Abstract: Two types of spinel cathode powders, LiMn₂O₄ and LiAl_0.1Mn_1.9O_3.9F_0.1, were synthesized by solid-state reaction, X-ray diffraction (XRD) patterns of the prepared samples were identified as the spinel structure with a space group of Fd3m. The cubic lattice parameter was determined from least-squares fitting of the XRD data. The LiAl_0.1Mn_1.9O_3.9F_0.1 sample showed a little lower initial capacity, but better cycling performance than the LiMn₂O₄ sample at both room temperature and an elevated temperature. The Vanderbilt method was used to test the electrochemical conductivity of the LiMn₂O₄ samples. The electrochemical impedance spectroscopy (EIS) method was employed to investigate the electrochemical properties of these spinel LiMn₂O₄ samples.