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Title: Probing the Release and Uptake of Water in α-MnO 2 · xH 2O

Alpha-MnO 2 is of interest as a cathode material for 3 V lithium batteries and as an electrode/electrocatalyst for higher energy, hybrid Li-ion/Li–O 2 systems. It has a structure with large tunnels that contain stabilizing cations such as Ba 2+, K + , NH 4 + , and H3O + (or water, H 2O). When stabilized by H 3O + /H 2O, the protons can be ion-exchanged with lithium to produce a Li 2O-stabilized α-MnO 2 structure. It has been speculated that the electrocatalytic process in Li–O 2 cells may be linked to the removal of lithium and oxygen from the host α-MnO 2 structure during charge, and their reintroduction during discharge. In this investigation, hydrated α-MnO 2 was used, as a first step, to study the release and uptake of oxygen in α-MnO 2. Temperature-resolved in situ synchrotron X-ray diffraction (XRD) revealed a nonlinear, two-stage, volume change profile, which with the aide of X-ray absorption near-edge spectroscopy (XANES), redox titration, and density functional theory (DFT) calculations, is interpreted as the release of water from the α-MnO 2 tunnels. The two stages correspond to H 2O release from intercalated H 2O species at lower temperatures and H 3O + speciesmore » at higher temperature. Thermogravimetric analysis confirmed the release of oxygen from α-MnO 2 in several stages during heating–including surface water, occluded water, and structural oxygen–and in situ UV resonance Raman spectroscopy corroborated the uptake and release of tunnel water by revealing small shifts in frequencies during the heating and cooling of α-MnO 2. Lastly, DFT calculations revealed the likelihood of disordered water species in binding sites in α-MnO 2 tunnels and a facile diffusion process.« less
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [3] ;  [1] ; ORCiD logo [1] ;  [1]
  1. Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States); Duke Univ., Durham, NC (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States); Northwestern Univ., Evanston, IL (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 29; Journal Issue: 4; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1389649

Yang, Zhenzhen, Ford, Denise C., Park, Joong Sun, Ren, Yang, Kim, Soojeong, Kim, Hacksung, Fister, Timothy T., Chan, Maria K. Y., and Thackeray, Michael M.. Probing the Release and Uptake of Water in α-MnO2 · xH2O. United States: N. p., Web. doi:10.1021/acs.chemmater.6b03721.
Yang, Zhenzhen, Ford, Denise C., Park, Joong Sun, Ren, Yang, Kim, Soojeong, Kim, Hacksung, Fister, Timothy T., Chan, Maria K. Y., & Thackeray, Michael M.. Probing the Release and Uptake of Water in α-MnO2 · xH2O. United States. doi:10.1021/acs.chemmater.6b03721.
Yang, Zhenzhen, Ford, Denise C., Park, Joong Sun, Ren, Yang, Kim, Soojeong, Kim, Hacksung, Fister, Timothy T., Chan, Maria K. Y., and Thackeray, Michael M.. 2016. "Probing the Release and Uptake of Water in α-MnO2 · xH2O". United States. doi:10.1021/acs.chemmater.6b03721. https://www.osti.gov/servlets/purl/1389649.
@article{osti_1389649,
title = {Probing the Release and Uptake of Water in α-MnO2 · xH2O},
author = {Yang, Zhenzhen and Ford, Denise C. and Park, Joong Sun and Ren, Yang and Kim, Soojeong and Kim, Hacksung and Fister, Timothy T. and Chan, Maria K. Y. and Thackeray, Michael M.},
abstractNote = {Alpha-MnO2 is of interest as a cathode material for 3 V lithium batteries and as an electrode/electrocatalyst for higher energy, hybrid Li-ion/Li–O2 systems. It has a structure with large tunnels that contain stabilizing cations such as Ba2+, K+ , NH4+ , and H3O+ (or water, H2O). When stabilized by H3O+ /H2O, the protons can be ion-exchanged with lithium to produce a Li2O-stabilized α-MnO2 structure. It has been speculated that the electrocatalytic process in Li–O2 cells may be linked to the removal of lithium and oxygen from the host α-MnO2 structure during charge, and their reintroduction during discharge. In this investigation, hydrated α-MnO2 was used, as a first step, to study the release and uptake of oxygen in α-MnO2. Temperature-resolved in situ synchrotron X-ray diffraction (XRD) revealed a nonlinear, two-stage, volume change profile, which with the aide of X-ray absorption near-edge spectroscopy (XANES), redox titration, and density functional theory (DFT) calculations, is interpreted as the release of water from the α-MnO2 tunnels. The two stages correspond to H2O release from intercalated H2O species at lower temperatures and H3O+ species at higher temperature. Thermogravimetric analysis confirmed the release of oxygen from α-MnO2 in several stages during heating–including surface water, occluded water, and structural oxygen–and in situ UV resonance Raman spectroscopy corroborated the uptake and release of tunnel water by revealing small shifts in frequencies during the heating and cooling of α-MnO2. Lastly, DFT calculations revealed the likelihood of disordered water species in binding sites in α-MnO2 tunnels and a facile diffusion process.},
doi = {10.1021/acs.chemmater.6b03721},
journal = {Chemistry of Materials},
number = 4,
volume = 29,
place = {United States},
year = {2016},
month = {12}
}