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Title: Poly(vinylidene fluoride) (PVDF) Binder Degradation in Li–O 2 Batteries: A Consideration for the Characterization of Lithium Superoxide

We show that a common Li–O 2 battery cathode binder, poly(vinylidene fluoride) (PVDF), degrades in the presence of reduced oxygen species during Li–O 2 discharge when adventitious impurities are present. This degradation process forms products that exhibit Raman shifts (~1133 and 1525 cm –1) nearly identical to those reported to belong to lithium superoxide (LiO 2), complicating the identification of LiO 2 in Li–O 2 batteries. We show that these peaks are not observed when characterizing extracted discharged cathodes that employ poly(tetrafluoroethylene) (PTFE) as a binder, even when used to bind iridium-decorated reduced graphene oxide (Ir-rGO)-based cathodes similar to those that reportedly stabilize bulk LiO 2 formation. We confirm that for all extracted discharged cathodes on which the 1133 and 1525 cm –1 Raman shifts are observed, only a 2.0 e /O 2 process is identified during the discharge, and lithium peroxide (Li 2O 2) is predominantly formed (along with typical parasitic side product formation). In conclusion, our results strongly suggest that bulk, stable LiO 2 formation via the 1 e /O 2 process is not an active discharge reaction in Li–O 2 batteries.
ORCiD logo [1] ;  [2] ; ORCiD logo [1] ;  [1] ;  [3] ;  [4] ;  [2] ; ORCiD logo [1]
  1. Univ. of California, Berkeley, CA (United States). Dept. of Chemical and Biomolecular Engineering; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Energy Storage and Distributed Resources Division
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Foundry
  3. Stanford Univ., Stanford, CA (United States). SUNCAT Center for Interface Science and Catalysis and Dept. of Chemical Engineering; SLAC National Accelerator Lab., Menlo Park, CA (United States)
  4. IBM Almaden Research Center, San Jose, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-76SF00515; AC02-05CH11231; DGE-1106400; NNX16AM56H; CBET-1604927
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry Letters
Additional Journal Information:
Journal Volume: 8; Journal Issue: 6; Journal ID: ISSN 1948-7185
American Chemical Society
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF); National Aeronautic and Space Administration (NASA)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1458486