "more favorable environmental footprint", according to Honda.
However, we have heard this kind of thing many times before, so the usual precautions and warnings apply. For example, the team still needs to understand how to stabilize the anodes and the cathodes, which tend to dissolve completely in the electrolyte. They are making some progress, even if further tests are underway, so we hope we are still not disappointed with the batteries that work well in the laboratories but not in the cars.