Needle-like Lifepo_4 Thin Films Prepared By An Off-axis Pulsed Laser Deposition Technique

摘要

Lithium iron phosphate (LiFePO_4) thin films were prepared by pulsed laser deposition with an off-axis geometry. Amorphous, needle-like and crystallized granular thin films were prepared on Si and titanium substrates. The preferred orientation of these crystallized LiFePO_4 thin films is (120). Microstructures of the deposited films are dependant on the substrate temperature (room temperature, 500 ℃ and 700 ℃) and Ar pressure (5 Pa and 30 Pa) in the chamber. The needle-like film grows following a self-shadowing mechanism. LiFePO_4 thin film with high crystallinity shows a voltage plateau which is a typical feature of the phase transition reaction for bulk material, while the sloped profiles are observed clearly in the charging and discharging curves of LiFePO_4 thin films with low cystallinity.