High-Ni layered LiNi0.83Co0.11Mn0.06O2 modified by Nb for Li-ion batteries

Abstract

High-Ni layered LiNixCoyMn1-x-yO2 cathode materials with a high discharge capacity have been extensively applied in many fields. However, the cycle life of these materials limits their wide applications because of their severe polarisation and large irreversible capacity. In this study, the first-principles calculation was used to determine changes in the conductive properties of LiNi0.83Co0.11Mn0.06O2 (NCM831) followed by doping with Nb. The theoretical results were used to increase the performance of the cathode material by surface coating LiNbO3 and doping Nb5+ into the crystal lattice of LiNbO3. The results show that the first cycle discharge capacities of NCM831 and its modified 1% Nb2O5 (NbO-1) at 1.0 C are 189.72 and 207.12 mAhg-1, respectively, while doping of the crystals with an appropriate Nb5+ ratio (0.25%:100%, 0.5%:100%, 0.75%:100%, and 1.0%:100%) enhanced their discharge capacity. The LiNbO3 nano-coating decreased the polarisation and charge transfer resistance of NCM831. The bare NCM831 and NbO-1 presented metallic properties, with a fairly large Li + diffusion coefficient. Nb5+ doping and LiNbO3 coating affected the crystal structure and surface morphology of NCM831 before and after cycling. These results provide insights into the experimental applications of first-principles calculation for Ni-rich layered LiNixCoyMn1-x-yO2 cathode materials.