Highly efficient flexible CNT based supercapacitors fabricated with magnetic BaFe12O19 nanoparticles and biodegradable components

Abstract This work reports the electrochemical characterization of flexible carbon nanotube (CNT) based asymmetric supercapacitors (SCs) made with ≈90% of biodegradable components. BaFe12O19, (BaFeO) nanoparticles (NPs) with sizes of 100-300 nm were introduced in the biodegradable SCs in order to enhance their electrochemical performance. These nanoparticles presented an hexagonal structure according to the analysis by X-ray diffraction. The electrochemical tests revealed that the capacitance and energy density of the SCs increased from 274.2 to 861.6 F g-1 and from 54.8 to 172.3 Wh kg-1 after decorating their anodes with BaFeO NPs. Surprisingly, a stable output voltage of 1.3 V was observed for the device containing BaFeO NPs during 10 h, suggesting a battery-like behavior not previously seen in flexible SCs fabricated with biodegradable components. The analysis of the SC electrodes by optical absorbance and XPS demonstrated the presence of oxygen vacancy defects, Ba1/Ba2 sites and Fe2+/Fe3+/Fe4+ ions, which acted as redox centers for the charge storage in the devices. The results obtained in this work demonstrate that making eco-friendly SCs is possible while maintaining a high electrochemical performance. Thus, our results are promising for the development of new biodegradable supercapacitors with similar capacities to these for batteries.