Long-term Stability Requirements Research Articles

In-situ synthesis of ferrocene modified formaldehyde-free phenolic resin and its temperature-resistant microwave absorbing coating

The requirements for long-term stability and thermal performance of resin-based coating materials are gradually increasing with the development of aerospace industry. As a low-toxicity aldehyde, terephthalaldehyde (TPA) with aromatic ring structure and high reactivity is an ideal formaldehyde substitute for synthesizing high thermal stability phenolic resins and coating candidate. In this work we provided a strategy for the synthesis of ferrocenecarboxaldehyde (Fc) in-situ modified TPA-phenol resin (PTPA-Fc), obtaining resin products with high glass transition temperatures at 302 °C. The non-isothermal curing process and activation energy changes of resins with different TPA-phenol ratios were further investigated. It was found that the highest cross-linking density of resin was achieved when TPA/phenol was 0.5, with the initial decomposition temperature (T5%) reached 378 °C. Afterwards, carbonyl iron powder (CIP) filled PTPA-Fc microwave absorbing coating was prepared. Due to the improved oxidation resistance, composite based on PTPA-Fc had an effective bandwidth of 3.1 GHz (14.5–17.6 GHz, thickness 3 mm) after 100 h heat treatment at 250 °C and could still cover the 9.5–18 GHz absorption band (with RL ≤ -5 dB) with 5 mm matching thickness, reflecting a good long-term thermal stability.

A novel detection method for ore-coke ratio of blast furnace based on structure-texture entropy of images

The ore-coke ratio is crucial for regulating gas flow distribution, enhancing permeability, and ensuring smooth operation of the blast furnace. Direct detection of the ore-coke ratio, leveraging the structure and texture differences in ore and coke images, is a widely accepted method. The harsh environment of the blast furnace results in unclear burden surface images, making it challenging to differentiate between ore and coke. This complicates image-based direct detection for ore-coke ratio, with few studies addressing this issue. This paper firstly introduces a structure-texture entropy, grounded in information entropy, to effectively differentiate between ore and coke. Then, a structure-texture enhancement algorithm based on image extreme dark features is proposed to optimize the accuracy of the structure-texture entropy. Finally, based on the high-accuracy structure-texture entropy, a novel algorithm for burden surface area extraction is presented. This method uses feature vector clustering and functional optimization for real-time ore-coke ratio detection. Industrial experiments demonstrate that the proposed method achieves high-accuracy ore-coke ratio detection, meeting the requirements for long-term stability of the blast furnace.

Method for in-orbit redesign for TianQin orbit configuration

The space-based gravitational wave observatory mission consists of three drag-free controlled spacecraft, which form an equilateral triangle configuration. Due to the injection error, the configuration will deviate from the originally designed one, and the injection configuration cannot keep stability for a long term, which will affect the performance of the gravitational wave detection. In this study, we propose a method for reconfiguration using multiple-revolution Lambert solutions. In addition, assuming that the real-time data of spacecraft’s motion states can be obtained with high accuracy and the propulsion system can ensure the magnitude and accuracy of maneuvers, and taking the cost of reconfiguration and configuration stability requirements into account, a novel method of redesigning configuration based on differential evolution algorithm is proposed. Finally, the numerical simulations show that the redesigned configuration not only can reduce the maneuver cost significantly, but also can meet the requirements of long-term stability requirements.

A highly stable electrode with low electrode-skin impedance for wearable brain-computer interface

