Journal of Alloys and Compounds
Volume 686, 25 November 2016, Pages 30-37
Effect of Al substitution sites on Li1−xAlx(Ni0.5Co0.2Mn0.3)1−yAlyO2cathode materials for lithium ion batteries
The effects of various Al concentration and substitution sites (including Li layer andtransition metallayer) on the structural andelectrochemical propertiesof LiNi0.5Co0.2Mn0.3O2(NMC) materials are systematically investigated.X-ray diffraction,X-ray photoelectron spectroscopyand electrochemical tests confirm that LiAlO2phase appears in Li1−xAlxNi0.5Co0.2Mn0.3O2samples and contributes to betterlithiumion diffusion coefficient. While Al prefer to form AlO solid solution in Li(Ni0.5Co0.2Mn0.3)1−yAlyO2samples, which can improve the structural stability of NMC. As expected, Al substituted samples with suitable dopant concentration exhibit remarkably enhanced electrochemical performances compared with pristine LiNi0.5Co0.2Mn0.3O2. Particularly, the Li0.99Al0.01Ni0.5Co0.2Mn0.3O2sample maintains 172.3 mAh g−1(1 C) with 90.9% capacity retention after 100 high-voltage cycles at 4.6 V charge cut-off. These results demonstrate that substitution of Li with low Al content has superior advantages for LiNi0.5Co0.2Mn0.3O2cathodes.