Dual lithium insertion and conversion mechanisms in a titanium-based mixed-anion nanocomposite |
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Authors: | Dambournet Damien Chapman Karena W Chupas Peter J Gerald Rex E Penin Nicolas Labrugere Christine Demourgues Alain Tressaud Alain Amine Khalil |
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Institution: | Chemical Sciences and Engineering Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States. damien_dambournet@yahoo.fr |
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Abstract: | The electrochemical reaction of lithium with a vacancy-containing titanium hydroxyfluoride was studied. On the basis of pair distribution function analysis, NMR, and X-ray photoelectron spectroscopy, we propose that the material undergoes partitioning upon initial discharge to form a nanostructured composite containing crystalline Li(x)TiO(2), surrounded by a Ti(0) and LiF layer. The Ti(0) is reoxidized upon reversible charging to an amorphous TiF(3) phase via a conversion reaction. The crystalline Li(x)TiO(2) is involved in an insertion reaction. The resulting composite electrode, Ti(0)-LiF/Li(x)TiO(2) ? TiF(3)/ Li(y)TiO(2), allows reaction of more than one Li per Ti, providing a route to higher capacities while improving the energy efficiency compared to pure conversion chemistries. |
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