Using the amorphous‑carbon derived from cigarette filters for the fabrication of highly efficient flexible supercapacitors and role of the Sr3.2Y0.8Fe1.5Co1.5O10 layered perovskite to enhance their electrochemical performance

Abstract

Eco-friendly solid-state supercapacitors (SCs) were fabricated using recycled cigarette filters and their electrochemical performance was studied. Firstly, new and smoked cigarette filters were pyrolyzed at 250 °C and obtained an amorphous‑carbon material, which consisted in particles of irregular shape mixed with other ones with folded sheet-like morphology. The amorphous‑carbon was mixed with graphene micro-flakes and it was employed to fabricate the energy storage devices. The flexible SC made with pyrolyzed new filter (PNF) had capacitance and energy density values of 623.4 F g−1 and 55.5 Wh kg−1, respectively, while the SC device made with pyrolyzed used filters (PUF) exhibited a capacitance and energy density of 1124.30 F g−1 and 188.9 Wh kg−1, respectively. The analysis by EDS demonstrated the presence of extra elements such as Ca, K, Mg and P in the PUF (which improved the ionic conductivity and electronic transport on the electrodes), therefore, the devices made with this PUF had 80 % more capacitance than the devices made with PNF. Later, the Sr3.2Y0.8Fe1.5Co1.5O10 (SYFECO) layered perovskite was incorporated on the SC electrodes made with PUF and obtained a higher capacitance and energy density of 2051.2 F g−1 and 210.3 Wh kg−1, respectively. Thus, the capacitance was enhanced by 82 % after adding the perovskite to the devices. Moreover, absorbance, Raman and XPS spectra were measured on the SC electrodes containing the SYFECO perovskite and they revealed the presence of oxygen vacancies, Co2+/Co3+ and Fe2+/Fe3+/Fe4+ species. Those ones were responsible for the charge storage by redox reactions. Hence, the results reported here corroborates that using recycled cigarette filters is a viable alternative for the manufacture of efficient SCs for portable/wearable applications.