scholarly journals Anomalous interfacial stress generation during sodium intercalation/extraction in MoS2 thin-film anodes

2019 ◽  
Vol 5 (1) ◽  
pp. eaav2820 ◽  
Author(s):  
Zhi Li ◽  
Keren Jiang ◽  
Faheem Khan ◽  
Ankur Goswami ◽  
Jun Liu ◽  
...  
Keyword(s):  
Compressive Stress ◽  
Electrode Materials ◽  
Storage Capacity ◽  
Interfacial Stress ◽  
Stress Generation ◽  
Electrode Degradation ◽  
Battery Design ◽  
Wide Range ◽  
Voltage Plateau ◽  
Long Lifetime

Although the generation of mechanical stress in the anode material is suggested as a possible reason for electrode degradation and fading of storage capacity in batteries, only limited knowledge of the electrode stress and its evolution is available at present. Here, we show real-time monitoring of the interfacial stress of a few-layer MoS2 system under the sodiation/desodiation process using microcantilever electrodes. During the first sodiation with a voltage plateau of 1.0 to 0.85 V, the MoS2 exhibits a compressive stress (2.1 Nm−1), which is substantially smaller than that measured (9.8 Nm−1) during subsequent plateaus at 0.85 to 0.4 V due to the differential volume expansion of the MoS2 film. The conversion reaction to Mo below 0.1 V generates an anomalous compressive stress of 43 Nm−1 with detrimental effects. These results also suggest the existence of a separate discharge stage between 0.6 and 0.1 V, where the generated stress is only approximately one-third of that observed below 0.1 V. This approach can be adapted to help resolve the localized stress in a wide range of electrode materials, to gain additional insights into mechanical effects of charge storage, and for long-lifetime battery design.

uMBD: A Materials-Ready Dispersion Correction that Uniformly Treats Metallic, Ionic, Covalent, and van der Waals Bonding

2019 ◽  
Author(s):  
Minho Kim ◽  
won june kim ◽  
Tim Gould ◽  
Eok Kyun Lee ◽  
Sébastien Lebègue ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Electrode Materials ◽  
Full Range ◽  
Van Der Waals ◽  
Dft Method ◽  
Dispersion Correction ◽  
Computational Overhead ◽  
System A ◽  
Battery Design

<p>Materials design increasingly relies on first-principles calculations for screening important candidates and for understanding quantum mechanisms. Density functional theory (DFT) is by far the most popular first-principles approach due to its efficiency and accuracy. However, to accurately predict structures and thermodynamics, DFT must be paired with a van der Waals (vdW) dispersion correction. Therefore, such corrections have been the subject of intense scrutiny in recent years. Despite significant successes in organic molecules, no existing model can adequately cover the full range of common materials, from metals to ionic solids, hampering the applications of DFT for modern problems such as battery design. Here, we introduce a universally optimized vdW-corrected DFT method that demonstrates an unbiased reliability for predicting molecular, layered, ionic, metallic, and hybrid materials without incurring a large computational overhead. We use our method to accurately predict the intercalation potentials of layered electrode materials of a Li-ion battery system – a problem for which the existing state-of-the-art methods fail. Thus, we envisage broad use of our method in the design of chemo-physical processes of new materials.</p>

scholarly journals LED Rail Signals: Full Hardware Realization of Apparatus with Independent Intensity by Temperature Changes

Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1291
Author(s):  
Giuseppe Schirripa Schirripa Spagnolo ◽  
Fabio Leccese
Keyword(s):  
Temperature Sensor ◽  
Energy Efficient ◽  
Light Emitting Diode ◽  
Junction Temperature ◽  
Light Emitting ◽  
Temperature Changes ◽  
Wide Range ◽  
International Regulations ◽  
Long Lifetime ◽  
Set Up

Nowadays, signal lights are made using light-emitting diode arrays (LEDs). These devices are extremely energy efficient and have a very long lifetime. Unfortunately, especially for yellow/amber LEDs, the intensity of the light is closely related to the junction temperature. This makes it difficult to design signal lights to be used in naval, road, railway, and aeronautical sectors, capable of fully respecting national and international regulations. Furthermore, the limitations prescribed by the standards must be respected in a wide range of temperature variations. In other words, in the signaling apparatuses, a system that varies the light intensity emitted according to the operating temperature is useful/necessary. In this paper, we propose a simple and effective solution. In order to adjust the intensity of the light emitted by the LEDs, we use an LED identical to those used to emit light as a temperature sensor. The proposed system was created and tested in the laboratory. As the same device as the ones to be controlled is used as the temperature sensor, the system is very stable and easy to set up.

