Unraveling the doping mechanisms in lithium iron phosphate

Abstract

As a result of the extensive research and application of LiFePO4 (LFP) in the past > 20 years, there is now a relatively in-depth understanding of its structural stability, phase transition mechanism and electrochemical properties. However, the difficulties faced by further improving the performance of LFP due to its intrinsic low electronic and ionic conductivity have not yet been effectively solved. In order to unlock the effect of transition metal doping on the physicochemical properties of LFP, we establish doping models for all 3d, 4d and 5d transition metals in LFP and compare and analyze their structural properties, band gaps, formation energies, elastic properties, anisotropies and lithiation/delithiation voltages using ab-initio computational screening. According to our screening results, the V-, Mn-, Ni-, Rh- and Os-doped LFP structures have excellent electrochemical properties and can be used as high-performance cathode materials for Li-ion batteries.