CO2 Superactivated Carbons Derived from Pistachio Shells and Coffee Grounds for Capacitive Energy Storage

Supercapacitors require electrode materials with highly developed microporosity, which can be easily achieved via chemical activation. Physical activation is a more practical and environmentally benign route because of its technical feasibility and the absence of corrosive reagents; however, it often results in less developed pore networks. Herein, we report a tailored CO2 activation strategy able to convert food waste into activated carbons with very high specific surface areas (2048–3195 m2 g−1) and suitable pore size distributions that make them strong candidates for supercapacitor electrodes. The electrochemical performance was investigated in the ionic liquid electrolyte EMImBF4, where the materials exhibited a high capacitance of up to 172 F g−1, good rate capability, and a stable cycling performance. The results demonstrate the technical feasibility of producing high-performance porous carbons using CO2 activation of biomass residues.