Nanostructured Carbon Composites from Cigarette Filter Wastes and Graphene Oxide Suitable as Electrodes for 3.4 V Supercapacitors

In this work we report an easy and ecofriendly approach for the preparation of activated carbon‐graphene composites using cigarette filter wastes as precursor and evaluate its potential application as electrodes for high energy electrochemical capacitors. Graphene‐biowaste derived carbon composites are tested as active electrode materials in three different electrolytes (ammonium salt‐based conventional organic electrolyte and two imidazolium‐based ionic liquids), which in some of the cases enable to extend the operating voltage windows up to 3.4 V. The incorporation of graphene into the carbon composites not only increase the electronic conductivity but also induce morphological and textural changes that favor the adsorption/desorption of large size ions. Electrical double layer capacitors assembled using these advanced carbon composites can deliver specific capacitances of ca. 160 F g−1 at 0.25 A g−1 which correspond to energy densities of ca. 65 Wh kg−1 at 210 W kg−1, when ionic liquids are used as electrolyte. Besides, a comprehensive three‐electrode study disclosed that the enhanced capacitance observed for these carbon composites in ionic liquids is related to the optimized textural properties, which improves the imidazolium‐cation adsorption. Activated carbon‐graphene composite: Novel carbon composites are synthesized from cigarette wastes and graphene oxide. The incorporation of graphene leads to 2D particles with tailored textural properties showing very promising results as electrodes for EDLCs in ionic liquids, delivering up to 60 Wh kg−1 and an excellent power retention for more than 10,000 cycles.