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Surface and Catalyst Driven Singlet Oxygen Formation in Li-O2 Cells

preprint
submitted on 17.04.2020 and posted on 20.04.2020 by Aleksej Samojlov, David Schuster, Jürgen Kahr, Stefan Freunberger
Large overpotentials upon discharge and charge of Li-O2 cells have motivated extensive research into heterogeneous solid electrocatalysts or non-carbon electrodes with the aim to improve rate capability, round-trip efficiency and cycle life. These features are equally governed by parasitic reactions, which are now recognized to be caused by the highly reactive singlet oxygen (1O2). However, the link between the presence of electrocatalysts and 1O2 formation in metal-O2 cells is unknown. Here, we show that, compared to pristine carbon black electrodes, a representative selection of electrocatalysts or non-carbon electrodes (noble metal, transition metal compounds) may both slightly reduce or severely increase the 1O2 formation. The individual reaction steps, where the surfaces impact the 1O2 yield are deciphered, showing that 1O2 yield from superoxide disproportionation as well as the decomposition of trace H2O2 are sensitive to catalysts. Transition metal compounds in general are prone to increase 1O2.

Funding

Austrian Research Promotion Agency (grant No. 845364)

European Research Council (grant agreement No 636069)

History

Email Address of Submitting Author

stefan.freunberger@ist.ac.at

Institution

IST Austria (Institute of Science and Technology Austria)

Country

Austria

ORCID For Submitting Author

0000-0003-2902-5319

Declaration of Conflict of Interest

The authors declare no competing financial interests

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