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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Carbon dioxide capture using resin-wafer electrodeionization

The present invention provides a resin-wafer electrodeionization (RW-EDI) apparatus including cathode and anode electrodes separated by a plurality of porous solid ion exchange resin wafers, which when in use are filled with an aqueous fluid. The apparatus includes one or more wafers comprising a basic ion exchange medium, and preferably includes one or more wafers comprising an acidic ion exchange medium. The wafers are separated from one another by ion exchange membranes. The fluid within the acidic and/or basic ion exchange wafers preferably includes, or is in contact with, a carbonic anhydrase (CA) enzyme to facilitate conversion of bicarbonate ion to carbon dioxide within the acidic medium. A pH suitable for exchange of CO2 is electrochemically maintained within the basic and acidic ion exchange wafers by applying an electric potential across the cathode and anode.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Carbon dioxide capture using resin-wafer electrodeionization

The present invention provides a resin-wafer electrodeionization (RW-EDI) apparatus including cathode and anode electrodes separated by a plurality of porous solid ion exchange resin wafers, which when in use are filled with an aqueous fluid. The apparatus includes one or more wafers comprising a basic ion exchange medium, and preferably includes one or more wafers comprising an acidic ion exchange medium. The wafers are separated from one another by ion exchange membranes. The fluid within the acidic and/or basic ion exchange wafers preferably includes, or is in contact with, a carbonic anhydrase (CA) enzyme to facilitate conversion of bicarbonate ion to carbon dioxide within the acidic medium. A pH suitable for exchange of CO2 is electrochemically maintained within the basic and acidic ion exchange wafers by applying an electric potential across the cathode and anode.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

An efficient gigawatt level X-band Cerenkov type oscillator without guiding magnetic field

This paper presents a novel modification of gigawatt level X-band Cerenkov type high power microwave oscillator without guiding magnetic field. A confining cathode is put forward to suppress the radial dispersion of the annular relativistic electron beam and accordingly improve its axial transportation to ensure further beam-wave interaction. An overmoded nonuniform slow wave structure is adopted in order to increase the power capacity of the oscillator and the efficiency of beam-wave interaction. A tapered collector is used to collect the beam, increase the Q-factor, and extract the microwave favorably. The simulation results indicate that a microwave is generated by the proposed oscillator with output power of 1.9 GW and frequency of 9.02 GHz, when the diode voltage and beam current are 620 kV and 9 kA, respectively. The corresponding power conversion efficiency is 34%.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

Carbon dioxide capture using resin-wafer electrodeionization

The present invention provides a resin-wafer electrodeionization (RW-EDI) apparatus including cathode and anode electrodes separated by a plurality of porous solid ion exchange resin wafers, which when in use are filled with an aqueous fluid. The apparatus includes one or more wafers comprising a basic ion exchange medium, and preferably includes one or more wafers comprising an acidic ion exchange medium. The wafers are separated from one another by ion exchange membranes. The fluid within the acidic and/or basic ion exchange wafers preferably includes, or is in contact with, a carbonic anhydrase (CA) enzyme to facilitate conversion of bicarbonate ion to carbon dioxide within the acidic medium. A pH suitable for exchange of CO.sub.2 is electrochemically maintained within the basic and acidic ion exchange wafers by applying an electric potential across the cathode and anode.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

An X-band high-impedance relativistic klystron amplifier with an annular explosive cathode

The feasibility of employing an annular beam instead of a solid one in the X-band high-impedance relativistic klystron amplifier (RKA) is investigated in theory and simulation. Small-signal theory analysis indicates that the optimum bunching distance, fundamental current modulation depth, beam-coupling coefficient, and beam-loaded quality factor of annular beams are all larger than the corresponding parameters of solid beams at the same beam voltage and current. An annular beam RKA and a solid beam RKA with almost the same geometric parameters are compared in particle-in-cell simulation. Output microwave power of 100 MW, gain of 50 dB, and power conversion efficiency of 42% are obtained in an annular beam RKA. The annular beam needs a 15% lower uniform guiding magnetic field than the solid beam. Our investigations demonstrate that we are able to use a simple annular explosive cathode immersed in a lower uniform magnetic field instead of a solid thermionic cathode in a complicated partially shielding magnetic field for designing high-impedance RKA, which avoids high temperature requirement, complicated electron-optical system, large area convergence, high current density, and emission uniformity for the solid beam. An equivalent method for the annular beam and the solid beam on bunching features is proposed and agrees with the simulation. The annular beam has the primary advantages over the solid beam that it can employ the immersing uniform magnetic field avoiding the complicated shielding magnetic field system and needs a lower optimum guiding field due to the smaller space charge effect.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

Negative space charge effects in photon-enhanced thermionic emission solar converters

