Improved electrochemical properties of MnO thin film anodes by elevated deposition temperatures: Study of conversion reactions

MnO thin films were grown on Cu-foil substrates at various temperatures by the pulsed laser deposition (PLO) technique. The elevated growth temperatures led to the improved storage capacity, initial Coulombic efficiency and rate performance of the thin film anodes. It also had an observable effect on the voltage polarization at the first discharge process, whereas negligible at the subsequent cycles. The origins for these behaviours were clarified. The superior electrochemical performance was attributed to the improved kinetic properties, which relate to the initial better crystallinity and more ordered microstructure of the films caused by the elevated deposition temperatures. The similar behaviour of voltage polarization in the cycles after the first discharge was ascribed to the similar nanocomposited structure induced by the initial conversion reaction. Moreover, the mechanisms for the low initial Coulombic efficiency and the large voltage polarization, which are the appealing and essential topics for the conversion reactions, were elucidated. (C) 2012 Elsevier Ltd. All rights reserved.