The mixed pine tree seed-like/disc-shaped microstructures of MnOx (x = 4/3 and 1) were synthesized using a simple microwave-assisted solvothermal synthesis and heat treatment under N2 atmosphere (heating rate 5 °C/min), without the need for carbon composite. This new mixed morphology showed high specific capacitance, as measured by the cyclic voltammetry (182 F g−1 at 1 mV s−1) and by the constant galvanostatic charge-discharge cycling (195 F g−1 at 0.1 A g−1). During the cycling process the specific capacitance of the material increased, which was caused by the partial electrochemical oxidation of the major phase Mn3O4 (x = 4/3) to MnO2 in a neutral electrolyte of 1 M Na2SO4. According to the galvanostatic charge-discharge cycling tests at 1 A g−1, this material also showed good capacitance retention for over 1000 cycles. MnOx synthesized herein can thus be a good candidate for the electrode material for electrochemical capacitors.
Bibliographical noteFunding Information:
The authors would like to thank Dr. Sang-Hoon Park, Mr. Myeong-Seong Kim, Mr. Chang-Wook Lee, and Mr. Jun-Hui Jeong at Yonsei University for their help and advices. This work was financially supported by the University Staff Development Consortium, the Office of the Higher Education Commission, Thailand (JS), the Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University (SMS and PP), and the National Research Laboratory of Energy Conversion & Storage Materials, Yonsei University, Seoul, South Korea (HKK, SWL, and KBK).
© 2015, Springer Science+Business Media New York.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Mechanics of Materials
- Electrical and Electronic Engineering
- Materials Chemistry