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Results for “High performance”

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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

A Tunable 3D Nanostructured Conductive Gel Framework Electrode for High-Performance Lithium Ion Batteries

This study develops a tunable 3D nanostructured conductive gel framework as both binder and conductive framework for lithium ion batteries. A 3D nanostructured gel framework with continuous electron pathways can provide hierarchical pores for ion transport and form uniform coatings on each active particle against aggregation. The hybrid gel electrodes based on a polypyrrole gel framework and Fe3O4 nanoparticles as a model system in this study demonstrate the best rate performance, the highest achieved mass ratio of active materials, and the highest achieved specific capacities when considering total mass, compared to current literature. This 3D nanostructured gelbased framework represents a powerful platform for various electrochemically active materials to enable the next-generation high-energy batteries.

25 ENERGY STORAGE↗
DOE OSTI2018

Facile electrostatic self-assembly of silicon/reduced graphene oxide porous composite by silica assist as high performance anode for Li-ion battery

Silicon(Si)/graphene composite has been regarded as one of the most promising candidates for next generation anode materials with high power and energy density in lithium ion batteries. Introduction of graphene in Si anodes could improve the electronic conductivity, suppress the severe volume expansion of Si, and facilitate the formation of stable solid electrolyte interphase, etc. However, traditionally mechanical mixing of Si and graphene cannot realize uniform distribution of Si particles on the graphene sheets, which would largely weaken the effectiveness of the graphene in the composite. In this work, nano-Si/reduced graphene oxide porous composite (p Si/rGO) has been fabricated by a facile electrostatic self-assembly approach via using SiO2 as the sacrificial template. Compared with the simply mechanically mixed nano-Si and rGO (Si/rGO), the nano-Si particles could be more uniformly dispersed among the rGO sheets in the p Si/rGO, which significantly increases its electronic conductivity. Moreover, the drastic volume expansion of nano-Si during repeated lithiation/delithiation cycles also has been effectively accommodated by the large number of pores left after removing the SiO2 template in the composite. Thus, the p Si/rGO presented largely enhanced electrochemical performances, showing a high reversible capacity up to 1849?mA?h?g-1 at 0.2?A?g-1 with good capacity retention, and high rate capability (535?mA?h?g-1 at 2?A?g-1).

Silicon, Reduced graphene oxide, Electrostatic sel↗
DOE OSTI2018

Structured Innovation of High-Performance Wave Energy Converter Technology: Preprint

Wave energy converter (WEC) technology development has not yet delivered the desired commercial maturity nor, and more importantly, the techno-economic performance. The reasons for this have been recognized and fundamental requirements for successful WEC technology development have been identified. This paper describes a multi-year project pursued in collaboration by the National Renewable Energy Laboratory and Sandia National Laboratories to innovate and develop new WEC technology. It specifies the project strategy, shows how this differs from the state-of-the-art approach and presents some early project results. Based on the specification of fundamental functional requirements of WEC technology, structured innovation and systemic problem solving methodologies are applied to invent and identify new WEC technology concepts. Using Technology Performance Levels (TPL) as an assessment metric of the techno-economic performance potential, high performance technology concepts are identified and selected for further development. System performance is numerically modelled and optimized and key performance aspects are empirically validated. The project deliverables are WEC technology specifications of high techno-economic performance technologies of TPL 7 or higher at TRL 3 with some key technology challenges investigated at higher TRL. These wave energy converter technology specifications will be made available to industry for further, full development and commercialisation (TRL 4 - TRL 9).

17 WIND ENERGY↗
DOE OSTI2017

High-Performance Pyrochlore-Type Yttrium Ruthenate Electrocatalyst for Oxygen Evolution Reaction in Acidic Media

Development of acid-stable electrocatalysts with low overpotential for oxygen evolution reaction (OER) is a major challenge for the production of hydrogen directly from water. We report in this paper a pyrochlore yttrium ruthenate (Y2Ru2O7-δ) electrocatalyst that has significantly enhanced performance towards OER in acid media over the best-known catalysts, with an onset overpotential of 190 mV and high stability in 0.1-M perchloric acid solution. X-ray absorption near-edge structure (XANES) indicates Y2Ru2O7-δ electrocatalyst had a low valence state that favors the high OER activity. Density functional theory (DFT) calculation shows this pyrochlore has lower band center energy for the overlap between Ru 4d and O 2p orbitals and therefore more stable Ru-O bond than RuO2, highlighting the effect of yttrium on the enhancement in stability. The Y2Ru2O7-δ pyrochlore is also free of expensive iridium metal, thus a cost-effective candidate for practical applications.

