In-situ Microstructural Investigations by Electron-beam Irradiation Induced Crystallization of Amorphous MoOᵪ Thin Films with High Performance for Li-ion Storage
By Chen, Wenhao; Zhang, Hong; Wang, Ying; Ma, Zhiyuan & Li, Zhicheng
Published in Electrochimica Acta
2014
Abstract
Amorphous MoOᵪ (a-MoOᵪ 2 < x < 3) thin films were deposited by a reactive magnetron sputtering method. As the Li-ion storage electrodes, the a-MoOᵪ thin films exhibit a high capacity of 338 μAh·cm⁻² (about 845 mAh·g⁻¹) at a current density of 90 μA cm⁻² even after 100 electrochemical cycles, and have a rate capacity of 158 μAh cm⁻² at a high current density of 2000 μA cm⁻². The phase analysis revealed that all the a-MoOᵪ thin films maintained an amorphous characteristic after having been charged-discharged at various stages. In-situ electron-beam irradiation (EBI) induced crystallization of the a-MoOᵪ thin films was performed by using a transmission electron microscopy. By analyzing the EBI induced crystalline phases of the a-MoOᵪ thin films, the possible electrochemical reactions during the charge-discharge processes were discussed. According to the developed investigation method, the possible electrochemical mechanism in the a-MoOᵪ thin films were proposed to undergo a conversion reaction such as MoOᵪ + 2xLi⁺ + 2xe− ↔ Mo + xLi₂O during the electrochemical processes.