High capacity surface route discharge at the potassium-O2 electrodeTools Chen, Yuhui and Jovanov, Zarko P. and Gao, Xiangwen and Liu, Jingyuan and Holc, Conrad and Johnson, Lee R. and Bruce, Peter G. (2018) High capacity surface route discharge at the potassium-O2 electrode. Journal of Electroanalytical Chemistry, 819 . pp. 542-546. ISSN 1873-2569
AbstractDischarge by a surface route at the cathode of an aprotic metal-O2 battery typically results in surface passivation by the non-conducting oxide product. This leads to low capacity and early cell death. Here we investigate the cathode discharge reaction in the potassium-O2 battery and demonstrate that discharge by a surface route is not limited to growth of thin (<10 nm) metal oxide layers. Electrochemical analysis and in situ Raman confirmed that the product of the cathode reaction is a combination of KO2 and K2O2, depending on the applied potential. Use of the low donor number solvent, acetonitrile, allows us to directly probe the surface route. Rotating ring-disk electrode, electrochemical quartz crystal microbalance and scanning electron microscope characterisations clearly demonstrate the formation of a thick > 1 μm product layer, far in excess of that possible in the related lithium-O2 battery. These results demonstrate a high-capacity surface route in a metal-O2 battery for the first time and the insights revealed here have significant implications for the design of the K-O2 battery.
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