To date, brain-computer interfaces (BCIs) have proved to play a key role in many medical applications, for example, the rehabilitation of stroke patients. For post-stroke rehabilitation, the BCIs require the EEG electrodes to precisely translate the brain signals of patients into intended movements of the paralyzed limb for months. However, the gold standard silver/silver-chloride electrodes cannot satisfy the requirements for long-term stability and preparation-free recording capability in wearable EEG devices, thus limiting the versatility of EEG in wearable BCI applications over time outside the rehabilitation center. Here, we design a long-term stable and low electrode-skin interfacial impedance conductive polymer-hydrogel EEG electrode that maintains a lower impedance value than gel-based electrodes for 29 days. With this technology, EEG-based long-term and wearable BCIs could be realized in the near future. To demonstrate this, our designed electrode is applied for a wireless single-channel EEG device that detects changes in alpha rhythms in eye-open/eye-close conditions. In addition, we validate that the designed electrodes could capture oscillatory rhythms in motor imagery protocols as well as low-frequency time-locked event-related potentials from healthy subjects, with similar or better performance than gel-based electrodes. Finally, we demonstrate the use of the designed electrode in online BCI-based functional electrical stimulation, which could be used for post-stroke rehabilitation.

Technologies for tunable gamma-ray lenses

The tunable gamma-ray lens has turned out to be a promising alternative to the classical fixed-energy Laue-lenses discussed in the past. We describe here our development work on a miniature pedestal with one-axis tilt adjustment. We also outline our design for an optical system, capable of monitoring the alignment of the many crystals needed. An added benefit of the tunable crystal pedestal is that it relieves both the demands for high precision in the crystal mounting and the stringent requirements for long-term stability of the support platform on which the crystals are mounted. Moreover, mounting the individual crystals on separate pedestals facilitates the use of double layers of crystals. Keywords: Gamma-ray astronomy, Telescope technology, Laue lenses

Near-Field IR Imaging and Spectroscopy of Interfaces and Interphases in Li-Ion Electrodes

Most Li-ion battery chemistries involve the creation or transformation of materials under non-equilibrium environments. Because these chemical energy storage systems operate beyond the thermodynamic stability limits of the electrolytes, reactions between electrodes and electrolyte result in the formation of new phases and interphases, which hinder further electrolyte decomposition and assure battery operation over the lifespan of the application. The basic physico-chemical properties and long-term stability of these surface layers known as the solid electrolyte interphase (SEI) determine the performance and durability of the entire system [1,2]. However, our understanding of how and why some materials function, and, equally importantly, why some materials with many ideal characteristics actually fail, is mainly rudimentary and empirical. The requirements for long-term stability of Li-ion batteries are extremely stringent and necessitate control of the chemistry at a wide variety of temporal and structural length scales. However, the spatial resolution of standard optical spectroscopic and imaging techniques is limited by diffraction to light beam sizes on the order of the wavelength of the source i.e., ∼10 μm for IR and∼500 nm in the visible range. The advent of near-field optical methods during the past decades has led to the development of new advanced techniques for chemical analysis. This presentation provides an overview of novel imaging and spectroscopic optical methodologies, which exploit micro and nano-manipulation techniques and single crystal model electrodes to provide sufficient sample definition suitable for advanced multifunctional far- and near-field optical scanning probes and electrochemical characterization techniques. The SEI chemistry is known to be highly heterogeneous at the nanoscale, and although many compounds have been suggested as contributing, their distribution, relative concentration and functionality remain poorly understood [2]. To address this challenge we used the apertureless near-field scanning optical microscopy (aNSOM) (3-9), which combines the high resolution of AFM with the chemical specificity of IR spectroscopy, to resolve the SEI chemistry at high (∼20 nm) spatial resolution. Examples of detailed in situ molecular characterization of graphite Sn and Si electrodes surface and bulk processes at the nano-level scale exceeding the diffraction limit will be discussed [7-9]. Acknowledgements This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy, under contract no. DE-AC02-05CH11231.

Prototype Sodium-Ion Batteries Using Air-Stable and Co/Ni-Free O3-Layered Metal Oxide Cathode

