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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Space water electrolysis: Space Station through advance missions

Static Feed Electrolyzer (SFE) technology can satisfy the need for oxygen (O2) and Hydrogen (H2) in the Space Station Freedom and future advanced missions. The efficiency with which the SFE technology can be used to generate O2 and H2 is one of its major advantages. In fact, the SFE is baselined for the Oxygen Generation Assembly within the Space Station Freedom's Environmental Control and Life Support System (ECLSS). In the conventional SFE process an alkaline electrolyte is contained within the matrix and is sandwiched between two porous electrodes. The electrodes and matrix make up a unitized cell core. The electrolyte provides the necessary path for the transport of water and ions between the electrodes, and forms a barrier to the diffusion of O2 and H2. A hydrophobic, microporous membrane permits water vapor to diffuse from the feed water to the cell core. This membrane separates the liquid feed water from the product H2, and, therefore, avoids direct contact of the electrodes by the feed water. The feed water is also circulated through an external heat exchanger to control the temperature of the cell.

Ronald J Davenport↗
DOE OSTI2024

Electrochemical Imaging of Precisely‐Defined Redox and Reactive Interfaces

Abstract Understanding the diverse electrochemical reactions occurring at electrode‐electrolyte interfaces (EEIs) is a critical challenge to developing more efficient energy conversion and storage technologies. Establishing a predictive molecular‐level understanding of solid electrolyte interphases (SEIs) is challenging due to the presence of multiple intertwined chemical and electrochemical processes occurring at battery electrodes. Similarly, chemical conversions in reactive electrochemical systems are often influenced by the heterogeneous distribution of active sites, surface defects, and catalyst particle sizes. In this mini review, we highlight an emerging field of interfacial science that isolates the impact of specific chemical species by preparing precisely‐defined EEIs and visualizing the reactivity of their individual components using single‐entity characterization techniques. We highlight the broad applicability and versatility of these methods, along with current state‐of‐the‐art instrumentation and future opportunities for these approaches to address key scientific challenges related to batteries, chemical separations, and fuel cells. We establish that controlled preparation of well‐defined electrodes combined with single entity characterization will be crucial to filling key knowledge gaps and advancing the theories used to describe and predict chemical and physical processes occurring at EEIs and accelerating new materials discovery for energy applications.

Edgecomb, Joseph↗
DOE OSTI2024

Electrochemical Imaging of Precisely‐Defined Redox and Reactive Interfaces

Abstract Understanding the diverse electrochemical reactions occurring at electrode‐electrolyte interfaces (EEIs) is a critical challenge to developing more efficient energy conversion and storage technologies. Establishing a predictive molecular‐level understanding of solid electrolyte interphases (SEIs) is challenging due to the presence of multiple intertwined chemical and electrochemical processes occurring at battery electrodes. Similarly, chemical conversions in reactive electrochemical systems are often influenced by the heterogeneous distribution of active sites, surface defects, and catalyst particle sizes. In this mini review, we highlight an emerging field of interfacial science that isolates the impact of specific chemical species by preparing precisely‐defined EEIs and visualizing the reactivity of their individual components using single‐entity characterization techniques. We highlight the broad applicability and versatility of these methods, along with current state‐of‐the‐art instrumentation and future opportunities for these approaches to address key scientific challenges related to batteries, chemical separations, and fuel cells. We establish that controlled preparation of well‐defined electrodes combined with single entity characterization will be crucial to filling key knowledge gaps and advancing the theories used to describe and predict chemical and physical processes occurring at EEIs and accelerating new materials discovery for energy applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Designing Anion-Exchange Ionomers with Oriented Nanoscale Phase Separation at a Silver Interface

