Regulating Zn(002) Deposition toward Long Life for Zn Metal Batteries

Regulating the Zn deposition orientation is an efficient way to suppress Zn dendrites and stabilize Zn anodes in aqueous Zn ion batteries (ZIBs). Few studies have been conducted to control Zn(002) deposition by altering the Zn2+ solvation structure with a cosolvent. Herein, the bifunctional high-polarity cosolvent hexamethylphosphoramide (HMPA) is proposed in an aqueous electrolyte. It not only suppresses the H2 evolution reaction via the reshaped Zn2+ solvation structure with decreased H2O activity but also induces Zn(002) deposition with a hexagonal-close-packed morphology due to the strong absorption ability of HMPA to Zn(002). With the optimized electrolyte, Zn dendrites and the HER are suppressed and an ultralong cycle life of 1500 cycles with 99.6% Coulombic efficiency is achieved in Zn||Cu cells. Zn||NH4V5O10 and Zn||polyaniline full cells exhibit improved cycling performances compared to that of the bare electrolyte. Our finding provides a feasible and promising way to stabilize Zn anodes and promote the commercial application of ZIBs.

Automated summary

Regulating the solvation structure of Zn2+ ions by using a bifunctional cosolvent, hexamethylphosphoramide (HMPA), in an aqueous electrolyte can effectively control the deposition orientation of Zn and suppress the formation of Zn dendrites. This study demonstrates that the optimized electrolyte with HMPA can achieve an ultralong cycle life of 1500 cycles and high Coulombic efficiency in Zn||Cu cells, and also improve the cycling performance of Zn||NH4V5O10 and Zn||polyaniline full cells.