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Atomic Insights into Aluminium-Ion Insertion in Defective Anatase for Batteries |
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| Authors: | Prof Christophe Legein Dr Benjamin J Morgan Dr Franck Fayon Dr Toshinari Koketsu Prof Jiwei Ma Dr Monique Body Dr Vincent Sarou-Kanian Dr Xian-Kui Wei Dr Marc Heggen Dr Olaf J Borkiewicz Prof Peter Strasser Dr Damien Dambournet |
| Institution: | 1. Institut des Molécules et des Matériaux du Mans (IMMM), UMR 6283 CNRS, Le Mans Université, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France;2. Department of Chemistry, University of Bath, BA2 7AY Bath, UK;3. CNRS, CEMHTI UPR3079, Université d'Orléans, 45071 Orléans, France;4. The Electrochemical Energy, Catalysis, and Materials Science Laboratory, Department of Chemistry, Technical University Berlin, 10623 Berlin, Germany;5. Sorbonne Université, CNRS, Physico-chimie des électrolytes et nano-systèmes interfaciaux, PHENIX, 75005 Paris, France
Institute of New Energy for Vehicles, School of Materials Science and Engineering, Tongji University, Shanghai, 201804 China;6. Forschungszentrum Juelich GmbH, 52425 Juelich, Germany;7. X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL, 60439 USA;8. Sorbonne Université, CNRS, Physico-chimie des électrolytes et nano-systèmes interfaciaux, PHENIX, 75005 Paris, France |
| Abstract: | Aluminium batteries constitute a safe and sustainable high-energy-density electrochemical energy-storage solution. Viable Al-ion batteries require suitable electrode materials that can readily intercalate high-charge Al3+ ions. Here, we investigate the Al3+ intercalation chemistry of anatase TiO2 and how chemical modifications influence the accommodation of Al3+ ions. We use fluoride- and hydroxide-doping to generate high concentrations of titanium vacancies. The coexistence of these hetero-anions and titanium vacancies leads to a complex insertion mechanism, attributed to three distinct types of host sites: native interstitial sites, single vacancy sites, and paired vacancy sites. We demonstrate that Al3+ induces a strong local distortion within the modified TiO2 structure, which affects the insertion properties of the neighbouring host sites. Overall, specific structural features induced by the intercalation of highly polarising Al3+ ions should be considered when designing new electrode materials for polyvalent batteries. |
| Keywords: | 27Al and 19F solid-state NMR insertion mechanism local distortion polyvalent ion batteries vacancies |