Evaluating Factors Affecting Li-ion Diffusivity in Ru-dopped LiFePO4

Ionic diffusivity plays a central role in the performance of the battery materials. We use molecular dynamics simulation based on on-the-fly machine learning potential to show that Li-ion diffusivity in well-known cathode lithium iron phosphate (LFP) increases when doped with transition metal dopant Ru. Our finding corroborates pertinent literature showing improved electrochemical performance of LFP upon Ru doping. This increment is accompanied by changes in lattice and its electronic properties, including reduction of lattice in the diffusion direction, appearance of defect states in the middle of band gap and vicinity of the conduction band, and reduction in Li-diffusion barrier. Our calculation informs parameters that affect ionic diffusivity in LFP, which may be used for machine learning-based materials design protocols.