Zincophilic polymer semiconductor as multifunctional protective layer enables Dendrite-Free zinc metal anodes

Abstract

Zinc (Zn) metal is considered as one of the most promising anodes for aqueous zinc-ion batteries due to its high theoretical capacity, low cost, and environmental benignity. However, the uncontrolled dendrite growth and parasitic side-reactions lead to low Coulombic efficiency and limited lifespan, severely affecting their applications. Herein, a stable and robust g-C3N4 is constructed on the surface of metallic Zn anode (g-C3N4@Zn), serving as a multifunctional protective layer. The nitrogen (N)-rich g-C3N4 layer exhibits inherent zincophilic properties, in which zinc ions can be bonded with N to form Zn-N bonds, resulting in homogenous nucleation and inhibiting dendrite growth. In addition, the hydrogen evolution reaction and the formation of by-products can be effectively relieved, which are attributed to the polymer layer blocking water from the Zn surface. More importantly, in-situ optical real-time monitoring, density functional theory calculations, and molecular dynamic simulations demonstrate the effectiveness of the zincophilic g-C3N4 layer in improving stability. As expected, the g-C3N4@Zn anode achieves a remarkable cycling lifespan of around 2900 h (up to four months) in symmetric cells, together with high cycling stability (1000 cycles) for g-C3N4@Zn//V3O7 H2O full batteries. Significantly, the new finding of the zincophilic g-C3N4 protective layer points to an alternative effective pathway to regulate Zn metal anodes for practical applications.