Aluminum-doped spinel-type LiMn2O4 cathode active materials have been synthesized by a microwave-assisted sol–gel method. The influence of synthesis conditions on the structural and electrochemical properties of LiAl0.1Mn1.9O4 was investigated by thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and charge/discharge experiments. The powders resulting from the microwave-assisted sol–gel method with good crystallinity and cubic spinel shapes deliver an initial discharge capacity of 120mAhg−1, present excellent rate capability, and the Coulombic efficiency of it almost approaches 99% after 30 cycles. These advantages make it attractive particularly for a practical application. In addition, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to characterize the reactions of Li ion insertion into and extraction from LiAl0.1Mn1.9O4 electrodes.