Challenges and strategies for constructing stable zinc metal anodes in mild aqueous zinc-ion batteries

Abstract

Zinc metal has the advantages of low cost, high safety, large theoretical specific capacity (820 mAh g−1) and low redox potential (−0.76 V vs. SHE), which makes aqueous zinc-ion batteries (AZIBs) promising candidates for electrochemical energy storage systems. However, uneven zinc deposition in Zn anode results in the formation and growth of zinc dendrites, which can puncture the separator and cause a short circuit in the battery. Owing to the mechanical rigidity and structural inhomogeneity of zinc dendrites, it is easy to fall off the zinc anode to form “dead zinc”, resulting in a reduction of active materials and a decline in battery capacity. In addition, by-reactions such as hydrogen evolution reaction (HER) and corrosion also occur, leading to a decrease in the stability of battery. In this paper, we first analyze the causes and basic mechanisms of the above key problems, and summarize the research progress in improving the stability of zinc anode in recent years, including zinc anode interface modification, deposition substrate design, electrolyte optimization and separator modification. Finally, we provide an outlook and critical analysis of the remaining challenges, prospects and future directions for the practical application of AZIBs.