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At least 307 records · Page 17

NASA Tech Briefs, January 2012

Contents of this issue are: (1) Energy-Based Tetrahedron Sensor for High-Temperature, High-Pressure Environments (2) Handheld Universal Diagnostic Sensor (3) Large-Area Vacuum Ultraviolet Sensors (4) Fiber Bragg Grating Sensor System for Monitoring Smart Composite Aerospace Structures (5) Health-Enabled Smart Sensor Fusion Technology (6) Extended-Range Passive RFID and Sensor Tags (7) Hybrid Collaborative Learning for Classification and Clustering in Sensor Networks (8) Self-Healing, Inflatable, Rigidizable Shelter (9) Improvements in Cold-Plate Fabrication (10) Technique for Radiometer and Antenna Array Calibration - TRAAC (11) Real-Time Cognitive Computing Architecture for Data Fusion in a Dynamic Environment (12) Programmable Digital Controller (13) Use of CCSDS Packets Over SpaceWire to Control Hardware (14) Key Decision Record Creation and Approval Module (15) Enhanced Graphics for Extended Scale Range (16) Debris Examination Using Ballistic and Radar Integrated Software (17) Data Distribution System (DDS) and Solar Dynamic Observatory Ground Station (SDOGS) (18) Integration Manager (19) Eclipse-Free-Time Assessment Tool for IRIS (20) Automated and Manual Rocket Crater Measurement Software (21) MATLAB Stability and Control Toolbox Trim and Static Stability Module (22) Patched Conic Trajectory Code (23) Ring Image Analyzer (24) SureTrak Probability of Impact Display (25) Implementation of a Non-Metallic Barrier in an Electric Motor (26) Multi-Mission Radioisotope Thermoelectric Generator Heat Exchangers for the Mars Science Laboratory Rover (27) Uniform Dust Distributor for Testing Radiative Emittance of Dust-Coated Surfaces (28) MicroProbe Small Unmanned Aerial System (29) Highly Stable and Active Catalyst for Sabatier Reactions (30) Better Proton-Conducting Polymers for Fuel-Cell Membranes (31) CCD Camera Lens Interface for Real-Time Theodolite Alignment (32) Peregrine 100-km Sounding Rocket Project (33) SOFIA Closed- and Open-Door Aerodynamic Analyses (34) Sonic Thermometer for High-Altitude Balloons (35) Near-Infrared Photon-Counting Camera for High-Sensitivity Observations (36) Integrated Optics Achromatic Nuller for Stellar Interferometry (37) High-Speed Digital Interferometry (38) Ultra-Miniature Lidar Scanner for Launch Range Data Collection (39) Shape and Color Features for Object Recognition Search (40) Explanation Capabilities for Behavior-Based Robot Control (41) A DNA-Inspired Encryption Methodology for Secure, Mobile Ad Hoc Networks (42) Quality Control Method for a Micro-Nano-Channel Microfabricated Device (43) Corner-Cube Retroreflector Instrument for Advanced Lunar Laser Ranging (44) Electrospray Collection of Lunar Dust (45) Fabrication of a Kilopixel Array of Superconducting Microcalorimeters with Microstripline Wiring Spacecraft Attitude Tracking and Maneuver Using Combined Magnetic Actuators (46) Coherent Detector for Near-Angle Scattering and Polarization Characterization of Telescope Mirror Coatings

