Al2O3-coated spinels were investigated with respect to their electrochemical characteristics. A Al2O3 coating on commercial LiMn2−x M x O4 (Nikki, Japan, M=Zr) was prepared by using the sol–gel method. AA analysis showed that manganese and lithium dissolution occurred during the coating process. XRD patterns show that increase in the lattice parameter of Al2O3-coated spinels is related to formation of a solid solution on the surface of active materials. Impedance results revealed that Al2O3-coated spinel has electronic resistance. However, The cell performance was enhanced with the Al2O3 coating. Al2O3 is regarded as a coating material for stable cycling performance.