Toward High Energy Density Aqueous Zinc-Ion Batteries: Recent Progress and Future Perspectives

Aqueous zinc-ion batteries (ZIBs) are promising next-generation battery system which can mitigate the prevailing issues on the conventional lithium-ion batteries. However, insufficient energy density with low operating voltage prevents the practical utilization of the aqueous system. Notably, aqueous ZIBs suffer from electrolyte decomposition due to its narrow electrochemical stability window (ESW) for 1.23 V. Also, studies on cathode active materials that store charge at an elevated voltage region is still in the initial stage. In this perspective, we cover the recent strategies for developing high-voltage aqueous ZIBs. First, electrolyte designs for expanding the ESW of an aqueous electrolyte are introduced based on their characterization, materials, and working mechanisms. Next, we propose the cathode active materials with high-working voltage. Furthermore, studies on zinc anodes are also briefly presented. Lastly, we summarize the as-reported strategies and provide insight for developing future ZIBs.