MXene‐Reduced Graphene Oxide Aerogel for Aqueous Zinc‐Ion Hybrid Supercapacitor with Ultralong Cycle Life

Abstract Although current energy storage devices are limited by their own shortcomings, their merits such as superior power density and cycling stability for supercapacitors (SCs), and high energy density for batteries cannot be ignored either. Constructing hybrid SCs (HSCs) with capacitor‐type electrodes and battery‐type electrodes can combine the advantages of SCs and batteries. Herein, a zinc‐ion HSC (ZHSC) is fabricated with a porous 3D MXene (Ti 3 C 2 T x )‐reduced graphene oxide aerogel cathode and zinc foil anode for the first time. As a result, the ZHSC exhibits excellent electrochemical performance with a high specific capacitance of 128.6 F g −1 at a current density of 0.4 A g −1 and a high energy density of 34.9 Wh kg −1 at a power density of 279.9 W kg −1 . More importantly, after 75 000 charge and discharge cycles at a current density of 5 A g −1 , the capacitance retention is still above 95% of the initial capacitance. This work provides a new way of thinking for developing high‐performance energy storage devices with superior energy, power density, and ultralong cycle life.