Thickness‐dependent high‐performance solid oxide fuel cells with Ba0.5Sr0.5Co0.8Fe0.2O3‐δ cathode

Abstract The electrochemical performance of solid oxide fuel cells (SOFCs) is highly reliant upon the properties of cathodes, including crystal structure, electrical conductivity, electrode thickness, and so on. Here, Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3‐δ (BSCF) is synthesized and served as the electrode for enabling high‐performance SOFCs. The effect of electrode thickness on the electrocatalytic activity is systematically investigated. The electrode thickness is adjusted in two ways. One is spray‐coating and then calcining once, and the other is performing the above process twice. On the basis of symmetrical cells configuration, the oxygen reduction reaction (ORR) activity of BSCF electrode with different thickness is evaluated and analyzed by the electrochemical impedance spectroscopy (EIS) technique and distribution of relaxation time (DRT). The obtained area‐specific resistances (ASRs) of electrodes on the oxygen ion conducting electrolyte Sm 0.2 Ce 0.9 O 1.90 (SDC) demonstrate the thickness‐dependent electrochemical activity in ORR of BSCF electrode. With an electrode thickness of 24 μm that controlled by conducting “spray‐coating and calcining” twice, the BSCF electrode displays the optimal electrochemical performance with an ASR of 0.072 Ω cm 2 in ambient air at 600°C. This strategy has allowed us to produce an electrode layer with optimal thickness, paving a new path for the design of high‐performance SOFCs.