Improved electrochemical performance of CoO_x-NiO/Ti₃C₂T_x MXene nanocomposites by atomic layer deposition towards high capacitance supercapacitors

Co-Ni bimetallic oxides were successfully deposited on Ti₃C₂T_x MXene nanosheets by atomic layer deposition technology and used as pseudocapacitive materials for supercapacitors. The uniform distribution of metal oxide nanoparticles on MXene nanosheets endows the pseudocapacitive materials more active sites and the synergistic effect between CoO_x and NiO greatly improves the electrochemical performance. Specifically, as the deposited cycle increased to 90, the sample showed the optimal electrochemical performance with specific capacitance up to 1960 F g⁻¹ (1 A g⁻¹), 20.3 times higher by than that of Ti₃C₂T_x MXene, excellent rate capability (87.3% capacitance retention, 1–18 A g⁻¹) and 90.2% capacitance retention after 8000 cycles.