Large-scale electrical energy storage systems are one of the core technologies in renewable energies and smart grid, among which sodium-ion batteries show great promise due to the abundant sodium resources. Searching for suitable electrode materials to satisfy the long-term stability requirement is an important step to realize the practical sodium-ion batteries. Recently, many layered NaxMO2 (M: 3d transition metals) oxides have been proposed as positive electrode materials for sodium-ion batteries. Layered metal oxides have attracted widespread attention as cathodes for sodium-ion batteries because of easy synthesis, highly reversible Na deintercalation/intercalation and high energy density. However, the practical applications have been hindered by two major challenges. Unlike LiMO2, almost all the Na x MO2 are not stable against moisture (either they can be oxidized by water/oxygen/carbon dioxide or water molecular can be intercalated into alkali metal layer). This will not only increase the substantial cost for material storage, transportation and battery production but also lead to the inconsistency of the battery performance. Therefore, it is very important to explore air-stable layered oxides in the viewpoint of practical applications. Furthermore, although significant progress has been made in new layered metal oxides with abundant elements such as Fe and Mn to form Na x Fe 1-y Mn y O2, their Na storage performance is not satisfactory. It is necessary to incorporate toxic Ni or Co into transition metal layer to achieve better performance. However, as noted above, Ni or Co is widely used in lithium-ion batteries, particularly, with the growing market of electric vehicles, the cost of Ni or Co will definitely increase. Therefore, this is not a good choice for sodium-ion batteries and it is essential to explore Ni/Co-free layered oxides with superior performance. Here we report a new Co/Ni-free layered oxide, O3-Na0.9[Cu0.22Fe0.30Mn0.48]O2, showing unexpectedly superior stability against moisture and excellent electrochemical cycling stability. A prototype sodium-ion battery using this cathode and hard carbon anode is demonstrated to have an energy density of 210 Wh/kg and superior rate capability and negligible capacity fade. These desirable characteristics meet the requirements for large-scale electrical energy storage, thus paving the way of developing low-cost and high-energy sodium-ion batteries for practical applications. On the basis of full cell system, we have developed the first 2 Ah practical soft package sodium-ion battery for room-temperature energy storage application in IOP-CAS. We will present the results in this talk. Acknowledgement. This work was supported by funding from the NSFC (51222210, 11234013) and the One Hundred Talent Project of the Chinese Academy of Sciences. References (1) Mu, L. Q.; Xu, S.Y.; Li, Y.M.; Hu, Y. -S.; Li, H.;Chen, L.Q.; Huang X.J. Adv. Mater. DOI: 10.1002/adma.201502449 (2) Pan, H. L.; Hu, Y. S.; Chen, L. Q. Energy Environ . Sci . 2013, 6, 2338-2360. (3) Xu, S.Y.; Wu, X.Y.; Li, Y.M.; Hu, Y. -S.; Chen, L.Q. Chin . Phys . B 201 4, 23,118202. (4) Mu, L. Q.; Hu, Y. -S.; Chen, L.Q. Chin. Phys. B 2015, 3, 038203. (5) Hu, Y. -S.; et al. Several Chinese patents have been filed. (6) Li, Y. M.; Xu, S. Y.; Wu, X. Y.; Yu, J. Z.; Wang, Y. S.; Hu, Y.-S.; Li, H.; Chen, L. Q.; Huang, X. J. J. Mater. Chem. A 2015, 3, 71-77.

Highly Efficient and Redox Stable Layered Perovskite Ceramic Anode for Hydrocarbon Solid Oxide Fuel Cell

Perovskite oxides with variable oxygen non-stoichiometry play a prominent role in many fields, including fuel cells, catalysis and gas storage. One interesting class of materials for solid oxide fuel cells (SOFCs) are cation ordered layered perovskite oxides due to their mixed ionic and electronic conductivity and fast oxygen kinetics. Even though progress has been made in cathode materials to lower the cathodic polarization, still it is also important for fuel cell technology to achieve efficient anode that meets the requirements for long term stability with enhanced tolerance to carbon buildup (coking) and sulfur contamination (poisoning) from hydrocarbon fuels. Here, we report identification of cation ordered layered perovskite oxide, PrBaMn2O5+δ redox-stable anode, with superior electrochemical performance in both hydrogen and hydrocarbons. Cation ordered PrBaMn2O5+δ are fabricated by the in-situ annealing of disordered Pr0.5Ba0.5MnO3-δ in reducing atmosphere directly from the fuel cell support. Our anode material shows high electrical conductivity of 8.16 S cm-1 in 5% H2 at 800 oC and demonstrates a peak power density ~1.3 Wcm-2 at 850 oC using propane as fuel.

