Synthesis and electrochemical performance of Li-rich xLi2MnO3•(1-x)LiMn1/3Ni1/3Co1/3O2 (x=0.2-0.5) cathode materials for lithium-ion batteries

Abstract

Li-excess transition metal oxides of the general composition xLi2MnO3•(1-x)LiMO2 (M=MnaNibCoc, a+b+c=1) are synthesized by coprecipitation method. Synthesis conditions for obtaining spherical particles with porous structure were determined. The influence of the oxide phase composition on their electrochemical performance as cathode materials is studied in lithium half-cells. All the samples show very high first-cycle coulombic efficiencies (more than 90%) in the voltage range of 2.5-4.8 V at a current density of 0.5C. It is reported that the Li-rich oxide of the composition 0.35Li2MnO3•0.65LiMn1/3Ni1/3Co1/3O2 shows the better cycling performance in terms both discharge capacity and energy density and the best rate capability compared with the samples with larger and smaller contents of Li2MnO3.