Abstract:

The practical performance of Li-O2 batteries suffers from interfacial instabilities associated with the reaction intermediates. These instabilities on the cathode-electrolyte interface dictate the direction of the oxygen evolution and reduction reactions (OER/ORR) in Li-O2 batteries. Despite intensive research on chemical instabilities in the reaction intermediates, there is limited work on understanding the importance of stress on the interfacial dynamics. To address this gap, in-situ curvature measurements were conducted to probe interfacial stress generation during electrochemical polarization on Au cathode in DMSO electrolytes. Charge accumulation induces tensile stress, whereas compressive stress generation is associated with the adsorbate-induced stress and mismatch strain between reaction intermediates and the Au surface. Abrupt stress relaxation on the onset of discharge presents evidence for a contribution of electrostriction stress. Adsorption of redox mediator nitrate ions induces compressive stress before ORR. Unique findings demonstrate the impact of interfacial stress on the OER/ORR in Li-O2 batteries.