Samojlov, Aleksej; Schuster, David; Kahr, Jürgen; Freunberger, Stefan AlexanderIST Austria
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.
S.A.F. thanks the International Society of Electrochemistry for awarding the Tajima Prize 2019 “in recognition of outstanding re- searches on Li-Air batteries by the use of a range of in-situ elec- trochemical methods to achieve comprehensive understanding of the reactions taking place at the oxygen electrode”. This article is dedicated to the special issue of Electrochmica Acta associated with the awarding conference. S.A.F. is indebted to and the Austrian Federal Ministry of Science, Research and Economy and the Austrian Research Promotion Agency (grant No. 845364 ) and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 636069). The authors thank J. Schlegl for manufacturing instrumentation, M. Winkler of Acib GmbH and G. Strohmeier for help with HPLC measurements, S. Eder for cyclic voltammetry measurements, and C. Slugovc for discussions and continuous support. We thank S. Borisov for access and advice with fluorescence measurements. We thank EL-Cell GmbH, Hamburg, Germany for providing the PAT-Cell-Press electrochemical cell.
Samojlov A, Schuster D, Kahr J, Freunberger SA. Surface and catalyst driven singlet oxygen formation in Li-O2 cells. Electrochimica Acta. 2020;362(12). doi:10.1016/j.electacta.2020.137175
Samojlov, A., Schuster, D., Kahr, J., & Freunberger, S. A. (2020). Surface and catalyst driven singlet oxygen formation in Li-O2 cells. Electrochimica Acta. Elsevier. https://doi.org/10.1016/j.electacta.2020.137175
Samojlov, Aleksej, David Schuster, Jürgen Kahr, and Stefan Alexander Freunberger. “Surface and Catalyst Driven Singlet Oxygen Formation in Li-O2 Cells.” Electrochimica Acta. Elsevier, 2020. https://doi.org/10.1016/j.electacta.2020.137175.
A. Samojlov, D. Schuster, J. Kahr, and S. A. Freunberger, “Surface and catalyst driven singlet oxygen formation in Li-O2 cells,” Electrochimica Acta, vol. 362, no. 12. Elsevier, 2020.
Samojlov A, Schuster D, Kahr J, Freunberger SA. 2020. Surface and catalyst driven singlet oxygen formation in Li-O2 cells. Electrochimica Acta. 362(12), 137175.
Samojlov, Aleksej, et al. “Surface and Catalyst Driven Singlet Oxygen Formation in Li-O2 Cells.” Electrochimica Acta, vol. 362, no. 12, 137175, Elsevier, 2020, doi:10.1016/j.electacta.2020.137175.
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