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Title: Crystal Chemistry of Electrochemically and Chemically Lithiated Layered αI-LiVOPO4

LiVOPO4 is an attractive cathode for lithium-ion batteries with a high operating voltage and the potential to achieve the reversible insertion of two lithium ions between VOPO4 and Li2VOPO4. Among the three known forms of LiVOPO4 (α, β, and αI), the αI-LiVOPO4 has a layered structure that could promote better ionic mobility and reversibility than others. However, a comprehensive study of its lithiated product is not available as αI-LiVOPO4 is metastable and difficult to prepare by conventional approaches. We present here a facile synthesis of highly crystalline αI-LiVOPO4 and αI-LiVOPO4/rGO nanocomposite by a microwave-assisted solvothermal method and its electrochemical/chemical lithiation. The LiVOPO4/rGO cathodes exhibit a high reversible capacity of 225 mAh g–1, indicating the insertion of more than one lithium into VOPO4. Both electrochemical and chemical lithiation imply a solid-solution reaction mechanism on inserting the second lithium into αI-LiVOPO4, but a two-phase reaction feature could also occur under certain conditions such as insufficient time for equilibration of Li+ diffusion in the structure. The fully lithiated new αI-Li2VOPO4 phase was characterized by combined Rietveld refinement of neutron diffraction and X-ray diffraction data and by bond-valence sum maps. The results suggest that αI-Li2VOPO4 retains the tetragonal P4/nmm symmetry of the parent αI-LiVOPO4more » structure, where the second lithium ions are located in the lithium layers rather than in the VOPO4 layers« less
 [1] ;  [2] ;  [1]
  1. Univ. of Texas, Austin, TX (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 27; Journal Issue: 19; Journal ID: ISSN 0897-4756
American Chemical Society (ACS)
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
25 ENERGY STORAGE lithium ion; battery; cathode; Li2VOPO4; microwave synthesis