We report performance of polymer electrolyte-based energy systems is significantly impacted by transport within the electrode catalyst layer, where ionomer thin films coat catalyst particles. Proton exchange ionomer thin films have been thoroughly characterized, but few studies have critically examined anion-exchange ionomer (AEI) thin films. Further, none have reported nanoscale phase separation for hydrocarbon AEIs, which is critical to mitigate transport resistances. In this work, a set of hydrocarbon-based AEIs with nanoscale phase separation are developed from tunable block copolymer systems composed of polyisoprene (PIp) and polychloromethylstyrene (PCMS). The effect of the PIp/PCMS ratio, architecture, and thickness on the thin-film morphology of the neutral block copolymer precursors on silicon and silver substrates is investigated using grazing-incidence small-angle X-ray scattering (GISAXS) and atomic force microscopy (AFM). AEIs are prepared by quaternizing with trimethylamine or methylpiperidine and their cation-dependent morphology is characterized at 60 °C and 95% RH. A perpendicularly aligned morphology is observed on silver, while no phase separation is observed on silicon, indicating that silver-polymer interfacial interactions drive phase separation. After quaternization, dipole-dipole interactions induce some disorder, but nanoscale phase separation is still maintained. GISAXS patterns are modeled using a Unified Fit approach to understand water uptake and swelling, and recommendations for AEI design are presented.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Zincate-Blocking-Functionalized Polysulfone Separators for Secondary Zn–MnO 2 Batteries

Alkaline zinc–manganese dioxide (Zn–MnO 2 ) batteries are well suited for grid storage applications because of their inherently safe, aqueous electrolyte and established materials supply chain, resulting in low production costs. With recent advances in the development of Cu/Bi-stabilized birnessite cathodes capable of the full 2-electron capacity equivalent of MnO 2 (617 mA h/g), there is a need for selective separators that prevent zincate (Zn(OH) 4 ) 2– transport from the anode to the cathode during cycling, as this electrode system fails in the presence of dissolved zinc. In this work, we present the synthesis of N-butylimidazolium-functionalized polysulfone (NBI-PSU)-based separators and evaluate their ability to selectively transport hydroxide over zincate. We then examine their impact on the cycling of high depth of discharge Zn/(Cu/Bi–MnO 2 ) batteries when inserted in between the cathode and anode. Initially, we establish our membranes’ selectivity by performing zincate and hydroxide diffusion tests, showing a marked improvement in zincate-blocking (D Zn (cm 2 /min): 0.17 ± 0.04 × 10 –6 for 50-PSU, our most selective separator vs 2.0 ± 0.8 × 10 –6 for Cellophane 350P00 and 5.7 ± 0.8 × 10 –6 for Celgard 3501), while maintaining similar crossover rates for hydroxide (D OH (cm 2 /min): 9.4 ± 0.1 × 10 –6 for 50-PSU vs 17 ± 0.5 × 10 –6 for Cellophane 350P00 and 6.7 ± 0.6 × 10 –6 for Celgard 3501). We then implement our membranes into cells and observe an improvement in cycle life over control cells containing only the commercial separators (cell lifetime extended from 21 to 79 cycles).

crossover↗
DOE OSTI2022

Fast charging of Li-ion cells: Effect of separator membranes and mapping of “safe lines” to avoid Li plating

An experimental method is introduced that uses microprobe Li/Cu reference electrodes to map "safe" charging regimes to avoid Li metal plating on graphite anodes at rates to 8C. With this method, a Li-ion cell closely approaches the Li plating condition but avoids descending into this regime. This "safe" approach is used to demonstrate effects of the microporous separator on Li plating in cells consisting of a layered nickel-manganese -cobalt oxide cathode and graphite anode. We argue that most of the difference in behaviors for different separators arises from time delayed Li + ion percolation through the membrane. In conclusion, our study suggests that explicitly treating kinetics of phase transitions in the lithiated graphite anode is essential for electrochemical models predicting "safe" lines for fast charging cells.

