Pseudocapacitive storage in cathode materials of aqueous zinc ion batteries toward high power and energy density

Abstract

The pseudocapacitive storage process consists of faradaic redox reactions that occur nearby or upon the surface of materials, which is promising to enable high power and energy density for rechargeable batteries. In recent years, aqueous zinc ion batteries (AZIBs) have been expected to be applied in the energy storage field due to the advantages of inherent safety and low cost. Unfortunately, the sluggish reaction kinetics caused by the divalent charge of zinc ions makes it a hard challenge to assure the capacity of the cathode materials at high current densities. As an efficient charge storage mode in AZIB cathode materials, the role of the pseudocapacitive storage process in enhancing the capacity at a high current density cannot be ignored. Herein, a brief review on high-rate AZIB cathode materials with a significant pseudocapacitive storage process is presented from the perspective of manganese-based materials, vanadium-based derivatives and others including Prussian blue analogs, organic compounds, NASICONs and metal sulfide. Among them, we focus on how those representative designs induce significant pseudocapacitive behavior. Finally, a future outlook is provided aiming to promote the development of a pseudocapacitive high-rate cathode for AZIBs.