Li-ion batteries are promising candidates for electrical energy storage in applications ranging from portable electronics to hybrid and electric vehicles. In this context, layered compounds in the Li1+delta(TMxMn1-x)(1-delta)O-2 family (TM=transition metal) have received much attention due to their high capacity and stability. In this Research News article we describe recent advances on structural characterization of Li-ion electrode materials using state-of-the-art electron microscopy. Direct evidence of the monoclinic nature of Li2MnO3 has been provided. It has been demonstrated that differences in Z-contrast imaging between Li2MnO3 and LiTMO2 may be used to screen samples for phase separation in the 10-100 nm scale.