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Title: Layered Lepidocrocite Type Structure Isolated by Revisiting the Sol–Gel Chemistry of Anatase TiO 2 : A New Anode Material for Batteries

Searches for new electrode materials for batteries must comply on financial and environmental costs to be useful in practical devices. The sol-gel chemistry has been widely used to design and implemented 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 DFT calculations, consists of a layered-type structure as found in the lepido-crocite. This phase presents the following general formula Ti 2-xxO 4-4x(OH) 4x.nH 2O (x ~ 0.5) where the substitution of oxide by hydroxide anions leads to the formation of titanium vacancies (•) and H 2O molecules are located in interlayers. Solid-state 1H NMR has enabled to characterize three main hydroxide environments that are Ti⟂-OH, Ti 22-OH and Ti3⟂-OH and layered H 2O molecules. The electrochemical properties of this phase were further investigated versus lithium and is shown to be very promising with reversible capacities of around 200 mAh.g -1 andmore » an operating voltage of 1.55 V. We further showed that the lithium intercalation proceeds via a solid-solution mechanism. 7Li solid-state NMR and DFT calculations allowed to identify lithium host sites that are located at the titanium vacancies and interlayer space with lithium being solvated by structural water molecules. The easy fabrication, the absence of lithium and easier recycling and the encouraging properties makes this class of materials very attractive for competitive electrodes for batteries. We thus demonstrate that the revisit of an “old” chemistry with advanced characterization tools allows discovering new materials of technological relevance.« less
Authors:
ORCiD logo [1] ;  [1] ;  [1] ;  [2] ; ORCiD logo [2] ;  [3] ;  [4] ; ORCiD logo [4] ;  [1] ; ORCiD logo [5] ; ORCiD logo [5]
  1. Sorbonne Universités, UPMC Univ Paris (France)
  2. Université Bretagne Loire, Université du Maine, UMR CNRS 6283 (France). Institut des Molécules et des Matériaux du Mans (IMMM)
  3. Univ. of Yamanashi, Kofu (Japan). Fuel Cell Nanomaterials Center
  4. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
  5. Sorbonne Universités, UPMC Univ Paris (France); Réseau sur le Stockage Electrochimique de l’Energie (RS2E), FR CNRS, Amiens (France)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 29; Journal Issue: 19; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division; Sorbonne Universites
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1411440