Li-O2 batteries are promising candidates for high energy demanding applications because their theoretical energy density is almost ten times higher than the Li-ion batteries. However, they suffer from severe interfacial instabilities associated with sluggish kinetics of the redox reactions and the insulating nature of the reduced oxygen species on the cathode surface. There are extensive studies about the impact of electrolyte chemistry such as ionic association strength of anions and solvent donor number of solvents on the electrochemical performance of Li-O2. However, governing mechanisms behind the impact of electrolyte chemistry on the electrochemical oxygen evolution / reduction reactions (OER/ORR) are not well known. In situ characterization of electrocatalytic reactions is must to elucidate the governing mechanism for OER/ORR at Li-O2 batteries. Here, I will present the role of electrolyte chemistry on the surface dynamics on Au electrocatalyst during electrochemical oxygen evolution and reduction reactions for Li-O2 Batteries. In this study, in situ stress measurements were utilized to investigate the impact of the electrolyte salt on nanoscale dynamic changes on the surface of the thin Au film cathode during charge / discharge of Li-O2 batteries. In situ stress measurements were conducted using a custom cell battery and multiple beam optical sensor (MOS)1. Stress measurements pointed out the contribution of charge-induced stress, adsorbate-induced surface stress, electrostriction stress, and intrinsic stress associated with the formation of discharge reaction products. In situ probing of these stress contributions allows to reveal the growth mechanism for discharge reaction products and the role of electrolyte chemistry on the oxidation of lithium peroxiode in Li-O2 batteries.

Elucidating the surface dynamics on Au Electrocatalyst during electrochemical oxygen evolution and reduction reactions at Li-O2 batteries via In Situ stress measurements

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ACS Fall 2022

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