Kim, Jaemin↗
DOE OSTI2015

Strong Lithium Polysulfide Chemisorption on Electroactive Sites of Nitrogen-Doped Carbon Composites For High-Performance Lithium–Sulfur Battery Cathodes

Despite the high theoretical capacity of lithium–sulfur batteries, their practical applications are severely hindered by a fast capacity decay, stemming from the dissolution and diffusion of lithium polysulfides in the electrolyte. A novel functional carbon composite (carbon-nanotube-interpenetrated mesoporous nitrogen-doped carbon spheres, MNCS/CNT), which can strongly adsorb lithium polysulfides, is now reported to act as a sulfur host. The nitrogen functional groups of this composite enable the effective trapping of lithium polysulfides on electroactive sites within the cathode, leading to a much improved electrochemical performance (1200 mAh g -1 after 200 cycles). The enhancement in adsorption can be attributed to the chemical bonding of lithium ions by nitrogen functional groups in the MNCS/CNT framework. Furthermore, the micrometer-sized spherical structure of the material yields a high areal capacity (ca. 6 mAh cm -2 ) with a high sulfur loading of approximately 5 mg cm -2 , which is ideal for practical applications of the lithium–sulfur batteries.

carbon materials↗
DOE OSTI2018

3D printed high performance strain sensors for high temperature applications

Realization of high temperature physical measurement sensors, which are needed in many of the current and emerging technologies, is challenging due to the degradation of their electrical stability by drift currents, material oxidation, thermal strain, and creep. In this paper, for the first time, we demonstrate that 3D printed sensors show a metamaterial-like behavior, resulting in superior performance such as high sensitivity, low thermal strain, and enhanced thermal stability. The sensors were fabricated using silver (Ag) nanoparticles (NPs), using an advanced Aerosol Jet based additive printing method followed by thermal sintering. The sensors were tested under cyclic strain up to a temperature of 500 °C and showed a gauge factor of 3.15 ± 0.086, which is about 57% higher than that of those available commercially. The sensor thermal strain was also an order of magnitude lower than that of commercial gages for operation up to a temperature of 500 °C. An analytical model was developed to account for the enhanced performance of such printed sensors based on enhanced lateral contraction of the NP films due to the porosity, a behavior akin to cellular metamaterials. Here, the results demonstrate the potential of 3D printing technology as a pathway to realize highly stable and high-performance sensors for high temperature applications.

47 OTHER INSTRUMENTATION↗
DOE OSTI2019

Functionalized Porous Aromatic Frameworks as High‐Performance Adsorbents for the Rapid Removal of Boric Acid from Water

Abstract This study demonstrates that functionalized, highly porous polymers are promising for the adsorptive capture of boric acid, a neutral contaminant that is difficult to remove from seawater using conventional reverse osmosis membranes. Appending N ‐methyl‐d‐glucamine (NMDG) to the pore walls of high‐surface‐area porous aromatic frameworks (PAFs) yields the adsorbents PAF‐1‐NMDG and P2‐NMDG in a simple two‐step synthesis. The boron‐selective PAFs demonstrate adsorption capacities that are up to 70% higher than those of a commercial boron‐selective resin, Amberlite IRA743, and markedly faster adsorption rates, owing to their higher NMDG loadings and greater porosities relative to the resin. Remarkably, PAF‐1‐NMDG is able to reduce the boron concentration in synthetic seawater from 2.91 to <0.5 ppm in less than 3 min at an adsorbent loading of only 0.3 mg mL −1 . The boron adsorption rate constants of both frameworks, determined via a pseudo‐second‐order rate model, represent the highest values reported in the literature—in most cases orders of magnitude higher than those of other boron‐selective adsorbents. The frameworks can also be readily regenerated via mild acid/base treatment and maintain constant boron adsorption capacities for at least 10 regeneration cycles. These results highlight the numerous advantages of PAFs over traditional porous polymers in water treatment applications.

Kamcev, Jovan↗