Zhongtao Ma1,Waynah Dacayan1,Christodoulos Chatzichristodoulou1,Kristian Mølhave1,Søren Simonsen1
Technical University of Denmark1
Zhongtao Ma1,Waynah Dacayan1,Christodoulos Chatzichristodoulou1,Kristian Mølhave1,Søren Simonsen1
Technical University of Denmark1
In response to climate change it is necessary to develop sustainable fuel production and storage technologies. Solid oxide electrolysis/fuel cell has recently become a research hotspot due to their high energy conversion efficiency <sup>1</sup>. However, its degradation mechanisms at high working temperatures are still unclear, advanced characterization methods are necessary to be further developed, especially<i> operando</i> techniques.<br/>Electrochemical impedance spectroscopy (EIS) is a classic technique in electrochemistry, and one of its advantages allows<i> operando </i>characterization on a running system without causing damage to the research object <sup>2</sup>.<br/>In this work we are combining an Environmental TEM <sup>3</sup>, and a heating and biasing TEM holder connected to a potentiostat for performing EIS in the TEM. This combination allows us to mimic the operation conditions of a solid oxide electrolysis/fuel cell. In addition, combining simultaneous EIS signal, one can investigate the structural/compositional evolutions and their effect on the electrochemical performance.<br/>We have investigated the feasibility of performing EIS in ETEM. An electrolyte-electrode barrier layer material, mixed ionic and electronic conductor Ce<sub>0.9</sub>Gd<sub>0.1</sub>O<sub>1.95-δ</sub> (GDC), which is widely used in the composite electrodes of the SOEC and SOFC cells <sup>4</sup>, was chosen as a test sample. Our preliminary results are consistent with the documented data in terms of ionic conductivity, electronic conductivity, activity of surface-gas exchange reactions, and chemical capacities, which verified the reliability of the EIS-TEM test.<br/>We believe the correlative EIS-TEM method will be crucial for understanding the electrochemical processes at nanoscale such as degradation in electrolysis cells, fuel cells and batteries.<br/><br/>1. Hauch, A.; Küngas, R.; Blennow, P.; Hansen, A. B.; Hansen, J. B.; Mathiesen, B. V.; Mogensen, M. B. <i>Science </i><b>2020,</b> 370, (6513), eaba6118.<br/>2. Balazs, G. B.; Glass, R. S. <i>Solid State Ionics </i><b>1995,</b> 76, (1), 155-162.<br/>3. Hansen, T. W.; Wagner, J. B.; Dunin-Borkowski, R. E. <i>Materials Science and Technology </i><b>2010,</b> 26, (11), 1338-1344.<br/>4. Chatzichristodoulou, C.; Ricote, S.; Foghmoes, S. P. V.; Glasscock, J.; Kaiser, A.; Hendriksen, P. V. <i>Solid State Ionics </i><b>2015,</b> 269, 51-56.