Energy Storage Science and Technology ›› 2016, Vol. 5 ›› Issue (6): 855-860.doi: 10.12028/j.issn.2095-4239.2016.0040

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Study on preparation and electrochemical properties of biomass-derived spherical activated carbon

MA Yuzhu1,2, ZHOU Cong3, YU Baojun1,2, CHEN Mingming1,2, WANG Chengyang1, 2   

  1. 1Key Laboratory for Green Technology of Ministry of Education, School of Chemical Engineering and Technology, 2Synergetic Innovation Center of Chemical Science and Engineering,Tianjin University, Tianjin 300072, China; 3Key Laboratory for Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, China
  • Received:2016-07-06 Revised:2016-07-15 Online:2016-11-01 Published:2016-11-01

Abstract: Spherical activated carbon has been fabricated via a simple solvent evaporation method followed by an activation process. The natural and renewable biomass material, leonardite humic acid (LHA) is used as the carbon source. The surface morphologies and pore parameters of the carbon spheres were analyzed by scanning electron microscope (SEM) and N2 physical adsorption-desorption instrument. Symmetric capacitor coin type cells were assembled using two spherical activated carbon electrodes. The electrochemical performance of supercapacitors is characterized by galvanostatic charge-discharge (GCD), cyclic voltammograms (CV) and electrochemical impedance spectroscopy (EIS) in 6 M KOH electrolyte. The results show that the obtained spherical activated carbon with good sphericity also possess high specific surface area ( 2034 m2/g) and pore volume (1.24 cm3/g). Meanwhile, the spherical activated carbon electrode materials exhibit a superior high specific capacitance of 319 F/g at a current density of 0.05 A/g. Remarkably, the sample also has outstanding cycling stability with a capacitance retention of 98.9% after 10,000 cycles. In addition, compared with powdered activated carbon, spherical activated carbon has better conductivity and presents more excellent rate capability and cycle performance. This suggests that the LHA-based spherical activated carbon should be a competitive and promising supercapacitor electrode material.

Key words: humic acids, spherical activated carbon, pore structure, supercapacitors