25 ENERGY STORAGE↗
DOE OSTI2020

Safe, Low-Cost, High Energy-Density, Solid-State Li-Ion Batteries

We developed intrinsically safe, robust, low-cost, high-energy-density solid-state Li-ion batteries, by integrating high conductivity garnet-type solid Li ion electrolytes and several different cathodes in tailored microstructures, fabricated by low-cost supported thin-film ceramic techniques, to overcome the primary technological barriers to next generation battery technology. In this ARPA-E project we employed Li-garnet solid-state electrolytes pioneered by one of the co-investigators (Thangadurai) which has room temperature (RT) conductivity of ~10 -3 S cm -1 . The highly stable garnet SSE allowed the use of S, NMC, and other cathodes with Li metal anodes without stability or flammability concerns. We studied the garnet’s stability when exposed to CO 2 and humidity (with or without an ALD coating) and showed that the material can be processed in ambient air for most steps prior to battery assembly, significantly reducing production costs. We extensively studied and scaled up the synthesis of the powder and explored external suppliers of garnet to determine the best pathway for commercial success. We used low-cost and scalable tapecasting fabrication methods to create porous-dense-porous “trilayer” solid electrolyte microstructures with a ~20 μm separating dense layer, and >70% porosity porous layers to host the electrodes. These scalable multilayer ceramic fabrication techniques, without need for dry rooms or vacuum equipment, also provide for dramatically reduced manufacturing costs. The tailored microstructured electrode supports (scaffold) increased interfacial area ~50x, overcoming the high impedance typical of planar geometry SSLiBs, resulting in record-setting 10 mA/cm 2 lithium cycling in a symmetric cell. We expanded our tapecasting ability and showed tapes >25m in length by the end of the project. We demonstrated the ability to sinter garnet without the use of a garnet powderbed, which could have been a major obstacle and waste of material at scale. At the same time, we expanded the size of our trilayers from coin cells (0.7 cm 2 ) to the full format design (30 cm 2 ). To develop full cells, we demonstrated 250 Wh/kg at room temperature with commercial NMC electrode films in a bilayer configuration. Similarly, we demonstrated 280 Wh/kg trilayer Li-S cells at room temperature with >90% capacity retention over 300 cycles. At 90°C we demonstrated 350 Wh/kg with a Li-S trilayer. The high thermal stability of the garnet electrolyte also enabled extended cycling (400 cycles) of a Li-TiS 2 cell at 150 °C, showcasing the exceptional safety and nonflammability of the solid-state trilayer batteries. Ion Storage Systems has taken this technology and knowledge to produce trilayer garnet electrolytes and is building out facilities to commercialize high performance solid state batteries. ISS has hired a strong staff, identified and communicated with a large number of potential partners, and successfully secured follow-on funding.

25 ENERGY STORAGE↗
DOE OSTI2024

Catalytic Reduction of Carbon Monoxide to Liquid Fuels with Recyclable Hydride Donors

Solar light absorption and catalysis are physically separated processes in natural photosynthesis. Natural cofactors, such as nicotinamide adenine dinucleotides (NADH), transport electrons and hydrogen to regulate and activate enzymes at remote locations. The physical separation of light absorption from catalysis provides some inspiration for artificial photosynthesis. One rather extreme implementation is to use copper wires to transport carriers from photovoltaic cells to dark electrodes, where catalysis occurs. Indeed, with a futuristic electrical grid powered solely by photovoltaics, solar capture could be separated from catalysis by hundreds of miles. An alternative approach, that bares more similarity to natural photosynthesis, employs mobile NADH/NAD + -like species that shuttle between the light absorber and a proximate, yet unilluminated, location where catalysis occurs. Additionally, such a remote approach to solar photocatalysis was recently proposed for the reduction of carbon oxides, CO 2 and CO, to methanol by cascade catalysis. This developing artificial photosynthetic approach offers the promise of catalytic generation of methanol and oxygen gas with sunlight as the sole energy source and CO 2 and water as the only chemical feedstocks. This Viewpoint evaluates the strengths and weaknesses of this approach with an emphasis on CO reduction catalysis with photorecyclable hydride donors while looking forward to what might reasonably be achieved with continued research.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Direct Measurements of Ionic Transport Behavior of Dual-Layer Porous Electrodes

