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Title: Redox chemistry of a binary transition metal oxide (AB 2 O 4 ): a study of the Cu 2+ /Cu 0 and Fe 3+ /Fe 0 interconversions observed upon lithiation in a CuFe 2 O 4 battery using X-ray absorption spectroscopy

Copper ferrite, CuFe 2 O 4, is a promising candidate for application as a high energy electrode material in lithium based batteries. Mechanistic insight on the electrochemical reduction and oxidation processes was gained through the first X-ray absorption spectroscopic study of lithiation and delithiation of CuFe 2 O 4. A phase pure tetragonal CuFe 2 O 4 material was prepared and characterized using laboratory and synchrotron X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. We used ex situ X-ray absorption spectroscopy (XAS) measurements to study the battery redox processes at the Fe and Cu K-edges, using X-ray absorption near-edge structure (XANES), extended X-ray absorption fine structure (EXAFS), and transmission X-ray microscopy (TXM) spectroscopies. EXAFS analysis showed upon discharge, an initial conversion of 50% of the copper(II) to copper metal positioned outside of the spinel structure, followed by a migration of tetrahedral iron(III) cations to octahedral positions previously occupied by copper(II). Then, upon charging to 3.5 V, the copper metal remained in the metallic state, while iron metal oxidation to iron(III) was achieved. Our results provide new mechanistic insight regarding the evolution of the local coordination environments at the iron and copper centers upon discharging and charging.
Authors:
 [1] ;  [2] ;  [3] ;  [3] ;  [2] ;  [2] ;  [2] ;  [4] ;  [5] ;  [5]
  1. Stony Brook Univ., NY (United States). Dept. of Chemistry
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). Energ Sciences Directorate
  3. Stony Brook Univ., NY (United States). Dept. of Materials Science and Engineering
  4. Stony Brook Univ., NY (United States). Dept. of Chemistry and Dept. of Materials Science and Engineering; Brookhaven National Lab. (BNL), Upton, NY (United States). Energ Sciences Directorate
  5. Stony Brook Univ., NY (United States). Dept. of Chemistry and Dept. of Materials Science and Engineering
Publication Date:
Report Number(s):
BNL-112584-2016-JA
Journal ID: ISSN 1463-9076; PPCPFQ
Grant/Contract Number:
SC00112704; AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Physical Chemistry Chemical Physics. PCCP (Print)
Additional Journal Information:
Journal Name: Physical Chemistry Chemical Physics. PCCP (Print); Journal Volume: 18; Journal Issue: 25; Journal ID: ISSN 1463-9076
Publisher:
Royal Society of Chemistry
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (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; electrode; lithium; batteries; electrochemical; spectroscopic; microscopy
OSTI Identifier:
1336123