Ethylene glycol-engineered LiFePO4: performance insights from experiment and theory

LiFePO4 is a widely studied cathode material for lithium-ion batteries. Here, experimental and theoretical analyses show that mechanically treating commercial LiFePO4 with ethylene glycol (EG) as a process control agent modifies its performance. This study uses X-ray photoelectron spectroscopy (XPS) to examine the oxidation states and chemical composition of LiFePO4. XPS results show that mechanical treatment of commercial LiFePO4 with EG does not change its elemental composition, oxidation states, or the shape of its valence band spectra. The most prominent facets of LiFePO4 were modeled using Density Functional Theory and slab models, revealing a stability order of ¿(311) < ¿(200) < ¿(211) < ¿(111) < ¿(101), with (311) being the most stable. Specifically, the EG molecule exhibited strong adsorption to the (101) and (211) surfaces, with adsorption energies of ¿1.79 and ¿1.32 eV, respectively. The EG molecule leads to charge donation and forms electrostatic and orbital interactions, as confirmed by charge and projected density of states analysis. Notably, the shift of the Li(2s) states toward the Fermi level on EG-modified (111) surfaces suggests that specific additives with favorable binding could produce easier detachment of Li+ ions of certain crystal facets. © 2025