Activated Carbon Bio-xerogels as Electrodes for Super Capacitors Applications

The objectives of this work are to evaluate the use of the lignin as precursor of carbon xerogels and to determinate the effect of porosity and surface functionalities on the electrochemical capacitance of the activated carbon bio-xerogels. Lignin replaced the resorcinol at a mass fraction between 0 and 0.086 (wt%). The organic carbon xerogels are H₃PO₄-activated at H₃PO₄/carbon ratio of 1/1 at 450°C to increase pore volume and surface area. Gravimetric capacitance values at 0.125 A/g, in a three-cell configuration, ranged from 138 to 234 F/g. Sample with a 0.086 content of lignin showed the best electrochemical behavior, which was associated with the high BET surface area (1243 m²/g), high volume (W₀(N₂)= 0.518 cm³/g) and width micropores (L₀(N₂)= 1.43 nm) and to the presence of pseudo faradic effects.