Electrochemical performances of Li-rich Mn-based layered structure cathodes optimized by compositional design

Abstract

Li-rich Mn-based xLi(2)MnO(3)center dot(1-x)LiMO2 (M = Ni, Co, Mn) cathode materials have attracted extensive attention because of their specific discharge capacity (250-300 mAh g(-1)). However, their applications are significantly limited due to disadvantages, such as the low efficiency, the fast capacity attenuation, and the poor rate capability. Therefore, it is important to investigate the mechanisms controlling the electrochemical properties and improve the performances. As a solid solution, xLi(2)MnO(3)center dot(1-x)LiMO2 is composed of the hexagonal phase LiMO2 and the monoclinic phase Li2MnO3. In this study, the influence of elements Ni and Li on the electrochemical properties of xLi(2)MnO(3)center dot(1-x)LiMO2 is systematically studied. It is found that the decrease of Li content can lead to the increase of LiMO2 in LixCo0.13Ni0.13Mn0.54O2 system. LiMO2 might span the whole grain with the Li deficiency, thus contributing to the rapid conduction of Li ions. Meanwhile, Li2MnO3 can benefit the structural stability. The synergistic effect of the two components results in the excellent electrochemical performances.