Abstract:Cathode material LiMn2O4 thin films were prepared through solution deposition followed by rapid thermal annealing. The phase identification and surface morphology were studied by X-ray diffraction and scanning electron microscopy. Electrical and electrochemical properties were examined by four-probe method, cyclic voltammetry and galvanostatic charge-discharge experiments. The results show that the film prepared by this method is homogeneous, dense and crack-free. As the annealing temperature and annealing time increase, the electronic resistivity decreases, while the capacity of the films increases generally. For the thin films annealed at different temperatures for 2 min, the thin film annealed at 800 ℃ has the best cycling behavior with the capacity loss of 0.021% per cycle. While for the thin films annealed at 750 ℃ for different times, the film annealed for 4 min possesses the best cycling performance with a capacity loss of 0.025% per cycle. For the lithium diffusion coefficient in LiMn2O4 thin film, its magnitude order is 10−11 cm2•s−1.

Key words: LiMn2O4; lithium ion; thin films; diffusion; electrochemical impedance spectroscopy