Hybrid Interface Enables Dendrite-Free Aqueous Zn-Metal Battery

Abstract

Aqueous zinc(Zn)-metal batteries (AZMBs) have attracted significant attention owing to their high safety, economy, and potential applications in stationary energy storage systems. However, AZMBs still suffer from low reversibility and short lifespan of the Zn anode, resulting from the instability of the Zn/electrolyte interface. Herein, a hybrid interface combining a solid electrolyte interphase (SEI) and an electrostatic shield layer was introduced into the AZMBs through a simple electrolyte-regulating strategy. This hybrid interface simultaneously establishes a Zn phosphate (Zn–P–O) based SEI and an NH4+-dominated electrostatic shield layer on the Zn anode. Comprehensive characterizations were performed to investigate the designed SEI in AZMBs, which can effectively induce uniform Zn deposition and suppress side reactions, achieving remarkable electrochemical performance. As a consequence, the Zn||Zn cell's lifespan is improved from 75 h to 2200 h at 2 mA cm–2, and the Zn||Cu asymmetrical cell presented stable operation for more than 1200 cycles (vs 455 cycles) with a high average coulombic efficiency of 99.58%. The designed SEI, accompanied by enhanced stability and practicability, was further applied to Zn||NaVO full cells, which presented remarkable lifespan for 3000-cycle (vs 427 cycles to failure) stable operation at 5 A g–1, discharging an initial specific capacity of 155.9 mAh g–1 and maintaining 103.9 mAh g–1 after operating for 1000 cycles.