Ultrahigh coulombic efficiency and long-life aqueous Zn anodes enabled by electrolyte additive of acetonitrile

Zinc metal is considered as one of the most promising aqueous batteries anode materials. However, undesired Coulombic Efficiency (CE) and cycle stability caused mainly by hydrogen evolution and dendrite growth during cycling hinder its practical application. Herein, a hybrid electrolyte with Anhydrous Acetonitrile (ACN) as the additive and the optimal volume ratio H2O:ACN=3:1 is developed to obtain a high CE Zn anode. The addition ACN could shield free water molecules and build a stable phase interface between Zn and electrolyte during cycle, as a result, the hydrogen evolution and dendrite growth are significantly suppressed. Based on this unique electrolyte, dendrite-free and stable Zn plating/stripping for 600 h, with the CE of 99.3 % is obtained. Besides, assembled Zn/V2O5 full battery can stabilize 1700 cycles at the rate of 1 C (with the capacity of 150 mA h g−1). This work illustrates a novel way to suppress hydrogen evolution in various aqueous batteries.