Effects of Nb2O5 and Gd2O3 doping on boron volatility and activity between glass seals and lanthanum-containing cathode

Abstract In planar Solid Oxide Fuel Cells (SOFCs), the boron species volatilize from glass seals, and react with lanthanum-containing cathodes (i.e., La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 − δ , LSCF) to form LaBO 3 under cathodic polarization, which decomposes the perovskite structure and consequently decreases the electrochemical activity of cathode. In this study, Nb 2 O 5 and Gd 2 O 3 are added to an aluminoborosilicate glass to reduce the boron volatility from glass and the reaction between sealing glass and LSCF cathode. Both Nb 2 O 5 and Gd 2 O 3 doping increases the network connectivity, but Nb 2 O 5 doping enhances the [BO 3 ] → [BO 4 ] transition and reduces the boron volatility from glass seals, thus effectively suppressing the deposition and poisoning of boron contaminants on the LSCF cathode. However, an obvious degradation of the electrocatalytic activity of LSCF occurs in the presence of Gd 2 O 3 -doped glass. The relationship between glass structure and glass/cathode interaction has been established to provide useful information for designing stable sealing materials for SOFC applications.