NiCo2O4 nanosheets grown on interconnected honeycomb-like porous biomass carbon for high performance asymmetric supercapacitors

Abstract

In this paper, NiCo₂O₄ nanosheets grown on interconnected honeycomb-like porous biomass carbon (HLPBC) have been successfully fabricated by carbonization combined with a facile hydrothermal process. Benefiting from the unique structure and reasonable pore size/pore size distribution, the as-obtained composite (HLPBC (0.1 g)/NiCo₂O₄) exhibits satisfactory capacitive behavior (1137.5 F g⁻¹ at a current density of 5 A g⁻¹) and an excellent cycling stability of 90.3% capacitance retention over continuous 5000 cycles. The HLPBC served as a scaffold to support the NiCo₂O₄ nanosheets. At the same time, it provides a pathway for transporting electrons with high speed. An asymmetric supercapacitor is fabricated using HLPBC/NiCo₂O₄ and activated carbon (AC) as positive and negative electrodes, respectively. The asymmetric supercapacitor can deliver a high energy density of 30.75 W h kg⁻¹ at a power density of 900 W kg⁻¹. These results suggest that HLPBC/NiCo₂O₄ can be a potential candidate for electrochemical energy storage devices.