Unveiling the potential of lithium fluoride phosphate (Li2MPO4F, M = Fe, V, Mn) for the next generation of lithium-ion batteries: A comparative study based on first principles and molecular dynamic simulations.

LiFePO 4 (LFP) cathode with olivine crystal structure has been a key player in safe and affordable energy storage, owing to its low-cost iron and high electrochemical stability within a voltage range of commercial electrolytes (2.8–3.4 V). To maintain these benefits while enhancing its energy density, Li 2 MPO 4 F was developed by introducing fluorine (F) and replacing iron with other transition metals (M). However, previous studies on these materials primarily measured performance within a limited voltage window (e.g., 2.5–4.5 V), making it challenging to analyze their performance under advanced electrolytes with a broader voltage range. In this study, we took a novel approach by utilizing first principles and molecular dynamic calculations to investigate the electrochemical performance of Li 2 MPO 4 F with three types of transition metals (M = V, Fe, Mn). This unique methodology, which includes calculations on theoretical voltages, atomic structures, and diffusion coefficient after structural optimization, allowed us to predict the impact of transition metals on cathode performance. By closely comparing the expected results, this study discusses the pros and cons of each cation substitution and suggests suitable cathode materials for batteries with high energy density and superior rate capability. Atomic simulations unveiled the intrinsic performance of Li 2 MPO 4 F (M = Fe, V, Mn) cathodes and their potential future usage in conjunction with electrolytes with a wide voltage window. These findings are crucial as they provide the criteria for selecting optimal cations suitable for energy density, cycle life, and rate performance. [Display omitted] • Role of transition metal (M) on the performance of Li 2 MPO 4 F was investigated. • Li x MnPO 4 F shows superior energy density, at the expense of short cycle life. • Li x FePO 4 F with slow Li diffusion shows long cycle life due to its sturdy structure. • Li x VPO 4 F has the lowest energy density but moderate cycle life and rate performance. • Criteria for suitable element (M) of fluorophosphate cathodes were proposed. [ABSTRACT FROM AUTHOR]