In thermionic energy converters, electrons in the gap between electrodes form a negative space charge and inhibit the emission of additional electrons, causing a significant reduction in conversion efficiency. However, in Photon Enhanced Thermionic Emission (PETE) solar energy converters, electrons that are reflected by the electric field in the gap return to the cathode with energy above the conduction band minimum. These electrons first occupy the conduction band from which they can be reemitted. This form of electron recycling makes PETE converters less susceptible to negative space charge loss. While the negative space charge effect was studied extensively in thermionic converters, modeling its effect in PETE converters does not account for important issues such as this form of electron recycling, nor the cathode thermal energy balance. Here, we investigate the space charge effect in PETE solar converters accounting for electron recycling, with full coupling of the cathode and gap models, and addressing conservation of both electric and thermal energy. The analysis shows that the negative space charge loss is lower than previously reported, allowing somewhat larger gaps compared to previous predictions. For a converter with a specific gap, there is an optimal solar flux concentration. The optimal solar flux concentration, the cathode temperature, and the efficiency all increase with smaller gaps. For example, for a gap of 3 μm the maximum efficiency is 38% and the optimal flux concentration is 628, while for a gap of 5 μm the maximum efficiency is 31% and optimal flux concentration is 163.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS2011

NASA Tech Briefs, February 2011

Topics covered include: Multi-Segment Radius Measurement Using an Absolute Distance Meter Through a Null Assembly; Fiber-Optic Magnetic-Field-Strength Measurement System for Lightning Detection; Photocatalytic Active Radiation Measurements and Use; Computer Generated Hologram System for Wavefront Measurement System Calibration; Non-Contact Thermal Properties Measurement with Low-Power Laser and IR Camera System; SpaceCube 2.0: An Advanced Hybrid Onboard Data Processor; CMOS Imager Has Better Cross-Talk and Full-Well Performance; High-Performance Wireless Telemetry; Telemetry-Based Ranging; JWST Wavefront Control Toolbox; Java Image I/O for VICAR, PDS, and ISIS; X-Band Acquisition Aid Software; Antimicrobial-Coated Granules for Disinfecting Water; Range 7 Scanner Integration with PaR Robot Scanning System; Methods of Antimicrobial Coating of Diverse Materials; High-Operating-Temperature Barrier Infrared Detector with Tailorable Cutoff Wavelength; A Model of Reduced Kinetics for Alkane Oxidation Using Constituents and Species for N-Heptane; Thermally Conductive Tape Based on Carbon Nanotube Arrays; Two Catalysts for Selective Oxidation of Contaminant Gases; Nanoscale Metal Oxide Semiconductors for Gas Sensing; Lightweight, Ultra-High-Temperature, CMC-Lined Carbon/Carbon Structures; Sample Acquisition and Handling System from a Remote Platform; Improved Rare-Earth Emitter Hollow Cathode; High-Temperature Smart Structures for Engine Noise Reduction and Performance Enhancement; Cryogenic Scan Mechanism for Fourier Transform Spectrometer; Piezoelectric Rotary Tube Motor; Thermoelectric Energy Conversion Technology for High-Altitude Airships; Combustor Computations for CO2-Neutral Aviation; Use of Dynamic Distortion to Predict and Alleviate Loss of Control; Cycle Time Reduction in Trapped Mercury Ion Atomic Frequency Standards; and A (201)Hg+ Comagnetometer for (199)Hg+ Trapped Ion Space Atomic Clocks.

Source record↗
DOE OSTI2015

Study on a discal TEM-TE{sub 11} mode converter loaded high-efficiency magnetically insulated transmission line oscillator

An integrative high power microwave device is proposed, which consists of a high-efficiency L-band Magnetically Insulated Transmission Line Oscillator (MILO) and a discal TEM–TE{sub 11} mode converter. The MILO with a shrunken load composed of a step-like cathode and a ladder-like beam collector can generate a 1.58 GHz, 5.7 GW microwave with the efficiency of 20.8% at the diode voltage of 560 kV in simulation. The discal converter utilizes a pair of sectorial two-double radial waveguides and a pair of sectorial cross section waveguides to adjust the phase-difference and realizes the mode conversion in a length of less than half wavelength at 1.58 GHz. In the preliminary experiment, the proposed device generates over 2 GW, 1.575 GHz microwave with the pulse duration of over 50 ns in a 420 kV diode voltage; the corresponding efficiency is 14.9%; the radiation pattern is the ideal TE{sub 11} mode.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Baselining Activity and Stability of ORR Catalysts and Electrodes for Proton Exchange Membrane Fuel Cells for Heavy-Duty Applications

