Synthesis and electrochemical performance of Li{sub 1+x}Ni{sub 0.5}Mn{sub 0.3}Co{sub 0.2}O{sub 2+{delta}} (0 {<=} x {<=} 0.15) cathode materials for lithium-ion batteries

Graphical abstract: Cycle behavior of Li{sub 1+x}Ni{sub 0.5}Mn{sub 0.3}Co{sub 0.2}O{sub 2+{delta}} cells (x = 0, 0.05, 0.10 and 0.15) obtained during cycling within the potential of 2.5-4.3 V. Highlights: Black-Right-Pointing-Pointer The spherical Li{sub 1+x}Ni{sub 0.5}Mn{sub 0.3}Co{sub 0.2}O{sub 2+{delta}} were synthesized by coprecipitation method. Black-Right-Pointing-Pointer Excess lithium improved the electrochemical performance. Black-Right-Pointing-Pointer Li{sub 1.10}Ni{sub 0.5}Mn{sub 0.3}Co{sub 0.2}O{sub 2+{delta}} showed the best electrochemical performance. Black-Right-Pointing-Pointer Li{sub 1.10}Ni{sub 0.5}Mn{sub 0.3}Co{sub 0.2}O{sub 2+{delta}} had the lowest charge transfer resistance. -- Abstract: In this work, layered lithium-excess materials Li{sub 1+x}Ni{sub 0.5}Mn{sub 0.3}Co{sub 0.2}O{sub 2+{delta}} (x = 0, 0.05, 0.10 and 0.15), of spherical morphology with primary nanoparticles assembled in secondary microspheres, were synthesized by a coprecipitation method. The effects of lithium content on the structure and electrochemical performance of these materials were evaluated by employing X-ray diffraction (XRD), inductive coupled plasma (ICP), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge tests. It is found that Li{sub 1.10}Ni{sub 0.5}Mn{sub 0.3}Co{sub 0.2}O{sub 2+{delta}}, i.e., Li[(Ni{sub 0.5}Mn{sub 0.3}Co{sub 0.2}){sub 0.95}Li{sub 0.05}]O{sub 2} showed the best electrochemical performance due to the highly ordered layered structure, reduced cation mixing and the lowest charge transfer resistance. Li{sub 1.10}Ni{sub 0.5}Mn{sub 0.3}Co{sub 0.2}O{sub 2+{delta}} delivered a discharge capacity of 145 mA h g{sup -1} at 125 mA g{sup -1} in the cut-off voltage of 2.5-4.3 V, and had a capacity retention of 100% after 50 cycles at room temperature.