First-principle study on the geometric and electronic structure of Mg-doped LiNiO₂ for Li-ion batteries

Ni-rich layered oxides have been widely studied as cathodes because of their high energy density. However, the gradual structural transformation during the cycle will lead to the capacity degradation and potential decay of the cathode materials. In this paper, first-principle calculations were used to investigate the formation energy, and geometric and electronic structure of Mg-doped LiNiO₂ cathode for Li-ion batteries. The results show that Mg doping has little effect on the geometric structure of LiNiO₂ but has great effect on its electronic structure. Our data give an insight into the microscopic mechanism of Mg-doped LiNiO₂ and provide a theoretical reference for experimental research, which is helpful to the design of safer and higher energy density Ni-rich cathodes.

In this work, all calculations were performed by the VASP package; the PBE functional in the generalized gradient approximation (GGA) was employed to describe the exchange-correlation interactions. An energy cutoff of 520 eV and a 5 × 5 × 3 Monkhorst-Pack mesh of k-point sampling in the Brillouin zone were chosen for all calculations. All atoms were relaxed until the convergences of 10^-5 eV/f.u in energy and 0.01 eV/Å in force were reached.