| Résumé | Thin films of manganese oxides have been grown by the pulsed laser deposition (PLD) process on silicon wafer and stainless steel substrates at different substrate temperatures and oxygen gas pressures. By proper selection of processing parameters such as temperature and oxygen pressure during the PLD process, pure crystalline phases of Mn 2O 3, Mn 3O 4 as well as amorphous phase of MnO x were successfully fabricated as identified by X-ray diffraction. The pseudo-capacitance behaviours of these different phases of manganese oxides have also been evaluated by the electrochemical cyclic voltammetry measured in 0.1 M Na 2SO 4 aqueous electrolyte at different scan rates. Their specific current and capacitance determined by electrochemical measurements were compared and the results show that crystalline Mn 2O 3 phase has the highest specific current and capacitance, while the values for crystalline Mn 3O 4 films are the lowest. The specific current and capacitance values of the amorphous MnO x films are lower than Mn 2O 3 but higher than Mn 3O 4. The specific capacitance of Mn 2O 3 films of 120 nm thick reaches 210 F g -1 at 1 mV s -1 scan rate with excellent stability and cyclic durability. This work has demonstrated that PLD is a very promising technique for screening high performance active materials for supercapacitor applications due to its excellent flexibility and capability of easily controlling chemical composition, microstructures and phases of materials. © 2011 Elsevier B.V. All rights reserved. |
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