Source record↗

NASA Tech Briefs, March 2014

Topics include: Data Fusion for Global Estimation of Forest Characteristics From Sparse Lidar Data; Debris and Ice Mapping Analysis Tool - Database; Data Acquisition and Processing Software - DAPS; Metal-Assisted Fabrication of Biodegradable Porous Silicon Nanostructures; Post-Growth, In Situ Adhesion of Carbon Nanotubes to a Substrate for Robust CNT Cathodes; Integrated PEMFC Flow Field Design for Gravity-Independent Passive Water Removal; Thermal Mechanical Preparation of Glass Spheres; Mechanistic-Based Multiaxial-Stochastic-Strength Model for Transversely-Isotropic Brittle Materials; Methods for Mitigating Space Radiation Effects, Fault Detection and Correction, and Processing Sensor Data; Compact Ka-Band Antenna Feed with Double Circularly Polarized Capability; Dual-Leadframe Transient Liquid Phase Bonded Power Semiconductor Module Assembly and Bonding Process; Quad First Stage Processor: A Four-Channel Digitizer and Digital Beam-Forming Processor; Protective Sleeve for a Pyrotechnic Reefing Line Cutter; Metabolic Heat Regenerated Temperature Swing Adsorption; CubeSat Deployable Log Periodic Dipole Array; Re-entry Vehicle Shape for Enhanced Performance; NanoRacks-Scale MEMS Gas Chromatograph System; Variable Camber Aerodynamic Control Surfaces and Active Wing Shaping Control; Spacecraft Line-of-Sight Stabilization Using LWIR Earth Signature; Technique for Finding Retro-Reflectors in Flash LIDAR Imagery; Novel Hemispherical Dynamic Camera for EVAs; 360 deg Visual Detection and Object Tracking on an Autonomous Surface Vehicle; Simulation of Charge Carrier Mobility in Conducting Polymers; Observational Data Formatter Using CMOR for CMIP5; Propellant Loading Physics Model for Fault Detection Isolation and Recovery; Probabilistic Guidance for Swarms of Autonomous Agents; Reducing Drift in Stereo Visual Odometry; Future Air-Traffic Management Concepts Evaluation Tool; Examination and A Priori Analysis of a Direct Numerical Simulation Database for High-Pressure Turbulent Flows; and Resource-Constrained Application of Support Vector Machines to Imagery.

Source record↗

In-Situ Wire Damage Detection System

An in-situ system for detecting damage in an electrically conductive wire. The system includes a substrate at least partially covered by a layer of electrically conductive material forming a continuous or non-continuous electrically conductive layer connected to an electrical signal generator adapted to delivering electrical signals to the electrically conductive layer. Data is received and processed to identify damage to the substrate or electrically conductive layer. The electrically conductive material may include metalized carbon fibers, a thin metal coating, a conductive polymer, carbon nanotubes, metal nanoparticles or a combination thereof.

Williams, Martha K.↗

Critical role of polymer-ceramic ion exchange for high conductivity composite electrolytes

Polymer-ceramic composites offer a path to enhance the transport and mechanical properties of solid electrolytes. However, an in-depth understanding of the extent and role of ion transport along and across polymer-ceramic interfaces in these systems is lacking. We have recently shown that Li-conducting Li 0.11 Na 0.24 K 0.02 La 0.43 TiO 2.82 (LMTO) nanorods can be prepared by a molten flux method, and the addition of 30–50 weight (wt.)% LMTO to a bis[(trifluoromethyl)sulfonyl]imide-vinyl ethylene carbonate-based single-ion conducting (SIC) polymer electrolyte leads to a two-fold enhancement in Li-ion conductivity, from 1.4 to 3.0 × 10 −5 S/cm at 30 °C. In the present study, we use NMR methods to identify the Li-ion transport pathways and determine the timescale of chemical exchange between the SIC polymer and LMTO ceramic components. Tracer exchange NMR indicates preferential transport through the polymer or polymer-interfacial regions, and exchange spectroscopy (EXSY) and a new isotope exchange method reveal negligible Li exchange between the SIC polymer and LMTO ceramic up to several days. Here, LMTO nanorods act as a passive filler. Our results further highlight that significant (e.g., 10- or 100-fold) conductivity enhancements in composite electrolytes can only be achieved 1) with ionically-conductive fillers, and 2) when both the ceramic and polymer components actively participate in long-range transport. For this, fast interfacial ion exchange is needed. In conclusion, this leads us to introduce a critical interfacial ion exchange time to evaluate whether a filler actively contributes to conduction in a composite electrolyte, and screen for promising polymer-ceramic pairings to accelerate the development of high conductivity solid electrolytes.

Battery, Solid electrolyte↗

Thermally conducting electron transfer polymers

New polymeric material exhibits excellent physical shock protection, high electrical resistance, and thermal conductivity. It is especially useful for electronic circuitry, such as subminiaturization of components and modular construction of circuits.

