Development of MCSF (M=La, Ba) Cathode Materials for Proton Conducting Fuel Cell Application

摘要

Two cathode materials for proton-conducting fuel cell (PCFC), La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) (LSCF) and Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ) (BSCF) were investigated regarding their microstructural and electrical properties under air containing atmosphere. The respective sample was prepared via a modified sol-gel method using an activated carbon as a dispersing agent and anodic aluminium oxide (AAO) templating method assisted with sol-gel process. The powders were subjected to X-ray Diffractometer (XRD) and Brunauer-Emmet-Teller (BET). A symmetrical half-cell of LSCF|BCZY|LSCF and BSCF|BCZY|BSCF (BCZY = BaCe_(0.54)Zr_(0.36)Y_(0.1)O_(2.95))was fabricated and characterized using an electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM). After calcined at T= 900 °C, both of the LSCF and BSCF demonstrated their single-phase structure and exhibited highly dispersed powders with large surface area as proven by BET result. For electrical analyses, impedance spectrum of the cathodes was referred only to the two main contributions of cathode responses which were charge transfer at cathode/electrolyte interface and oxygen adsorption/dissociation on the cathode surface. At 600 °C, the polarization resistance of LSCF half-cell (R_p = 4.94 ?.cm~2) was comparable to BSCF (R_p =4.50 ?.cm~2). SEM images revealed no delamination along the electrolyte/ electrode interface after EIS measurements as no sign of crack was observed for both samples. It can be concluded that the microstructure of the cathode layer can be tailored by altering the sample's preparation route which in turn to enhance the PCFC performance.