Nanoscale cathode modification for high performance and stable low-temperature solid oxide fuel cells (SOFCs)

Abstract

The application of nano-electrocatalysts to solid oxide fuel cells (SOFCs) provides opportunities to enhance performance. However, due to high sintering and operating temperature of SOFCs, nanostructured electrodes tend to agglomerate, losing its high surface area and catalytic activity. Here we report a high performance, surface modified La0.6Sr0.4Co0.2Fe0.8O3-δ-Ce0.9Gd0.1O2-δ (LSCF-GDC) cathode for low-temperature SOFCs, prepared by solution infiltration. By carefully co-controlling the low calcination and operating temperature (< 650 °C), the growth of infiltrated nano-particles is impeded and the oxygen reduction reaction (ORR) is activated. Using isotopic exchange, we show that these nano-electrocatalysts significantly decreases the apparent activation energy for oxygen dissociation, leading to high intrinsic catalytic activity in addition to high surface area. Consequently, maximum power densities of the modified SOFCs are two times higher than pristine cells. Moreover, we demonstrate these nanoelectrocatalysts remain highly active over 1300 h at 600 °C and exhibit exceptional stability under transient current loads, an essential feature for portable and automotive applications. Our results highlight a simple method to dramatically improve the performance and stability of low-temperature operating SOFCs by retaining nanoscale electrocatalysts (< 10 nm) being active toward the ORR.