Unveiled mechanism of prolonged stability of Zn anode coated with two-dimensional nanomaterial protective layers toward high-performance aqueous Zn ion batteries

Abstract

Rechargeable aqueous zinc (Zn) ion batteries (AZIBs) are gaining popularity in large-scale energy storage due to their low cost, high safety, and environmental friendliness; however, dendrite growth and side reactions in Zn metal anodes limit their practical applications. Additionally, the difficulty of developing successful passivation of Zn anodes, combined with large-area coating of protective layers, remains a major limitation to the commercialization of AZIBs. Here, we introduce two-dimensional (2D) nanomaterials including MoS₂, h-BN, and Ti₃C₂T_x MXene as protective layers for Zn anodes, created on a Zn surface using a scalable, large-area spray-coating process. Examinations of electrochemical performance-related material characterizations revealed that a specific type of 2D material with an optimal thickness prevents vertical growth of Zn dendrites, as well as side reactions including hydrogen evolution and corrosion, resulting in stable device operation with minimal overpotential and extended life, even under harsh measurement conditions. The highly stable MoS₂@Zn anode allowed the MoS₂@Zn//MnO₂ full cell to achieve significantly more stable capacity retention, compared with the bare Zn//MnO₂ cell. Our versatile and scalable solution-based coating technique for easily forming large-area 2D protective layers on Zn anodes offers new insights concerning improvements to AZIB reliability and performance.