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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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26 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Revisiting the Role of Conductivity and Polarity of Host Materials for Long-Life Lithium–Sulfur Battery

Despite their high theoretical energy density and low cost, lithium-sulfur batteries (LSBs) suffer from poor cycle life and low energy efficiency owing to the polysulfides shuttle and the electronic insulating nature of sulfur. Conductivity and polarity are two critical parameters for the search of optimal sulfur host materials. However, their role in immobilizing polysulfides and enhancing redox kinetics for long-life LSBs are not fully understood. In this work we have conducted an evaluation on the role of polarity over conductivity by using a polar but nonconductive platelet ordered mesoporous silica (pOMS) and its replica platelet ordered mesoporous carbon (pOMC), which is conductive but nonpolar. It is found that the polar pOMS/S cathode with a sulfur mass fraction of 80 wt% demonstrates outstanding long-term cycle stability for 2000 cycles even at a high current density of 2C. Furthermore, the pOMS/S cathode with a high sulfur loading of 6.5 mg cm -2 illustrates high areal and volumetric capacities with high capacity retention. Complementary physical and electrochemical probes clearly show that surface polarity and structure are more dominant factors for sulfur utilization efficiency and long-life, while the conductivity can be compensated by the conductive agent involved as a required electrode material during electrode preparation. The present findings shed new light on the design principles of sulfur hosts towards long-life and highly efficient LSBs.

25 ENERGY STORAGE↗
DOE OSTI2022

Structure/Interface Coupling Effect for High-Voltage LiCoO 2 Cathodes

LiCoO 2 (LCO) is widely applied in today's rechargeable battery markets for consumer electronic devices. However, LCO operations at high voltage are hindered by accelerated structure degradation and electrode/electrolyte interface decomposition. To overcome these challenges, co-modified LCO (defined as CB-Mg-LCO) that couples pillar structures with interface shielding are successfully synthesized for achieving high-energy-density and structurally stable cathode material. Benefitting from the "Mg-pillar" effect, irreversible phase transitions are significantly suppressed and highly reversible Li + shuttling is enabled. Interestingly, bonding effects between the interfacial lattice oxygen of CB-Mg-LCO and amorphous Co x B y coating layer are found to elevate the formation energy of oxygen vacancies, thereby considerably mitigating lattice oxygen loss and inhibiting irreversible phase transformation. Meanwhile, interface shielding effects are also beneficial for mitigating parasitic electrode/electrolyte reactions, subsequent Co dissolution, and ultimately enable a robust electrode/electrolyte interface. As a result, the as-designed CB-Mg-LCO cathode achieves a high capacity and excellent cycle stability with 94.6% capacity retention at an extremely high cut-off voltage of 4.6 V. We report these findings provide new insights for cathode material modification methods, which serves to guide future cathode material design.

25 ENERGY STORAGE↗
DOE OSTI2021

The Role of Metal Oxides in Li-S Batteries: A High-Areal-Capacity Sulfur Composite Cathode Investigation

Compared to lithium-ion batteries (LIB), lithium-sulfur (Li-S) batteries have low cost and high theoretical specific energy (2510 Wh/kg or about 10 times of the LIB). However, Li-S batteries have several challenges, including large volume expansion, poor utilization of the end products, sluggish kinetics of polysulfides, and crossover, so-called the "shuttle effect". To address these issues, we have introduced metal oxides to the Li-S electrode to develop a metal-oxide-sulfur composite electrode. We aim to use metal oxides to assist the Li-S formation (dissociation) during discharge (charge) cycles. We elect to focus on LIB-based metal oxides to ensure that the added material can contribute storage capacity to the battery. Our cathodes are fabricated by both the conventional slurry casting and air-controlled electrospray. LIB electrode materials, such as Li(Ni 0.6 Mn 0.6 Co 0.2 )O 2 , LiMn 2 O 4 , Li 2 TiO 3 , etc, were incorporated with the sulfur-carbon composite and their charge-discharge performances are compared. We found that the presence of metal oxides increased sulfur utilization with stable cycling performance, even in cells with high areal capacities. To unveil the interactions between lithium metal oxides and sulfur, the cathodes were analyzed by various characterization techniques, including scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, and electrochemistry. The analysis of the role of the oxides will be presented along with the reaction mechanism.

