Comprehensive study of used cigarette filters-derived porous activated carbon for Supercapacitors: From biomass waste to sustainable energy source

The exploration of biomass-waste-derived carbon electrodes for sustainable electrochemical energy storage devices is an attractive green strategy for waste reduction and energy source development. Used cigarette filters are biomass waste, and they are toxic and environmentally hazardous. Nearly-one million metric tons of used cigarette filters are disposed worldwide each year. In this study, the porous activated carbon as a supercapacitor electrode was derived from used cigarette filters, which are mainly composed of cellulose acetate, via a two-step chemical method: hydrothermal carbonization followed by potassium hydroxide activation at temperatures ranging from 600 to 800 °C. Different porosity could be obtained by varying the activation temperature, altering the capacitive performance of the porous activated carbon electrodes. The porous activated carbon possessing a large total pore volume of 1.73 cm3 g−1 was created. A symmetric supercapacitor containing two identical electrodes made of the used cigarette filters-derived porous activated carbon could exhibit high specific capacitance of 52 F g−1 and 42 F g−1 at current densities of 0.25 A g−1 and 10 A g−1 in 6 M KOH and excellent cycling stability (97.2 % retention after 5000 charge–discharge cycles at a current density of 1 A g−1). The high energy density of 7.2 Wh kg−1 at a power density of 127 W kg−1 could be delivered, fulfilling the high-performance supercapacitor characteristics and commercially promising.