Enhanced hydrophobicity of the current collector modifier for Zn anode endows improved longevity.

Abstract

Though zinc-ion batteries have gained intensive attention recently, their application prospects have long been hampered by Zn dendrite evolution and water-involved side reactions, especially for thin and highly utilized Zn anodes. Coating a modified layer on the current collector is a common strategy to improve the reversibility of Zn plating/stripping. Hydrophilic modifier with high zincophilicity, usually affords uniform Zn deposition but exhibits intrinsic limitations in repelling water molecules, while hydrophobic modifiers shows excellent water-resistance. To enhance side-reaction inhibition, we increased the hydrophobicity of the CuTCNQ modifier by replacing CuTCNQ with its fluorinated analog, Cu(F4-TCNQ), on the Cu current collector. The hydrophobicity was enhanced, as indicated by a contact angle of 139.2°, which endowed the Zn anode with a remarkably electrochemical longevity by regulating the crystallographic arrangement of Zn metal, and preventing water-involved hydrogen evolution reactions as well as surface corrosion. The symmetric cell with F4-TCNQ@Cu as the anode current collector operated stably for up to 990 h at a current density of 2 mA cm^-2. This performance surpassed that of bare Cu (190 h) and the hydrophobic analog TCNQ@Cu (450 h). This work provides a new strategy for the design of high-utilization zinc anodes and offers a unique perspective on evaluating the effect of hydrophobicity on the lifespan of Zn battery.