Flower-like ternary metal of Ni-Co-Mn hydroxide combined with carbon nanotube for supercapacitor

Multi-metal hydroxides based on nickel, cobalt, and manganese are considered as promising materials of working electrode for supercapacitor owing to their unique physical and chemical properties. The combination of multi-metal hydroxide with carbon material can further improve their electrochemical performance. In this work, nickel-cobalt-manganese hydroxide/carbon nanotube (CNT) composite was synthesized using a simple hydrothermal method and used as working electrode material for a supercapacitor. The experimental results show that the addition of carbon nanotubes can effectively improve the electrochemical performance of nickel-cobalt-manganese ternary metal hydroxides. NiCoMn(OH)6/CNT composites exhibit a specific capacity of 2136.2 F g−1 at 1 A g−1 and still retain a specific capacity of 1914 F g−1 at 10 A g−1, demonstrating excellent rate capability. Besides, the composite maintains 77% specific capacity after 2000 cycles, showing good cycle stability. The asymmetric supercapacitor assembled with NiCoMn(OH)6/CNTs as the positive electrode material and activated carbon (AC) as the negative electrode also has good electrochemical performance. It shows high specific capacity of 150.88 F g−1 at 1 A g−1 and still has a specific capacity of 81.17 F g−1 at 20 A g−1, which retains 53.8% of the initial specific capacity.