Electrochemical properties of cathodes made of (La,Sr)(Fe,Co)O3 containing admixtures of nanoparticles of cupric oxide and intended for fuel cells with a solid electrolyte based on ceric oxide

The electric and electrochemical characteristics of cathodes made of La0.6Sr0.4Fe0.8Co0.2O3-delta (LSFC) and intended for fuel cells with electrolytes based on ceric oxide are studied. Adding cupric oxide into the LSFC cathode is shown to exert a favorable effect of the properties of the LSFC-CuO/SDC electrode system, where SDC stands for the CeO2-Sm2O3 electrolyte. The effect produced by cupric oxide when added in the form of nanopowder is perceptibly greater than in the case of micropowdered CuO. Adding a mere 0.5 wt % of nanopowdered CuO reduces the LSFC cathode resistance nearly ten-fold. The cathode's adhesion to the electrolyte substantially improves as well, which makes it possible to lower the cathode's firing temperature by 100 degrees C. The maximum of electrochemical activity is intrinsic to cathodes containing 2 wt % CuO, with the caking temperature of 1000 degrees C. According to a 2011-h life test of the LSFC-SDC composite cathodes containing nanopowdered CuO, temporal stability of their electrochemical characteristics improves with the SDC content. The time dependences of the polarization resistance of cathodes containing 40-50 wt % SDC look like decaying exponential curves. The steady-state polarization resistance, calculated on the basis of this, is equal to 0.1-0.2 ohm cm At an overvoltage of less than 100 mV, the cathodes may provide for a current density of 0.5-1.0 A cm(-2).