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Title: In-situ X-ray absorption spectroscopy analysis of capacity fade in nanoscale-LiCoO{sub 2}

The local structure of nanoscale (∼10–40 nm) LiCoO{sub 2} is monitored during electrochemical cycling utilizing in-situ X-ray absorption spectroscopy (XAS). The high surface area of the LiCoO{sub 2} nanoparticles not only enhances capacity fade, but also provides a large signal from the particle surface relative to the bulk. Changes in the nanoscale LiCoO{sub 2} metal-oxide bond lengths, structural disorder, and chemical state are tracked during cycling by adapting the delta mu (Δμ) technique in complement with comprehensive extended X-ray absorption fine structure (EXAFS) modeling. For the first time, we use a Δμ EXAFS method, and by comparison of the difference EXAFS spectra, extrapolate significant coordination changes and reduction of cobalt species with cycling. This combined approach suggests Li–Co site exchange at the surface of the nanoscale LiCoO{sub 2} as a likely factor in the capacity fade and irreversible losses in practical, microscale LiCoO{sub 2}. - Graphical abstract: Electrochemical cycling of Li-ion batteries has strong impact on the structure and integrity of the cathode active material particularly near the surface/electrolyte interface. In developing a new method, we have used in-situ X-ray absorption spectroscopy during electrochemical cycling of nanoscale LiCoO{sub 2} to track changes during charge and discharge and between subsequent cycles.more » Using difference spectra, several small changes in Co-O bond length, Co-O and Co-Co coordination, and site exchange between Co and Li sites can be tracked. These methods show promise as a new technique to better understand processes which lead to capacity fade and loss in Li-ion batteries. - Highlights: • A new method is developed to understand capacity fade in Li-ion battery cathodes. • Structural changes are tracked during Li intercalation/deintercalation of LiCoO{sub 2}. • Surface structural changes are emphasized using nanoscale-LiCoO{sub 2} and difference spectra. • Full multiple scattering calculations are used to support Δμ analysis.« less
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [4]
  1. NRC/NRL Cooperative Research Associate, U.S. Naval Research Laboratory, Washington, DC 20375 (United States)
  2. Chemistry Division, Code 6113, U.S. Naval Research Laboratory, Washington, DC 20375 (United States)
  3. Electronics Science and Technology Division, Code 6812, U.S. Naval Research Laboratory, Washington, DC 20375 (United States)
  4. Chemistry Division, Code 6189, U.S. Naval Research laboratory, Washington, DC 20375 (United States)
Publication Date:
OSTI Identifier:
22309028
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 203; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 77 NANOSCIENCE AND NANOTECHNOLOGY; ABSORPTION; ABSORPTION SPECTROSCOPY; CATHODES; CHEMICAL STATE; CLATHRATES; COBALT; ELECTROLYTES; FINE STRUCTURE; LEAD; LITHIUM IONS; NANOPARTICLES; NANOSTRUCTURES; SIMULATION; SPECTRA; SURFACE AREA; SURFACES; X RADIATION; X-RAY SPECTROSCOPY