Li-rich layer-structured cathode materials formulated as xLi₂MnO₃ -(1-x)LiMO₂(M = Mn, Ni, Co, etc.) have received much attention due to their surprisingly high reversible capacity for Li-ion battery applications. For the understanding of these materials, a systematic study on complicated crystal structures and reaction mechanisms during electrochemical charge/discharge cycles is employed. Although Li-rich layer-structured cathode material show a reversible capacity as high as 250 mAh/g at low rate, its electrochemical properties such as capacity loss at first cycle, rate capability and capacity fading still need to be examined and characterized. In this study, several compositions of xLi₂MnO₃ -(1-x)LiMO₂ (M = Mn, Ni, Co, etc.) were investigated.

The TEM structural analysis shows that the evidence of spinel phase after cycling. It is believed that the transition from layered structure to spinel structure may induce a large lattice distortion resulting in lattice breakdown and capacity. In additions, the phase transition is caused by the redox reaction of transition metal ions through charging/discharging tests. Thus, the cycling behavior of Li-rich layer-structured oxides is studied by changing the oxidation state of transition metal ions in the layered structures. XRD, SEM, TEM will be used for characterization of cycled cathode materials.