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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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In various embodiments, techniques for fabricating solid oxide fuel cells utilize setter plates composed of or having outer surfaces composed of materials unreactive with species found in the layers of the cell.
Chemistry of fuel cell reactions - Potentials of zero charge, electrocatalysis, electrode reactions, model porous electrode, potential sweep, and proton transfer across double layers
Design and development of the ion-exchange membrane fuel cell intended to furnish electric power and drinking water to the gemini spacecraft
For the first time a long-term (500 h) durability study in direct methanol fuel cells (DMFCs) is carried out on a Platinum Group Metal-free (PGM-free) cathodic electro-catalyst commercially available on market. The electro-catalyst is tested for 500 h at a fixed cell voltage (0.3 V), recording the polarization curves during the operation. A drastic decrease in performance is observed after the first 100 h (from 220 to 75 mA cm –2 ); afterwards, the decrease is flatter, passing from 75 to 25 mA cm –2 (at 500 h). The causes of this performance degradation are investigated by postmortem physicochemical analyzes, such as X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) with X-ray energy dispersive analysis (EDX). Finally, possible reasons of degradation are indicated to be PGM-free catalyst aggregation, carbon and nitrogen species decrease, Ruthenium dissolution and migration from the anode to the cathode, poisoning both membrane and cathode catalyst.
Fuel cell systems using storable propellants as primary or secondary reactants
Gaseous electrolytes and electrode behavior at elevated temperatures evaluated for battery and fuel cell application
High performance lightweight electrodes for hydrogen-oxygen fuel cells
A number of advancements have been realized by a continuing research program to develop higher chemically stable porous matrix structures with high bubble pressure (crossover resistance) for use as separators in potassium hydroxide electrolyte fuel cells. More uniform, higher-bubble-pressure asbestos matrices were produced by reconstituting Johns-Manville asbestos paper; Fybex potassium titanate which was found compatible with 42% KOH at 250 F for up to 3000 hr; good agreement was found between bubble pressures predicted by an analytical study and those measured with filtered structures; Teflon-bonded Fybex matrices with bubble pressures greater than 30 psi were obtained by filtering a water slurry of the mixture directly onto fuel cell electrodes; and PBI fibers have satisfactory compatibility with 42% KOH at 250 F.
The evolution of Pt nanoparticles supported on carbon nanotubes is analyzed before and after electrochemical potential cycling, using identical location aberration-corrected transmission electron microscopy, for applications in proton exchange membrane fuel cells. The work is focused on the half-cell accelerated stress test protocol of potential cycles ranging between 1.0 and 1.5 V RHE to represent the start-up/shutdown settings of a fuel cell vehicle. The research work reveals that particle migration and coalescence are key mechanisms for a reduction in the Pt nanoparticle surface area at the early stages of potential cycling. Further, the mechanism for particle movement and coalescence is attributed to carbon corrosion, catalyzed either by Pt or by bulk corrosion of the carbon nanotubes. Carbon corrosion results in the appearance of carbon vacancies at the carbon nanotube/Pt nanoparticle interface during cycling, as well as the formation of edge and surface defects. During cycling, the concentration of the dissoluble Pt increases. As soon as a significant amount is reached, subnanometer/atomic clusters emerge on the carbon nanotube support, which can move and coalesce, or redeposit on the surface of larger particles through Ostwald ripening.
Electrolyte pulsing using carbon electrode for improved fuel cell operation
Single cells with potassium titanate matrices for improved cycle life performance of hydrogen- oxygen regenerative fuel cells
The design and operation of a methanol concentration sensor suitable for use with direct methanol fuel cells is described.
An effective strategy for generating combined heat and power (CHP) systems is to use the combustion of hydrocarbons to provide fuel reforming and heat production for solid oxide fuel cell (SOFC) operation. Though tubular SOFCs (tSOFCs) are well suited to the thermal cycling associated with combustion systems, they have a geometric limitation which requires significant alteration to the combustion chamber. These alterations can be eliminated by producing an anode supported internal cathode-tSOFC (IC-tSOFC) which can be directly integrated into the chamber with minimal alterations. Novel methods used to produce IC-tSOFCs are discussed in this work. Scanning electron microscopy (SEM) and performance characterization are used to analyze fabricated cells. Finally, with a peak power density of 369 mW∙cm –2 , and an open circuit voltage (OCV) of 0.98 V, it is confirmed that novel production methods for IC-tSOFCs have been successful.
This effort produces a fully-passive surface power generation capability for fuel cell technology. The concept replaces the actively pumped thermal management of a state of the art (SOA) fuel cell/electrolyzer stack with a passive 2-phase thermosyphon for heat transport and a passive shape memory actuating radiator for temperature management.
Current/voltage data was obtained for specially made corrosion electrodes of some oxides and of gold materials for the purpose of developing a screening test of catalysts and supports for use at the cathode of the alkaline fuel cell. The data consists of measurements of current at fixed potentials and cyclic voltammograms. These data will have to be correlated with longtime performance data in order to fully evaluate this approach to corrosion screening. Corrosion test screening of candidates for the oxygen reduction electrode of the alkaline fuel cell was applied to two substances, the pyrochlore Pb2Ru2O6.5 and the spinel NiCo2O4. The substrate gold screen and a sample of the IFC Orbiter Pt-Au performance electrode were included as blanks. The pyrochlore data indicate relative stability, although nothing yet can be said about long term stability. The spinel was plainly unstable. For this type of testing to be validated, comparisons will have to be made with long term performance tests.
Thermal cycling, life tests, degradation rates, and reactant flow distributions of fuel cell stacks
This report highlights recent changes in the FCEB market, status updates for deployments, and a detailed performance evaluation of a large fleet of FCEBs operated by Foothill Transit in California during the period from June 2023 to December 2024.
The global effort to introduce polymer electrolyte fuel cells for clean and renewable energy to the market is increasing the demand for high performance, robust and affordable membrane electrode assemblies (MEAs). There is not yet a standard method for large scale production of MEAs, or the methods employed are generally unsatisfactory in terms of quality and performance. A large number of published data of newly developed catalyst and electrolyte materials, claim to improve the state of the art, but are often not fully comparable due to different experimental studies and experimental designs. This article summarizes the trends in material developments and emerging MEA-manufacturing techniques. The materials and techniques are systematically compared in terms of cell performance and scalability. Current and future scientific challenges are identified and analysed based on published findings over the past five years. Finally, the results of the cited papers have been quantitatively compared to each other and to the internal benchmarks used in each cited work to provide a complete picture of the state of the art in PEFC MEA manufacturing.