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Bubble-driven anodic gas in molten salt electrolytes

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Abstract

Herein online mass spectrometry is used to record real-time concentration curves of anodic gases released during the electrochemical oxidation of graphite anodes in molten CaCl2. The shape of these curves suggests that electrochemical oxidation is rate limited by the mass transport of oxidant ions to the anode surface. Anodic gas bubbles are formed and released from nucleation sites at this surface. Although the applied voltage is less than the decomposition voltage, an unexpectedly high release of Cl2 gas indicates continuous decomposition of molten CaCl2. The origin of experimentally observed anodic gas bubbling is explained using phase-field simulations of a rising gas bubble in molten CaCl2.

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Acknowledgements

C.O. is grateful to Metalysis Ltd. for help with mass spectrometry, staff at The University of Manchester for useful discussions, and the financial support provided by the Engineering and Physical Sciences Research Council (UK) and Metalysis Ltd.

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  1. School of Chemical Engineering and Analytical Science, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK

    C. Osarinmwian

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Osarinmwian, C. Bubble-driven anodic gas in molten salt electrolytes. Appl. Phys. A 123, 150 (2017). https://doi.org/10.1007/s00339-017-0788-6

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