Many-Particle Na-Ion Dynamics in NaMPO4 Olivine Phosphates (M = Mn, Fe)

Flack, T., Jobbins, S. A., Boulfelfel, S. E. and Leoni, S. ORCID: https://orcid.org/0000-0003-4078-1000 2024. Many-Particle Na-Ion Dynamics in NaMPO4 Olivine Phosphates (M = Mn, Fe). Hanaor, D. A. H., ed. Computational Design of Battery Materials, Vol. 150. Springer, Cham, pp. 137-167. (10.1007/978-3-031-47303-6_5)

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Abstract

NaMPO4 (M = Mn, Fe) olivine phosphates represent less expensive, safer and sustainable alternatives to Lithium-ion materials for battery applications. Compared to their lithium analogues, NaMPO4 materials exist in two structures, maricite and olivine. Their implementation calls for an in-depth investigation of diffusion/conduction mechanisms, including conductivity dimensionality and how structural features map onto Na pathways. In this work, we present a refined version of our finite temperature molecular dynamics “shooting” approach, originally designed to enhance Li hopping probability in lithiated olivine compounds. We perform a comparative analysis of ion mobility in both Mn and Fe olivine materials, focused on many-particle effects. Therein, we identify main [010] diffusion channels, as well as means of inter-channel couplings, in the form of Na cross-channel [001] hopping, which markedly impact the overall mobility efficiency as measured by self-diffusion coefficients. Through introduction of antisite defects, additional pathways along [100] appear, which are specific for Na olivine phosphates, indicating limited transferability of observations made on the Li compounds, both qualitatively and quantitatively. The overall diffusion figures of merit result from the competition and cooperation among different translocation channels, including self-doping. This clearly supports the need for many-particle approaches for reliable mechanistic investigations and for battery materials benchmarking, due to the complex nature of the diffusion and transport mechanisms. In this chapter we illustrate translocation mechanisms in detail, from which diffusion constants are evaluated.

Item Type:	Book Section
Date Type:	Publication
Status:	Published
Schools:	Chemistry
Publisher:	Springer, Cham
ISBN:	9783031473029
ISSN:	03034216
Last Modified:	05 Aug 2024 12:31
URI:	https://orca.cardiff.ac.uk/id/eprint/171130

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