Byrd, N. R.↗

Methods of enhancing conductivity of a polymer-ceramic composite electrolyte

Methods for enhancing conductivity of polymer-ceramic composite electrolytes are provided which include forming a polymer-ceramic composite electrolyte film by a melt casting technique and uniaxially stretching the film from about 5 to 15% in length. The polymer-ceramic composite electrolyte is also preferably annealed after stretching such that it has a room temperature conductivity of from 10.sup.-4 S cm.sup.-1 to 10.sup.-3 S cm.sup.-1. The polymer-ceramic composite electrolyte formed by the methods of the present invention may be used in lithium rechargeable batteries.

Kumar, Binod↗

Ion conducting organic/inorganic hybrid polymers

This invention relates to a series of organic/inorganic hybrid polymers that are easy to fabricate into dimensionally stable films with good ion-conductivity over a wide range of temperatures for use in a variety of applications. The polymers are prepared by the reaction of amines, preferably diamines and mixtures thereof with monoamines with epoxy-functionalized alkoxysilanes. The products of the reaction are polymerized by hydrolysis of the alkoxysilane groups to produce an organic-containing silica network. Suitable functionality introduced into the amine and alkoxysilane groups produce solid polymeric membranes which conduct ions for use in fuel cells, high-performance solid state batteries, chemical sensors, electrochemical capacitors, electro-chromic windows or displays, analog memory devices and the like.

Meador, Maryann B.↗

Superionic conduction in solid polymer electrolytes – decoupling ion transport from segmental relaxation

Solvent-free, solid polymer electrolytes (SPEs) are promising candidates for next-generation, electrochemical energy storage systems due to their potential to enhance safety and performance, enable flexible device architectures, and streamline manufacturing processes. Conventional SPEs suffer from limited ionic conductivity due to the strong coupling between ion transport and (generally slow) polymer segmental relaxation. The realization of superionic conduction in SPEs, in which ions move faster than the structural relaxation of the polymers, requires a shift in design principles to promote this type of decoupled ion motion. In this perspective, we discuss how polymer architecture, ion–ion correlations, and ion–polymer interactions can unlock superionic behavior. We highlight several key design features, such as crystallinity, bulky side groups, high molecular weight, and percolating ionic aggregation, with a focus on creating low-barrier transport pathways in various polymer systems. We also demonstrate opportunities to combine polymer chemistry and data science through high-throughput and automated screening approaches to reveal how phase behavior, ion dynamics, and ionic interactions govern transport, thereby potentially enabling data-driven discovery of superionic polymer electrolyte materials.

Yang, Mengying [Univ. of Delaware, Newark, DE (Uni↗

Ion-Conducting Dynamic Solid Polymer Electrolyte Adhesives

Cross-linked polymer electrolytes containing structurally dynamic disulfide bonds have been synthesized to investigate their combined ion transport and adhesive properties. Dynamic network polymers of varying cross-link densities are synthesized via thiol oxidation of a bisthiol monomer, 2,2'-(ethylenedioxy)diethanethiol, and tetrathiol cross-linker, pentaerythritol tetrakis(3-mercaptopropionate). At optimal loading of lithium bis(trifluoromethane-sulfonyl-imide) (LiTFSI) salt, the ionic conductivities (σ) at 90 °C are about 1 × 10–4 and 1 × 10–5 S/cm at the lowest and highest cross-linking, respectively. Notably, in comparison to the equivalent nondynamic network, the dynamic network shows a positive deviation in σ above 90 °C, which suggests the enhancement of ion transport occurs from the difference in structural relaxation on account of the dissociation of disulfide bonds. Lap shear adhesion and conductivity tests on ITO-coated glass substrates reveal the dynamic network exhibits a higher adhesive shear strength of 0.2 MPa (vs 0.03 MPa for the nondynamic network) and higher σ after the application of external stimulus (UV light or heat). The adhesive strength and σ are stable over multiple debonding/rebonding cycles and, thus, demonstrating the utility of these structurally dynamic networks as solid polymer electrolyte adhesives.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Mechanically robust and superior conductive n-type polymer binders for high-performance micro-silicon anodes in lithium-ion batteries

