Hydrophobic Organic-Electrolyte-Protected Zinc Anodes for Aqueous Zinc Batteries

Aqueous Zn batteries are promising energy-storage devices. However, their lifespan is limited by irreversible Zn anodes owing to water decomposition and Zn dendrite growth. Here, we separate aqueous electrolyte from Zn anode by coating a thin MOF layer on anode and filling the pores of MOF with hydrophobic Zn(TFSI)(2)-tris(2,2,2-trifluoroethyl)phosphate (TFEP) organic electrolyte that is immiscible with aqueous Zn(TFSI)(2)-H2O bulk electrolyte. The MOF encapsulated Zn(TFSI)(2)-TFEP forms a ZnF2-Zn-3(PO4)(2)solid electrolyte interphase (SEI) preventing Zn dendrite and water decomposition. The Zn(TFSI)(2)-TFEP@MOF electrolyte protected Zn anode enables a Zn||Ti cell to achieve a high average Coulombic efficiency of 99.1 % for 350 cycles. The highly reversible Zn anode brings a high energy density of 210 Wh kg(-1)(of cathode and anode mass) and a low capacity decay rate of 0.0047 % per cycle over 600 cycles in a Zn||MnO(2)full cell with a low capacity ratio of Zn:MnO(2)at 2:1.