Highly Reversible and Safe Zn Rechargeable Batteries Based on Triethyl Phosphate Electrolyte.

Zinc metal is an attractive anode material for next generation batteries. However, dendrite growth and limited Coulombic efficiency (CE) during cycling are the major roadblocks towards widespread commercialization of batteries employing Zn-anode. In this work, for the first time we report the adoption of triethyl phosphate (TEP) as a sole and co-solvent with aqueous electrolyte to obtain highly stable and dendrite-free Zn-anode. Stable Zn plating/stripping for over 3000 hours was obtained accompanied with a CE of 99.68%. The SEM images of the Zn-anodes revealed highly porous interconnected dendrite-free Zn-deposits. Characteristic special morphology, high CE, safety and durability of Zn-anode is realized in the TEP-based electrolyte. The electrolyte displayed good compatibility with both Zn-anode and potassium copper Hexacyanoferrate (KCuHCf) cathode for Zn ion battery (ZIBs). The full cell showed long cycle life over 1000 times and high rate capability. The present work is a contribution towards cost-effective and safe battery systems.