To improve power and cycling performance of lithium-ion batteries, dual-layer or porosity-gradient electrodes have been proposed. By engineering a higher porosity close to the separator, the intention is to improve ion transport where it is most impactful. In this research, MacMullin numbers of two dual-layer anode samples are tested using an impedance measurement technique developed previously. To characterize the microstructure of each layer independently, we developed an improved transmission-line model that accounts for each layer's properties.Virtual experiments using COMSOL Multiphysics to simulate impedance measurements are used to examine and improve the accuracy of the numerical inversion procedure. The results for the two dual-layer anodes studied show that MacMullin numbers follow expected trends, though the anodes are quite different from each other.

Dual-Layer Electrodes↗
NASA NTRS2012

Measurements and Simulations of Surface Dielectric Barrier Discharges Used as Plasma Actuators

This report is a Ph.D. dissertation performed under NRA cooperative agreement and submitted as part of the final report. Asymmetric surface dielectric barrier discharges (DBDs) have shown promise for use as aerodynamic actuators for active flow control. In this project we studied DBD actuators experimentally and numerically. Our DBDs used a symmetric triangular high voltage waveform to generate plasma in atmospheric pressure air. Time-averaged measurements indicated that the induced force of a single barrier actuator design (one electrode insulated from the plasma) can be increased exponentially above the results of previous studies by decreasing both the length and thickness of the electrode exposed to the plasma. This increased force may allow these devices to control flow separation in a wider range of flow environments. Experiments using an intensified digital camera to examine the plasma on time scales of a few nanoseconds showed that, in addition to the previously-observed filamentary and jet-like plasma structures, discharges with very thin exposed electrodes exhibited a weak but constant plasma immediately adjacent to those electrodes. In double-barrier actuators (both electrodes insulated), decreasing the diameter of the narrower electrode lead to increasing forces, and recorded images showed the simultaneous existence of both filamentary and jet-like plasma structures. The development and application of a time-dependent, two-dimensional computational fluid plasma model has aided in understanding the detailed physics of surface DBDs at all-time scales. For simulated single-barrier discharges, the model qualitatively reproduced the filamentary and jet-like micro-discharge structures. The model was somewhat successful in reproducing the observed characteristics of double-barrier actuators. For both actuator geometries, the model indicated that the majority of the forces induced on the neutral gas occur in between micro-discharges as the plasmas decay.

Hoskinson, Alan R.↗
NASA NTRS2008

Directed Growth of Carbon Nanotubes Across Gaps

An experiment has shown that when single-walled carbon nanotubes (SWNTs) are grown by chemical vapor deposition in the presence of an electric field of suitable strength, the nanotubes become aligned along the electric field. In an important class of contemplated applications, one would exploit this finding in fabricating nanotube transistors; one would grow SWNTs across gaps between electrodes that would serve, subsequently, as source and drain contacts during operation of the transistors. In preparation for the experiment, a multilayer catalyst comprising a 20-nmthick underlayer of iridium (platinum group), a 1-nm-thick middle layer of iron, and a 0.2-nm-thick outer layer of molybdenum was ion-beam sputtered onto a quartz substrate. A 25 micrometers-diameter iron wire was used as a shadow mask during the sputtering to create a 25 micrometers gap in the catalyst. Then electrical leads were connected to the catalyst areas separated by the gap so that these catalyst areas would also serve as electrodes. The substrate as thus prepared was placed in a growth chamber that consisted of a quartz tube of 1-in. (2.54-cm) diameter enclosed in a furnace. SWNTs of acceptably high quantity and quality were grown in 10 minutes with methane at atmospheric pressure flowing through the chamber at a rate of 1,000 standard cubic centimeters per minute at a temperature of 900 C. To prevent oxidation of the SWNTs, the chamber was purged with 99.999-percent pure argon before and after growth, and the chamber was cooled to less than 300 C before opening it to the atmosphere after growth. When no voltage was applied across the gap, the SWNTs grew in random directions extending out from the edges of the catalyst at the gap. When a potential of 10 V was applied between the catalyst/electrode areas to create an electric field across the gap, the SWNTs grew across the gap, as shown in the figure.

