ISIS Neutron and Muon Source Data Journal
This is a page describing data taken during an experiment at the ISIS Neutron and Muon Source. Information about the ISIS Neutron and Muon Source can be found at https://www.isis.stfc.ac.uk.
Untangling polymorphism & ion transport in high-capacity Na2Fe2F7 via operando ?SR
Abstract: Weberite-type Na Fe F is a promising, sustainable Na-ion cathode combining high capacity (~150 mAh g ), exceptional cycling stability, and minimal volume change. Its performance, however, is strongly governed by polymorphism: low-temperature synthesis yields mixed monoclinic-orthorhombic phases with fast kinetics, while high-temperature routes produce pure monoclinic material with sluggish Na transport. Our DFT results show lower Na migration barriers in the orthorhombic polymorph (~0.55 eV) than in the monoclinic (~0.66 eV), but direct experimental evidence of Na diffusion is still lacking. Conventional electrochemical methods cannot isolate bulk Na motion or track its evolution with Fe oxidation state during cycling. Operando SR uniquely probes local Na dynamics in real time (10 -10 s) within the bulk lattice, providing information inaccessible to any other technique. We will perform temperature-dependent and operando SR on two synthetically controlled polymorphs to quantify Na hopping rates, activation energies, and their evolution with state of charge. These measurements will establish the first synthesis-structure-transport relationship in fluoride-based weberites, identify voltage regions of suppressed Na mobility, and demonstrate operando SR as a benchmark method for probing ion dynamics in complex battery materials.
Principal Investigator: Professor Serena Cussen
Local Contact: Dr Peter Baker
Experimenter: Dr John Wilkinson
Experimenter: Dr Innes McClelland
Experimenter: Miss Jipeng Zhang
Experimenter: Miss Jessie Isufaj
Experimenter: Mr Max Fitzgerald
DOI: 10.5286/ISIS.E.RB2610567
ISIS Experiment Number: RB2610567
| Part DOI | Instrument | Public release date | Download Link |
|---|---|---|---|
| 10.5286/ISIS.E.RB2610567-1 | EMU | 11 June 2029 | Download |
Publisher: STFC ISIS Neutron and Muon Source
Data format: RAW/Nexus
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Data Citation
The recommended format for citing this dataset in a research
publication is as:
[author], [date], [title], [publisher],
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For Example:
Professor Serena Cussen et al; (2026): Untangling polymorphism & ion transport in high-capacity Na2Fe2F7 via operando ?SR, STFC ISIS Neutron and Muon Source, https://doi.org/10.5286/ISIS.E.RB2610567
Data is released under the CC-BY-4.0 license.