Activity and stability of electrodes with Pt and PtCo alloy catalysts supported on high surface area carbon, hereafter to as a-Pt/C and d-PtCo/C, were evaluated for heavy-duty applications. Both catalysts had nearly identical Pt loading (50-wt% Pt on carbon and 0.25 mg Pt cm −2 ) and had undergone thermal treatment to stabilize them by growing the average particle size to 4–5 nm. Both were subjected to 90,000 (90 k) standard accelerated stress tests (AST) cycles consisting of 0.6–0.95 V square wave potentials, 3-s hold at upper and lower potential limits in H 2 /N 2 at 1.5 atm, 80 °C and 100% RH. Test protocols were developed to monitor the performance losses and characterize them in terms of activity for the oxygen reduction reaction (ORR), oxygen transport in the electrode and proton transport in the membrane and cathode catalyst layer. Despite the nearly double initial ORR activity, the PtCo/C electrode degraded faster due to the leaching of Co from the catalyst that had started even before the imposition of the AST potential cycles. Commensurate with Co leaching, Co poisoning of ionomer is responsible for the inferior performance of d-PtCo/C electrode at high current densities both before and after AST.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2016

LiCoO 2 -Based Fiber Cathodes for Electrospun Full Cell Li-ion Batteries

Here, particle/polymer electrospinning was used to prepare fiber mat cathodes containing LiCoO 2 nanoparticles, carbon powder, and poly(vinylidene fluoride) for Li-ion batteries. The fibers had a high LiCoO 2 particle content (70 wt%) which allowed for a high gravimetric capacity of 90 mAh g -1 (corresponding to 128 mAh g$-1\atop{LiCoO2}$) at 0.1C (1C = 274 mAh g$-1\atop{LiCoO2}$). Cathode performance was stable in a half cell with 78% capacity retention over 200 cycles at 0.5C. Unlike previous work on electrospun LiCoO 2 nanofibers prepared using sol-gel chemistry and high temperature processing, the particle/polymer fiber mat cathodes reported here were made thick with a high fiber volume fraction for high areal and volumetric capacities at fast charge/discharge rates (e.g., 0.81 mAh cm -2 and 62 mAh cm -3 at 2C) which were much greater than that of a slurry cast cathode of the same composition (0.004 mAh cm -2 and 0.30 mAh cm -3 at 2C). Full cells containing a LiCoO 2 /C/PVDF fiber mat cathode and C/PVDF fiber mat anode were also prepared and characterized. These electrospun batteries exhibited a high energy density of 144 Wh kg -1 at 0.1C and an areal capacity of 1.03 mAh cm -2 at 1C. The excellent performance of the electrospun particle/polymer cathodes and anodes is attributed to electrolyte penetration throughout the 3D fiber electrode mats, a large electrode/electrolyte interfacial area, and short Li + transport pathways between the electrolyte and active material nanoparticles in the radial fiber direction.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2014

Solid Oxide Fuel Cell Cathodes: Unraveling the Relationship Between Structure, Surface Chemistry and Oxygen Reduction

In this work we have considered oxygen reduction reaction on LSM and LSCF cathode materials. In particular we have used various spectroscopic techniques to explore the surface composition, transition metal oxidation state, and the bonding environment of oxygen to understand the changes that occur to the surface during the oxygen reduction process. In a parallel study we have employed patterned cathodes of both LSM and LSCF cathodes to extract transport and kinetic parameters associated with the oxygen reduction process.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2014

Organic photovoltaic cell incorporating electron conducting exciton blocking layers

The present disclosure relates to photosensitive optoelectronic devices including a compound blocking layer located between an acceptor material and a cathode, the compound blocking layer including: at least one electron conducting material, and at least one wide-gap electron conducting exciton blocking layer. For example, 3,4,9,10 perylenetetracarboxylic bisbenzimidazole (PTCBI) and 1,4,5,8-napthalene-tetracarboxylic-dianhydride (NTCDA) function as electron conducting and exciton blocking layers when interposed between the acceptor layer and cathode. Both materials serve as efficient electron conductors, leading to a fill factor as high as 0.70. By using an NTCDA/PTCBI compound blocking layer structure increased power conversion efficiency is achieved, compared to an analogous device using a conventional blocking layers shown to conduct electrons via damage-induced midgap states.

14 SOLAR ENERGY↗
DOE OSTI2016

Printed biofuel cells

Methods, systems, and devices are disclosed for implementing a biofuel cell device for extracting energy from a biofuel. In one aspect, a biofuel cell device includes a substrate, an anode including a catalyst to facilitate the conversion of a fuel in a biological fluid in an oxidative process that releases electrons captured at the anode, thereby extracting energy from the fuel substance, a cathode configured on the substrate adjacent to the anode and separated from the anode by a spacing region, and a load electrically coupled to the anode and cathode via electrical interconnects to obtain the extracted energy as electrical energy.

