P. Indra Devi, Manish Srivastava, Debabrata Mishra
ABSTRACT Supercapacitors have gained substantial attention as devices for storing energy. This is because of their exceptional power density, rapid charging‐discharging process, and longer lifetime. In this study, a hydrothermal synthesis procedure was followed to prepare two distinct nanostructures: cobalt ferrite (CoFe 2 O 4 ) nanoparticles and cobalt ferrite‐reduced graphene oxide (CoFe 2 O 4 /RGO) nanocomposite. Our results indicate that CoFe 2 O 4 NPs has a specific capacity of 44.12 mA h g −1 at 0.5 A g −1 , whereas CoFe 2 O 4 /RGO nanocomposite has a specific capacity of 198.62 mA h g −1 at the same current density. Subsequently, we utilized the positive electrodes as CoFe 2 O 4 /RGO nanocomposite and RGO as the negative electrode to fabricate asymmetric supercapacitor devices. For the CoFe 2 O 4 /RGO//RGO asymmetric supercapacitor device, we measure a specific capacity of 60.15 mA h g −1 (@1 Ag −1 ). The energy density and power density of the device are found to be 13.36 W h kg −1 and 802 W kg −1 , respectively, at the same current density. Notably, when subjecting the CoFe 2 O 4 /RGO//RGO asymmetric supercapacitor devices to a 0.5 T external magnetic field, a significant enhancement in specific capacity was recorded, with an increase of ∼36% (81.96 mA h g −1 ) at 1 A g −1 of current density.