Study on the Li1-xNi0.5Mn1.5O4 for Lithium Ion Batteries: a First-Principles Theory

The crystal structure, voltage and capacity of Li1-xNi0.5Mn1.5O4 were studied by using the first principle theory. The results show that the structure of Li1-xNi0.5Mn1.5O4 has changed, and the lattice parameter decreased from 8.342 Å to 8.247 Å with the decrease of Li content. But the change in each direction is the same, so the octahedral structure is unchanged in the process of de-lithium. The length of Ni-O and Mn-O bonds decreases with the increase of de-lithium. The Mn-O bond decreases from 2.101 Å to 1.911 Å, while the Ni-O bond decreases from 2.065 Å To 1.965 Å. The total energy decrease from - 28731.220 eV to -27178.422 eV, and the voltage decreased from 4.7 V to 4.3 V with the reduction of Li amount. All the formation energy of Li1-xNi0.5Mn1.5O4 (P4332) is negative, which display that the structure of crystal is stable with no phase separation. The theoretical capacity reduced from 146 mAhg-1 to 0 with the increase of delithiated amount or Li/Mn molar ratio.