Enhanced electrochemical performance of La-doped Li-rich layered cathode material

Abstract

A series of promising lithium-rich cathode materials with excellent electrochemical properties were successfully synthesized by calcining precursors and lithium salts. The structure, morphology, element valence state, cyclic voltammetry and electrochemical impedance were used to study the properties of the materials. The doped La3+ had great influence on the structure and electrochemical properties of the materials. XRD results displayed that La3+ was incorporated into the material lattice resulted in the formation of layered-spinel hetero-structure, the decrease of cation mixing and the expansion of c lattice parameter. The discharge capacity decreased after La3+ was doped into Li[Li0.2Mn0.54Ni0.13Co0.13]O2, which was due to La3+ was non-electrochemical active element did not participate in the electrical reaction. Although the discharge capacity was reduced after La3+ doping, the initial coulombic efficiency, cycling performance and rate capability were all improved. Among the prepared samples, Li[Li0.2Mn0.54Ni0.13Co0.125]La0.005O2 delivered the best electrochemical performance and highest lithium ions diffusion coefficient, which can be ascribed to its stable and ordered layered-spinel hetero-structure.