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This paper presents a novel planar proton exchange membrane fuel cell (PEMFC) stack designed for portable electronic devices, consisting of twenty homemade membrane electrode assemblies (MEAs) arranged on a planar surface and three printed circuit boards (PCBs, including anode, interlayer and cathode PCBs) used to load these MEAs. The current collectors and electrical connectors are manufactured using printed circuit technology. The inlet holes of reaction gases are also machined on PCB substrates. The output performance tests are performed on the MEAs and the assembled planar PEMFC stack. The results show that the power densities of the MEAs and the planar PEMFC stack are 0.6 W/cm2 and 0.361 W/cm2 at rated voltage under ambient temperature and forced convection air conditions, respectively. The stability tests are also conducted on the planar PEMFC stack, and the results show no significant fluctuations in output current. The feasibility of the application of planar PEMFC stacks in portable electronic devices is preliminarily demonstrated, and the improvement directions for further improving the output performance are proposed accordingly. • A planar PEMFC stack is designed and evaluated experimentally. • The planar PEMFC stack is constructed based on printed circuit technology. • The power densities of the planar PEMFC stack are 0.6 W/cm2 at rated voltage. • Discharge and stability tests reveal the good application feasibility of planar PEMFC stack. [ABSTRACT FROM AUTHOR]

Ammonia is a useful energy carrier for solid oxide fuel cell (SOFC) with advantages over hydrogen. Understanding of the performance and stability of ammonia-fed SOFC operated at elevated pressure (p) is an important step towards the development of high-efficiency hybrid SOFC power system with micro gas turbine (MGT). This paper reports cell performance, electrochemical impedance spectra (EIS), and stability measurements of a pressurized ammonia-fed anode-supported SOFC at p = 1–5 atm and T = 750–850°C using a planar (50 × 50 mm2) single-full-cell (400 μm Ni-YSZ anode/3 μm YSZ electrolyte/12 μm LSC-GDC cathode). The full cell together with metallic frames and current collectors are sandwiched by a pair of rib-channel flow distributors (interconnectors) in a high-pressure testing facility. Results show that pressurization and increasing temperature enhance the ammonia-fed SOFC performance significantly having almost the same power densities as those of hydrogen/nitrogen-fed SOFC, as substantiated and explained by EIS data and an equivalence circuit model where the effects of p and T on ohmic, gas diffusion, and gas conversion impedances are shown. Moreover, the loaded short (10 h) stability tests at 700°C and 0.8 V for 1 atm/3 atm cases reveal no/little power degradation, where the microstructures without any crack within the scale of SEM observation and nearly the same element atomic percentages of Ni-YSZ anode surfaces from EDX spectra are found. These results suggest that the pressurized ammonia-fed SOFC is a promising candidate for the hybrid SOFC-MGT power generation. • A planar NH 3 -fed anode-supported SOFC (ASC) is measured at 1–5 atm and 750–850°C. • Power and electrochemical impedance of a pressurized NH 3 -fed ASC are reported. • Gas diffusion/conversion impedances are analyzed by an equivalent circuit model. • NH 3 -ASC stability tests at 3-atm show little degradation at 700°C and 0.8 V. • Pressurized NH 3 -fed SOFC is a promising candidate for hybrid power generation. [ABSTRACT FROM AUTHOR]

In order to elucidate the reasons for enhanced activity and stability of the alloy catalyst, PtCr/C was prepared by an incipient wetness method and heat-treatments. In single-cell test, the catalysts heat-treated at 900 °C showed the highest performance (about 70% higher than JM Pt/C at 700 mV) because of the alloy effect. Stability of the alloy catalysts was investigated with several accelerated-stress tests. The heavy dissolution of Cr was observed especially in the beginning of operation. The undissolved Cr is considered to take part in the formation of complete alloying. Before and after cell operation, the ratio of Cr to S in the Nafion membrane was measured by EPMA. Within Cr/S of 10% in the Nafion membrane, the conductivity changed a little, but as the Cr/S exceeded more than 10% the serious reduction of conductivity was observed. The catalyst heat-treated at 900 °C showed applicable performance and stability in real cell operations. [ABSTRACT FROM AUTHOR]