Electrochemical behavior of a carbonaceous mesophase sphere/activated carbon composite

Carbonaceous mesophase spheres and medium coal tar pitch with a weight ratio of 3 were mixed in absolute ethanol solution, to which KOH was added to form a slurry. The slurry was heated to 800℃ to carry out KOH activation. The structure of the resulting material was examined by scanning electron microscopy and X-ray diffraction. Electric double layer capacitors and half-cells were fabricated to investigate its electrochemical performance. The material exhibited good performance in both LiPF₆/(ethylene carbonate + dimethyl carbonate) and Et₄NBF₄/acetonitrile electrolytes with a high reversible capacity of 306.6mAh/g (0.2C) in the half-cell and a capacitance of 25.8F/g in the capacitor. The material showed a favorable rate performance and good cycle stability.