Synthesis of activated carbon from black liquor for the application of supercapacitor

In the present study, black liquor carbonization has been investigated by hydrothermal process. The activated carbon from the carbonization of black liquor (AC-BL) and biomass-based activated carbon from citrus sinensis flavedos (AC-OP) has been investigated for suitability in supercapacitor application. The study has analyzed the electrochemical measurement of both AC-BL and AC-OP in electrochemical stations. The role of stable hydroxyl molecules on the surface of carbon material has been observed and its effective conductivity is studied. The superior performance of AC-OP-derived nanoporous carbon has fast ionic and electronic diffusion of the electrolyte in and out of the pores during charging and discharging due to high surface area. AC-BL exhibited with an EDLC mechanism, but AC-OP shows the pseudocapacitance property. The porous structure and oxygen doping characteristics in AC-BL can influence the potential electrode material for applications in the field of supercapacitors. With the help of this movement, the electronic conductivity of the AC-BL has been increased. In general, the electrochemical stability of the EDLC is far better than the pseudocapacitor. From the GCD analysis, it is observed that the specific capacitance of 17.4 and 148.2 F g⁻¹ is obtained from GCD spectra for AC-BL and AC-OP, respectively. From the EIS analysis, the ESR value is very small for AC-BL (60 Ω), when compared to AC-OP (155 Ω). To conclude that the EIS results of low conductivity by AC-BL have the potential to be future supercapacitors with enhanced treatment in carbonization techniques.