Sustainable Supercapacitors Based on Polypyrrole-Doped Activated Biochar from Wood Waste Electrodes

Abstract

The synthesis of high-performance carbon-based materials from biomass residues for electrodes has been considered a challenge to achieve in supercapacitor-based production. In this work, activated biochar has been prepared as the active electrode material for supercapacitors (SCs), and an effective method has been explored to boost its capacitive performance by employing polypyrrole (PPy) as a biochar dopant. The results for physicochemical characterization data have demonstrated that PPy doping affects the biochar morphology, specific surface area, pore structure, and incorporation of surface functionalities on modified biochar. Biochar-PPy exhibited a surface area of 87 m2 g−1, while pristine biochar exhibited 1052 m2 g−1. The SCs were assembled employing two electrodes sandwiched with PVA solid-state film electrolyte as a separator. The device was characterized by standard electrochemical assays that indicated an improvement of 34% in areal capacitance. The wood electrodes delivered high areal capacitances of 282 and 370 mF cm−2 at 5 mA cm−2, for pure biochar and biochar doped with PPy, respectively, with typical retention in the capacitive response of 72% at the end of 1000 cycles of operation of the supercapacitor at high current density, indicating that biochar-PPy-based electrode devices exhibited a higher energy density when compared to pure biochar devices.

Keywords

• wood waste
• wood electrodes
• wood-based supercapacitors
• polypyrrole
• pseudocapacitance