Development of (La,Sr)MnO₃-based cathodes for intermediate temperature solid oxide fuel cells

Conventional (La, Sr)MnO₃ (LSM) electrodes modified by ion impregnation methods showed promising potential as cathodes for intermediate temperature solid oxide fuel cells. After impregnation of ionic conducting-type Gd_0.2Ce_0.8(NO₃)_x nitrite salt solution into the LSM structure, electrochemical activity of LSM electrodes for the O₂ reduction reaction was substantially enhanced. At 700°C, the electrode polarization resistance of impregnated LSM electrodes decreased to 0.72 Ω cm² as compared to 26.4 Ω cm² for pure LSM electrodes, a reduction in electrode polarization resistance by 36 times. The polarization losses were also reduced substantially. At 300 mA cm^-2 and 700°C, overpotential for the O₂ reduction was reduced from 0.79 V on pure LSM to 0.19 V on impregnated LSM electrodes, a reduction in overpotential by four times. Ion-impregnated LSM electrodes showed better performance than those of LSM/Y₂O₃-ZrO₂ and LSM/(Gd,Ce)O₂ composite electrodes as reported in the literature.