Delzeit, Lance↗
NASA NTRS1984

NASA Redox Storage System Development Project

The Redox Storage System Technology Project was jointly supported by the U.S. Department of Energy and NASA. The objectives of the project were to develop the Redox flow battery concept and to probe its technical and economic viability. The iron and chromium redox couples were selected as the reactants. Membranes and electrodes were developed for the original mode of operating at 25 C with the reactants separated by an ion-exchange membrane. Analytical capabilities and system-level operating concepts were developed and verified in a 1-kW, 13-kWh preprototype system. A subsequent change was made in operating mode, going to 65 C and using mixed reactants. New membranes and a new electrode catalyst were developed, resulting in single cell operation as high as 80 mA/sq cm with energy efficiencies greater than 80 percent. Studies indicate a likely system cost of about $75/kWh. Standard Oil of Ohio (Sohio) has undertaken further development of the Redox system. An exclusive patent license was obtained from NASA by Sohio. Transfer of Redox technology to Sohio is supported by the NASA Technology Utilization Office.

Hagedorn, N. H.↗
DOE OSTI2024

Bilayer Ion Trap Design for 2D Arrays

Junctions are fundamental elements that support qubit locomotion in two-dimensional ion trap arrays and enhance connectivity in emerging trapped-ion quantum computers. In surface ion traps they have typically been implemented by shaping radio frequency (RF) electrodes in a single plane to minimize the disturbance to the pseudopotential. However, this method introduces issues related to RF lead routing that can increase power dissipation and the likelihood of voltage breakdown. Here, we propose and simulate a novel two-layer junction design incorporating two perpendicularly rotoreflected (rotated, then reflected) linear ion traps. The traps are vertically separated, and create a trapping potential between their respective planes. The orthogonal orientation of the RF electrodes of each trap relative to the other provides perpendicular axes of confinement that can be used to realize transport in two dimensions. While this design introduces manufacturing and operating challenges, as now two separate structures have to be precisely positioned relative to each other in the vertical direction and optical access from the top is obscured, it obviates the need to route RF leads below the top surface of the trap and eliminates the pseudopotential bumps that occur in typical junctions. Here in this paper the stability of idealized ion transfer in the new configuration is demonstrated, both by solving the Mathieu equation analytically to identify the stable regions and by numerically modeling ion dynamics. Our novel junction layout has the potential to enhance the flexibility of microfabricated ion trap control to enable large-scale trapped-ion quantum computing.

42 ENGINEERING↗
NASA NTRS2000

A Diamond Electron Tunneling Micro-Electromechanical Sensor

A new pressure sensing device using field emission from diamond coated silicon tips has been developed. A high electric field applied between a nano-tip array and a diaphragm configured as electrodes produces electron emission governed by the Fowler Nordheim equation. The electron emission is very sensitive to the separation between the diaphragm and the tips, which is fixed at an initial spacing and bonded such that a cavity is created between them. Pressure applied to the diaphragm decreases the spacing between the electrodes, thereby increasing the number of electrons emitted. Silicon has been used as a substrate on which arrays of diamond coated sharp tips have been fabricated for electron emission. Also, a diaphragm has been made using wet orientation dependent etching. These two structures were bonded together using epoxy and tested. Current - voltage measurements were made at varying pressures for 1-5 V biasing conditions. The sensitivity was found to be 2.13 mV/V/psi for a 20 x 20 array, which is comparable to that of silicon piezoresistive transducers. Thinner diaphragms as well as alternative methods of bonding are expected to improve the electrical characteristics of the device. This transducer will find applications in many engineering fields for pressure measurement.

