Preparation of highly porous binderless activated carbon electrodes from fibres of oil palm empty fruit bunches for application in supercapacitors

Fibres from oil palm empty fruit bunches, generated in large quantities by palm oil mills, were processed into self-adhesive carbon grains (SACG). Untreated and KOH-treated SACG were converted without binder into green monolith prior to N2-carbonisation and CO2-activation to produce highly porous binderless carbon monolith electrodes for supercapacitor applications. Characterisation of the pore structure of the electrodes revealed a significant advantage from combining the chemical and physical activation processes. The electrochemical measurements of the supercapacitor cells fabricated using these electrodes, using cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge–discharge techniques consistently found that approximately 3 h of activation time, achieved via a multi-step heating profile, produced electrodes with a high surface area of 1704 m2 g−1 and a total pore volume of 0.889 cm3 g−1, corresponding to high values for the specific capacitance, specific energy and specific power of 150 F g−1, 4.297 Wh kg−1 and 173 W kg−1, respectively.