Preparation Of BCAS Sealing Glass And Application For Planar SOFC Single Cell Testing

Solid oxide fuel cell （SOFC） is a high efficiency, no pollution device which canconvert the chemical energy into the electrical energy directly, it contains two mainlystructure of tubular and planar. The planar solid oxide fuel cell （p-SOFC） is better thanthe tubular solid oxide fuel cell due to its simply manufacturing, low cost and highcurrent density characteristics. But there are many technical problems need to be solvedin the planar solid oxide fuel cell, the sealing technology is one of the problems.Therefore, the performance of the sealing materials is important in the sealing of thesingle cells.The BCAS sealing glass for the planar solid oxide fuel cell was prepared by thequenching process in this paper. The characteristic temperature of the BCAS glass wastold from the differential thermal analysis （DTA） and the thermal expansion. The glasstransition temperature is534℃, the softening temperature is728℃, the initialtemperature of crystallization is699℃. The coefficient of thermal expansion of BCAS ismatched with YSZ and Crofer22APU during20℃to534℃in the research. Thecoefficient of thermal expansion of initial BCAS glass is11.4×10^-6K^-1, the CTE afterheat treatment for50h is11.3×10^-6K^-1, the CTE after heat treatment for100h is11.2×10^-6K^-1at750℃. The result shows good thermal stability of the glass.The crystallization of the BCAS glass was observed after heat treatment for a longtime at750℃. The crystalline phases devitrified from the glass are BaSiO₃, BaCaSiO₄and BaAl₂Si₂O₈. The crystal structure is needle told from the SEM micrographs. Thesealing interfaces of glass with electrolyte and anode are combined closely, which haveno change after heat treatment for a long time.In this paper, the electrical performance of the large cells sealed by the BCASsealing glass was tested. The ratio of LSM and YSZ in the cathode has effects on theelectrical performance, the electrical performance of the cell is better when the ratio ofLSM and YSZ is6:4. During the test, the electrical performance of the single celldegraded when the operation time increased，degradation rate is6.1%. The electricalperformance of the cell degraded after thermal cycle, degradation rate is7.9%. The decayrate increased with the thermal cycle times. The open circuit voltage of the cell wasalways about1.2V during280h operation which indicated that the BCAS glass was goodfor sealing. Furthermore, the BCAS sealing glass is a good sealant for planarintermediate temperature solid oxide fuel cells.