Preparation and electrochemical performances of xLi2MnO3·(1-x) LiNi0.45Co0.2Mn0.35O2 (0 ≤ x ≤ 1) for high-power lithium-ion batteries

In this paper, a series of cathode materials xLi2MnO3·(1-x) LiNi0.45Co0.2Mn0.35O2 (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, 1) were prepared by a carbonate co-precipitation method followed by a two-step sintering process. The effects of different x values on the phase structure, particles size distribution, tap density and electrochemical properties of as-prepared samples were systematically studied. The results display that the two phases between Li2MnO3 and LiNi0.45Co0.2Mn0.35O2 have a better synergistic effect: firstly, suitable amount of Li2MnO3 can stabilize the hexagonal α-NaFeO2 layered structure of OLO and inhibit the mixing positions of Li+ and Ni2+. Secondly, when the x value is 0.5 (MCO-0.5), spherical precursors have the most monodispersed particles size distribution (d = 0.72) and the highest tap density (1.82 g cm−3) among all prepared powders. Finally, 0.5Li2MnO3·0.5LiNi0.45Co0.2Mn0.35O2 (OLO-0.5) delivers a high initial discharge capacity (220 mAh g−1 at 0.1C) and a superior cyclic stability (~ 96% after 100 cycles). Moreover, OLO-0.5 provides the best rate capability owing to the highest discharge capacity when the C-rate increases from 0.1 to 10C.