Diffusion and surface charge studies of waste cow dung derived highly porous carbon as a facile electrode for solid-state supercapacitors.

Carbon-based materials generated from biowaste have recently attracted interest due to their exceptional surface and conductive properties. Cow dung derived porous carbon (CDPC) with a 3D structure and linked pores is synthesized in this study, making it an alternative electrode for supercapacitors (SC). Herein, we studied the diffusion and surface charge contribution and their relationship with the scan rate. Diffusion charge contribution is more prevalent at lower scan rates. Furthermore, a large fraction of surface charge contribution of 69.2 % at a high scan rate of 100 mV/s indicates rapid electrochemical kinetics and hence high-rate performance even at higher current densities. In addition, utilizing a 1 M H 2 SO 4 electrolyte, the CDPC electrode has attained a high specific capacitance value of 210 F/g at 0.5 A/g. Furthermore, symmetrical solid-state SC device displayed high energy density of 36 Wh/kg at good power density of 800 W/kg along with remarkable cyclic stability of 92.6 % after 10,000 charge-discharge cycles. Hence, these findings demonstrate that investigating surface and diffusion charge contributions opens up new avenues for tuning the supercapacitor performance. [Display omitted] • Waste cow dung derived carbon obtained by hydrothermal carbonization and activation • Surface and diffusion charge contribution studies are performed for CDPC electrode. • Solid-state symmetrical SC assembled using two CDPC electrodes and gel electrolyte • Device retains long cycle life of 92.6 % after 10,000 charge-discharge cycles. • Device delivers high energy density of 40 Wh/kg at a power density of 907 W/kg. [ABSTRACT FROM AUTHOR]