Northeast Center for Chemical Energy Storage (NECCES)

NECCES Mission Statement : To develop an understanding of how key electrode reactions occur, and how they can be controlled to improve electrochemical performance, from the atomistic level to the macroscopic level through the life-time of the operating battery. The design of the next generation of rechargeable batteries requires both the development of new chemistries and the fundamental understanding of the physical and chemical processes that occur in these complex systems. Although some significant advances have been made to prepare and utilize new materials, efforts towards the understanding of mechanisms have waned. This will eventually choke efforts to efficiently develop new materials if this issue is not addressed now. Batteries are inherently complex and dynamic systems, their electrochemistry, phase transformations, and transport processes often varying throughout their lifetime. Although often viewed as simple to use by the customer, their successful operation relies heavily on a series of complex mechanisms, involving thermodynamic instability in many parts of the charge- discharge cycle and the formation of metastable phases. The requirements for long-term stability are extremely stringent and necessitate control of the chemistry at a wide variety of temporal and structural length scales. This in turn necessitates the development and use of new characterization tools to monitor these processes. The overall goal is to understand the transformations (and their rates) that occur in an electrode composite structure, from the atomistic level to the macroscopic level, throughout the lifetime of the functioning battery. The four-year scientific research goals are: Close the gap between the theoretical and practical energy density for intercalation compounds.Attain reversible multi-electron transfer in a cathode material using lithium.Understand performance limiting transport in positive electrode structures from the local through the meso to the macroscale. Enable new chemistries involving electrode systems that were previously considered intractable for use in batteries.

Long-term thermal regimes of the Qinghai-Tibet Railway embankments in plateau permafrost regions

Ten years of ground temperature data (2003–2013) indicate that the long-term thermal regimes within embankments of the Qinghai-Tibet Railway (QTR) vary significantly with different embankment structures. Obvious asymmetries exist in the ground temperature fields within the traditional embankment (TE) and the crushed-rock basement embankment (CRBE). Measurements indicate that the TE and CRBE are not conducive to maintaining thermal stability. In contrast, the ground temperature fields of both the crushed-rock sloped embankment (CRSE) and the U-shaped crushed-rock embankment (UCRE) were symmetrical. However, the UCRE gave better thermal stability than the CRSE because slow warming of deep permafrost was observed under the CRSE. Therefore, the UCRE has the best long-term effect of decreasing ground temperature and improving the symmetry of the temperature field. More generally, it is concluded that construction using the cooling-roadbed principle meets the design requirements for long-term stability of the railway and for train transport speeds of 100 km h−1. However, temperature differences between the two shoulders, which exist in all embankments shoulders, may cause potential uneven settlement and might require maintenance.

Novel Copper-Containing Layered Oxide Cathode for Room-Temperature Stationary Sodium-Ion Batteries

