Towards an atomic-level understanding of the structure and behaviour of organic anode materials for Na-ion and Li-ion batteries Valerie Seymour 1,2 , Tommy Whewell 1,2 , John Griffin 1,2 1 Department of Chemistry, Lancaster University, Lancaster, LA1 4YB, UK, 2 The Faraday Institution, Quad One, Harwell Science and Innovation Campus, Didcot OX11 0RA, UK Organic redox-active molecules are attractive candidates as negative electrode materials for a number of reasons including: low-voltage electrochemistry, environmental sustainability, and structure diversity. 1 Insight into structure- property correlations at multiple levels is important for further understanding and development. Nuclear magnetic resonance (NMR) provides element-specific atomic-level detail, and is very versatile, with applications to physical and life sciences, including chemistry and materials science. Furthermore, solid-state NMR is a powerful tool for materials in the solid state, particularly in cases where diffraction methods are of limited use. It can probe local environments and identify species, thereby providing structural and mechanistic insights. Combined experimental- computational solid-state NMR studies, using the NMR crystallography approach, 2 enables the opportunity to validate or rule out possible structural models. Solid-state NMR is well suited to the study of battery materials at different stages of charge. The structures of the reduced phases and sodiation mechanisms for organic anode materials are currently not well understood. For sodiated (or lithiated) anode materials solid-state NMR can provide insight into the location of the additional Na (or Li) content, as well as changes to the local environments of the structure on their insertion. DFT models enable the prediction of NMR parameters for different arrangements of additional ions inserted into the framework. These can then be used to aid interpretation of the experimental NMR spectra, providing detailed insight. The structures of model sodium and lithium anode materials have been studied through synthetic approaches, experimental XRD and solid-state NMR, as well as complementary DFT calculations. Results will be presented on the preparation and characterisation of promising battery materials, such as sodium organic framework anode materials, to examine sodiation and lithiation mechanisms. References 1. 1. A. V. Desai, R. E. Morris, A. R. Armstrong, ChemSusChem 2020,13, 4866. 2. 2. T. Whewell,V. R. Seymour,K. Griffiths,N. R. Halcovitch,A. V. Desai,R. E. Morris,A. R. Armstrong,J. M. Griffin, Magn. Reson. Chem. 2022, 60, 489.
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