Composition-Regulated Charge Storage in Ti2NbC2T x MXene/MoAl1– x B MBene 2D/2D Hybrid Electrodes for Asymmetric Supercapacitors

In this study, hybrid electrodes were fabricated by combining ordered double-transition-metal Ti2NbC2Tx MXene (MX) with MoAl1–xB MBene (MB) for supercapacitor applications. To investigate the effect of MB content, hybrid electrodes containing 10–40 wt % MB were prepared on carbon cloth (CC) via spray coating. Electrochemical measurements identified MX-MB20 as the optimum composition, delivering a specific capacitance of 530 F g–1 at 0.5 A g–1. Kinetic analyses revealed that MX-MB20 exhibited a markedly higher diffusion-controlled contribution, particularly at low scan rates, compared with the individual MX and MB electrodes, indicating that hybridization altered the charge-storage kinetics. An asymmetric supercapacitor (ASC) assembled using the optimized MX-MB20 electrode delivered a specific capacitance of 99 F g–1 at 0.5 A g–1 and retained approximately 94% of its initial capacitance after 10,000 cycles. The ASC also achieved an energy density of 26.9 Wh kg–1 at a power density of 359 W kg–1. These results demonstrate that MB content plays a key role in regulating the charge-storage behavior and electrochemical performance of the MX-MB hybrid system.