With the tremendous development of renewable energies such as solar and wind powers, the smooth integration of their energies into the grid, thus improving the grid reliability and utilization, critically needs large-scale energy storage systems with long-life, high efficiency, high safety and low cost. Among the various energy storage technologies, electrochemical approach represents one of the most promising means to store the electricity in large-scale because of the flexibility, high energy conversion efficiency and simple maintenance. Due to the highest energy density among practical rechargeable batteries, lithium-ion batteries have been widely used in the portable electronic devices and would undoubtedly be the best choice for the electric vehicles. However, the rarity and non-uniform distribution of lithium in the Earth’s crust (0.0065%) may limit their large scale application in renewable energy. In this regard, room-temperature sodium-ion batteries with lower energy density compared with lithium-ion batteries have been reconsidered particularly for such large-scale applications, where cycle life and cost are more essential factors than energy density owing to the abundant sodium resources (2.75%) and potentially low cost as well as similar “rocking-chair” sodium storage mechanism as lithium1-11. Searching for suitable electrode materials to satisfy the long-term stability requirement is an important step to realize the large-scale energy storage. Recently, many layered Na x MO2 (M: 3d transition metals) oxides have been proposed as positive electrode materials for sodium-ion batteries. Amongst them, in general, only layered oxides containing Ni or Co transition metal show promising Na storage performance in terms of high storage capacity, high rate capability and long cycling stability. However, Ni and Co are toxic and their oxides are relatively expensive, which would certainly increase the cost of the battery and is unfavorable for large-scale energy storage applications. Herein, we found that Cu2+/Cu3+ redox couple in such layered oxides is electrochemically active and highly reversible in sodium-ion batteries12. Take P2-Na0.68Cu0.34Mn0.66O2 as the first example, this material shows a reversible capacity of ca. 70 mAh/g with an average storage voltage of 3.8 V vs. Na+/Na. To the best of our knowledge, this is the first time to realize the reversible change of Cu2+/Cu3+ redox couple with high Na storage voltage and small polarization. Copper is harmless, and is already very common in our daily life. In addition, the cost of copper oxide is only half of that of nickel oxide. Based on this important finding, it is possible to use copper to design new layered oxides with similar Na storage performance as that of Ni or Co containing layered oxides. Therefore, we further optimize a series of air-stable NaaDxMnyFezCu1-x-y-zO2 (D(Dopant): Mg, Al, etc.) layered oxides13,14. The preliminary results are very promising and will be presented in this talk (Figure 1).

Using FLI maps for preliminary spacecraft trajectory design in multi-body environments

Fast Lyapunov Indicator (FLI) maps are presented as a tool for solving spacecraft preliminary trajectory design problems in multi-body environments with long-term stability requirements. In particular, the FLI maps are shown to provide a global overview of the dynamics in the restricted three-body problem that can guide mission designers in selecting long-term stable regions of phase space which are inherently more robust to model parameter perturbations. The FLI is also shown to numerically detect the normally hyperbolic manifolds associated with unstable periodic orbits. These, in turn, provide a global map of the principal heteroclinic connections between the various resonance regions which form the basic backbone of dynamical transfers design. Examples of maps and transfers are provided in the restricted three-body problem modeling the Jupiter–Europa system.

Double Perovskites as Anode Materials for Solid-Oxide Fuel Cells

Extensive efforts to develop a solid-oxide fuel cell for transportation, the bottoming cycle of a power plant, and distributed generation of electric energy are motivated by a need for greater fuel efficiency and reduced air pollution. Barriers to the introduction of hydrogen as the fuel have stimulated interest in developing an anode material that can be used with natural gas under operating temperatures 650 degrees C < T < 1000 degrees C. Here we report identification of the double perovskites Sr2Mg(1-x)MnxMoO(6-delta) that meet the requirements for long-term stability with tolerance to sulfur and show a superior single-cell performance in hydrogen and methane.

The Obsolescence of Migration: Long-Term-Storage of Digital Code on Stable Optical Media

Future accessibility to information requires on one hand a stable media that reliably stores the information content and that, one the other hand offers accessibility with the tools available in the future. Today, institutions have to rely on proprietary technology. Most of them, hard-drives, magnetic tapes, or DVDs, do not fulfill the requirements of long-term stability and accessibility. Thus, an ideal storage solution for archival purposes should meet the following requirements: it should offer high stability, high data density, low costs per GByte, should be easy to handle, undemanding regarding to the infrastructure, and technology independent.An example of a technology independent and reliable method to store data is human readable symbolic code, such as written text. In this case, the interface to access the data is reduced to the eye of the observer. Considering this fact, we propose to investigate a data carrier based on photographic material of high stability, on which digital information of any kind can be stored as visible digital barcode. Thanks to the visibility of the data, it is possible to recover the information with any digital scanning or camera device of appropriate quality. As photographic material is usually based on more than one layer of dyes, each layer can be used as a separate data channel. The quantization depth of each channel leads to a digital code over a higher than binary alphabet. Fragmenting and distributing the data on the film can increase resistance against local deterioration.The available technology at the time of the future digitization and interpretation of the archived information is unknown. Thus, the complexity of information retrieval will be simplified by a sophisticated encoding procedure, an asymmetric approach common in data compression. Such a sophisticated asymmetric codec requires an optimized interaction of information carrier and digital code. We will analyze state of the art photographic material to evaluate its properties. Taking into account the characteristic features of the data carrier, the digital code will be optimized regarding data density, robustness and simplicity. Furthermore, highly sophisticated error correction will be applied to the data to enhance security. The presented approach combines the positive aspects of digital data and an ultra stable medium like microfilm (estimated lifetime up to 500 years at room temperature) and leads to an archival media with an expected storage capacity of up to 700 MByte per sheet (104x148mm2 color microfiche).

