Revealing the H2O/Na environments in Hydrated Manganese Iron Prussian White: a D/H exchange and machine-learning-assisted MD simulation study
4 affiliations
- 1Univ. Grenoble Alpes, CEA, Liten, DEHT
- 2Univ. Grenoble Alpes, CEA, IRIG, MEM
- 3Univ. Grenoble Alpes, CEA, CNRS, Grenoble INP, IRIG, SyMMES
- 4Institut Laue-Langevin 71 avenue des Martyrs, cedex 9, Grenoble, France, 38042
Abstract
Manganese-iron Prussian blue analogs (MnFePBA) are promising sodium-ion battery positive electrodes, offering capacities comparable to LiFePO4 while avoiding critical metals such as cobalt and nickel. Despite their promise, the role of water in the PBA framework remains a central point of contention: some studies report severe first-cycle capacity loss and electrolyte decomposition driven by water co-extraction during cycling, while others show that hydration stabilizes a monoclinic phase capable of smooth, solid-solution sodiation which delivers superior long-term cycling stability. This disagreement is compounded by unresolved structural ambiguity of hydrated PBAs—conventional XRD cannot reliably distinguish sodium from water due to their similar electron densities, and existing neutron diffraction and computational studies disagree on where each species resides within the framework. Here, we address this gap by characterizing deuterated/hydrated (D/H) samples with neutron powder diffraction (NPD) and solid-state 2H/1H NMR to achieve improved contrast and spectral resolution between sodium and water environments, alongside machine-learned interatomic potential molecular dynamics (MLIP-MD) simulations that capture finite-temperature dynamics and configurational sampling beyond the reach of static DFT. NMR confirms consistent local environments across isotopically exchanged samples and resolves distinct signals for interstitial and coordinated water. Contrary to the prevailing XRD-based consensus, our combined NPD and MLIP-MD analysis reveals that water occupies body-center sites while sodium resides at face-center and off-face-center positions—the reverse of the commonly accepted structural model. These findings offer a revised atomic-scale picture of hydrated MnFePBA and establish a methodology for systematically probing hydration effects across the broader PBA family.
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BibTeX
@misc{yang2026revealing,
title = {{Revealing the H2O/Na environments in Hydrated Manganese Iron Prussian White: a D/H exchange and machine-learning-assisted MD simulation study}},
author = {Yuan-Chi Yang and Lena Pineau and Diganta Sarkar and Loic Simonin and David Peralta and Katharina Märker and Gaël De Paëpe and Quentin Berrod and Emmanuelle Suard and Ambroise Van Roekeghem and Quentin Jacquet},
howpublished = {ChemRxiv},
year = {2026},
month = aug,
doi = {10.26434/chemrxiv.15008106/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008106/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Revealing the H2O/Na environments in Hydrated Manganese Iron Prussian White: a D/H exchange and machine-learning-assisted MD simulation study
AU - Yuan-Chi Yang
AU - Lena Pineau
AU - Diganta Sarkar
AU - Loic Simonin
AU - David Peralta
AU - Katharina Märker
AU - Gaël De Paëpe
AU - Quentin Berrod
AU - Emmanuelle Suard
AU - Ambroise Van Roekeghem
AU - Quentin Jacquet
PY - 2026
DA - 2026/08/31
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008106/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008106/v1
AB - Manganese-iron Prussian blue analogs (MnFePBA) are promising sodium-ion battery positive electrodes, offering capacities comparable to LiFePO4 while avoiding critical metals such as cobalt and nickel. Despite their promise, the role of water in the PBA framework remains a central point of contention: some studies report severe first-cycle capacity loss and electrolyte decomposition driven by water co-extraction during cycling, while others show that hydration stabilizes a monoclinic phase capable of smooth, solid-solution sodiation which delivers superior long-term cycling stability. This disagreement is compounded by unresolved structural ambiguity of hydrated PBAs—conventional XRD cannot reliably distinguish sodium from water due to their similar electron densities, and existing neutron diffraction and computational studies disagree on where each species resides within the framework. Here, we address this gap by characterizing deuterated/hydrated (D/H) samples with neutron powder diffraction (NPD) and solid-state 2H/1H NMR to achieve improved contrast and spectral resolution between sodium and water environments, alongside machine-learned interatomic potential molecular dynamics (MLIP-MD) simulations that capture finite-temperature dynamics and configurational sampling beyond the reach of static DFT. NMR confirms consistent local environments across isotopically exchanged samples and resolves distinct signals for interstitial and coordinated water. Contrary to the prevailing XRD-based consensus, our combined NPD and MLIP-MD analysis reveals that water occupies body-center sites while sodium resides at face-center and off-face-center positions—the reverse of the commonly accepted structural model. These findings offer a revised atomic-scale picture of hydrated MnFePBA and establish a methodology for systematically probing hydration effects across the broader PBA family.
ER -