Achieving performance and longevity with butane-operated low-temperature solid oxide fuel cells using low-cost Cu and CeO2 catalysts

Abstract

The use of thin-film solid oxide fuel cells (TF-SOFCs) can effectively lower the operating temperature of a typical solid oxide fuel cell (SOFC) below 600 °C, while maintaining high efficiency and using low-cost catalysts. However, the fuel flexibility in SOFCs becomes a significant challenge at lower operating temperatures, resulting in the need for expensive noble-metal catalysts. The effective implementation of low-cost catalysts, Cu and CeO₂, in a TF-SOFC presents a solution to this problem. Cu is inserted directly near the electrolyte–anode interface via a combination of pulsed laser deposition and sputtering to assist the electrochemical reactions, and the anode support, which constitutes the main volume of the cell, is infiltrated with CeO₂ to effectively facilitate thermochemical reforming reactions. A comprehensive study of catalyst-modified cells (Cu–Ce-cell, Ce-cell, and Cu-cell) and a Ni/YSZ reference cell (ref-cell) is performed over n-butane fuel in an operating temperature range of 500 to 600 °C. The cell incorporating Cu and CeO₂ (Cu–Ce-cell) shows a record high performance for a hydrocarbon-fueled SOFC, with a peak power density of 1120 mW cm⁻² at 600 °C. Cu and CeO₂ improve the activity of the steam reforming reaction, and CeO₂ expands the triple-phase boundary, increasing the electrochemical activity. Cu–Ce-cell also degrades at a much slower rate than ref-cell. Post-reaction analysis proves that the drastic improvement in longevity is achieved as a result of the enhanced carbon deposition resistance of Cu–Ce-cell.