Magnetic Field Induced Improved Performance of Asymmetric Supercapacitor Device Based on <scp>RGO</scp> and <scp>CoFe</scp> ₂ O ₄ / <scp>RGO</scp> Nanocomposite

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.