Effect of cathode/ anode area ratio on the electrochemical measurements of anode-supported solid oxide fuel cells

• Main Author: Tan, Gerald Wei Quan.
• Other Authors: Chan Siew Hwa
• Format: Final Year Project
• Language: English
• Published: 2011
• Subjects: DRNTU::Engineering::Mechanical engineering::Energy conservation; DRNTU::Engineering::Mechanical engineering::Alternative, renewable energy sources
• Online Access: http://hdl.handle.net/10356/46132
• Institution: Nanyang Technological University

As a clean and efficient energy source, solid oxide fuel cells (SOFCs) are increasingly gaining popularity around the globe. In order to make it as efficient as possible, many improvements have been made and one of them is the fabrication of anode-supported SOFCs with thin film electrolyte. An anode-supported SOFC cell generally has a cathode which is smaller in area than the supporting anode. Currently, the power densities of the anode-supported SOFC are calculated by normalizing the measured power outputs with the area of the cathode. This, however, may cause a difference in the normalized power densities for the anode-supported cells with different geometrical configurations. This project mainly deals with the performance evaluation of anode-supported (SOFCs) with varying geometrical configurations relating to the area ratio of the La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) – Gd0.1Ce0.9O1.95 (GDC) composite cathode and nickel (Ni) – yttria-stabilized zirconia (YSZ) composite anode. The samples that were fabricated and tested consist of cathode/anode area ratios between 0.25 to 0.8 with 2 different cell sizes of 20mm and 14mm in diameter. For that of the 20mm diameter cells, results show that the smaller the cathode/anode area ratio, the higher the power density measured. This trend is consistent with all cell sizes and electrode ratios and is mainly attributed to the specific configuration of anode-supported SOFCs and the normalization based on the cathode area. With an area ratio of 0.8, the highest power density measured at 800°C was 1.25W/cm2, while that of the 0.25 was measured at 2.11W/cm2. The experiment shows that by using a cathode size which is significantly smaller than the anode, the power density could effectively be increased by 2 times. The tested cells with 14mm diameter at 800°C displayed the same relation between the electrode area ratio and the power density. The results also evidently show that a cell, with a 0.4 cathode/anode area ratio, with a diameter of 14mm produced a higher measured power density of 2.15W/cm2 than a 20mm diameter cell which was measured at 1.99W/cm2.