Journal of Solid State Electrochemistry

, Volume 17, Issue 5, pp 1357–1368

Effect of alkaline and alkaline–earth cations on the supercapacitor performance of MnO2 with various crystallographic structures

  • Chen-Chen Ji
  • Mao-Wen Xu
  • Shu-Juan Bao
  • Chang-Jun Cai
  • Rui-Ying Wang
  • Dian-Zeng Jia
Original Paper

DOI: 10.1007/s10008-013-2001-y

Cite this article as:
Ji, C., Xu, M., Bao, S. et al. J Solid State Electrochem (2013) 17: 1357. doi:10.1007/s10008-013-2001-y

Abstract

The electrochemical performances of the α-, γ-, and δ-MnO2 with different crystallographic structures were systematically investigated in 0.5 mol/L Li2SO4, 0.5 mol/L Na2SO4, 1 mol/L Ca(NO3)2, and 1 mol/L Mg(NO3)2 electrolytes. The results showed that the electrochemical performances of the manganese dioxides depended strongly on the crystallographic structures of MnO2 as well as the cation in the electrolytes. Because the δ-MnO2 consists with layers of structure and the interlayer separation is 7 Å, which is suitable for insertion/extraction of some alkaline and alkaline–earth cations, the δ-MnO2 electrode showed the higher specific capacitance than that of α-MnO2 and γ-MnO2. We also found that the α-, γ-, and δ-MnO2 electrodes in the Mg(NO3)2 electrolyte showed a higher specific capacitance, while all the α-, γ-, and δ-MnO2 electrodes in the Li2SO4 electrolyte exhibited a better cycle life. The reason for the different behavior of Li+ and Mg2+ during the charge/discharge process can be ascribed to the charge effect of the cations in the electrolytes. The ex situ X-ray diffraction (XRD) and long-time cyclic voltammogram measurements were used to systematically study the energy storage mechanism of MnO2-based electrodes. A progressive crystallinity loss of the materials is also observed upon potential cycling at the oxidized states. A reasonable charge/discharge mechanism is proposed in this work.

Keywords

Alkaline cationsAlkaline–earth cationsMnO2Supercapacitor performanceVarious crystallographic structures

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Chen-Chen Ji
    • 1
  • Mao-Wen Xu
    • 2
  • Shu-Juan Bao
    • 1
  • Chang-Jun Cai
    • 1
  • Rui-Ying Wang
    • 1
  • Dian-Zeng Jia
    • 1
  1. 1.Key Laboratory of Material and Technology for Clean Energy, Ministry of Education; Key Laboratory of Advanced Functional Materials, Xinjiang Autonomous Region; Institute of Applied ChemistryXinjiang UniversityUrumqiPeople’s Republic of China
  2. 2.Texas Materials InstituteUniversity of Texas at AustinAustinUSA