Unraveling dynamical behaviors of zinc metal electrodes in aqueous electrolytes through an operando study

Metallic zinc is an ideal anode material for aqueous rechargeable zinc-ion batteries (ZIBs) owing to its high capacity in theory, low redox potential, high security and low cost. However, metallic zinc anodes suffer from an inferior long-term cycling stability, due to zinc dendrite growth, zinc corrosion and other factors. Elucidating potential reasons for these issues is desperately needed for large-scale applications of metallic zinc anodes. Herein, we aim to parse zinc stripping/plating behaviors and dendrite growth in various aqueous electrolytes and explore the mechanism of failure process of metallic zinc electrodes by combining an operando transmission electron microscope (TEM) technique, electrochemical analysis and theoretical calculation. Besides, effects and acting mechanism of Mn2+ and CF3SO3− in zinc-salt aqueous electrolytes on zinc plating/stripping behavior were investigated. The results demonstrated that adding Mn2+ could suppressed zinc dendrite growth by forming manganese-based compounds clusters around zinc electrodes during zinc plating process. In addition, dendrite-free anode was garnered when Zn(CF3SO3)2 was employed as electrolyte, enabling the superior stability and excellent reversibility of Zn/Zn symmetric cell. This work not only reports a deep understanding of zinc stripping/plating behaviors in aqueous electrolytes, but also provides effective strategies to achieve long-term stable zinc anodes and ZIBs.