A Universal Superhydrophobic-Ionophilic Interfacial Strategy for Cycling Stable Aqueous Zinc Metal Electrodes under Low Current Density

Abstract

A key challenge to apply aqueous zinc-metal batteries (AZMBs) as next-generation energy storage devices is to eliminate the adverse reactions of hydrogen evolution, especially in low current. Here, superhydrophobic and ionophilic artificial solid electrolyte interface (HI-SEI) on zinc anode is proposed and constructed by enhancing roughness and etching ion channels in universal polysiloxane polymer backbones. The HI-SEI exhibits superhydrophobicity with high contact angle of 151.5° and ionophilicity with low activation energy of 23.97 kJ mol−1. Thus, the HI-SEI isolates Zn metal and solvent water and promotes desolvation kinetics of Zn2+. Besides, the HI-SEI alters the double electric layer structure to form a compact layer hardly any adsorbed solvent water, achieving a small nucleation overpotential of 5 mV and low self-corrosion current density of 0.95 µA cm−2. Moreover, a symmetric cell with HI-SEI@Zn anode has a cycle life of >1330 h at low current of 0.1 mA cm−2. And a full cell with HI-SEI@Zn anode and NaV3O8-1.5H2O cathode provides long cycle life and low capacity degradation (180 mAh g−1 after 1100 cycles). Hopefully, SEI designs based on such a strategy will be able to improve the low-current cycling performance of the next-generation AZMBs.