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.