An in-depth understanding of improvement strategies and corresponding characterizations towards Zn anode in aqueous Zn-ions batteries

Combining the unique advantages of aqueous electrolytes and metallic Zn anode, rechargeable aqueous Zn-ion batteries (ZIBs) are of great promise for large-scale energy storage applications due to their inherent high safety, low cost, and environmental friendliness. As the essential component of ZIBs, Zn metal anode suffers from severe dendrite formation and inevitable side reactions (e.g. corrosion and hydrogen evolution) in aqueous electrolytes, which leads to low Coulombic efficiency and inferior cycling stability, impeding their large-scale applications. To be compatible with satisfactory aqueous ZIBs, Zn anode has been modified from various perspectives and focus areas. Herein, based on their intrinsic characteristics, we review the related improvement strategies for Zn anode, including interphase, substrate, and bulk design, so as to achieve an in-depth understanding of Zn anode optimization. Furthermore, the timely summary of characterization methods for Zn anodes are also performed for the first time, from both thermodynamic and kinetics perspectives, which is particularly helpful for beginners to understand the complicated characterizations and employ suitable methods. Finally, certain noteworthy points are put forward for subsequent investigation of aqueous ZIBs. It is expected that this review will enlighten researchers to explore more efficient optimization strategies for Zn anode in aqueous electrolytes.& COPY; 2022 Institute of Process Engineering, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communi-cations Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

This review discusses the optimization strategies for the zinc anode in rechargeable aqueous zinc-ion batteries (ZIBs), including interfacial engineering, substrate design, and bulk material modulation, to improve their Coulombic efficiency and cycling stability. In addition, characterization methods for zinc anodes are summarized from thermodynamic and kinetic perspectives, which are helpful for beginners to understand the complex properties and choose suitable methods. Finally, certain noteworthy points are proposed for further research on rechargeable aqueous ZIBs.