Electrochemical characterization of the SOEC electrolyte air electrode interface fabricated by femtosecond laser micromachining

BASBUS J.F.; MARTINA AZZOLINI; FEDERICO BASSI; MASSIMO VIVIANI; SABRINA PRESTO

Congreso; CNCF2022; 2022

High-temperature solid oxide electrolysis cells (HT-SOEC) are one of the most promising technologies for the production of green hydrogen. Most of the optimization efforts are concentrated on the electrodes, where electrochemical reactions involve ionic species, electrons and gas molecules. In addition to composition, microstructure significantly contributes to the efficiency of electrodes. Porous composite structures made of homogeneous mixture of two solid phases and pores have been widely investigated and still represent state-of-art of the HT-SOEC electrodes. Computational studies found that non-homogenous spatial distribution of solids and pores may positively affect the performance, thanks to increased length of interfaces and optimized diffusion length 1,2.The novelty of the work is the deposition of a La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) porous electrode over Ce0.8Sm0.2O1.90 (SDC) dense electrolyte with a columnar shape prepared by femtosecond laser micromachining (FLM). Scanning electron microscopy (SEM) and white light interferometry (WLI) images of patterned SDC surface indicate that the columnar electrolyte are dense cylinders 20 µm wide, 40 µm high and separated from each other by (i) 40 or (ii) 80 µm (see Figure 1)The electrochemical behavior of half-cells with patterned working electrode was tested by electrochemical impedance spectroscopy (EIS) at constant temperature (600 °C) for >100 hours, in order to determine the polarization resistance (Rp). In addition, half-cell with flat working electrode was also measured as a reference. A significant decrease of Rp was observed respect to the reference, although associated to progressive degradation of performances.1. Delloro, F. & Viviani, M. Simulation study about the geometry of electrode-electrolyte contact in a SOFC. J. Electroceramics 29, 216–224 (2012).2. Cebollero, J. A. et al. Optimization of laser-patterned YSZ-LSM composite cathode-electrolyte interfaces for solid oxide fuel cells. J. Eur. Ceram. Soc. (2019). doi:10.1016/j.jeurceramsoc.2019.02.049