Two types of air-cooled modular polymer membrane fuel cells (PEMFC) stacks with full equipment were constructed and investigated as components of hybrid power sources. The first, a 2-kW PEMFC stack, was assembled from two 1-kW PEMFC modules electrically connected in parallel and compared with a commercial PEMFC stack built from one 2-kW PEMFC module. The second, a 500-W PEMFC stack, was assembled with three modules connected in parallel. It was found that the two-module PEMFC stack was capable of operation with nominal power of 2 kW. Analysis of the distribution of the air cooling system in both modules was also conducted. The two-module PEMFC stack reduced hydrogen consumption compared to the reference 2-kW PEMFC stack consisting of only one module. The elaborated two-module PEMFC stack was successfully tested in a propulsion system designed to supply an electrical engine with a propeller. The electrical performance of the three-module PEMFC stack was tested separately as well as in a hybrid system in connection with a 5 s Li-Pol battery. It was found that the elaborated PEMFC stack was capable of operation with nominal power of 500 W and variable rapid dynamic electrical loads. It was also successfully tested as a power source to supply servomechanisms and other auxiliary devices.

Comparative studies were performed on variations in the ABO₃ perovskite structure, chemical stability in a CO₂-H₂ gas atmosphere, and electrical conductivity measurements in air, hydrogen, and humidity-involving gas atmospheres of monophase orthorhombic Ba_1−xSr_xCe_0.9Y_0.1O_3−δ samples, where 0 < x < 0.1. The substitution of strontium with barium resulting in Ba_1−xSr_xCe_0.9Y_0.1O_3−δ led to an increase in the specific free volume and global instability index when compared to BaCe_0.9Y_0.1O_3−δ. Reductions in the tolerance factor and cell volume were found with increases in the value of x in Ba_1−xSr_xCe_0.9Y_0.1O_3−δ. Based on the thermogravimetric studies performed for Ba_1−xSr_xCe_0.9Y_0.1O_3−δ, where 0 < x < 0.1, it was found that modified samples of this type exhibited superior chemical resistance in a CO₂ gas atmosphere when compared to BaCe_0.9Y_0.1O_3−δ. The application of broadband impedance spectroscopy enabled the determination of the bulk and grain boundary conductivity of Ba_1−xSr_xCe_0.9Y_0.1O_3−δ samples within the temperature range 25–730 °C. It was found that Ba_0.98Sr_0.02Ce_0.9Y_0.1O_3−δ exhibited a slightly higher grain interior and grain boundary conductivity when compared to BaCe_0.9Y_0.1O_3−δ. The Ba_0.95Sr_0.05Ce_0.9Y_0.1O_3−δ sample also exhibited improved electrical conductivity in hydrogen gas atmospheres or atmospheres involving humidity. The greater chemical resistance of Ba_1−xSr_xCe_0.9Y_0.1O_3−δ, where x = 0.02 or 0.05, in a CO₂ gas atmosphere is desirable for application in proton ceramic fuel cells supplied by rich hydrogen processing gases.

E3S Web of Conferences, open access proceedings in environment, energy and earth sciences

The development of new chemically resistant anodes for protonic ceramic fuel cells (PCFCs) is urgently required to avoid the costly deep hydrogen purification method. Ba_0.95Ca_0.05Ce_0.9Y_0.1O_3−δ (5CBCY), which is more chemically resistant than BaCaCe_0.9Y_0.1O_3−δ, was here tested as a component of a composite NiO–5CBCY anode material. A preparation slurry comprising 5CBCY_, NiO, graphite, and an organic medium was tape cast, sintered and subjected to thermal treatment in 10 vol.% H₂ in Ar at 700 °C. Differential thermal analysis, thermogravimetry, quadrupole mass spectrometry, X-ray diffraction analysis, scanning electron microscopy, the AC four-probe method and electrochemical impedance spectroscopy were used for the investigation. The electrical conductivity of the Ni–5CBCY in H₂–Ar at 700 °C was 1.1 S/cm. In the same gas atmosphere but with an additional 5 vol.% CO₂, it was slightly lower, at 0.8 S/cm. The Ni–5CBCY cermet exhibited repeatable electrical conductivity values during Ni-to-NiO oxidation cycles and NiO-to-Ni reduction in the 5CBCY matrix, making it sufficient for preliminary testing in PCFCs.