DFT + U study of structural, electronic, optical and magnetic properties ofLiFePO4 Cathode materials for Lithium-Ion batteries

Abstract In this study, we have investigated the structural, electronic, optical, and
magnetic properties of LiFePO4 (LFP), which is a prominent cathode material
for lithium-ion batteries (LIBs). In order to analyse the properties of LFP, we have
carried out the calculations using Density Functional Theory (DFT) combined with
the Hubbard (U) correction (i.e., DFT + U), as implemented in the quantum-
espresso (QE) code. We performed the structural optimization and found that
LFP has a stable olivine structure with equilibrium parameters of a = 4.64 ˚A, b =
5.98 ˚A, and c = 10.34 ˚A. It is shown that LFP has a direct band gap value of
3.82 eV, which is very close to experiment values of 3.6-4.0 eV. The projected
density of states (PDOS) of the LFP closely matches with experimental reports
of the electronic structure of the material, where the Fe 3d states form tight
bands above the O 2p band. The analysis of optical properties shows a significant
absorption property in the visible spectrum, reflecting its additional potential for
photoactive application. We have also examined the magnetic properties, which
reveal that LFP exhibits antiferromagnetic ordering, which plays a critical role in
the stability of the material during lithium cycling. The investigated properties of
LFP in this work, thus, highlight its viability as an effective cathode material for
the next-generation battery technologies with a multifaced applications.