25 ENERGY STORAGE↗
DOE OSTI2025

Size-Selective Nanoporous Atomically Thin Graphene Separators for Lithium–Sulfur Batteries

Lithium–sulfur batteries (LSBs) are extensively researched for their high energy densities but are hindered by the lithium polysulfide (LiPS) shuttling effect, which results in poor cyclability. A popular mitigation strategy is separator modification, where a LiPS trapping material is slurry-coated onto a conventional microporous polypropylene (PP) separator. This additional mass and volume unfortunately compromise the overall energy density of the LSB. This study aims to take a separator modification approach that avoids this issue. Nanoporous atomically thin membranes (NATMs) made of graphene are gaining attention for their scalable synthesis, tunable pore size, and negligible pore length. Herein, we apply a well-characterized graphene NATM for reasons similar to those of a size-selective interlayer in LSBs. The tailored pore size of ∼0.7–1.0 nm and atomic thinness facilitate the passage of Li + (solvated ionic diameters ∼0.54–1.26 nm) and blockage of larger LiPS (solvated ionic diameters ∼0.81–1.69 nm) without adding significant impedances or mass. The sulfur confinement is confirmed through scanning electron microscopy and energy-dispersive X-ray spectroscopy elemental analysis of the Li anode. An LSB with a NATM@PP separator shows virtually no capacity loss over 150 cycles, demonstrating efficacy of size-selective molecular sieving using NATMs in LSBs.

battery separator↗
NASA NTRS2008

Intelligent Memory Module Overcomes Harsh Environments

Solar cells, integrated circuits, and sensors are essential to manned and unmanned space flight and exploration, but such systems are highly susceptible to damage from radiation. Especially problematic, the Van Allen radiation belts encircle Earth in concentric radioactive tori at distances from about 6,300 to 38,000 km, though the inner radiation belt can dip as low as 700 km, posing a severe hazard to craft and humans leaving Earth s atmosphere. To avoid this radiation, the International Space Station and space shuttles orbit at altitudes between 275 and 460 km, below the belts range, and Apollo astronauts skirted the edge of the belts to minimize exposure, passing swiftly through thinner sections of the belts and thereby avoiding significant side effects. This radiation can, however, prove detrimental to improperly protected electronics on satellites that spend the majority of their service life in the harsh environment of the belts. Compact, high-performance electronics that can withstand extreme environmental and radiation stress are thus critical to future space missions. Increasing miniaturization of electronics addresses the need for lighter weight in launch payloads, as launch costs put weight at a premium. Likewise, improved memory technologies have reduced size, cost, mass, power demand, and system complexity, and improved high-bandwidth communication to meet the data volume needs of the next-generation high-resolution sensors. This very miniaturization, however, has exacerbated system susceptibility to radiation, as the charge of ions may meet or exceed that of circuitry, overwhelming the circuit and disrupting operation of a satellite. The Hubble Space Telescope, for example, must turn off its sensors when passing through intense radiation to maintain reliable operation. To address the need for improved data quality, additional capacity for raw and processed data, ever-increasing resolution, and radiation tolerance, NASA spurred the development of the Radiation Tolerant Intelligent Memory Stack (RTIMS).

Source record↗
NASA NTRS2005

JSC Pharmacy Services for Remote Operations

The Johnson Space Center Pharmacy began operating in March of 2003. The pharmacy serves in two main capacities: to directly provide medications and services in support of the medical clinics at the Johnson Space Center, physician travel kits for NASA flight surgeon staff, and remote operations, such as the clinics in Devon Island, Star City and Moscow; and indirectly provide medications and services for the International Space Station and Space Shuttle medical kits. Process changes that occurred and continued to evolve in the advent of the installation of the new JSC Pharmacy, and the process of stocking medications for each of these aforementioned areas will be discussed. Methods: The incorporation of pharmacy involvement to provide services for remote operations and supplying medical kits was evaluated. The first step was to review the current processes and work the JSC Pharmacy into the existing system. The second step was to provide medications to these areas. Considerations for the timeline of expiring medications for shipment are reviewed with each request. The third step was the development of a process to provide accountability for the medications. Results: The JSC Pharmacy utilizes a pharmacy management system to document all medications leaving the pharmacy. Challenges inherent to providing medications to remote areas were encountered. A process has been designed to incorporate usage into the electronic medical record upon return of the information from these remote areas. This is an evolving program and several areas have been identified for further improvement.

