Electrocrystallization orientation regulation of zinc metal anodes: strategies and challenges

Zinc (Zn) metal is the mostly studied anode materials for aqueous Zn ion batteries (ZIBs) mainly because of its excellent energy-storage nature and resource superiority. However, the usual spatial irregularity of Zn deposition morphologies (dendrite, mossy, etc.) often causes unsatisfactory battery performance such as low Coulombic efficiency (CE) and serious side reactions, which fundamentally restrict the commercial development of ZIBs. Horizontally oriented Zn (HO-Zn) deposition morphology has been demonstrated as a dendrite-free spatial structure which can maintain high CE and can be used as high utilization Zn anode. Therefore, it is of scientific importance to regulate the deposition morphology of Zn metal, realizing horizontal orientation and spatial regularity. This is vital for significantly improve battery performances of Zn metal anode. In this review, we will systematically summarize physical/chemical principles and material design strategies of HO-Zn deposition. The key factors affecting interfacial electrocrystallization of Zn including intrinsic crystallographic feature of Zn crystal, substrate properties and mass transfer characters in electrolyte and on electrode surface are discussed in detail. Finally, the recent progress and future challenges on constructing HO-Zn deposition structures are analyzed. This review can provide a new perspective for designing metal anodes (Zn, etc.) facing commercial application in the future.