Nano-Porous Self-Supporting Ta2O5 Thin Film Electrode for Highly Reversible Li Ion Storage

Nano-porous Ta2O5 thin film electrodes are prepared by magnetron sputtering at low pressure in the presence of an oxygen atmosphere with an inert gas. The sputtered Ta2O5 thin film is subsequently annealed at 350 degrees C for 2h in high pure N-2 (Ta2O5-350) to introduce oxygen deficiency. The Ta2O5-350 electrode possesses highly reversible lithium ion storage and good rate capability, which has high specific capacities of about 480 mAh g(-1) at a rate of 0.1C. Furthermore, after 2000 cycles at a rate of 5C the Ta2O5-350 electrode shows no obvious capacity decay and retains specific capacity of about 160 mAhg(-1). The excellent lithium storage properties of Ta2O5-350 electrode can be correlated to the nano-porous electrode architecture and oxygen deficiency.