Layered Lepidocrocite Type Structure Isolated by Revisiting the Sol–Gel Chemistry of Anatase TiO2: A New Anode Material for Batteries

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Searches for new electrode materials for batteries must take into account financial and environmental costs to be useful in practical devices. The sol–gel chemistry has been widely used to design and implement new concepts for the emergence of advanced materials such as hydride organic–inorganic composites. Here, we show that the simple reaction system including titanium alkoxide and water can be used to stabilize a new class of electrode materials. By investigating the crystallization path of anatase TiO2, an X-ray amorphous intermediate phase has been identified whose local structure probed by the pair distribution function, 1H solid-state NMR and density functional theory (DFT) calculations, consists of a layered type structure as found in the lepidocrocite. This phase presents the following general formula Ti2–x□xO4–4x(OH)4x·nH2O (x ∼ 0.5) where the substitution of oxide by hydroxide anions leads to the formation of titanium vacancies (□) and H2O molecules are located in interlayers. Solid-state 1H NM...