Optimization of electrochemical performance of Ca₃Co ₂O₆ cathode on yttria-stabilized zirconia electrolyte for intermediate temperature solid oxide fuel cells

Ca₃Co₂O₆ (CCO) is synthesized by solid state reaction for intermediate temperature solid oxide fuel cells (IT-SOFCs) on yttria-stabilized zirconia (YSZ) electrolyte. Thermal expansion coefficient (TEC), electrical conductivity (σ) and chemical compatibility of CCO with YSZ are characterized. The experiment results show that CCO and YSZ are chemical compatible only up to 800 °C. By introducing a Sm_0.2Ce _0.8O_1.9 (SDC) interlayer to avoid the direct contact of CCO with YSZ, the area specific resistance (ASR) of CCO cathode is significantly decreased from 13.06 ω cm² to 0.60 ω cm² at 750 °C. Furthermore, the addition of frit can lower the sintering temperature of the cathode to ∼800 °C, also resulting in a remarkable decreasing of the ASR to 3.87 ω cm² at 750 °C.