DEVELOPMENT OF SUPERCAPACITORS USING COMPOSITE ELECTRODES OF CARBON NANOTUBE/CELLULOSE NANOFIBRILS AND REDOX GEL POLYMER ELECTROLYTES
supercapacitor; carbon nanotubes; cellulose nanofibrils; poly(vinyl alcohol); redox electrolyte
Supercapacitors (SCs) are electrochemical energy storage devices that have a high specific power but retain a low energy density. Strategies to overcome this limitation have been developed in recent years, such as the addition of redox compounds to the electrolyte. Furthermore, in order to expand the number of practical applications of SCs, the construction of solid polymeric electrolytes is of interest, as it allows the assembly of flexible cells and the construction of miniaturized devices in various geometric formats. In this sense, the present work aimed to develop hybrid SCs built with composite electrodes of carbon nanotubes/cellulose nanofibrils and redox gel polymeric electrolytes based on poly(vinyl alcohol). Polymeric electrolytes were added with different redox compounds: methylene blue, hydroquinone and indigo carmine. Polymeric electrodes and electrolytes were characterized, solid cells employing two redox additives (biredox) were constructed and their electrochemical performance evaluated. Finally, the biredox SC achieved specific capacitance, energy density and power density of 7.46 F g-1, 0.55 Wh kg-1 and 360.17 W kg-1, respectively, being able to retain 81.0% of its initial capacitance at the end of 2000 evaluated cycles.