| dc.description.abstract | The first part of this study aimed to develop a carbon-resistant anode for methane-fueled protonic ceramic fuel cells (PCFC) that is better than the conventional Ni-BCZY anode. The Ni1-xCux-BCZY alloy in the PCFC anode was prepared using a solid-state reaction process. Ni is doped with Cu to the anode-supported single cell′s performance curve and electrochemical impedance spectrum were measured and analyzed under methane and hydrogen. The results showed that the Ni0.9Cu0.1 cell performed best when introduced to hydrogen and methane. Regarding cell performance, the highest power density reached 409.5 mW/cm2 and 177.6 mW/cm2, respectively. Results show that doping a small amount of cobalt will not affect the cell performance when introducing methane. On the other hand, doping too much copper will reduce cell performance. This work demonstrates the usability of the Ni1-xCux-BCZY alloy anode for methane fuel, and helps to develop alloy anodes for solid oxide fuel cell power generation using methane.
The second part of this study aims to obtain a dense, high-quality electrolyte. The proton conducting electrolyte BaCe0.6Zr0.2Y0.2O3 (BCZY) sintering for the protonic ceramic fuel cell (PCFC) was carried out at a relatively high temperature. However, when the porous anode substrate and the electrolyte film are co-sintered, the high sintering temperature often leads to the coarsening of the NiO-BCZY anode, thereby reducing the number of electro-catalytic active sites for H2 oxidation and reduced cell performance. A scalable nanoball milling process is proposed to reduce the electrolyte sintering temperature to maintain a three-phase boundary and enhance electron and proton transport in PCFC anodes. Using the nanoball milling process, the BCZY nanoparticles′ diameter was reduced by more than half (from 297 nm to 131 nm). The co-sintering temperature can be lowered. The cell sintered at 1400 °C showed the highest peak power density of 490 mW/cm2, 38% higher than the non-nano-milling process. The significant improvement in cell performance can be attributed to the lower co-sintering temperature, which reduces the coarsening of the NiO anode. This preserves a more substantial number of H2 electrocatalytically active sites. Electrochemical impedance measurements show a 50% reduction in charge transfer resistance, demonstrating the oxidation of Ni in cell operation.
The nano-powder was further applied to the anode functional layer. The nano-powder (135.4 nm) was ball-milled for 4 hours and applied to the anode functional layer of the solid oxide fuel cell to prepare different nano AFL layers, including one layer of nano AFL and two layers of nano AFL. The power densities of the layered nano-AFL, the original, and nano-combined composite AFL are 286.1 mW/cm2, 463.3 mW/cm2, and 534.1 mW/cm2, respectively. It can be found that the cell performance of the original and nano-combined composite AFL has been significantly improved. Compared with the original anode functional layer, its power density increases by 9%. Further EIS analysis shows that the activation polarization RPh of composite AFL has a clear downward trend. Since the average particle diameter of nano-AFL is reduced by half, more three-phase interfaces are added, decreasing activation polarization. It is known from the results that the application of the nanometer manufacturing process to AFL in this study can effectively increase the interface contact with the electrolyte, reduce ohmic impedance and polarization resistance, and further improve cell performance.
The third part of this study proposes a new method that can improve the contact interface between the porous interface layer and the electrolyte. By co-sintering the porous interface layer and the electrolyte, a better contact interface can be achieved, and the interface impedance in the cell can be reduced. This results in higher power density. This research results show that the maximum power density of the co-sintered electrolyte porous interface layer cell measured at 800°C is 429.3 mW/cm2. Compared with the pre-sintered electrolyte porous interface layer cell (336.4 mW/cm2), the maximum power density of the cell is improved by 17.2%, and the ohmic impedance is reduced by about 30.8%. The results show that by co-sintering the porous interface layer and the electrolyte, a better contact interface can be achieved to reduce the impedance and further improve the cell performance of PCFC. | en_US |