A 3V Asymmetric Flexible Magnetic Field-Incorporated Solid-State Supercapacitor Using Anodic Bi2Fe4O9 with an Ionic Liquid-Incorporated Polymer-Membrane as Electrolyte

The recent advancements in electrochemical energy storage performance, which are influenced by magnetic fields, have facilitated the expansion of supercapacitor research. This study investigates the impact of an external magnetic field on the ability of supercapacitors, using bismuth iron oxide (Bi₂Fe₄O₉) as the material, to store charge. When subjected to a magnetic field of 150 G at a current density of 1.5 A/g, the composite oxide has 791.1 Fg^–1 specific capacitance. A magnetic field rearranges electrons and ions, increasing ion mobility at the electrode–electrolyte boundary. Moreover, we coated both sides of the ionic liquid-containing Nafion with manganese vanadium oxide (MnV₂O₇) and magnetically improved Bi₂Fe₄O₉ to form an asymmetric solid-state supercapacitor. In order to complete the creation of a solid-state asymmetric supercapacitor, gold is applied to both sides of the Nafion membrane. Here, the Nafion membrane also serves as an electrolyte separator. At a current density of 5 mA/cm² or 0.8 A/g, the solid-state asymmetric supercapacitor exhibits remarkable specific capacity (225.9 mAhg^–1), volumetric (21.4 Fcm^–3), and areal (0.81 Fcm^–2) capacitance. The device exhibits a specific power of 13750 Wkg^–1 and a higher specific energy of 338.9 Whkg^–1. Moreover, the device capacitance remains at 87.1% even after 10,000 cycles.