Facile synthesis of novel sulfonated polyaniline functionalized graphene using m-aminobenzene sulfonic acid for asymmetric supercapacitor application

Sulfonated polyaniline (SPANI) functionalized reduced graphene oxide (SPANI/G-1) was prepared by aniline initiated polymerization of m-aminobenzene sulfonic acid in presence of graphene oxide (GO), followed by reduction with hydrazine hydrate. Fourier transform infrared, Raman, and X-ray photoelectron spectroscopy analyses confirmed successful surface modification of graphene using SPANI. The presence of sulfonic acid groups in SPANI accelerated the redox reaction and provided pseudocapacitance. SPANI/G-1 based electrode showed high specific capacitance of 1107 F g⁻¹ at a current density of 1 A g⁻¹ in a three electrode set up. An asymmetric supercapacitor (ASC) device was fabricated using SPANI/G-1 as positive electrode and chemically reduced GO (RGO) as a negative electrode. ASC showed specific capacitance of 157 F g⁻¹ at a current density of 1.5 A g⁻¹ and 94% retention in specific capacitance after 5000 charge-discharge cycles at a current density of 3.8 A g⁻¹. The ASC exhibited maximum energy density of 31.4 W h kg⁻¹ and a large power density of 14,764 W kg⁻¹. Nyquist data of the device was fitted with Z-view and different components (solution resistance, charge-transfer resistance and Warburg elements) were calculated from the fitted curve.