A study of process parameters of LSM and LSM-YSZ composite cathode films prepared by screen-printing

A screen-printing technique was developed to fabricate porous cathode film for solid oxide fuel cells. Several key process parameters such as the selection of binders, the mesh of screen, sintering temperature and sintering time were investigated and reported. SEM results showed that the selected process parameters exerted obvious influences on the structure of the screen-printed cathode film. Impedance spectra data were used to evaluate the performance of cathode films made by different process parameters. The optimized process parameters were as follows: ethyl cellulose used as a binder, 120 mesh screen-printing sintering at 1200 °C for 2 h. Based on the optimized parameters, the polarization resistance of pure LSM cathode was 0.396 Ω cm² at 800 °C; the LSM-YSZ composite cathode displayed R_p value of 0.2027 Ω cm² at 850 °C, 0.2463 Ω cm² at 800 °C and 0.5168 Ω cm² at 750 °C, respectively. The performance of the LSM-YSZ composite cathode improved significantly after being polarized at 300 mA cm^-2 and 800 °C for 150 h. After 150 h, the over-potential of the composite cathode was stable.