1789
Role of Superoxide Anion in the Oxygen Reduction Reaction in Non-Aqueous Electrolytes with a Proton or Lithium Source

Thursday, 2 June 2016: 16:00
Sapphire Ballroom M (Hilton San Diego Bayfront)
Y. Zhang, X. Zhang, J. Wang (Changchun Institute of Applied Chemistry), Y. Chen (University of Oxford, Department of Materials), W. C. McKee (Louisiana State University), P. G. Bruce (University of Oxford), Y. Xu (Louisiana State University), and Z. Peng (Changchun Institute of Applied Chemistry)
The non-aqueous Li-air (O2) battery has generated a great deal of research interest because it potentially possesses far greater gravimetric energy storage density than today’s rechargeable battery technologies.1-4  Presently non-aqueous Li-O2 batteries suffer from irreversible reactions, including those due to impurities such as residual protons and proton-containing compounds that can react with reduced oxygen species.  To eliminate or alleviate the undesired reactions, it is crucial to have a fundamental understanding of the reactive oxygen species involved in the oxygen reduction reaction (ORR). 

In this talk we will present the results of a series of electrochemical studies of the ORR on a gold electrode in non-aqueous dimethyl sulfoxide (DMSO) electrolytes containing a proton or lithium source with TBAClO4 as supporting ions.  The superoxide anion (O2-), the one-electron reduction product of O2, is identified in situ spectroscopically in both systems.  When the DMSO contains phenol as the proton source, O2-, not HO2, appears as the first stable intermediate during the ORR upon cathodic scans, with H2O2 co-appearing at high overpotentials.5  When instead LiClO4 is added to DMSO, again O2- is the first reaction intermediate to be detected, whereas surface LiO2 does not appear until the potential is much more negative of the Li2O2 formation potential.  The stability of O2- vs. the other reduced O2 species is rationalized based on first-principles theoretical modelling and calculations.  Our studies show that the ORR mechanism depends intimately on the electrode potential and electrolyte composition, and contribute new mechanistic understanding for this reaction that is of fundamental importance to electrochemical energy storage and conversion technologies.

1. P.G. Bruce, S.A. Freunberger, L.J. Hardwick, J.-M. Tarascon, Nat. Mater. 2012, 11, 19.

2. J. Lu, L. Li, J.-B. Park, Y.-K. Sun, F. Wu, K. Amine, Chem. Rev. 2014, 114, 5611.

3. A.C. Luntz, B.D. McCloskey, Chem. Rev. 2014, 114, 11721.

4. R. Black, B. Adams, L.F. Nazar, Adv. Energy Mater. 2012, 2, 801

5. Z. Peng, Y. Chen, P.G. Bruce, Y. Xu, Angew. Chem. Int. Ed. 2015, 54, 8165.

See more of: General Electrocatalysis III
See more of: L02: Electrocatalysis 8
See more of: Physical and Analytical Electrochemistry, Electrocatalysis, and Photoelectrochemistry
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