The layered LiNiM_0.5Mn_0.5O₂ cathode material for lithium ion batteries was synthesized in atmosphere at 850℃ for 24 h. XRD analysis, SEM and electrochemical tests were used to characterize the composition, structure, appearance and electrochemical performances of the aimed material. The lattice parameters of the hexagonal layered LiNiM_0.5Mn_0.5O₂ (space group R3m) with an α-NaFeO₂ structure are a=0. 2897 nm, c=1. 431 nm. The composition studies show that the predominant oxidation states of Ni and Mn in the compound are 2+ and 4+ respectively with small content of Ni³⁺ and Mn³⁺ ions. The material shows the electrochemical properties like LiCo_xNi_1-xO₂ cathode material. Initial discharge capacities of 145, 153, 195 mAh·g^-1 were respectively obtained in the range of 2.8～4.2, 2.8～4.4, 2.8～4.7 V, and its electrochemical stability descended with the increase of the charge-discharge voltage. The material also retains the primary layered structure after 20 charge-discharge cycles.

Key words: lithium-ion battery, cathode material, LiN_0.5Mn_0.5O₂, layered