Improvement in Mechanical Strength of LaGaO₃-based Solid Electrolyte by Dispersion of Metal Oxide

Abstract

We have been developing a planar type Solid Oxide Fuel Cell (SOFC) using LaGaO₃-based oxide as an electrolyte in order to lower the operating temperature. A large power density higher than 350 mW/cm² at 650°C was achieved by adoption of 230μm thickness La_0.8Sr_0.2Ga_0.8Mg_0.15Co_0.05O_3-σ (LSGMC) for the electrolyte so far. In this study, Effects of oxide doping into LaGaO₃-based solid electrolyte on the mechanical property has been investigated in detail. It was found that doping of several kind of oxides is effective for improving the mechanical strength. In particular, MgO doped LSGMC maintained power generation performance while the mechanical property was improved. The SEM observations of the sintered samples revealed that the matrix grains were significantry smaller than "plain" LSGMC and MgO particles dispersed alway matrix grains boundaries.