Comparative Study of LiMn2O4 Thin Films Heat-treated by Conventional and Rapid Thermal Annealing

Cathode meterial LiMn2O4 thin films were prepared by solution deposition followed by conventional thermal annealing (CTA) and rapid thermal annealing (RTA) using lithium acetate and manganese acetate as starting materials. The phase and surface morphology identification was done by X-ray diffraction and scanning electron microscopy. The electrochemical properties of the thin films were carried out by cyclic voltammetry, charge-discharge experiments, electrochemical impedance spectroscopy and potential step technique. The results show that both thin films are homogeneous and crack-free. Compared with the CTA derived thin films, the RTA derived ones with smaller grain size are more smooth and dense. The CTA and RTA derived LiMn2O40.050% and 0.037% per cycle after being cycled 100 times, respectively. The diffusion coefficient of lithium ion in the CTA derived LiMn2O4 thin-film electrode is 4.59×10-11 cm2/s, and that of lithium ion in the RTA derived one is 3.86×10-11 cm2/s.