Influence of Thickness on the Properties of Solution-derived LiMn2O4 Thin Films

LiMn2O4 thin films of different thickness were derived from solution deposition and heat treated by rapid thermal annealing. The phase identification and surface morphology were studied by X-ray diffraction and scanning electron microscopy. The electrochemical properties of the films were examined by galvanostatic charge-discharge experiments and electrochemical impedance spectroscopy. LiMn2O4 thin films of different thickness derived from solution deposition and rapid thermal annealing are homogeneous and crack free with the grain size between 20 nm and 50 nm. The specific capacity of these films is between 42 and 47 mu Ah.cm(2).mu m(-1). The capacity decreases 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 film thickness increases from 0.18 mu m to 1.04 mu m. The lithium diffusion coefficients of these films are in the same order of 10(-11) cm(2).s(-1).