The paper presents the results of the study of phase composition and electrochemical performance of lithium-manganese oxide spinel with excess lithium of nominal composition of Li1 + xMn2O4 obtained by solid-phase method. It was established that samples with x = 0.1 and 0.2 were composite materials with LiMn2O4 being the basic phase and Li2MnO3 being the impurity (3 and 7 mas.%, respectively) also comprising trace amounts of MnO2.