Facile hydrothermal synthesis of NiCo₂O₄- decorated filter carbon as electrodes for high performance asymmetric supercapacitors

A simple hydrothermal method is developed for the growth of NiCo₂O₄ nano-needle arrays on a filter paper carbon (FC) substrate for use as a high performance electrode for supercapacitors. The as-synthesized NiCo₂O₄/C composites exhibited high specific capacitance (995.2 F g⁻¹ at a current density of 10 A g⁻¹) and excellent cycling performance (no capacitance loss after 3000 cycles). The 3D framework of the FC substrate not only prevents the aggregation of NiCo₂O₄ nanoparticles, but also improves its electrical conductivity, thus leading to excellent electrochemical performance. Moreover, an asymmetric supercapacitor was assembled by using the NiCo₂O₄/C composites and activated carbon as the positive and negative electrode, respectively, and provided a maximum energy density of 20.87 Wh kg⁻¹ at a power density of 374.6 W kg⁻¹ and a maximum power density of 7.48 kW kg⁻¹ at an energy density of 11.43 Wh kg⁻¹ within a potential window of 0–1.5 V, demonstrating the potential of the composites for use in high performance energy storage systems.