Regulating zinc ion transport behavior and solvated structure towards stable aqueous Zn metal batteries

Aqueous Zn metal batteries (AZMBs) with intrinsic safety, high energy density and low cost have been regarded as promising electrochemical energy storage devices. However, the parasitic reaction on metallic Zn anode and the incompatibility between electrode and electrolytes lead to the deterioration of electrochemical performance of AZMBs during the cycling. The critical point to achieve the stable cycling of AZMBs is to properly regulate the zinc ion solvated structure and transfer behavior between metallic Zn anode and electrolyte. In recent years, numerous achievements have been made to resolve the formation of Zn dendrite and interface incompatible issues faced by AZMBs via optimizing the sheath structure and transport capability of zinc ions at electrode-electrolyte interface. In this review, the challenges for metallic Zn anode and electrode-electrolyte interface in AZMBs including dendrite formation and interface characteristics are presented. Following the influences of different strategies involving designing advanced electrode structure, artificial solid electrolyte interphase (SEI) on Zn anode and electrolyte engineering to regulate zinc ion solvated sheath structure and transport behavior are summarized and discussed. Finally, the perspectives for the future development of design strategies for dendrite-free Zn metal anode and long lifespan AZMBs are also given.