Quasi-solid-state flexible asymmetric supercapacitor based on ferroferric oxide nanoparticles on porous silicon carbide with redox-active p-nitroaniline gel electrolyte

Micro- and mesoporous silicon carbide (SiC)/ferroferric oxide (Fe₃O₄) composites (SiC/Fe₃O₄) were prepared (to develop novel supercapacitor electrode materials) via chemical deposition of Fe₃O₄ on SiC surfaces by chemical reduction of an Fe precursor. Based on the synergistic contributions between the electric double layer capacitive contribution of SiC and the pseudocapacitive contribution of Fe₃O₄, the SiC/Fe₃O₄ electrode exhibits outstanding charge storage capacity, exhibiting a specific capacitance of 423.2 F g⁻¹ at 5 mV s⁻¹ with high capacitance retention ratio over a wide range of scan rates (81.8% at 500 mV s⁻¹). In conjunction with a capacitive SiC positive electrode in a quasi-solid-state PVA-KOH-p-nitroaniline (PVA-KOH-PNA) gel electrolyte, it resulted in a unique redox-active flexible solid-state asymmetric supercapacitor device. Due to the vigorous redox reactions of Fe₃O₄ nanoparticles and the p-nitroaniline redox active electrolyte, the device delivers outstanding capacitive performance (specific capacitance of 97.6 F g⁻¹ at 5 mV s⁻¹) with maximum energy density of 48.94 Wh kg⁻¹ at power density of 463.64 W kg⁻¹, surpassing many recently reported flexible supercapacitors. Therefore, these novel electrode materials with unique redox-active solid-state electrolytes may find promising applications in flexible energy storage devices.