Challenges and strategies on Zn electrodeposition for stable Zn-ion batteries

Rechargeable zinc-ion batteries (ZIBs) are emerging as one of the most promising next-generation energy storage systems owing to their advantages of abundant resources, low cost, good safety and stability. However, current ZIBs suffer from low capacity, poor rechargeability and low Coulombic efficiency (CE) due to a series of issues associated in the Zinc (Zn) electrodeposition process, including the formation of Zn dendrites, hydrogen evolution, Zn corrosion, passivation and morphological variation. In this review, we focus on discussing the problems and solutions in the Zn electrodeposition, aiming to provide practical strategies on the future development of stable ZIBs. In order to understand these issues, we firstly elaborate the formation mechanism, influencing factors and their interactions in the Zn electrodeposition process. We then provide a comprehensive summary of their causative mechanisms and the corresponding strategies, including novel Zn anodes, optimization of electrolytes, innovative separators, electrotherapy strategies, precise electrodeposition and smart cell design. Moreover, we highlight opportunities and future directions of stable ZIBs with controllable Zn electrodeposition for large-scale energy storage applications.