Assessing Electro-chemo-mechanics of Layered Cuprate-based Thin Films by Controlling Oxygen Defect Type and Concentration through Electrochemical Pumping

Three major criteria are required for a good solid oxide fuel cell (SOFC) electrode: 1) High electronic and ionic conductivities, 2) High electrocatalytic activity towards oxygen surface exchange reaction, and 3) Good chemical... [ view full abstract ]

Three major criteria are required for a good solid oxide fuel cell (SOFC) electrode: 1) High electronic and ionic conductivities, 2) High electrocatalytic activity towards oxygen surface exchange reaction, and 3) Good chemical and chemo-mechanical stability. Conventional method of assessing these electro-chemo-mechanical properties requires doping different concentrations of aliovalent cations and/or controlling atmosphere. These, however, are constrained by solubility limits of dopants, the range of oxygen partial pressures readily experimentally achievable, and require knowledge of the applicable defect chemical model. In this study, we control oxygen defect types and concentrations in promising rare earth cuprate (RE₂CuO₄: RE = rare earth) SOFC cathode materials by electrochemical pumping of oxygen through an yttria-stabilized zirconia supporting electrolyte. These layered perovskites can incorporate both oxygen interstitials and vacancies, thereby broadening the range of investigations. Oxygen nonstoichiometry values are determined by in-situ measurement of chemical capacitance and are correlated with surface kinetics, in-plane conductivities, and chemo-mechanical properties.