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Title: Crystal Chemistry of Electrochemically and Chemically Lithiated Layered α I-LiVOPO 4

LiVOPO 4 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 VOPO 4 and Li 2VOPO 4. Among the three known forms of LiVOPO 4 (α, β, and αI), the α I-LiVOPO 4 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-LiVOPO 4 is metastable and difficult to prepare by conventional approaches. We present here a facile synthesis of highly crystalline αI-LiVOPO 4 and α I-LiVOPO 4/rGO nanocomposite by a microwave-assisted solvothermal method and its electrochemical/chemical lithiation. The LiVOPO 4/rGO cathodes exhibit a high reversible capacity of 225 mAh g –1, indicating the insertion of more than one lithium into VOPO 4. Both electrochemical and chemical lithiation imply a solid-solution reaction mechanism on inserting the second lithium into α I-LiVOPO 4, 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 α I-Li 2VOPO 4 phase was characterized by combined Rietveld refinement of neutron diffraction and X-ray diffractionmore » data and by bond-valence sum maps. The results suggest that αI-Li 2VOPO 4 retains the tetragonal P4/nmm symmetry of the parent α I-LiVOPO 4 structure, where the second lithium ions are located in the lithium layers rather than in the VOPO 4 layers« less
Authors:
 [1] ;  [2] ;  [1]
  1. Univ. of Texas, Austin, TX (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 27; Journal Issue: 19; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; lithium ion; battery; cathode; Li2VOPO4; microwave synthesis
OSTI Identifier:
1265668