Characteristics of La0.8Sr0.2Ga0.8Mg0.2O3-δ-supported micro-tubular solid oxide fuel cells with bi-layer and tri-layer electrolytes

Abstract

In this study, La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM)-supported micro tubular solid oxide fuel cells (T-SOFCs) with two different configurations, one containing an LSGMCe0.6La0.4O2-δ (LDC) bi-layer electrolyte (Cell A) and one containing an LDCLSGMLDC tri-layer electrolyte (Cell B), were fabricated using extrusion and dip-coating. After optimizing the paste formulation for extrusion, the flexural strength of the dense and uniform LSGM micro-tubes sintered at 1500°C was determined to be approximately 144 MPa. Owing to the insertion of an LDC layer between LSGM electrolyte and La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF)LSGM cathode, the ohmic resistances of Cell B were slightly larger than those of Cell A at the operating temperatures investigated, mainly because of interfacial resistance, but Cell B exhibited slightly lower polarization resistance than Cell A. The maximum power densities (MPDs) of Cell A were 0.25, 0.35, 0.43, and 0.47Wcm-2 at 650, 700, 750, and 800°C, respectively, which are slightly larger than those of Cell B, i.e., 0.23, 0.33, 0.42, and 0.41Wcm-2, respectively, owing to the facts that Cell A exhibited a slightly higher open-circuit voltage and a smaller Rt value. Cell A containing the LSGM (288μm)LDC (8μm) bilayer electrolyte can be operated at approximately 650°C with an MPD value of approximately 0.25Wcm-2; however, a similarly structured single cell containing a Zr0.8Sc0.2O2-δ (ScSZ) (210μm) electrolyte need to be operated at 900°C, and one containing an Ce0.8Gd0.2O2-δ (GDC; 285μm)ScSZ (8μm) bi-layer electrolyte has to be operated at 700°C. Thus, the advantage of using LSGM as an electrolyte for micro T-SOFC single cells is apparent.