Eur. Phys. J. Appl. Phys. 99, 20 (2024)
https://doi.org/10.1051/epjap/2024240037

Original Article

Density functional theory calculations applied to olivine-like NaMnPO₄ with transition metal substitutions for energy storage applications

¹ Chouaib Doukkali University of El Jadida, National School of Applied Sciences, Energy Science Engineering Lab, El Jadida, Morocco
² Research Institute for Solar Energy and New Energies (IRESEN), Rabat, Morocco
³ TCPAM, Polydisciplinary Faculty, Sultan Moulay Slimane University, Mghila, Beni-Mellal, Morocco
⁴ Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000, Grenoble, France
⁵ Laboratory of Applied Chemistry of Materials, Faculty of Science, Mohammed V University in Rabat, Avenue Ibn Batouta BP.1014, Rabat, Morocco

^* e-mail: laghzizi@fsr.ac.ma

Received: 3 March 2024
Accepted: 23 July 2024
Published online: 9 September 2024

Abstract

In this study, Density Functional Theory (DFT) calculations are applied to evaluate the structural and thermodynamic properties of MPO₄ and NaMPO₄ as cathode materials for sodium-ion batteries (SIBs). Using the modified Perdew-Burke-Ernzerhof (PBE) method and the projector augmented wave (PAW) method, the effect of metal substitution in MPO₄ and NaMPO₄ lattices (M = Mn, Fe, Co, Ni,), as well as Fe-Ni substituted NaMnPO₄ was examined for its structural and electrochemical characteristics. As NaMnPO₄ has less ionic and electronic conductor, the partial substitution of Mn by simultaneous Ni and Fe gives good physicochemical properties useful for good cathode materials in SIBs. For NaMn_0.5Ni_0.25Fe_0.25PO₄, its optimal values of gravimetric capacity (154 mAh.g⁻¹), bandgap energy (0.45 eV) and intercalation potential (3.54 V) appeared very interesting to be an attractive cathode material for SIBs. Na⁺ diffusion required less energy in NaFePO₄, NaMnPO₄, and Fe-Ni co-doped NaMnPO₄ systems, promoting a rapid recharge rate and good ionic conductivity thanks to the desodiation process in creating a mixed oxidation state particularly for Fe and Mn atoms.