| Cu-based perovskite-type oxides as air electrodes for Solid Oxide Cells Keyun Li1; Anna Niemczyk2; Konrad Swierczek1; Yevgeniy Naumovich2; Jakub Kupecki2; Anna Olszewska1; Kun Zheng3; Bogdan Dabrowski4; 1AGH UNIVERSITY OF SCIENCE AND TECHNOLOGY, FACULTY OF ENERGY AND FUELS, Krakow, Poland; 2INSTITUTE OF POWER ENGINEERING - RESEARCH INSTITUTE, Warsaw, Poland; 3AGH UNIVERSITY OF SCIENCE AND TECHNOLOGY, Krakow, Poland; 4POLISH ACADEMY OF SCIENCES, INSTITUTE OF PHYSICS, Warsaw, Poland; PAPER: 189/AdvancedMaterials/Regular (Oral) SCHEDULED: 18:15/Tue. 29 Nov. 2022/Saitong ABSTRACT: Reversible solid oxide cells (rSOC), which can act as an electricity and heat generator converting the chemical energy of fuel, as well as an electrolyzer generating hydrogen in the reversed mode operation (exploiting surplus electrical energy), are considered as unique energy conversion devices [1, 2]. Their application seems to be especially suitable in the dispersed power systems, possibly enabling to address unresolved problems of power grid balancing. For their effective work, electrochemical reactions taking place at the electrodes must be sufficiently fast and reversible, which requires for the electrode materials to possess a number of specific properties, including high electrocatalytic activity and suitable thermomechanical properties. Nowadays, Co-based perovskite-type oxides are most widely-used compounds for the air electrodes, however, political and environmental factors indicate a need to replace Co with other 3d transition metal elements. In various proposed materials Co was successfully replaced by e.g. Fe or Mn [3, 4], there are not so many papers available on the possible introduction of Cu. However, several already published works show that Cu-based perovskite-type oxides can work effectively when used in the SOCs [5]. In this work, different issues related to the development of Cu-containing air electrode compounds are discussed, focused on the proposed RE<sub>1-x</sub>A<sub>x</sub>Cu<sub>x</sub>O<sub>3-δ</sub> (RE: selected rare-earth elements, A: selected alkaline-earth metals) perovskite-type oxides. The considered materials were explored concerning their crystal lattice, thermal expansion behavior, oxygen content, as well as mixed ionic-electronic transport properties. For the exemplary La<sub>1.5</sub>Ba<sub>1.5</sub>Cu<sub>3</sub>O<sub>7±δ</sub>, two synthesis routes, sol-gel and solid-state, allowed to successfully obtain pure material. The synthesized perovskite exhibits favorable physicochemical characteristics, including layered crystal structure, and mixed Cu<sup>2+</sup>/Cu<sup>3+</sup> states, which can be linked with the enhanced activity of the oxygen reduction/oxygen evolution reactions. The stabilized layered crystal structure with P4/mmm symmetry is beneficial to the enhanced electrical conductivity, at the same time allowing to keep moderate thermal expansion coefficient (ca. 15.5·10<sup>-6</sup> K<sup>-1</sup> at 50-900 °C). Additionally, laboratory-scale button-type cells (in the electrolyte-supported and the anode-supported configurations) could be manufactured and tested in terms of their electrochemical performance, confirming applicability of the developed material. References: [1] A. Arsalis, Renew Sustain Energy Rev. 105 (2019) 391-414 [2] U.M. Damo et al., Energy 168 (2019) 235-246 [3] F. Tietz et al., J. Power Sources 156, 20–22 (2006). [4] A. Olszewska et al., J. Mater. Chem. A 6(27) (2018) 13271-13285 [5] A. Niemczyk et al., J. Mater. Chem. A 7(48) (2019) 27403-27416 |
