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Title: Operando Synchrotron XRD Investigation of Silver Metal Formation upon Electrochemical Reduction of Silver Iron Pyrophosphate (Ag 7Fe 3(P 2O 7) 4)

The formation of conductive metallic silver upon electrochemical reduction and lithiation of Ag 7Fe 3(P 2O 7) 4 is investigated. Alternating current impedance spectroscopy measurements show a 34% decrease in charge transfer resistance upon one electron equivalent (ee) of reduction, which is coincident with the formation of a Ag metal conductive network evidenced by both ex situ and operando X-ray diffraction. Quantitative assessment of Ag metal formation derived from operando XRD shows that only Ag + ions are reduced during the first 3ee, followed by simultaneous reduction of Ag + and Fe 3+ reduction for the next 5ee (3ee to 8ee), culminating in reduction of the remaining Ag +. Scanning electron microscopy images show smaller Ag metal crystallite size and shorter nearest neighbor distance between and among Ag particles with higher depth of discharge. A high rate intermittent pulsatile discharge test is conducted where the cell delivers 12 total pulses during full discharge to probe the effect of Ag metal formation on the Li/Ag 7Fe 3(P 2O 7) 4 cell electrochemistry. The Ohmic resistance is derived from the voltage drop of each pulse. The resistance is 65 Ω initially, reaches its minimum of 26 Ω at 4.5 ee discharge, andmore » levels off at 35 Ω after 7.0 ee reduction. In conclusion, the initial Ag reduction is more significant for the conductive network formation indicated by the decrease of both R ct and Ohmic resistance, which facilitates the high power output of the cell.« less
Authors:
 [1] ;  [2] ; ORCiD logo [3] ; ORCiD logo [4] ;  [5]
  1. Stony Brook Univ., NY (United States). Dept. of Chemistry
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
  3. Stony Brook Univ., NY (United States). Dept. of Chemistry; Stony Brook Univ., NY (United States). Dept. of Materials Science and Chemical Engineering
  4. Stony Brook Univ., NY (United States). Dept. of Chemistry; Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States). Dept. of Materials Science and Chemical Engineering
  5. Stony Brook Univ., NY (United States). Dept. of Chemistry; Stony Brook Univ., NY (United States). Dept. of Materials Science and Chemical Engineering
Publication Date:
Report Number(s):
BNL-114140-2017-JA
Journal ID: ISSN 1932-7447
Grant/Contract Number:
SC0012704; SC0012673; AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 121; Journal Issue: 22; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States); Energy Frontier Research Centers (EFRC) (United States). Center for Mesoscale Transport Properties (m2M)
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:
1376168

Zhang, Yiman, Kirshenbaum, Kevin C., Marschilok, Amy C., Takeuchi, Esther S., and Takeuchi, Kenneth J.. Operando Synchrotron XRD Investigation of Silver Metal Formation upon Electrochemical Reduction of Silver Iron Pyrophosphate (Ag7Fe3(P2O7)4). United States: N. p., Web. doi:10.1021/acs.jpcc.7b03723.
Zhang, Yiman, Kirshenbaum, Kevin C., Marschilok, Amy C., Takeuchi, Esther S., & Takeuchi, Kenneth J.. Operando Synchrotron XRD Investigation of Silver Metal Formation upon Electrochemical Reduction of Silver Iron Pyrophosphate (Ag7Fe3(P2O7)4). United States. doi:10.1021/acs.jpcc.7b03723.
Zhang, Yiman, Kirshenbaum, Kevin C., Marschilok, Amy C., Takeuchi, Esther S., and Takeuchi, Kenneth J.. 2017. "Operando Synchrotron XRD Investigation of Silver Metal Formation upon Electrochemical Reduction of Silver Iron Pyrophosphate (Ag7Fe3(P2O7)4)". United States. doi:10.1021/acs.jpcc.7b03723. https://www.osti.gov/servlets/purl/1376168.
@article{osti_1376168,
title = {Operando Synchrotron XRD Investigation of Silver Metal Formation upon Electrochemical Reduction of Silver Iron Pyrophosphate (Ag7Fe3(P2O7)4)},
author = {Zhang, Yiman and Kirshenbaum, Kevin C. and Marschilok, Amy C. and Takeuchi, Esther S. and Takeuchi, Kenneth J.},
abstractNote = {The formation of conductive metallic silver upon electrochemical reduction and lithiation of Ag7Fe3(P2O7)4 is investigated. Alternating current impedance spectroscopy measurements show a 34% decrease in charge transfer resistance upon one electron equivalent (ee) of reduction, which is coincident with the formation of a Ag metal conductive network evidenced by both ex situ and operando X-ray diffraction. Quantitative assessment of Ag metal formation derived from operando XRD shows that only Ag+ ions are reduced during the first 3ee, followed by simultaneous reduction of Ag+ and Fe3+ reduction for the next 5ee (3ee to 8ee), culminating in reduction of the remaining Ag+. Scanning electron microscopy images show smaller Ag metal crystallite size and shorter nearest neighbor distance between and among Ag particles with higher depth of discharge. A high rate intermittent pulsatile discharge test is conducted where the cell delivers 12 total pulses during full discharge to probe the effect of Ag metal formation on the Li/Ag7Fe3(P2O7)4 cell electrochemistry. The Ohmic resistance is derived from the voltage drop of each pulse. The resistance is 65 Ω initially, reaches its minimum of 26 Ω at 4.5 ee discharge, and levels off at 35 Ω after 7.0 ee reduction. In conclusion, the initial Ag reduction is more significant for the conductive network formation indicated by the decrease of both Rct and Ohmic resistance, which facilitates the high power output of the cell.},
doi = {10.1021/acs.jpcc.7b03723},
journal = {Journal of Physical Chemistry. C},
number = 22,
volume = 121,
place = {United States},
year = {2017},
month = {5}
}