Grape seed carbons for studying the influence of texture on supercapacitor behaviour in aqueous electrolytes

Microporous carbon materials having a negligible contribution of mesopores have been synthesised by cyclic oxidation/desorption of grape seeds char using air, ozone and HNO3 as oxidant agents. By adequate selection of the operating conditions (oxidation procedure and number of cycles), it is possible to tune the volume and pore size distribution (PSD) of carbon materials and therefore determine the influence of carbon textural properties on the electrochemical behaviour of carbon–carbon symmetric supercapacitors operating in different aqueous electrolytes. The results confirm that although energy density can be improved using neutral electrolytes because of their higher stability potential window compared to acidic or basic electrolytes, it is important to adapt the textural properties of the carbon materials to improve the ions’ diffusion inside the porosity for assuring the charging of the double layer at high current densities to reach high power densities.