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Title: Mechanism of electrochemical lithiation of a metal-organic framework without redox-active nodes

Metal-organic frameworks (MOFs) have many potential uses for separations, storage, and catalysis, but their use as intercalation hosts for batteries has been scarce. In this article, we examine the mechanism of Li insertion in a MOF to provide guidance to future design efforts in this area. As a model system, we choose UiO-66, a MOF with the formula (Zr 6O 4(OH) 4) 4 (1,4-benzenedicarboxylate) 6, as an electrode material for lithium-ion batteries; this MOF is of special interest because the zirconium is not redox active. We report both quantum mechanical characterization of the mechanism and experimental studies in which the material is synthesized as nanoparticles to reduce diffusion lengths for lithium ions and increase the contact area with a conductive carbon phase. The calculated changes in the IR spectra of UiO-66 and lithiated UiO-66 are consistent with the experimental FTIR results. Here we found experimentally that this MOF can maintain a specific discharge capacity of at least 118 mAh/g for 30 lithiation and delithiation cycles at a rate of C/5, exhibiting good cyclability. Density functional electronic structure calculations show that the charge transfer during lithiation is mainly from Li to node oxygens and carboxylate oxygens, that is, it involves anionsmore » rather than cations or aromatic rings, and they provide a mechanistic understanding of the potential for increased Li capacity because the theoretical capacity of UiO-66 with Li at the oxygens in the metal oxide nodes and the carboxylate linkers is more than 400 mAh/g. The lithiation process greatly decreases the bandgap of UiO-66, which is expected to increase its electronic conductivity. Finally, the electrode material was also characterized by X-ray diffraction and scanning electron microscopy, which were consistent in confirming that smaller particle sizes were obtained in lower-temperature syntheses.« less
Authors:
 [1] ; ORCiD logo [2] ;  [3] ;  [3] ;  [3] ; ORCiD logo [2] ;  [3]
  1. Shanghai Univ. of Engineering Science, Shanghai (China). College of Chemistry and Chemical Engineering; Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemistry
  2. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemistry, and Dept. of Chemistry, Chemical Theory Center, and Supercomputing Inst.
  3. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemistry
Publication Date:
Grant/Contract Number:
SC0008662; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 144; Journal Issue: 19; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Research Org:
Univ. of Minnesota, Minneapolis, MN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE
OSTI Identifier:
1471092
Alternate Identifier(s):
OSTI ID: 1253396