Low‐Temperature Micro‐Solid Oxide Fuel Cells with Partially Amorphous La_0.6Sr_0.4CoO_{3‐<i>δ</i>} Cathodes

Abstract

Partially amorphous La 0.6 Sr 0.4 CoO 3‐ δ (LSC) thin‐film cathodes are fabricated using pulsed laser deposition and are integrated in free‐standing micro‐solid oxide fuel cells (micro‐SOFC) with a 3YSZ electrolyte and a Pt anode. A low degree of crystallinity of the LSC layers is achieved by taking advantage of the miniaturization of the cells, which permits low‐temperature operation (300–450 °C). Thermomechanically stable micro‐SOFC are obtained with strongly buckled electrolyte membranes. The nanoporous columnar microstructure of the LSC layers provides a large surface area for oxygen incorporation and is also believed to reduce the amount of stress at the cathode/electrolyte interface. With a high rate of failure‐free micro‐SOFC membranes, it is possible to avoid gas cross‐over and open‐circuit voltages of 1.06 V are attained. First power densities as high as 200–262 mW cm −2 at 400–450 °C are achieved. The area‐specific resistance of the oxygen reduction reaction is lower than 0.3 Ω cm 2 at 400 °C around the peak power density. These outstanding findings demonstrate that partially amorphous oxides are promising electrode candidates for the next‐generation of solid oxide fuel cells working at low‐temperatures.