Title: Lithium Intercalation in Anatase Titanium Vacancies and the Role of Local Anionic Environment

Abstract

The structure of bulk and nondefective compounds is generally described with crystal models built from well mastered techniques such the analysis of an X-ray diffractogram. The presence of defects, such as cationic vacancies, locally disrupt the long-range order, with the appearance of local structures with order extending only a few nanometers. To probe and describe the electrochemical properties of cation-deficient anatase, we investigated a series of materials having different concentrations of vacancies, i.e., Ti_1–x–y$$\square$$_x+yO_2–4(x+y)F_4x(OH)_4y, and compared their properties with respect to defect-free stoichiometric anatase TiO2. At first, we characterized the series of materials Ti_1–x–y$$\square$$_x+yO_2–4(x+y)F_4x(OH)_4y by means of pair distribution function (PDF), ¹⁹F nuclear magnetic resonance (NMR), Raman and X-ray photoelectron spectroscopies, to probe the compositional and structural features. Second, we characterized the insertion electrochemical properties vs metallic lithium where we emphasized the beneficial role of the vacancies on the cyclability of the electrode under high C-rate, with performances scaling with the concentration of vacancies. The improved properties were explained by the change of the lithium insertion mechanism due to the presence of the vacancies, which act as host sites and suppress the phase transition typically observed in pure TiO₂, and further favor diffusive transport of lithium within the structure. NMR spectroscopy performed on lithiated samples provides evidence for the insertion of lithium in vacancies. By combining electrochemistry and DFT-calculations, we characterized the electrochemical signatures of the lithium insertion in the vacancies. Importantly, we found that the insertion voltage largely depends on the local anionic environment of the vacancy with a fluoride and hydroxide-rich environments, yielding high and low insertion voltages, respectively. Lastly, this work further supports the beneficial use of defects engineering in electrodes for batteries and provides new fundamental knowledge in the insertion chemistry of cationic vacancies as host sites.

Authors:

Ma, Jiwei  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-4209-7667"

Li, Wei ^[2]; Morgan, Benjamin J. ^[3]; Światowska, Jolanta ^[4]; Baddour-Hadjean, Rita ^[5]; Body, Monique ^[6]; Legein, Christophe  ^[6];

• Search DOE PAGES for author "Legein, Christophe"
• Search DOE PAGES for ORCID "0000-0001-7426-8817"

Borkiewicz, Olaf J. ^[7]; Leclerc, Sandrine ^[2]; Groult, Henri ^[2]; Lantelme, Frédéric ^[2]; Laberty-Robert, Christel  ^[8];

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• Search DOE PAGES for ORCID "0000-0003-3230-3164"

Dambournet, Damien  ^[9]

• Search DOE PAGES for author "Dambournet, Damien"
• Search DOE PAGES for ORCID "0000-0003-3831-2643"

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+ Show Author Affiliations

1. Sorbonne Univ., Paris (France). Physico-chimie des électrolytes et nano-systèmes interfaciaux, PHENIX; Tongji Univ., Shanghai (China). Inst. of New Energy for Vehicles, School of Materials Science and Engineering
2. Sorbonne Univ., Paris (France). Physico-chimie des électrolytes et nano-systèmes interfaciaux, PHENIX
3. Univ. of Bath, Bath (United Kingdom). Dept. of Chemistry
4. PSL Research Univ., Paris (France). Inst. de Recherche de Chimie Paris (IRCP)
5. CNRS-Univ. Paris Est, Thiais (France). Inst. de Chimie et des Matériaux Paris-Est
6. Le Mans Univ.-CNRS, Le Mans (France). Inst. des Molécules et Matériaux du Mans
7. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS), X-ray Science Division
8. Sorbonne Univ., Paris (France). Collège de France, Lab. de Chimie de la Matière Condensée de Paris; Réseau sur le Stockage Electrochimique de l’Energie (RS2E), Amiens (France)
9. Sorbonne Univ., Paris (France). Physico-chimie des électrolytes et nano-systèmes interfaciaux, PHENIX; Réseau sur le Stockage Electrochimique de l’Energie (RS2E), Amiens (France)

Publication Date:

Sat Apr 07 00:00:00 EDT 2018

Research Org.:

Argonne National Laboratory (ANL), Argonne, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1484020

Grant/Contract Number:  

AC02-06CH11357

Resource Type:

Accepted Manuscript

Journal Name:

Chemistry of Materials

Additional Journal Information:

Journal Volume: 30; Journal Issue: 9; Journal ID: ISSN 0897-4756

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE