Time-resolved SERS study of the oxygen reduction reaction in ionic liquid electrolytes for non-aqueous lithium-oxygen cells

Radjenovic, Petar M and Hardwick, Laurence J ORCID: 0000-0001-8796-685X (2018) Time-resolved SERS study of the oxygen reduction reaction in ionic liquid electrolytes for non-aqueous lithium-oxygen cells FARADAY DISCUSSIONS, 206. pp. 379-392. ISSN 1359-6640, 1364-5498

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Abstract

Superoxide (O<inf>2</inf>^-) is the key intermediate formed during oxygen reduction in non-aqueous electrolytes. One significant obstacle towards the realisation of a practical lithium-oxygen (Li-O<inf>2</inf>) battery is electrolyte instability in the presence of radical oxides, principally superoxide. Here we use the Raman active bands of O<inf>2</inf>^- as a diagnostic molecule for probing the influence of the electrolyte on reaction processes and intermediaries at the electrode surface. In situ surface enhanced Raman studies of the interface at a roughened Au electrode with controlled and dynamic surface potentials were performed in two ionic liquids with differing properties: 1-butyl-1-methyl-azepenium bis(trifluoromethanesulfonyl)imide (Aze<inf>14</inf>TFSI), which has a large/soft cation, and triethylsulfonium bis(trifluoromethanesulfonyl)imide (TESTFSI), which has a relatively small/hard and e^- accepting cation. The counter-cation and potential were seen to significantly influence the radical nature, or Lewis basicity of O<inf>2</inf>^-. The analysis of peak intensities and Stark shifts in O<inf>2</inf>^- related spectral bands allowed for key information on its character and electrolyte interactions to be elucidated. Time-resolved studies of dynamic surface potentials permitted real time observation of the flux and reorientation of ions at the electrode/electrolyte interface.

Item Type:	Article
Uncontrolled Keywords:	34 Chemical Sciences, 3406 Physical Chemistry
Depositing User:	Symplectic Admin
Date Deposited:	06 Jun 2017 15:29
Last Modified:	16 Jun 2026 05:18
DOI:	10.1039/c7fd00170c
Related Websites:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3007837
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