Electrochemical Investigation of Composite Nano La0.6Sr0.4Co0.2Fe0.8O3-δ Infiltration into LSGM Scaffold Cathode on LSGM Electrolyte

Abstract

As a potential intermediate temperature SOFC cathode, a nano La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) infiltrated into a porous La0. 8Sr0. 2Ga0. 8Mg0. 2O3-δ (LSGM) scaffold cathode was evaluated in combination with a LSGM electrolyte. A XRD analysis revealed resistive phases of LaSrGa3O7 and LaSrGaO4 present in the LSCF/LSGM binary system with sintering over 950 oC. To fabricate a nano catalyst infiltrated into the LSGM scaffold cathode, the porous LSGM scaffold is formed at high temperature (1250 oC). Nano catalysts are coated on the scaffold surface using an infiltration technique and fired at 850oC in air. The cathode polarization resistance (Rp) of nano LSCF infiltrated into the LSGM scaffold cathode was 0.02 Ωcm2, 0.11 Ωcm2, and 0.66 Ωcm2 at 800oC, 700oC, and 600oC, respectively. To improve the oxygen reduction reaction, a Pt/LSCM composite solution was infiltrated into the LSGM scaffold cathode. However, the Rp of the nano Pt/LSCM composite infiltrated into the LSGM scaffold cathode was increased to 0.90 Ωcm2 at 700 oC, despite the Pt has higher electrochemical activity for oxygen reduction than LSCF (Rp for LSCM infiltration was 0.317 Ωcm2 at 700oC).