Optimization of La0.6Sr0.4Co0.2Fe0.8O3-α - Ba(Ce0.6Zr0.4)0.9Y0.1O3-δ cathode composition for proton ceramic fuel cell application

Abstract

Composite cathodes consisting of different compositional ratios of La0.6Sr0.4Co0.2Fe0.8O3-α (LSCF) and Ba(Ce0.6Zr0.4)0.9Y0.1O3-δ (BCZY64), namely 100LSCF:0BCZY64 (L10B0), 70LSCF:30BCZY64 (L7B3), 50LSCF:50BCZY64 (L5B5) and 30LSCF:70BCZY64 (L3B7) were prepared via wet chemistry method. The symmetrical cell with a configuration of electrode|BCZY64|electrodewas fabricated using dry-pressingmethod for the electrolyte substrate and spin-coating technique for the cathode layer. The proton conduction in the composite cathode increases as the amount of proton-conducting phase increases as verified by the water uptake measurement performed via thermogravimetric analysis. The thickness of the composite cathode layer is about 15 μm as observed by a scanning electron microscope and exhibits a well-connected particle network with sufficient porosity for oxidant diffusion (20-30%). The electrochemical performance of the symmetrical cell was investigated by electrochemical impedance spectroscopy in humidified air. The area-specific resistance (ASR) values of the tested cathodes follow the order of L7B3 < L10B0 < L5B5 < L3B7 and are 0.07 < 0.24 < 0.30 < 0.52W•cm2 at 700°C, respectively. The correlation between the cathode performance and cathode composition was investigated and the corresponding mechanism was systematically postulated.

Keywords

• perovskite
• fuel cell
• electrodes
• composite cathode
• impedance spectroscopy