The effect of thickness on the properties of solution-deposited LiMn2O4 thin films

LiMn2O4 thin films of different thickness were prepared by solution deposition. The phase identification and surface morphology were studied by X-ray diffraction and scanning electron microscopy. The electrochemical properties of the thin films were examined by cyclic voltammetry and galvanostatic charge-discharge experiments. The films of different thickness are homogeneous with very small grains and narrow grain size distribution. The specific capacity difference of these films is small with their values between 42 and 47 μAh (cm2 μm)−1 at the discharge current density of 100 μA cm−2. However, the capacity difference of these films becomes larger with the increase of discharge current density. The capacity loss per cycle increases from 0.012 to 0.16% after being cycled 50 times as the thickeness of thin films increases from 0.18 to 1.04 μm. The diffusion coefficients of lithium ion in the films of different thickness are about 10−11 cm2 s−1.