A facial and effective way to prepare high-performance hetero-structured composite cathode for intermediate temperature solid oxide fuel cells

A hetero-structured composite porous cathode has been prepared by mixing 90 wt% single-phase perovskite (SP1) La0·6Sr0·4Co0·2Fe0·8O3-δ (LSCF1132) and 10 wt% Ruddlesden-Popper layered perovskite (RP3) LaSrCo0·2Fe0·8O4-δ (LSCF2144) nano-powders. The powders were separately synthesized by wet chemical coprecipitation (CP5) method, and subsequently mixed by ball-milling to obtain the composite CP-LSCF214-113 cathode with RP/SP hetero-interface. The hetero-interface has been confirmed by XRD and TEM. The polarization impedance (Rp) of symmetrical cell with the composite cathode achieved 0.024 and 0.147 Ω cm2 at 800 and 700 °C, decreasing 65% and 72% of the cathode impedance of CP-LSCF113, respectively. An anode supported SOFC with the CP-LSCF214-113 composite cathode achieved maximum power density of 1.02 W cm−2 at 800 °C. The CP-LSCF214-113 based single cell also showed acceptable stability similar to CP-LSCF113 based cell over 100 h at 700 °C. Moreover, the CP-LSCF214-113 effectively inhibits the coarsening of grains and the growth of RP phase. The solid state reaction (SSR6) method was used for comparison. Our results revealed that the CP method combined with ball-milling and subsequent calcining is an effective way to construct RP/SP hetero-interface in porous cathodes for intermediate temperature solid oxide fuel cells (IT-SOFCs).