Intermediate-Temperature Ceramic Fuel Cells with Thin Film Yttrium-Doped Barium Zirconate Electrolytes

Structural and microstructural properties as well as the fuel cell performance of anhydrous proton conducting yttria-doped barium zirconate (BYZ) membranes were investigated. The membranes were nominally about 100 nm thick and were fabricated by both atomic layer deposition (ALD) and pulsed laser deposition (PLD) techniques on micromachined Si substrates. Electrochemical cells (H-2, Pt/BYZ/Pt, air) were fabricated using porous platinum electrodes deposited by sputtering. The cells were tested in the temperature regime 200-450 degrees C. Power densities of 136 mW/cm(2) at 400 degrees C employing a BYZ membrane fabricated by ALD and 120 mW/cm(2) at 450 degrees C employing a BYZ fabricated by PLD clearly represent the highest reported values in the literature at these temperatures. The difference in the cell performances for the ALD BYZ versus PLD BYZ membranes is attributed to differences in their surface morphology and interfacial microstructure.