Pulsed laser deposition and characterization of LiMn2O4thin Films for applications in Li Ion rechargeable battery systems

Abstract

ABSTRACTMost studies focused on fundamental aspects of cathode materials in lithium ion battery employ porous electrodes, which are made of polymer bonded transition metal oxide powders mixed with conductors such as carbon. However, the powder morphology and the presence of carbon and polymeric binders affect the physical, chemical and electrochemical behaviors significantly. Therefore, transition metal oxide based materials in thin film form, which are dense and contain no additives, are emerging as promising alternatives to study fundamental properties in lithium ion batteries. Pulsed laser ablation (PLD) was used to deposit highly textured thin and thick porous films of LiMn2O4. Effect of various parameters such as substrates and deposition conditions were studied on the microstructure of these films. Microstructure studies of these films were carried out using x-ray diffraction and scanning electron microscopy. The electrochemical measurements were carried out in a glove box using cyclic voltammetery, electrochemical cycling and AC Impedance spectroscopy in a half-cell configuration with lithium metal as an anode and reference electrode and LiMn2O4film as a cathode. Results indicate differences in film morphology greatly effect electrochemical kinetics of Li intercalation and de-intercalation. Thin films show good electrochemical characteristics such as high rate capability, good coulombic efficiency and rechargeability till 400 cycles.