Engineering surface electronic of MXene to boost pseudocapacitive behavior

Despite exhibiting impressive capacitance performance in acidic electrolytes, MXene electrodes surfer from poor electrochemical performance in neutral electrolytes. Consequently, improving the capacitance performance of MXene electrodes within neutral electrolytes is imperative for their advancement in energy storage applications. Herein, an alloying strategy was employed to incorporate the V element into the M-site of Ti3C2 MXene. Theoretical calculations reveal that the incorporation of V atoms enhances the electronic conductivity, enlarges the work function, and improves the chemical affinity and adsorption capacity of MXene towards electrolyte ions, which are conducive to improving the capacitance performance of MXene. The as-synthesized V0.2Ti2.8C2 MXene electrode exhibits good capacitance performance and demonstrates good electrochemical stability with a specific capacitance retention as high as 86% after 10,000 charging/discharging cycles at 10 A/g. This work provides a universal strategy for developing high-performance MXene electrodes in neutral electrolyte.