Structural in Situ Study of the Thermal Behavior of Manganese Dioxide Materials: Toward Selected Electrode Materials for Supercapacitors
- 29 November 2010
- journal article
- research article
- Published by American Chemical Society (ACS) in ACS Applied Materials & Interfaces
- Vol. 2 (12), 3493-3505
- https://doi.org/10.1021/am100669k
Abstract
The thermal behavior of a series of MnO2 materials was investigated toward MnO2 microstructures under inert atmospheres. The byproduct formed during MnO2 heat treatments from the room temperature to 800 °C were characterized by in situ X-ray diffraction analyses. It was found that annealing spinel and ramsdellite phases caused the formation of MnO2 pyrolusite at 200 °C, Mn2O3, at 400 °C, and then Mn3O4 at higher temperatures. In the case of cryptomelane and birnessite phases, the heating process resulted in the formation of K0.51Mn0.93O2 at 600 °C, while Mn3O4 was also formed and still present up to 800 °C. Heat-treating Ni-todorokite and OMS-5 up to about 450 °C led to the formation of NiMn2O4 and NaxMnO2, respectively, and again Mn3O4 at higher temperatures. All of these structural transformations were correlated to resulting weight losses of MnO2 powders, measured by thermogravimetric analyses, during the heating process. Cyclic voltammetry measurements were performed in the presence of 0.5 M K2SO4 aqueous solution for annealed cryptomelane, K0.51Mn0.93O2, and Mn3O4-based electrodes. It was found that MnO2 cryptomelane is electrochemically stable upon heating. The long-term charge/discharge voltammetric cycling revealed that the specific capacitance of Mn3O4-based electrode is significantly improved from 14 F·g(-1) (after 20 cycles) to 123 F·g(-1) (after 500 cycles).Keywords
This publication has 44 references indexed in Scilit:
- Fabrication of MnO2-pillared layered manganese oxide through an exfoliation/reassembling and oxidation processJournal of Power Sources, 2009
- Electrochemical Oxidation of Mn∕MnO Films: Mechanism of Porous Film GrowthJournal of the Electrochemical Society, 2006
- Synthesis of metal-doped todorokite-type MnO2 and its cathode characteristics for rechargeable lithium batteriesJournal of Power Sources, 2005
- Structure of Birnessite Obtained from Decomposition of Permanganate under Soft Hydrothermal Conditions. 1. Chemical and Structural Evolution as a Function of TemperatureChemistry of Materials, 2005
- Structural evolution upon heating of sol–gel prepared birnessitesThermochimica Acta, 2003
- Anodic behaviour of manganese in alkaline mediumElectrochimica Acta, 2001
- Thermochemistry of manganese oxides in reactive gas atmospheres: Probing redox compositions in the decomposition course MnO2 → MnOThermochimica Acta, 1997
- Transformations of manganese oxides under different thermal conditionsJournal of Thermal Analysis and Calorimetry, 1996
- Characterization of the thermal genesis course of manganese oxides from inorganic precursorsThermochimica Acta, 1992
- Les Phases KxMnO2 (x ≤ 1)Zeitschrift für anorganische und allgemeine Chemie, 1976