High-Performance Low-Temperature Solid Oxide Fuel Cells By Atomic Layer Deposition of Yttria-Stabilized Zirconia on Silver Cathode

Abstract

There have been lots of effort to lower the operating temperature of solid oxide fuel cell (SOFC) below intermediate temperature (IT) regime (< 500 °C) because the high operating temperature (> 800 °C) of SOFCs causes various problems such as thermal stress, mechanical degradation and long startup time. At sub-IT, sluggish oxygen reduction reaction (ORR) at the cathode surface is considered as the rate determining step and it limits the practical use of SOFC at sub-IT region. Although Pt is known as the best catalyst for ORR, it is uneconomical due to its high price. Ag is considered as a great alternative for Pt cathode because of its high ORR activity and its relatively lower price compared to Pt. However, Ag agglomerates easily even at the low temperature region due to its low thermal stability. This agglomeration causes radical decrease of triple phase boundary (TPB) region where ORR occurs. In this study, we introduce atomic layer deposited yttria-stabilized zirconia (ALD YSZ) nano-particulate on Ag cathode in order to expand the TPB region of the cathode. ALD YSZ nano-particulate was deposited on the surface of porous Ag cathode made by DC sputtering. Fuel cell performance of Ag-ALD YSZ cathode was evaluate at the region of 250–450 °C. We will discuss the enhanced performance of ALD YSZ-treated Ag cathode in terms of morphology, electrochemical impedance and fuel cell performance.