Zinc‐Ion Hybrid Supercapacitors: Progress and Future Perspective

The increasing concern on the safety risks associated with the flammable organic electrolytes in alkali‐ion batteries and the pursuit of both high energy density and power density in one device has spurred the investigation of aqueous multivalent metal ion hybrid supercapacitors. Zinc‐ion hybrid supercapacitors (ZIHSCs) have the advantages of low standard potential, high theoretical capacity and good safety in aqueous electrolytes. In this review, the recent advancements achieved in ZIHSCs have been summarized and discussed. The progress in cathode, anode, electrolyte and the approaches adoptable to improve the electrochemical performance of ZIHSCs have been categorized. Mechanism investigation through different ex‐situ and in‐situ methods, incorporation of multi‐functionality and integration are also demonstrated. Adoption of more in‐situ characterization methods to understand the electrochemical mechanism of ZIHSCs is encouraged. Future development of ZIHSCs with higher active materials utilization rate and power output for practical applications is envisioned, assembly of ZIHSCs with more functionality is also expected. Zinc outside the box: Zn‐ion hybrid supercapacitors are attracting more and more attentions because of their high capacity, good safety, low costs, and satisfactory energy and power densities. Their progress of electrochemical performance can be achieved by adopting approaches in cathode, anode, and electrolyte, and investigating charge/discharge mechanism. Additionally, multi‐functional and integrated systems of Zn‐ion hybrid supercapacitors are desirable.