Comparative study of Li(Mn0.5-xNi0.5-xM2x)O2 (M=mg, Co, Al, Ti; x=0, 0.025)Cathode Materials for rechargeable Lithium batteries

Abstract

Due to its advantages in cost, safety, and environmental impact, Li(Mn0.5Ni0.5)O2 is considered a possible alternative to LiCoO2 and LiNiO2 Cathode Materials For rechargeable Li-ion batteries. In this Work, Li(Mn0.5Ni0.5)O2 doped with metal ions of various valency, Mg 2+, Co3+, Al3+, Ti4+, have been synthesized using a manganese-nickel hydroxide, and the electochemical and thermal properties of the cathode materials have been examined. Appropriate amounts of LiOH, Manganese-nickel hydroxide, Mg(OH)2, Al(OH)3, Co(OH)3, and TiO2 were mixed and calcined at 1000oC for 15-24 h in air. The powder X-ray diffraction patterns of Li(Mn0.5Ni0.5)O2 and Li(Mn0.475Ni0.475M0.05)O2 are shown in Fig. 1. All of the peaks could be indesed based on th R3m structure, which indicates that the synthesized materials were phase-pure, layerd structure. In Fig.2 are shown typical charge/discharge curves of Li/Li(Mn0.475Ni0.475Al0.005)O2 cells. Li/Li(Mn0.475Ni0.475Al0.005)O2 exhibits smooth, monotonous charge/discharge curves at 2.8-4.3V and excellent capacity retention. All the other cathode materials, Li(Mn0.5Ni0.5)O2 and Li(Mn0.475Ni0.475Ti0.05)O2 showed similar charge/discharge curves to LiLi(Mn0.5Ni0.5)O2 and Li(Mn0.475Ni0.475Al0.05)O2 , but their capacities were lower than that of LiLi(Mn0.5Ni0.5)O2 and Li(Mn0.475Ni0.475Al0.05)O2