High-Performance Oriented V[sub 2]O[sub 5] Thin Films Prepared by DC Sputtering for Rechargeable Lithium Microbatteries

Crystalline thin films of vanadium pentoxide have been deposited by dc sputtering using a vanadium target. Depending on the power applied, two set of samples thick characterized by a 00l or an h 00 preferred orientation have been synthesized. Investigation of their respective electrochemical properties as positive electrode for rechargeable lithium microbatteries has been performed in liquid electrolyte. The h 00 oriented deposits exhibit a better electrochemical behavior in terms of rate capability, polarization, and cycling properties in the voltage range . Specific capacities of 25 and are recovered after at in the potential windows and , respectively. A better electronic conductivity combined with a high porosity induced by a specific morphology are thought to be responsible for this attractive behavior. X-ray diffraction experiments clearly indicate Li insertion results in a continuous increase of the interlayer distance and a contraction of the parameter with in without the emergence of the δ phase as expected in the bulk material. Using the same procedure, a thick film has been prepared with the h 00 preferred orientation to optimize the cycling performance. An excellent rechargeability has been proved in the voltage range because a specific capacity of is still available at a high current density of , showing a good kinetic behavior and a good adherence to the substrate. The present study suggests very thick h 00-oriented deposits can be prepared with high specific capacities and long cycle life.