Active organic–inorganic sol gel with high thermal stability for nonlinear optical applications

Second-harmonic generation and thermal stability of hybrid photosensitive sol-gel films doped with a side-chain electro-optic chromophore have been studied. Nonlinear optic coefficient d33 has been derived for the cross-linked and noncross-linked sol-gel films. The d33 of the cross-linked hybrid sol-gel film shows high stability at elevated temperature. No evident degradation in d33 was observed at 110 °C and only 20% of d33 decayed in 15 min at 180 °C. The results indicate that the film can meet the long-term stability requirement for optical components.

An AC Josephson source for Johnson noise thermometry

We have adapted the Josephson arbitrary waveform synthesizer to create a quantized voltage noise source suitable for calibrating the cross-correlation electronics of a Johnson noise thermometer system. The requirements of long term stability and low voltage amplitude allow dramatic simplification of the bias electronics compared to previous bias techniques. We describe the waveform synthesis, the bias technique, and the superconducting integrated circuit used to generate the pseudo-noise waveforms.

Electrocatalyst performance in industrial water electrolysers

Electrocatalyst materials used in industrial water electrolysis equipment must meet stringent requirements for long-term stability. Low electrode overvoltages must be sustained over prolonged periods of normal operation, including power interruptions. This paper presents an overview of the catalyst systems currently favoured for use in alkaline electrolyte. Performance data covering test periods exceeding 30 000 h are presented for representative commercial electrocatalysts. Results obtained in 100 000-A unipolar cells are correlated in detail with expectations based on measurements in laboratory and pilot-plant equipment. Particular attention is given to the effects of open-circuit conditions on electrode stability. An accelerated reverse-potential cycling test is described which allows identification of materials expected to withstand industrial operating conditions. It is found that the better materials which have been identified can be used with confidence, at least in electrolysers of the unipolar design in which potential variations encountered during current interruptions are modest.

A Highly Collimated Monochromatic Ion Probe System with an Energy Range of 0.5 to 50 KeV

All components of an interdependent system are complexly related. Ion source materials and performance, ion optics, magnetic optics, deceleration schemes and so forth are not easily treated as independent elements. The severe requirements of long term stability and fine optics must be watched by the realities of space charge, attrition, and simplistic items such as cost and practical operation. We trust we have demonstrated a mix of these odd parameters for good performance and long term stability

Microcomputer-Controlled Precision Pneumatic Pressure Generator

An increasing variety of avionics require precision pneumatic pressure stimuli during organization and intermediate maintenance. The accuracy and long-term stability requirements approach the best mercurial standards. Pressure stimuli must be coordinated and varied at precise rates that are beyond the frequency response of mercury columns and many electromechanical sensors. Test systems are frequently required to simultaneously monitor and evaluate unit under test (UUT) response and generate pneumatic stimuli. In addition, the environment is frequently hostile, maintainability is paramount, performance must always be known and warmup time must be nil. Comprehensive trade studies, tests, and analyses were performed. This initial work indicated a new pressure generator should be a "smart" instrument and should use a pressure sensor not a density sensor. Current field and production experience indicates performance objectives have been exceeded and this new type of precision pressure generator can be readily incorporated in a variety of test systems or be used "stand-alone". This paper discusses the design implementation, features, and characteristics of this microcomputer controlled precision pneumatic pressure generator-a new "smart" test instrument.