Facile Synthesis of Pineapple Waste-Derived Carbon and Polyaniline Composite for High-Energy-Density Asymmetric Supercapacitors

Pineapple peel has been chosen as a biowaste precursor to synthesize activated carbon via KOH activation at 800 °C (PP-800). Further, the in situ chemical oxidation method was used to synthesize a composite of PP-800 with polyaniline (PANI). The successful formation of the composite (PP-800/PANI) was confirmed via X-ray diffraction (XRD), and Raman and Fourier-transform infrared (FTIR) spectra. PP-800/PANI when tested in 1 M H2SO4 in a three-electrode configuration showed a higher specific capacitance (377 F/g) than that of PP-800 (328 F/g) and PANI (92.4 F/g) at 2 A/g. This is due to the significant enhancement in the diffusion contribution for PP-800/PANI (86.25%) than that of PP-800 (61.7%) and PANI (49.9%) counterparts at 20 mV/s, which leads to the maximum utilization of the electrochemical surface area. Further, an asymmetrical supercapacitor device, PP-800/PANI//PP-800, was fabricated, which delivered a high energy density of 51.2 Wh/kg at a decent power density of 380 W/kg with 90% cyclic stability after 10,000 charge–discharge cycles.