Performance and Aging of Microtubular YSZ‐based Solid Oxide Regenerative Fuel Cells

Abstract

Fuel electrode supported microtubular solid oxide fuel cells (SOFC) fabricated at ICMA have been characterized in both solid oxide steam electrolyser (SOEC) and fuel cell modes. The cells consists of a fuel electrode supporting tube of Ni/YSZ with 40% porosity, 400 µm thickness, 2.4 mm diameter and 100-150 mm length, a 15 m thick YSZ electrolyte and a 50vol% LSM/YSZ composite air electrode of 20 m thickness and LSM/YSZ (80/20 vol%) up to 2 cm 2 area as current collector in the air side. Platinum paste and wires were used as interconnectors in the air chamber and Ni felt in the fuel side.SOFC and SOEC experiments were performed at temperatures between 750 and 950 ºC using synthetic air in the oxygen electrode and different partial pressures of steam in the fuel side. Analysis of the polarization contributions to the j-V curve in FC operation mode was performed using theoretical models, as discussed in the text. The effect of the steam concentration and temperature on the electrolysis and fuel cell experiments is presented and discussed. The cells are reversible in both modes of operation at low fuel conversion rates. According with previous observations, when cells are operated at high steam conversion rates the cell voltage tends to saturate. Irreversible damage was observed by SEM at the YSZoxygen electrode interface after operation, probably due to the electrolyte reduction produced at high voltages.

Tailoring the Microstructure of a Solid Oxide Fuel Cell Anode Support by Calcination and Milling of YSZ

“…For example, at 1.5 V and 800 °C, the measured current density for the CY cell was increased by a factor of two in comparison with the TY cell (−1380 mA cm −2 and −690 mA cm −2 , respectively). The performance of the TY cell is similar to other micro-tubular SOEC cells reported in the literature25. From our knowledge, the SOEC performance of the CY cell is the highest reported for micro-tubular electrolysis cells26.…”

Highly stable microtubular cells for portable solid oxide fuel cell applications

“…It is very remarkable that almost zero degradation was obtained after the initial stabilization of the cell. This result is consistent with other durability studies found in the literature for microtubular cells [6,25]. Those results confirm that durability of microtubular cells is lower than for planar cells, where typical degradation rates of above 1% per 1000 h -1 are usually found [36].…”

“…Subsequently YSZ was deposited as the electrolyte and co- For the electrochemical studies, microtubular cells were sealed into alumina tubes using ceramic sealing and then introduced in a three-zone tubular furnace with a homogeneous hot zone of 5 cm in length. Additional information about the placement of the electrical contacts and the experimental set up can be found in references [ 25 ] and [ 26 ]. Electrochemical impedance spectroscopy (EIS), potentiodynamic and chronoamperostatic studies were performed using a VSP Potentiostat/Galvanostat (Princeton Applied Research, Oak Ridge, US).…”

Pinning-down polarization losses and electrode kinetics in cermet-supported LSM solid oxide cells in reversible operation

“…The j-V behavior is characteristic of Ni-YSZ/YSZ/LSM-YSZ solid oxide electrolyzer cells [26][27][28][29]. In the previous work [4], the apparent linear j-V behavior at low electrolysis currents was found to be the compensation of increasing gas concentration polarization, i.e.…”