Controlling the growth of these discharge products, at the oxygen cathode interface, is imperative to realising the theoretical capacity of this family of energy storage devices. The enhanced discharge capacity causes decreased charging kinetics, and blocking of pores within the cathode. By employing in situ electrochemical atomic force microscopy (AFM), specific conclusions of how and where the nucleation of these products can be ascertained. Already two differing models have been presented in the literature on the formation of Li2O2 on gold and highly ordered pyrolytic graphite (HOPG) cathodes. Wen et al8 concluded that nanoparticles of Li2O2 initially form at step edge, or defect, sites on HOPG and subsequent formation of Li2O2 plates then occur. Liu et al9 have recently presented a different model whereby no nanoplate formation is seen and only toroidal features are observed later in the discharge reaction.
This talk will focus on the group’s research and findings on how Li2O2, NaO2, and KO2, at a HOPG cathode, initially form and subsequently nucleate at cathodic interfaces. Discussion will touch upon how the electrochemistry can be related to electrode substrate and electrolyte composition. This will be presented with in situ Raman spectroscopic studies that identify intermediate and surface species during the oxygen reduction reaction.
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