Water-in-salt electrolyte Zn/LiFePO4 batteries

Abstract Aqueous zinc batteries could offer a high theoretical energy density at an economical cost. However, their broader applications are limited by low practical energy density and poor reversibility of the Zn anode. In this work, we demonstrate that a water-in-salt electrolyte based on zinc and lithium salts enables dendrite-free Zn plating/stripping at a high coulombic efficiency of nearly 100%. The electrolyte also enables Zn/LiFePO4 full battery to achieve a high energy density of 107.5 Wh kg−1 and maintain 70% of energy density after 1000 cycle at a 3C rate.