High-Voltage Rechargeable Aqueous Zinc-Based Batteries: Latest Progress and Future Perspectives

Rechargeable aqueous zinc-based batteries (AZBs) have been recently considered as desirable energy storage devices for renewable energy storage because of their high theoretical capacity, low cost, and high safety. Despite the inspiring achievements in this field, the energy density of AZBs is still far below expectation, which directly hinders their practical application as next-generation secondary cells. To address this issue, previously, reseach efforts have been mainly dedicated to the improvement of capacity by designing different kinds of high-capacity electrode candidates, especially the cathode materials. In recent years, elevation of the output voltage for energy density improvement has gained more and more attention. The main limitation of the relatively low output voltage of AZBs lies in the narrow electrochemically stable window of aqueous electrolytes, which results in limited choice of cathode materials with high potential. Herein, by summarizing recently reported work in this field, the strategies applied to high-voltage AZB construction are classified into two categories, from the aspects of electrode and battery structure. Classic examples of each category are discussed in detail, and their respective advantages/defects are compared and commented on. Finally, further challenges are elaborated to provide more insights into this area.