Lithium intercalation and transport behavior in a Ta2O5 film fabricated by pulsed laser deposition

Electrochemical and isothermal transient ionic current (ITIC) methods have been successfully employed for the first time to investigate the lithium insertion and transport behavior in a Ta2O5 film prepared by pulsed laser deposition. Cyclic voltammogram and potential step measurements were used to examine the insertion processes of Li ions into Ta2O5 film electrodes. The potential step measurements showed that the Li ion diffusion constants in beta -Ta2O5 film electrodes were dependent on the stepping potential and found to be in the range of 5.2 X 10(-14) to 3.8 X 10(-12) cm(2)/s. Based on the ITIC measurements, the Li-ion diffusion constants in beta -Ta2O5 film electrodes were estimated to be in the range of 2.6 similar to5.2 10(-15) cm(2)/s. In addition, the trap states in beta -Ta2O5 film should be responsible for the typical ITIC curves. (C) 2000 The Electrochemical Society. S0013-4651(00)08-125-8. All rights reserved.