Stoner, Paul S.↗
NASA NTRS2001

First Experimental Demonstration of Full-Duplex Optical Communication on a Single Beam

The satellite industry is driven by the need to reduce costs. One way they have sought to do this is by reducing the size and weight of the satellite because of the extremely high cost per kilogram incurred launching a payload into orbit. The main difficulty in this approach is the lack of power capacity in a small satellite. One of the largest loads on a satellite's power system is the communications system. This has driven the need for a low-power communications system. This document examines a novel method of communicating optically with a low-Earth-orbit satellite from the ground without the need for a laser on the payload. The goal is to show the feasibility of such a system as a solution to the small satellite low-powered communication problem. Specially, that the system described herein: is capable of ground to low-Earth-orbit communications, has very little space-borne mass, and draws little power from the satellite. First, the system (hereafter referred to as LOWCAL "Lightweight Optical Wavelength Communication without A Laser in space") will be explained with details of the formats used and the link budgets. Discussions will be presented on the development of some of the system hardware (the laser diode driver, liquid crystal driver, and decision electronics for both the up and down links.) Finally, experimental test results of the entire system operating in a laboratory environment are presented and compared to theory. The results of the laboratory experiment support the original thesis: retro-modulated optical communications can meet the needs of the small satellite community. The system is capable of 10-kbps communication, has low space-borne mass, and draws little power from the satellite (less than 100-mW measured for the laboratory experiment, less than 1.5-W calculated for the Shuttle experiment).

Garrett, Christopher David↗
NASA NTRS2002

Ion Storage Tests with the High Performance Antimatter Trap (HiPAT)

The NASA/Marshall Space Flight Centers (NASA/MSFC) Propulsion Research Center (PRC) is evaluating an antiproton storage system, referred to as the High Performance Antiproton Trap (HiPAT). This interest stems from the sheer energy represented by matter/antimatter annihilation process with has an energy density approximately 10 order of magnitude above that of chemical propellants. In other terms, one gram of antiprotons contains the equivalent energy of approximately 23 space shuttle external tanks or ET's (each ET contains roughly 740,000 kgs of fuel and oxidizer). This incredible source of stored energy, if harnessed, would be an enabling technology for deep space mission where both spacecraft weight and propulsion performance are key to satisfying aggressive mission requirements. The HiPAT hardware consists of a 4 Tesla superconductor system, an ultra high vacuum test section (vacuum approaching 10(exp -12) torr), and a high voltage confinement electrode system (up to 20 kvolts operation). The current laboratory layout is illustrated. The HiPAT designed objectives included storage of up to 1 trillion antiprotons with corresponding lifetimes approaching 18 days. To date, testing has centered on the storage of positive hydrogen ions produced in situ by a stream of high-energy electrons that passes through the trapping region. However, due to space charge issues and electron beam compression as it passes through the HiPAT central field, current ion production is limited to less then 50,000 ions. Ion lifetime was determined by counting particle populations at the end of various storage time intervals. Particle detection was accomplished by destructively expelling the ions against a micro-channel plate located just outside the traps magnetic field. The effect of radio frequency (RF) stabilization on the lifetime of trapped particles was also examined. This technique, referred to as a rotating wall, made use of a segmented electrode located near the center of the trap on which various phases of a particular frequency were applied. Various experiments were performed illustrating the ability of an RF drive to both prolong and reduced the lifetimes of various ion species depending on the selected frequency. HiPAT is now being reconfigured for testing with an ion source that will provide both positive and negative hydrogen ions from an external source. This ion system shall provide higher fill capacity (order of million of ions per shot), stacking of multiple shots, and injection schemes typical of a realistic antiproton delivery system.

Martin, James J.↗