Albin, Sacharia↗
DOE OSTI2020

Bismuth Detection in Alkaline Electrolyte via Anodic Stripping Voltammetry for Battery Separator Evaluation

Abstract Anodic stripping voltammetry (ASV) has been widely used for the detection of several heavy metal ions in neutral and acidic solution, in many cases employing electrodes and/or solutions incorporating Bi. In this work we demonstrate that Bi(OH) 4 − ion concentration can be measured in highly alkaline 8.5 M KOH solution using ASV. The addition of Pb in similar concentrations to the Bi(OH) 4 − being measured is shown to improve both the sensitivity and precision of the method. When the Pb additive is employed, a formal limit of detection of 8.5 ppb is achieved, compared to 17.3 ppb when the Pb additive is not used. Due to the use of Bi additives in alkaline battery chemistries, it follows that separators which limit Bi(OH) 4 − diffusion into the bulk electrolyte and away from the electrodes are of interest. For this purpose, we utilize ASV to determine Bi(OH) 4 − diffusion rates through Celgard 3501, cellophane 350P00, and Nafion 211. Bi(OH) 4 − crossover rates, as determined by ASV, are shown to be repeatable and consistent with expectations from the known separator structure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Structure and Potential–Dependent Selectivity in Redox–Metallopolymers: Electrochemically Mediated Multicomponent Metal Separations

Electro-responsive functional materials can play a critical role in selective metal recovery and recycling due to the need for molecular differentiation between transition metals in complex mixtures. Redox-active metallopolymers are a promising platform for electrochemical separations, offering versatile structural tuning and fast electron transfer. First, through a judicious selection of polymer structure between a main-chain metallopolymer (polyferrocenylsilane) and a pendant-group metallopolymer (polyvinylferrocene), charge-transfer interactions and binding strength toward competing metal ions are tuned, which as a result, dictate selectivity. For example, almost an order of magnitude increase in separation factor between chromate and meta-vanadate can be achieved, depending on polymer structure. Second, these metallopolymer electrodes exhibit potential-dependent selectivity that can even flip ion preference, based solely on electrical means—indicating a control parameter that is orthogonal to structural modifications. Finally, this work presents a framework for evaluating electrochemical separations in multicomponent ion mixtures and elucidates the underlying charge-transfer mechanisms resulting in molecular selectivity through a combination of spectroscopy and electronic structure calculations. Furthermore, the findings demonstrate the applicability of redox-metallopolymers in tailored electrochemical separations for environmental remediation, value-added metal recovery, waste recycling, and even mining processing.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

A Flexible, Redox-Active, Aqueous Electrolyte-Based Asymmetric Supercapacitor with High Energy Density Based on Keratin-Derived Renewable Carbon

This work exploits the advantage of asymmetric configuration over symmetric supercapacitor in designing high energy density flexible devices from two active electrode materials–keratin-based renewable-resource hierarchically porous carbon and hydrous ruthenium oxide (RuO 2 ). Here, the asymmetric device exhibits significantly high capacitance. Conventional estimation of energy storage parameters, however, cannot be applied for devices with a Faradaic energy storage contribution via redox charge transfer mechanism. Therefore, this work applies a precise measurement of pseudocapacitance contribution at various scan rates to correct the device data that reveals effective capacitance of 120 F g –1 with the energy density of 37 W h kg –1 at 776 W kg –1 . It also retains excellent rate capability, >74% at high current density 25 A g –1 . The charge storage activity and device stability can be further enhanced by introducing redox-active electrolytes that improve specific capacitance, but the rate capabilities deteriorate at high current densities. Further, the principle of asymmetric electrode design is applied to fabricate a bending-tolerant, flexible device by depositing active electrode material on wire-shaped current collector followed by coupling those separated with polyvinyl alcohol gel containing redox electrolyte; it yields 36.8 mF cm –1 specific capacitance at a 0.2 mA cm –1 current density.

36 MATERIALS SCIENCE↗