The influence of PEEK as a pore former on the microstructure of brush-painted LSCF cathodes

Abstract

At lower operation temperature of intermediate temperature solid oxide fuel cells (IT-SOFC), polarization resistance was recognized as a limiting step because polarization at cathode is dependent on the rate of oxygen reduction reaction. The enhancement of cathode microstructure is one of the effective ways to improve the reaction rate. Pore former addition method is proven to be able to tailor the microstructure of cathode. The addition of polyether ether ketone (PEEK) as pore former was evaluated and compared with common pore formers (corn starch and graphite) for the microstructure cathode layer. Brush painting technique was used to deposit cathode layer on anode/electrolyte dual layer support hollow fiber. X-ray diffraction (XRD) analysis had proven that the resulting layer was free from impurities after the sintering treatment. Corn starch was able to induced cathode layer with coarse and large interconnected pores for efficient gas diffusion, as was proven by the SEM analysis. Additionally, SEM analysis also showed the formation of fine micropores throughout the layer when graphite was used as the pore former that can provide the increase in triple phase boundary region (TPB) in the layer. PEEK was able to generate both high porosity for oxygen diffusion to the reactive sites and increased number of TPB by the formation of fine microstructure pores in the cathode layer.