Activated carbon derived from natural sources and electrochemical capacitance of double layer capacitor

Carbon materials have been synthesized from areca fibres by burning them in an oven at 150°C, which is then gradually raised to 500°C for 1 h under flowing nitrogen at a heating rate of 10°C/min. The electrochemical double layer performance of these prepared carbon materials from natural sources is studied in 0.1 M Na₂SO₄. Two types of electrodes have been prepared; first one with synthesized non-activated carbon and second with activated carbon using KOH and steam. Surface properties of the prepared carbon materials are studied using scanning electron microscopy. The surface area of the activated carbon is found to be 250 m²/g. The electrochemical properties of activated and non-activated carbons are evaluated by using cyclic voltammetry and AC impedance spectroscopy. Supercapacitors have been fabricated symmetrically using these electrodes and their electrochemical properties are studied. Specific capacitance as high as 47 F/g in 0.1 M Na₂SO₄ electrolyte is obtained and it shows excellent cyclability with a coulombic efficiency of 95% at current density of 3 mA/g for 1000 cycles. The electrochemical performance of the high surface area carbon in the neutral electrolyte medium is found to be significantly high, and the reasons are discussed.