Fluoride ion electrochemical cell

A secondary electrochemical cell comprising:

• a positive electrode comprising a first fluoride ion host material;
• said positive electrode having a first standard electrode potential;
• a negative electrode comprising a second fluoride ion host material, said negative electrode having a second standard electrode potential, wherein the difference between said first standard electrode potential and said second standard electrode potential is greater than or equal to about 3.5 V;
• and
• an electrolyte provided between said positive electrode and said negative electrode;
• said electrolyte capable of conducting fluoride ion charge carriers, said electrolyte comprising a fluoride salt and a solvent;
• wherein at least a portion of said fluoride salt is present in a dissolved state, thereby generating said fluoride ion charge carriers in said electrolyte;
• wherein said fluoride salt has the formula MFn, wherein M is a metal other than lithium, and n is an integer greater than 0;
• wherein said positive electrode and said negative electrode reversibly exchange said fluoride ion charge carriers with said electrolyte during charging or discharging of said electrochemical cell;
• wherein said fluoride ion charge carriers are fluoride ions (F−).