Assembling Co₃O₄ Nanoparticles into MXene with Enhanced electrochemical performance for advanced asymmetric...

MXenes with unique 2D open structure, large surface-area-to-volume ratios, high pseudo-capacitance, and conductivity are attractive for advanced supercapacitor electrodes. However, the restacking issue of MXenes hinders ion accessibility, resulting in the reduction of volume performance, mass load, and speed capability. To address these issues, a facile hydrothermal synthesis strategy is proposed to fabricate Co₃O₄ nanoparticles-MXene (Co-MXene) composite by the self-assembly process. Co₃O₄ nanoparticles, introduced in the MXene matrix, effectively prevent self-restacking and shorten ion/electron transport paths. Consequently, the obtained Co-MXene electrode delivers the high-performance of 1081F g^-1 at a current density of 0.5 A g^-1, surpassing the pristine MXene electrode (89F g^-1 at 0.5 A g^-1). Being assembled into asymmetric supercapacitors (ASC), a high energy density of 26.06 Wh kg^-1 at 700 W kg^-1 was realized. After 8000 cycles, the ASC device maintains 83% of initial specific capacitance at 2 A g^-1. This work highlights a simple and efficient method for developing high-performance MXene-based electrodes for supercapacitors.