Materials Development in Hybrid Zinc-Ion Capacitors

High-performance energy storage devices have an exceptional role in modern applications such as green transportation, consumer electronics and electrical systems. Recently, the hybrid supercapacitor has gained great interest among researchers that adopt a combination of capacitive and battery-type electrodes to increase the energy density without sacrificing the power performance. Different types of hybrid energy storage devices have been reported recently including lithium-ion capacitor (LIC), sodium-ion capacitor (NIC) and potassium-ion capacitor (KIC). However, these devices are based on alkali metals such as Li, Na and K which are extremely reactive and consistently used with flammable organic electrolytes that intensify serious safety issues. Hybrid devices based on multivalent ions including Mg²⁺, Ca²⁺, Al³⁺ and Zn²⁺ have achieved considerable attraction due to their rapid charge transfer kinetics and high capacity as well as energy density. Herein, we reviewed the recent developments in the anode and cathode materials of Zinc ion hybrid capacitors (ZICs). The design, construction and working of supercapacitor (SC), Zinc ion battery (ZIB) and ZIC have been discussed along with their charge storage mechanism. Finally, based on the published work, our views on future developmental opportunities have been discussed.