Advanced porous N-doped MXene/graphene/porous carbon as self-standing thick electrode for zinc-ion hybrid supercapacitors with wide working temperature range

The sluggish ion and electron transport in thick electrodes, coupled with the instability of conventional electrolytes, has severely limited the practical application of zinc-ion hybrid supercapacitors (ZIHCs), especially in extreme environments. In this work, a novel porous MXene/graphene/porous carbon (MGPN) cathode with high mass loading, integrated with a hydrogel electrolyte is developed to achieve outstanding electrochemical performance over a wide working temperature range. This unique architecture and multicomponent endows the MGPN with highly efficient ion and electron transport channels along with abundant active sites, which results in a high areal capacitance of 5.9 F cm −2 under the high mass loading of 20 mg cm −2 at 10 mA cm −2 . Benefiting from the fast ion and electron transport kinetics of MGPN and the high ionic conductivity of the hydrogel electrolyte, the assembled ZIHC possesses an impressive areal capacity of 0.08 mAh cm −2 and a high areal energy density of 67.3 μWh cm −2 at 80 °C. Moreover, the device retains 73.4 % of its room-temperature capacity even at −20 °C, demonstrating remarkable temperature adaptability. This study presents a viable approach for the development of high-performance energy storage systems capable of operating in extreme temperature environments.