Enhancing coking tolerance of flat-tube solid oxide fuel cells for direct power generation with nearly-dry methanol

Abstract

The state-of-the-art Ni/yttria-stabilized zirconia (YSZ) anodes in direct methanol solid oxide fuel cells (SOFCs) are vulnerable to carbon deposition. We propose two strategies to enhance coking tolerance of the cell, focusing on promoting the oxygen storage capacity of the Ni/YSZ anode and the methanol conversion in flat-tube SOFCs with an active area of 60 cm2. The Ni/YSZ anodes are decorated with nanosized gadolinia-doped ceria (GDC) by wet impregnation method and the fuel channels are filled with extra GDC-Ni/YSZ catalyst. Through these measures, carbon deposition in the modified cells is mitigated, and therefore the steam/carbon (S/C) ratio for successful long-term cell operation is significantly lowered, and the cell durability is improved. A GDC-Ni/YSZ cell with extra catalyst is operated for over 1200 h directly on methanol under low S/C ratios at 750 °C and carbon deposition is considerably suppressed. In addition, the degradation mechanism of the cell directly fueled with nearly-dry methanol (S/C = 0.1) is investigated. This work provides insight into efficient and durable SOFCs using biofuels, towards renewable energy conversion in large-scale commercial applications.