Initial Coulombic Efficiency Improvement of the Li-Rich Layered Oxide Cathodes Via Tellurium Doping

Abstract

Li-rich layered oxide cathodes have the advantages of higher capacity and lower cost. However, they suffer from low initial Coulombic efficiency, which impose a great obstacle for their practical applications. In this work, a series of cathode matrials Li1.2Mn0.48-xTexNi0.16Co0.16O2(x=0, 0.02, 0.05 and 0.1) were synthesized via a co-precipitation. Structural characterizations revealed that the Te6+ doping samples with a suitable amount show low cation mixing, indicating an enhanced ordered layer structure. The electrochemical experiments show that the initial Coulombic efficiencies of the Li1.2Mn0.48-xTexNi0.16Co0.16O2 Li-rich material is largely improved by the tellurium substitution for manganese, and the highest value is about 88% with 272 mAh g-1 initial discharge capacity at room temperature when the content of doping tellurium is 0.05. These results prove that tellurium doping can effectively improve the initial Coulombic efficiency of these cathode materials during the first cycle process via enhancing the electrical conductivity and increasing structural stability of these Li-rich layered materials with a tellurium element introduction. Figure 1