Li Storage Properties of (1-x-y)Li[Li1/3Mn2/3]O2-xLiFeO2-yLiNiO2 Solid Solution Cathode Materials

Abstract

Uniform solid solution of (1-x-y)Li[Li1/3Mn2/3]O2-xLiFeO2-yLiNiO2 (x+y≤0.5) were prepared by citric acid assisted sol-gel process including three-step of “preparation of wet gel—formation of spray-dried gel—annealing at high temperature”, and the effects of composition on the Li-storage properties of as-prepared samples were investigated by XRD, XPS and charge-discharge tests. The results indicate that all samples prepared at 650 °C ~800 °C show pure hexagonal phase (or monoclinic phase). Obvious cooperative effects are observed for the samples with suitable amount of composited LiNiO2 and LiFeO2 (x+y≈0.3~0.4), which can present high capacity of >210 mAhg-1, good structural stability and cycling performance. In view of capacity, cycling performance and cost, the samples with x+y≈0.3~0.4 and x/y=1.6~3.0 are considered to be more promising new cobalt-free cathode materials with high capacity of more than 240 mAhg-1.