An aqueous copper battery enabled by Cu 2+ /Cu + and Cu 3+ /Cu 2+ redox conversion chemistry.

We propose an aqueous copper battery via Cu 2+ /Cu + and Cu 3+ /Cu 2+ redox conversion chemistry on an activated carbon (AC) electrode enabled by a 30 m ChCl + 1 m CuCl 2 electrolyte, where Cu 3+ /Cu 2+ redox promotes the discharge capacity by ∼50 mA h g -1 at ∼1.0 V vs. Ag/AgCl with stable cycling.