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Synthesis and enhanced electrochemical supercapacitive properties of manganese oxide nanoflake electrodes

Title
Synthesis and enhanced electrochemical supercapacitive properties of manganese oxide nanoflake electrodes
Author
홍진표
Keywords
Electrochemical supercapacitor; Manganese oxide nanoflake; Sputtering; Thin film
Issue Date
2015-05
Publisher
PERGAMON-ELSEVIER SCIENCE LTD
Citation
ENERGY, v. 83, Page. 532-538
Abstract
MnO2+delta (Manganese oxide) nanoflakes were synthesized for use as electrode material in electrochemical supercapacitors. The nanoflakes were produced via RF-magnetron sputtering with various excess oxygen contents (delta), and the electrochemical supercapacitive properties of the Mn2+delta nanoflakes were investigated as a function of delta with the use of a Na2SO4 electrolyte. The excess oxygen (delta) induces the MnO2+delta nanoflakes to form a thin open structure, and mu-Raman measurements revealed that the MnO2+delta nanoflakes formed a bimessite phase with a layered structure. X-ray photoelectron spectroscopy was used to obtain quantitative information on both the oxidation state and the chemical composition of the nanoflake electrodes. The crystallinity of the nanoflakes improved when the oxygen partial pressure increased during sputtering. At an optimal delta similar to 0.6, the electrochemical stability and the capacity retention significantly improved, and electrochemical impedance spectroscopy revealed that easy access of Na+ ions into the nanoflakes at an optimal delta value resulted in a low diffusion resistance, playing a key role in determining the improvement in the supercapacitor characteristics. (C) 2015 Elsevier Ltd. All rights reserved.
URI
http://www.sciencedirect.com/science/article/pii/S0360544215002133http://hdl.handle.net/20.500.11754/24736
ISSN
0360-5442; 1873-6785
DOI
10.1016/j.energy.2015.02.058
Appears in Collections:
COLLEGE OF NATURAL SCIENCES[S](자연과학대학) > PHYSICS(물리학과) > Articles
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