Compared with nanostructured silicon (Si), the Si microparticle (SiMP) has more commercial prospects due to its low cost. However, SiMPs suffer from unavoidable fracture during electrochemical cycling owing to their significant volume change. Here we develop a series of novel n-type conductive polymer binders (CPBs) for SiMP anodes in lithium-ion batteries owing to their superior properties. Extraordinary electrochemical performance of cells with such unique binders could be achieved, which is because these designed polymers contain electron-withdrawing oxadiazole ring groups and easily ionizable sulfonate polar groups, exhibiting excellent ionic conductivity, outstanding wettability to the electrolyte, and improved electronic conductivity after doping. Moreover, the coexistence of rigid and flexible chains enables them to have exceptional strength and ductility. Besides, a unique electrochromic approach has been utilized to investigate the energy gap of the CPBs in n-doping states. The ionic and electronic conductivities of prepared CPBs in an eigenstate and n-doping state have been systematically studied by the electrochemical method, filling the current research gap in this field. Due to the high conductivity of b-POD, the capacity of SiMPs (4200 mA h g –1 ) can be almost entirely released during the first cycle of discharge, while the SiMP anodes prepared with the PAALi or CMC binder show a much lower initial capacity. Here, the high conductivity of b-POD also endows it with better cycling performance than non-conductive binders especially at high current densities, demonstrating its excellent fast-charging ability. More essentially, this work provides polymer binders without any intricate structural designs to obtain high-performance SiMP batteries, significantly enhancing their practical applications.

25 ENERGY STORAGE↗

Electrospinning of PVdF-HFP: novel composite polymer electrolytes (CPES) with enhanced ionic conductivities for lithium-sulfur batteries

The invention relates to lithium ion batteries and, more particularly, to lithium ion conducting composite polymer electrolyte separators. The separators include a nanofiber mat composed of electrospun nanofibers. The nanofibers include a polymer having one or more polar halogen groups, a lithium-containing solid or liquid electrolyte and nanoparticle filler. The polymer, electrolyte and filler are combined to form a solution that is subjected to the electro-spinning process to produce electrospun nanofibers in the form of the mat.

Kumta, Prashant N.↗

A Single‐Ion Conducting Borate Network Polymer as a Viable Quasi‐Solid Electrolyte for Lithium Metal Batteries

Abstract Lithium‐ion batteries have remained a state‐of‐the‐art electrochemical energy storage technology for decades now, but their energy densities are limited by electrode materials and conventional liquid electrolytes can pose significant safety concerns. Lithium metal batteries featuring Li metal anodes, solid polymer electrolytes, and high‐voltage cathodes represent promising candidates for next‐generation devices exhibiting improved power and safety, but such solid polymer electrolytes generally do not exhibit the required excellent electrochemical properties and thermal stability in tandem. Here, an interpenetrating network polymer with weakly coordinating anion nodes that functions as a high‐performing single‐ion conducting electrolyte in the presence of minimal plasticizer, with a wide electrochemical stability window, a high room‐temperature conductivity of 1.5 × 10 −4 S cm −1 , and exceptional selectivity for Li‐ion conduction ( t Li+ = 0.95) is reported. Importantly, this material is also flame retardant and highly stable in contact with lithium metal. Significantly, a lithium metal battery prototype containing this quasi‐solid electrolyte is shown to outperform a conventional battery featuring a polymer electrolyte.

Shin, Dong‐Myeong↗

Electronic and Magnetic Properties of Oligomers and Chains of Poly(benzodifurandione) (PBDF), A Highly Conducting n-Type Polymer

