Interfacial Mo(VI)/Mo(IV) Redox‐Mediated Ultrafast Charge Storage in MXene/Carbon Nanotube Hybrid Electrodes in Acidic Media

Enhancing the energy density of supercapacitors while maintaining high power output is critical for sustainable energy storage applications. Herein, the fabrication of an MXene/carbon nanotube (MXene/CNT) composite electrode via a one‐step ultrasonication process, coupled with a redox‐additive electrolyte to improve electrochemical performance,being is reported. The incorporation of sodium molybdate (Na 2 MoO 4 ) into a sulfuric acid (H 2 SO 4 ) electrolyte significantly enhances faradaic charge storage, extends the electrochemical window, and improves charge transfer kinetics. The resulting system exhibits a specific capacitance of 152 F g − 1 at 3 A g − 1 , a substantial increase compared to 47 F g − 1 at the same current density in H 2 SO 4 . Moreover, the energy density of the MXene/CNT composite electrode in the sodium molybdate redox additive reaches 41 Wh kg − 1 , nearly doubling that of the conventional H 2 SO 4 electrolyte, with the power density being almost the same in both cases. This enhancement is attributed to the redox interactions between MoO 4 2− ions and H + ions, which facilitate efficient charge storage. These findings highlight the potential of redox‐active electrolytes in advancing next‐generation sustainable supercapacitors for high‐performance energy storage.