Electrochemical engineering of anode with zincophilic polymer interface for reversible zinc battery

Abstract

Aqueous rechargeable zinc-ion batteries are emerging as green and safe energy devices owing to their high energy density and eco-friendliness. The bottleneck is the inhomogeneous nucleation resulting in the growth of Zn dendrites and the parasitic side reactions at the anode. Herein, an electrochemical anode engineering strategy is demonstrated to curb the uncontrolled dendritic growth and side reactions. It involves the in situ generation of a solid-electrolyte interface based on a Zn nanoparticle-embedded poly(acrylic acid) hybrid layer (PAA-nZn) on the anode. The homogeneously distributed polar functionalities and porous nature of the polymer regulate the uniform zinc ion flux, and the embedded zinc particle serves as nucleation sites for zinc plating. The hybrid layer reduces the nucleation overpotential and promotes instantaneous nucleation. The symmetrical cell made with PAA-nZn@Zn has a lifecycle of >860 h with a voltage gap of 28 mV. The full cell fabricated by pairing the engineered anode with α-MnO₂ cathode showed a high discharge specific capacity of 238.3 mAh g⁻¹ at 0.2 A g⁻¹ with a capacity retention of 81.76% after 200 cycles and a long lifecycle. The electrochemical engineering of the anode suppresses the dendritic growth and protects the anode from unwanted side reactions and passivation.