Ni_1−xCu_x/Ce_0.9Gd_0.1O_1.95 cermet anodes for intermediate-temperature solid oxide fuel cells fueled with simulated biogas; their electrochemical performance and ability to inhibit carbon deposition

Abstract

Solid oxide fuel cells (SOFCs) are power generation systems that exhibit high energy conversion efficiency. Biogas is a renewable energy source generated by the fermentation of waste and its application as a fuel for SOFCs has attracted much attention to improve its effective utilization rate. Inhibiting carbon deposition from fuel on the anode is a critical problem in the development of SOFCs fueled with biogas. The electrochemical performance and ability to inhibit carbon deposition of nickel-copper alloy (Ni_1−xCu_x; x = 0.0, 0.2, 0.4, 0.6)/gadolinium-doped ceria (Ce_0.9Gd_0.1O_1.95; GDC) cermet anodes were investigated for intermediate-temperature solid-oxide fuel cells (IT-SOFCs) at 700 °C using humidified (3 vol % H₂O) simulated biogas with a molar ratio of CH₄/CO₂ = 2/1 as the fuel. The Ni_1−xCu_x/GDC anodes effectively inhibited carbon deposition on the anodes with increasing Cu content, although cell performance deteriorated. Moreover, the Ni_0.6Cu_0.4/GDC and Ni_0.4Cu_0.6/GDC anodes led to stable outputs of the cells during the 24 h electrochemical tests with minimal change in cell performance. In conclusion, the Ni_0.6Cu_0.4/GDC and Ni_0.4Cu_0.6/GDC anodes were found to be promising for biogas fuel at an intermediate temperature of 700 °C. These results provide a guideline for the practical application of IT-SOFCs directly fueled with actual biogas.