09 BIOMASS FUELS↗
DOE OSTI2021

Effect of Pressure and Temperature on Carbon Dioxide Reduction at a Plasmonically Active Silver Cathode

Here, carbon dioxide reduction at a plasmonically active silver cathode was investigated by varying the pressure and temperature at multiple applied potentials under both dark and illuminated conditions to understand the mechanism of selectivity changes driven by plasmon-enhanced electrochemical conversion. Carbon dioxide partial pressures (P Co 2 ) from 0.2 to 1 atm were studied during linear sweep voltammetry and chronoamperometry at -0.7, -0.9, and -1.1 V RHE . At a given applied overpotential the total current density increased with increasing P Co 2 in both the dark and the light, but there were significant differences in the Tafel behavior between dark and illuminated conditions. The reduction of CO 2 to carbon monoxide (CO) was found to have first-order behavior with respect to P Co 2 at all applied potentials in both the dark and the light, likely indicating no change in the rate-determining step upon illumination. Activity for the hydrogen (H 2 ) evolution reaction decreased with increasing P Co 2 at slightly different rates in the dark and the light at each applied potential, making it unclear if light is influencing CO or H 2 intermediate adsorbate coverage. Both formate and methanol production showed no dependence on P Co 2 under any conditions, but the true reaction orders may be masked by the much higher activity for CO and H 2 at the silver cathode. The investigation of product distribution with temperature at 14, 22, and 32°C at -0.7, -0.9, and -1.1 V RHE in both the dark and the light demonstrated that the selectivity changes observed upon illumination are not caused by local heating of the cathode surface.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Long-Term Cr Poisoning Effect on LSCF-GDC Composite Cathodes Sintered at Different Temperatures

Here, the impact of sintering temperature on Cr-poisoning of solid oxide fuel cell (SOFC) cathodes was systematically studied. La 0.6 Sr 0.4 Fe 0.8 Co 0.2 O 3-δ - Ce 0.9 Gd 0.1 O 2-δ symmetric cells were aged at 750°C in synthetic air with the presence of Crofer 22 APU, a common high temperature interconnect, over 200 hours and electrochemical impedance spectroscopy (EIS) was used to determine the degradation process. Both the ohmic resistance (R Ω ) and polarization resistance (R P ) of LSCF-GDC cells, extracted from EIS spectra, for different sintering temperatures increase as a function of aging time. Furthermore, the Cr-related degradation rate increases with decreased cathode sintering temperature. The polarization resistance of cathode sintered at lower temperature (950°C) increases dramatically while aging with the presence of Cr and also significantly decreases the oxygen partial pressure dependence after aging. The degradation rate shows a positive correlation to the concentration of Cr. The results indicate that decreased sintering temperature increases the total surface area, leading to more available sites for Sr-Cr-O nucleation and thus greater Cr degradation.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2020

Conductive spinels derived from Co–Mn based alloy precursor for SOFC cathode-side contact application

The utilization of gas-atomized Co–Mn based alloy precursor is a promising approach to lowering the sintering temperature of the spinel contact layer and enhancing its performance. In this work, simulated interconnect/contact/cathode cells are employed to investigate the effects of different metallic precursors (i.e., three Co–Mn based alloy powders and a mixture of Co + MnO 2 powders) on the microstructure and performance of the reactively-sintered MnCo 2 O 4 -based contact layer. While excellent overall electrical performance is observed for all the cells with the four contact precursors during 1000-h testing at 800 °C in air, the cell with the Ce-doped alloy contact precursor shows the lowest cell area specific resistance (ASR) and ASR degradation rate. Cross-sectional observation of the tested cells is conducted to assess the compatibility of the contact layer with adjacent components as well as its effectiveness in reducing the Cr 2 O 3 scale growth and blocking Cr migration from the interconnect to the cathode.

08 HYDROGEN↗
DOE OSTI2025

Controlling Interlayer Disorder Toward Reversible Phase Transition in a Layered Sodium Manganese Oxide Cathode

Sodium manganese oxides are promising Na-ion battery cathodes but they suffer from irreversible phase transitions during electrochemical reactions. Most strategies to date have aimed to suppress the phase transitions by stabilizing their layered structures through limiting the content of extractable Na + . Here, we conversely increase atomic disorder in the Na-birnessite, a layered sodium manganese oxide, and thereby modulate its phase transition behavior toward improved electrochemical reversibility. Our study reveals that Mn vacancies and Mn migrated into the interlayer affect interlayer local environment of Na + and water molecules consequently enhancing Na + mobility. We observe better capacity retention for disordered “D-Na-birnessite”, which undergoes a reversible phase transition from the birnessite-type structure to an O′3-type α-Na x MnO 2 -like structure through another intermediate metastable birnessite-type phase. In conclusion, this research highlights the positive effects of atomic disorder to regulate phase transition routes for achieving superior electrochemical reversibility, finally paving the way to overcoming the limits of layered oxide cathodes.

Kang, Seongkoo [Korea Univ., Seoul, (Korea, Republ↗