Mitigating voltage and capacity fading of lithium-rich layered cathodes by lanthanum doping

La-doped lithium-rich layered oxide material Li1.2Mn0.54−xNi0.13Co0.13LaxO2 (x = 0.01, 0.02, 0.03) is firstly synthesized via a solvothermal method and subsequent high-temperature calcination technique. The effects of La substitution for partial Mn on the structure and electrochemical performance of materials are systematically studied by inductively coupled plasma optical emission spectroscopy (ICP-OES), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscope (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and electrochemical measurement. The results reveal that La is effectively and homogenously doped into the materials, which can expand pathway for intercalation/deintercalation of Li+ ions. In addition, owing to La doping, the Li1.2Mn0.52Ni0.13Co0.13La0.02O2 sample exhibits 93.2% capacity retention after 100 cycles at 1 C. More importantly, this doping can effectively restrain the decrease of average discharge voltage upon cycling, which is one of the longstanding fatal drawbacks for lithium-rich layered oxide material. Moreover, La doping can stabilize the layered framework upon long term cycling and suppress voltage fading, and thus resulting in the better cycling performance. Additionally, the rate capability is also improved by La doping due to the higher diffusion velocity of Li+ ions.