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Surface Engineering Strategy Using Urea To Improve the Rate Performance of Na2Ti3O7 in Na-Ion Batteries |
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| Authors: | Dr Sara I R Costa Dr Yong-Seok Choi Dr Alistair J Fielding Dr Andrew J Naylor Dr John M Griffin Prof?Dr Zdeněk Sofer Prof David O Scanlon Dr Nuria Tapia-Ruiz |
| Institution: | 1. Department of Chemistry, Lancaster University, Lancaster, LA1 4YB UK
The Faraday Institution, Harwell Campus, Didcot, OX11 0RA UK;2. The Faraday Institution, Harwell Campus, Didcot, OX11 0RA UK Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ UK Thomas Young Centre, University College London, Gower Street, London, WC1E 6BT UK;3. School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, L3 3AF UK;4. Department of Chemistry—Ångström Laboratory, Uppsala University, Box 538, 75121 Uppsala, Sweden;5. Department of Chemistry, Lancaster University, Lancaster, LA1 4YB UK;6. Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, 16628 Prague 6, Czech Republic;7. The Faraday Institution, Harwell Campus, Didcot, OX11 0RA UK Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ UK Thomas Young Centre, University College London, Gower Street, London, WC1E 6BT UK Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE UK |
| Abstract: | Na2Ti3O7 (NTO) is considered a promising anode material for Na-ion batteries due to its layered structure with an open framework and low and safe average operating voltage of 0.3 V vs. Na+/Na. However, its poor electronic conductivity needs to be addressed to make this material attractive for practical applications among other anode choices. Here, we report a safe, controllable and affordable method using urea that significantly improves the rate performance of NTO by producing surface defects such as oxygen vacancies and hydroxyl groups, and the secondary phase Na2Ti6O13. The enhanced electrochemical performance agrees with the higher Na+ ion diffusion coefficient, higher charge carrier density and reduced bandgap observed in these samples, without the need of nanosizing and/or complex synthetic strategies. A comprehensive study using a combination of diffraction, microscopic, spectroscopic and electrochemical techniques supported by computational studies based on DFT calculations, was carried out to understand the effects of this treatment on the surface, chemistry and electronic and charge storage properties of NTO. This study underscores the benefits of using urea as a strategy for enhancing the charge storage properties of NTO and thus, unfolding the potential of this material in practical energy storage applications. |
| Keywords: | anode Na2Ti3O7 and Na2Ti6O13 oxygen vacancies sodium titanate sodium-ion batteries urea |