Embedding carbon nanofibers on nickel oxide for supercapacitor applications

Abstract

Supercapacitor electrode intrinsic electrochemical performance is mainly dependent on their structures. Thus, a lot of attention has been garnered on the logical synthesis of supercapacitor electrodes with appropriate structures. The transition metal oxide and porous carbon composite have shown outstanding porosity and electrical conductivity. This makes them a promising candidate as a supercapacitor electrode. Nevertheless, their complex synthesis and unpredictable instability remain a significant obstacle. The porous network of the Carbon Nanofiber (CNF) and Nickel Oxide (NiO) may offer plenty of pathways for the transfer of ions and encourage a sufficient interaction between the active ingredient and the electrolyte. Moreover, their composite network may account for stable and excellent pseudocapacitance. In this study, we propose a simple process employing an ultrasonication technique for embedding different weight percent of CNF on NiO to synthesize CNF/NiO nanocomposite. When evaluated as an electrode for asymmetric supercapacitor configuration, the nanocomposite with 2 weight percent of CNF (CNF-2) offered better performance in terms of low response time (~ 12 s) and low bulk resistance (~ 0.76 Ω). In comparison to other nanocomposite, the optimized one revealed excellent rate capability (capacitance retention of ~ 74% even after scan rates of 100 mV s⁻¹). CNF-2 exhibited a high specific capacitance of 173.4 F g⁻¹ at a current load of 1 A g⁻¹; and long cycling stability (95.2% capacitance retention even after 5000 cycles). Moreover, the optimized composite revealed a maximum specific energy of 6.1 Wh kg⁻¹ at a respective specific power of 1.4 kW kg⁻¹. The method highlighted in this investigation benefits from ease of use, environmental friendliness, and potential for large-scale production. It also offers prospects for the design and development of electrode materials of the future for energy storage and conversion devices.