Rechargeable Aqueous Zinc-Ion Batteries with Mild Electrolytes: A Comprehensive Review

Different from the contrary-old alkaline Zn-based batteries, aqueous zinc-ion batteries (ZIBs) refer to a series of safe, long-life and low-cost secondary batteries with divalent Zn²⁺ working as charge carriers. Compared to market dominant lithium ion batteries (LIBs) and Pb-acid batteries, aqueous ZIBs feature a precious balance between safety, cost, lifetime, environmental benignity and energy/power density, due to their unique chemistry. The high performances of these batteries stem from the high-capacities and large redox potential differences of cathodes/anodes, along with the swift redox reactions in the high ionic conductive aqueous electrolytes. With all components being intrinsically safe, stable, low cost and non-corrosive, aqueous ZIBs hold promising prospects in application fields ranging from large scale energy storage systems to wearable electronics. In this paper, we comprehensively reviewed significant advances in aqueous ZIBs since their innovation in 1986, regarding the Zn²⁺-storage mechanisms/design of cathodes, side reactions/stabilizing strategies of anodes/electrolytes, and especially the influence/optimization of current collectors and separators. Finally, a conclusion and outlook on current challenges and research trends of ZIBs is provided. This review attempts to present a general picture of the exploration and evolution of aqueous ZIBs, and to provide some guides for the further development of these energetic yet safe energy storage devices.