This concept article aims to emphasize how to fabricate green and safe water-abundant Zn metal batteries. Several typical and advanced strategies towards water-abundant electrolyte systems are reviewed. We hope to arouse the attention of researchers for safer and greener aqueous Zn metal batteries when a large amount of toxic or expensive non-aqueous components are added into electrolytes.

Abstract

Aqueous Zn metal batteries have been regarded as promising candidates as an alternative to Li-ion batteries in large-scale energy storage systems due to their low-cost, safe and environmentally benign advantages. However, because of the introduction of solvent water, several problems, for example dendrites, parasite reactions, hydrogen evolution, and so on, are brought into aqueous Zn metal batteries. Regrettably, when trying to solve these problems, most efforts have taken the form of adding a large amount of non-aqueous components, which are usually harmful to the environment and not conducive to greener and safer aqueous batteries. In this Concept, we will introduce several electrolyte systems and mainly focus on how to build a water-abundant electrolyte with fewer non-aqueous components. This work will review the literature and offer instructive guidance for environmentally benign Zn metal batteries.