Influence of the activation parameters on the electrochemical performance of chemically activated graphene materials

In this work, activated graphene-like materials were obtained by varying both, the ratio of activated agent/graphene precursor and the activation temperature. The resulting materials were then characterized, resulting in higher values of specific surface area (SSA) when increasing the impregnation ratio at each temperature, reaching values up to 1325 m² g⁻¹. Gravimetric capacitances ranging between 11.0 and 49.0 F g⁻¹ when charging/discharging at 0.5 A g^-1 were obtained. The highest capacitance value was achieved not for samples with the highest SSA but with a micropore volume up to ~ 63 % of total pore volume. Overall, the capacitance values decreased significantly at activation temperatures of 600 and 700 °C at 2:1 and 4:1 impregnation ratios, regardless of an enhanced SSA, which could be explained considering the release of surface oxygenated functional groups during the thermal treatment. These results present the activated graphene materials as promising electrodes in energy storage devices.