Preparation of Activated Carbons for Electrochemical Capacitors by Microwave Heating

Abstract:

Activated carbons (ACs) were prepared from lignite by microwave heating with KOH as activation agent, the effects of the weight ratio of KOH to coal and microwave heating time on the pore structure of ACs were investigated by N₂ adsorption. The electrochemical characteristics of electrochemical capacitors (ECs) with ACs as electrodes in 3mol/L KOH electrolyte were evaluated by galvanostatic charge/discharge cycling, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the BET specific surface area and total pore volume of ACs (denoted as AC-R3) can reach 2097m²/g and 1.19cm³/g respectively when the weight ratio of KOH to coal is 3:1 and the microwave heating time is 10 min. The ECs with AC-R3 as electrodes presents a high specific capacitance of 335F/g at a low current density of 50mA/g and still remains 288F/g even at a high current density of 5A/g, it has excellent cycling stability and low leakage current, and the residual specific capacitance is as high as 93.6% after 1000 cycles under the current density of 2.5A/g. The results have demonstrated that the microwave heating with KOH activation is an efficient approach to prepare ACs with high performance for ECs. Keywords: Activated Carbons; Microwave Heating; Electrochemical Capacitors; Electrochemical Characteristics

• Periodical: Materials Science Forum (Volumes 704-705)
• Pages: 1061-1067
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.704-705.1061
• Online since: December 2011
• Authors: Bao Lin Xing, Lun Jian Chen, Chuan Xiang Zhang, Hui Guo
• Keywords: Activated Carbon (AC), Electrochemical Capacitors, Electrochemical Characteristics, Microwave Heating

References

[1] A.B. Fuertes, G. Lota and T.A. Centenob: Electrochimica Acta, Vol. 50 (2005), p.2799.

[2] C.X. Zhang, D.H. Long and B.L. Xing: Electrochemistry Communications, Vol. 10 (2008), p.1809.

[3] G. Lota, T.A. Centeno and E. Frackowiak: Electrochimica Acta, Vol. 53 (2008), p.2210.

[4] K. Jurewicza, K. Babel and A. Ziolkowski: Journal of Physics and Chemistry of Solids, Vol. 65 (2004), p.269.

[5] Elzbieta Frackowiak: Phys. Chem. Chem. Phys., Vol. 9 (2007), p.1774.

[6] A.G. Pandolfo and A.F. Hollenkamp: Journal of Power Sources, Vol. 157 (2006), p.11.

[7] Q. Jiang, X.F. Zhao and B. Huang: Acta Phys., Vol. 25 (2009), p.757.

[8] C.X. Zhang, R. Zhang and B.L. Xing: New Carbon Materials, Vol. 25 (2010), p.129.

[9] D. Kalpana, S.H. Chob and S.B. Leeb: Journal of Power Sources, Vol. 190 (2009), p.587.

[10] F.C. Wu and R.L. Tseng: Microporous and Mesoporous Materials, Vol. 80 (2005), p.95.

[11] W. Li, L.B. Zhang and J.H. Peng: Industrial Crops and Products, Vol. 27 (2008), p.341.

[12] Turgay Taya and Suat Ucar: Journal of Hazardous Materials, Vol. 165 (2009), p.481.

[13] D. Lozano-Castello, M.A. Lillo-Rodenas and D. Cazoria-Amoros: Carbon, Vol. 39 (2001), p.741.

[14] K.B. Yang, J.H. Peng and C. Srinivasakannan: Bioresource Technology, Vol. 101 (2010), p.6163.

[15] Mitsuhiro Kubota, Atsushi Hata and Hitoki Matsuda: Carbon, Vol. 47 (2009), p.2805.

[16] Y.B. Ji, T.H. Li and L. Zhu: Applied Surface Science, Vol. 254 (2007), p.506.

[17] F.K. Yuen and B.H. Hameed: Advances in Colloid and Interface Science, Vol. 149 (2009), p.19.

[18] H.L. Guo and Q.M. Gao: Journal of Power Sources, Vol. 186 (2009), p.551.

[19] K. Kierzek, E. Frackowiak and G. Lota: Electrochimica Acta, Vol. 49 (2004), p.515.

[20] J. Li, X.Y. Wang and Y. Wang: Journal of Non-Crystalline Solids, Vol. 354 (2008), p.19.