The seminal development of highly electrically conducting polyacetylene via oxidative or reductive treatment (“doping”) has continuously inspired the search for other conducting π-conjugated polymers. Recently, poly(benzodifurandione), PBDF, was reported to have unexpected solubility given the absence of side chains and to exhibit an unprecedented, high electrical conductivity upon reduction (“n-doping”), with protons acting as counterions. Here, we theoretically investigate the electronic and magnetic properties of PBDF by taking long oligomers and one-dimensional (1D) periodic chains as model systems. With the oligomer models, we characterize the formation of polarons and bipolarons in n-doped PBDF. Our results indicate that singlet bipolarons tend to be the energetically most favorable species when protons bind to two closely located carbonyl groups in nearest-neighbor benzodifurandione moieties. The calculations on the 1D periodic chain models show that the positions of the protonated carbonyl groups determine the metallic, semiconducting, or insulating nature of a PBDF chain. When the protonated carbonyl groups are all situated on the same side of a PBDF chain, a stable helical chain configuration is found that exhibits ferromagnetic behavior. Our findings elucidate the mechanism of polaron and bipolaron formation in long oligomers of n-doped PBDF and highlight the fascinating electronic and magnetic properties of periodic 1D chains. Furthermore, these studies also provide a stepping stone for investigations of PBDF thin films, for which two- and three-dimensional structures must be considered.

36 MATERIALS SCIENCE↗

In Situ Formation of Li 3 P Layer Enables Fast Li + Conduction across Li/Solid Polymer Electrolyte Interface

Abstract Solid‐state polymer electrolytes provide better flexibility and electrode contact than their ceramic counterparts, making them a worthwhile pursuit for all‐solid‐state lithium‐metal batteries. However, their large Li/solid state electrolyte interfacial resistance, small critical current density, and rapid lithium dendrite growth during cycling still limit their viability. Owing to these restrictions, all‐solid‐state cells with solid polymer electrolytes must be cycled above room‐temperature and with a small current density. These problems can be mitigated with an in situ formed artificial solid electrolyte interphase that rapidly conducts Li + ions. Herein, a Li 3 P layer formed in situ at the Li‐metal/solid polymer electrolyte interphase is reported that significantly reduces the electrode/electrolyte interfacial resistance. Additionally, this layer increases the wettability of the solid polymer by the metallic lithium anode, allowing for the critical current density of lithium symmetric cells to be doubled by homogenizing the current density at the interface. All‐solid‐state Li/Li symmetric cells and Li/LiFePO 4 cells with the Li 3 P layer show improved cycling performance with a high current density.

Wu, Nan↗

Ionic Conductivity Enhancement of Polymer Electrolytes by Directed Crystallization

Here, we report that hot stretching of poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) can lead to a preferred orientation of PEO crystalline lamellae, thereby reducing the tortuosity of the ion-conduction pathway along the thickness direction of the SPE film, causing improved ionic conductivity. The hot stretching method is implemented by stretching SPE films above the melting point of PEO in an inert environment followed by crystallization at room temperature while maintaining the applied strain. The effect of hot stretching on the crystalline orientation, crystallinity, morphology, and ion transport in PEO with two types of salts, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium triflate (LiCF3SO3), is investigated in detail. Wide-angle X-ray scattering (WAXS) and small-angle X-ray scattering (SAXS) show that the orientation of PEO crystalline lamellae induces the formation of a short ion-conduction pathway along the through-plane direction of the SPE films, leading to 1.4- to 3.5-fold enhancement in the through-plane ionic conductivity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

A Study of Space Environment Effect on Highly Thermally Conductive Hybrid Carbon Fiber Polymer Composites

A set of novel highly thermally conductive hybrid carbon fiber (CF) polymer composites has been developed for lightweight thermal radiator applications in space missions. This study investigates the effects of the space environment on these materials following exposure in low-Earth orbit (LEO) during the Materials International Space Station Experiment (MISSE)-17 flight mission, where samples experienced 159 days of combined atomic oxygen (AO), ultraviolet (UV) radiation, high vacuum, space radiation and thermal cycling. Post-flight characterization included weight loss, surface morphology, thermo-optical properties, molecular structures, glass transition temperature, thermal degradation and thermal conductivity analyses. The pyrolytic graphite sheet (PGS) samples exhibited negligible weight loss, stable thermo-optical property, and only minor oxidation signature on the exposed surface. Although AO erosion of the epoxy polymer matrix was evident, carbon nanotube (CNT)-infused PGS/CF epoxy composites retained high thermal emissivity and preserved their high thermal conductivities. These results demonstrate that the novel highly thermally conductive hybrid CF composites possess strong environmental resilience and are promising candidates for lightweight thermal radiators and thermal management components in future space exploration missions.

Space Environment↗