Comparison of electronic property and structural stability of LiMn2O4 and LiNi0.5Mn1.5O4 as cathode materials for lithium-ion batteries

The electronic property and structural stability of LiMn2O4 and LiNi0.5Mn1.5O4 with Fd  3¯m space group are investigated by density functional theory (DFT) plane-wave pseudopotential method. The calculated values of Mn(Ni)–O bond lengths are found to be consistent with the reported experimental values. Due to the Ni doping, the significant shortening of Mn(Ni)–O bond strengthens the structural stability of spinel. The electronic properties of spinel show that the bonding between O and metal (Mn and Ni) is also strengthened due to the Ni doping, and then it improves the structural stability of LiNi0.5Mn1.5O4. Ni-doped spinel has a lower formation enthalpy than that of the pristine, indicating that the Ni doping improves the structural stability of spinel.

Research highlights
► Quantitative analysis of the electronic properties and structural stability for spinel by DFT methods.
► The shortening of Mn(Ni)–O bond strengthens the M–O bonding and the structural stability of spinel due to Ni doping.
► The decrease of formation enthalpy after Ni doping indicates that LiNi0.5Mn1.5O4 has higher structural stability than that of the pristine.