Effect of Extraction Temperature on Hyper-coal Structure and Electrochemistry of Coal-Based Activated Carbon

The Inner Mongolia lignite was used to prepare hyper-coal (HPC) at different temperatures by N-methylpyrolidone during KOH extraction. To explore the effect of extraction temperatures on activated carbons (ACs), the activation was operated at the same condition, m(KOH):m(coal)=3:1 and activated at 650 degrees C for 2 hours. The results show that the extraction temperature of HPC has great effect on the electrochemical properties of HPC-based ACs. Comparing the ash contents, surface oxo-functional groups, the specific surface areas, pore structures and electrochemical performances of the corresponding ACs with the lignite, the HPC prepared at 330 degrees C is in possession of the most suitable reactivity and its specific surface area of corresponding ACs could reach 1 252 m(2).g(-1) with appropriate amount of surface oxo-function groups. Besides, the specific capacitor could still retain almost 90% in 3 mol.L-1 KOH electrolyte at 50 mA.g(-1) reaching 322 F.g(-1), and a capacity retention as high as near 90% was achieved at 2 000 mA.g(-1).