Characteristics of La_0.8Sr_0.2Ga_0.8Mg_0.2O_3−δ-supported micro-tubular solid oxide fuel cells with bi-layer and tri-layer electrolytes (original) (raw)

Journal of the Ceramic Society of Japan

In this study, La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3¹¤ (LSGM)-supported micro tubular solid oxide fuel cells (T-SOFCs) with two different configurations, one containing an LSGMCe 0.6 La 0.4 O 2¹¤ (LDC) bi-layer electrolyte (Cell A) and one containing an LDCLSGM LDC 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 La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3¹¤ (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 0.47 W cm ¹2 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 0.41 W cm ¹2 , respectively, owing to the facts that Cell A exhibited a slightly higher open-circuit voltage and a smaller R t value. Cell A containing the LSGM (288¯m)LDC (8¯m) bilayer electrolyte can be operated at approximately 650°C with an MPD value of approximately 0.25 W cm ¹2 ; however, a similarly structured single cell containing a Zr 0.8 Sc 0.2 O 2¹¤ (ScSZ) (210¯m) electrolyte need to be operated at 900°C, and one containing an Ce 0.8 Gd 0.2 O 2¹¤ (GDC; 285¯m)ScSZ (8¯m) 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.