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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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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Mechanistic Investigation of Redox Processes in Zn-MnO2 battery in Mild Aqueous Electrolytes

Zinc-MnO2 based batteries have acquired attention for grid-level applications, due to impressive theoretical performance, cost effectiveness and intrinsic safety. However, there are still many challenges that remain elusive due to the complex and controversial mechanisms of operation that hinders commercialization. In this work, the detailed redox processes that occur at the cathode during Zn-MnO2 battery operation are elucidated. Using a blend of structural and electrochemical techniques, the redox pairs that occur during operation are mechanistically studied while also showcasing the true impact of the electrolyte additive (0.1 M MnSO4) in a 1 M ZnSO4 electrolyte. An electrochemical quartz-crystal microbalance (EQCM) has been leveraged to reveal the effect of zinc hydroxy sulfate salt (Zn4SO4(OH)6·nH2O) and zinc manganese oxide (ZnxMnyOz) dissolution/deposition, which are believed to be major components during discharge and charge conditions. . These results provide insight not currently available, allowing a holistic view of the electrochemical reaction mechanisms during battery operation.

Rodriguez Perez, Ismael A.↗
NASA NTRS1983

The electrochemical fluorination of polymeric materials for high energy density aqueous and non-aqueous battery and fuel cell separators

A computerized system was established and the electrochemical fluorination of trichloroethylene, polyacrylic acid and polyvinyl alcohol in anhydrous hydrogen fluoride was attempted. Both solid substrates as well as membranes were used. Some difficulties were found in handling and analyzing the solid substrates and membranes. Further studies are needed in this area. A microprocessor aided electrochemical fluorination system capable of obtaining highly reproducible experimental results was established.

Liu, C. C.↗
DOE OSTI2018

Final Report for the Project Characterization and Valorization of Aqueous Phases Derived from Liquefaction and Upgrading of Bio-Oils

The Characterization and Valorization of Aqueous Phases Derived from Liquefaction and Upgrading of Bio-Oils project developed processes to extract value from the organics within aqueous streams derived from biomass direct liquefaction processes. The focus of the project was twofold. First, we characterized a diverse set of aqueous streams from numerous processes and feedstocks. The characterization effort served to inform this project toward development around the most prevalent compounds to maximize versatility and impact. We analyzed diverse streams from hydrothermal liquefaction of lignocellulosic, algal, and waste feedstocks; catalytic fast-pyrolysis aqueous phases; fast-pyrolysis aqueous phases; and aqueous phases produced by hydroprocessing of fast-pyrolysis bio-oil. Second, thermochemical catalytic processes were developed to convert aqueous-phase organics into useful products. These processes focused mostly on organic acids and specifically acetic acid, which was found to be ubiquitous from the characterization effort. A La x Zr y O z catalyst was discovered and developed for the ketonization of acids to ketones in the condensed aqueous phase. A dual-bed steam reforming process was developed to convert acids and other organics to hydrogen for bio-oil hydroprocessing. The dual-bed reforming process consisted of a ketonization step followed by a steam reforming step with Co as the active metal. The dual-bed process significantly reduced the rate of coke deposition versus direct steam reforming of the organic acids and beneficially produced CH 4 below the equilibrium value. Finally, we demonstrated direct conversion of aqueous-phase organics to olefins over a Zn x Zr y O z catalyst. Each thermochemical catalytic process was demonstrated with process-derived aqueous mixtures. Model compounds were used to benchmark performance and optimize conditions, but emphasis was placed on utilizing “real” aqueous streams whenever possible. A liquid-liquid extraction process using methyl tert-butyl ether as the solvent was developed to segregate dissolved inorganic species and sugars from desirable light oxygenates such as acids and alcohols. Furthermore, a carbon treatment to remove color bodies was employed after it was found the presumably heavy organic chromophore species deactivated catalysts. These economic separation processes allowed for the successful demonstration of stable catalytic processing in the condensed-phase ketonization, dual-bed reforming, and direct olefin production processes for tens to hundreds of hours, which were limited only by the quantity of feed available. Techno-economic analysis of these processes demonstrated the impact possible when capturing “waste” organics as valuable products. The condensed-phase ketonization process for converting aqueous stream acids to ketones followed by reduction and dehydration to olefins sold as a co-product resulted in the reduction of the minimum fuel selling price by about 13% compared to the anaerobic-digestion, aqueous-phase treatment base case (3.74 to 4.29/GGE). The dual-bed reforming process was commensurate in price to the anaerobic digestion base case (4.24 versus 4.29/GGE). However, the need for external natural gas to produce hydrogen for bio-oil hydroprocessing was eliminated, thereby lowering the carbon impact of the process.

09 BIOMASS FUELS↗