The effect of glass sealing stabilization on LSM-YSZ cathode poisoning and oxygen reduction reaction processes in solid oxide fuel cell

The perovskite structure and electrochemical activity of (La0.80Sr0.20)0.95MnO3-x-(Y2O3)0.08(ZrO2)0.92 (LSM-YSZ) composite cathode can be significantly affected by volatile boron species originated from sealing glass-ceramics. Herein, we investigate the impact of doping the varying Er2O3 content (ranging from 0 to 4%) into an aluminoborosilicate glass to mitigate boron volatilization, its interaction with the LSM-YSZ cathode and consequent effects on its electrochemical performance. The results reveal that the volatility of boron species can be significantly suppressed by introducing Er oxide into the glass network by enhancing the conversion of [BO3] to [BO4] units, thereby increasing the binding energy of boron and strengthening of the glass structure. Moreover, the electrocatalytic performance for the O2 reduction reaction on the LSM-YSZ/8YSZ/LSM-YSZ symmetric cells is studied under open-circuit conditions in the presence and absence of glass sealants. The analyses utilizing electrochemical impedance spectroscopy (EIS) and distribution of the relaxation times (DRT) analysis indicate that the electrocatalytic performance of LSM-YSZ cathodes can be enhanced in the presence of glass with 4% Er2O3 (GE4). This enhancement in the electrocatalytic activity of the LSM-YSZ electrode for the oxygen reduction reaction (ORR) is attributed to formation of the thin layer on the electrode surface, leading to a notable reduction in the polarization resistance (Rp) from 0.81 ohm cm2 in the glass absence to 0.45 ohm cm2 in the presence of GE4. However, DRT analysis demonstrates that the prolonged exposure of the cathode to GE4 causes a deterioration in cell performance primarily due to the blocking the cathode active sites, which impedes dominant cathode processes of oxygen dissociative adsorption/desorption and charge transfer and consequently reducing kinetics of the ORR. This study investigates the impact of doping varying amounts of Er2O3 (0-4%) in aluminoborosilicate glass sealant on reducing boron species volatility and their consequent interaction on LSM-YSZ composite cathode in solid oxide fuel cells (SOFCs). The results demonstrate that incorporating Er2O3 significantly reduces boron volatility, strengthens the glass structure network, and enhances the electrocatalytic activity of the LSM-YSZ electrode for the oxygen reduction reaction. image