Fabrication and Testing of Anode Supported Protonic Ceramic Fuel Cells in Biogas

Abstract

Protonic Ceramic fuel cells (PCFCs) offer a low-pollution technology to generate electricity electrochemically with high efficiency when compared to that of combustion engines [1]. PCFCs also offer the advantage of keeping fuel electrode (anode) undiluted, with the water formation taking place at the air electrode (cathode) side. Thin electrolyte membranes are preferred, to reduce the ohmic losses during the fuel cell test [2], with the most common electrolyte materials being alkaline earth doped cerates, zirconates and their solid solutions, due to high proton conductivity and low activation energy. Nonetheless, the chemical instability of BaCeO3 in acidic atmospheres and the high sintering temperature and resistive grain boundaries of BaZrO3 are the main problems currently limiting their application in PCFCs [3]. As a compromise, the composition 40% Ce substituted Ba (Zr, Y) O3-δ, lying in the solid solution between the zirconate and cerate materials, has been received great attention due to improving the chemical stability of the cerate, while maintaining high total protonic conductivity[4][5]. In the present work, anode (Ni-BaCe(1-x)Zr(x-y)Y(1-x-y)O3-δ) supported thin electrolyte membrane (~6µm thickness) protonic cells were developed by a spin coating technique, with a triple conducting cathode (H+/O2-/e-) is deposited on this electrolyte/anode half-cell, figure 1. The performance of the complete PCFC cell is tested in biogas, an important feedstock from bio-waste mainly consisting of CH4 and CO2. The behavior of the triple conducting cathode, fuel utilization, carbon deposition and overall performance (I-V-P) comparison results will be discussed in detail. Acknowledgments The authors gratefully acknowledge funding from the FCT, POPH, PTDC/CTM/100412/2008, FCT Investigator Programme, IF/01344/2014/CP1222/CT0001, PTDC/CTM-ENE/6319/2014, QREN, FEDER and COMPETE Portugal and the European Social Fund, European Union.