Rational design of flower-like Co–Zn LDH@Co(H2PO4)2 heterojunctions as advanced electrode materials for supercapacitors

2021 ◽  
Vol 50 (13) ◽  
pp. 4643-4650
Author(s):  
Miao He ◽  
Yi He ◽  
Xinyi Zhou ◽  
Qiang Hu ◽  
Shixiang Ding ◽  
...  
Keyword(s):  
Energy Storage ◽  
Specific Capacitance ◽  
Rational Design ◽  
Electrode Materials ◽  
Storage Capacity ◽  
Energy Storage Capacity

The device exhibits 95.3% retention in specific capacitance after 5000 cycles and possesses superior energy-storage capacity.

scholarly journals Origin of long lifetime of band-edge charge carriers in organic–inorganic lead iodide perovskites

2017 ◽  
Vol 114 (29) ◽  
pp. 7519-7524 ◽  
Author(s):  
Tianran Chen ◽  
Wei-Liang Chen ◽  
Benjamin J. Foley ◽  
Jooseop Lee ◽  
Jacob P. C. Ruff ◽  
...  
Keyword(s):  
High Performance ◽  
Carrier Lifetime ◽  
Charge Carriers ◽  
Band Edge ◽  
Lead Iodide ◽  
Solar Cell Performance ◽  
Photovoltaic Materials ◽  
Wide Range ◽  
Long Lifetime ◽  
Photon Recycling

Long carrier lifetime is what makes hybrid organic–inorganic perovskites high-performance photovoltaic materials. Several microscopic mechanisms behind the unusually long carrier lifetime have been proposed, such as formation of large polarons, Rashba effect, ferroelectric domains, and photon recycling. Here, we show that the screening of band-edge charge carriers by rotation of organic cation molecules can be a major contribution to the prolonged carrier lifetime. Our results reveal that the band-edge carrier lifetime increases when the system enters from a phase with lower rotational entropy to another phase with higher entropy. These results imply that the recombination of the photoexcited electrons and holes is suppressed by the screening, leading to the formation of polarons and thereby extending the lifetime. Thus, searching for organic–inorganic perovskites with high rotational entropy over a wide range of temperature may be a key to achieve superior solar cell performance.

Novel Co3O4/Carbon Nanofiber Composite Electrode with High Li-Storage Capacity for Lithium Ion Batteries

2011 ◽  
Vol 197-198 ◽  
pp. 1113-1116 ◽  
Author(s):  
Wen Li Yao ◽  
Jin Qing Chen ◽  
An Yun Li ◽  
Xin Bing Chen
Keyword(s):  
Composite Materials ◽  
Lithium Ion Batteries ◽  
Electrode Materials ◽  
Storage Capacity ◽  
Carbon Nanofiber ◽  
Negative Electrode ◽  
Lithium Ion ◽  
Reversible Capacity ◽  
Cycling Performance ◽  
Li Storage

The platelike Co3O4/carbon nanofiber (CNF) composite materials were synthesized by the calcination of β-Co(OH)2/CNF precursor prepared by a surfactant-free hydrothermal method. As negative electrode materials for lithium-ion batteries, the platelike Co3O4/CNF composites can deliver a high reversible capacity of 900 mAh g-1 for a life extending over hundreds of cycles at a current density of 100 mA g-1. The high Li-storage capacity and excellent cycling performance for Co3O4/CNF composite materials may mainly attribute to the beneficial effect of the CNFs addition on enhancing structural stability and electrical conductivity of Co3O4 platelets.

Polymer characterization

2004 ◽  
Author(s):  
Ian L. Hosier ◽  
Alun S. Vaughan
Keyword(s):  
Molecular Weight ◽  
Electrode Materials ◽  
Polymeric Materials ◽  
Optical Nonlinearity ◽  
Polymer Science ◽  
New Materials ◽  
Wide Range ◽  
Step Growth ◽  
Step Growth Polymerization ◽  
Increasing Demand

Polymer science is, of course, driven by the desire to produce new materials for new applications. The success of materials such as polyethylene, polypropylene, and polystyrene is such that these materials are manufactured on a huge scale and are indeed ubiquitous. There is still a massive drive to understand these materials and improve their properties in order to meet material requirements; however, increasingly polymers are being applied to a wide range of problems, and certainly in terms of developing new materials there is much more emphasis on control. Such control can be control of molecular weight, for example, the production of polymers with a highly narrow molecular weight distribution by anionic polymerization. The control of polymer architecture extends from block copolymers to other novel architectures such as ladder polymers and dendrimers. Cyclic systems can also be prepared, usually these are lower molecular weight systems, although these also might be expected to be the natural consequence of step-growth polymerization at high conversion. Polymers are used in a wide range of applications, as coatings, as adhesives, as engineering and structural materials, for packaging, and for clothing to name a few. A key feature of the success and versatility of these materials is that it is possible to build in properties by careful design of the (largely) organic molecules from which the chains are built up. For example, rigid aromatic molecules can be used to make high-strength fibres, the most highprofile example of this being Kevlar®; rigid molecules of this type are often made by simple step-growth polymerization and offer particular synthetic challenges as outlined in Chapter 4. There is now an increasing demand for highly specialized materials for use in for example optical and electronic applications and polymers have been singled out as having particular potential in this regard. For example, there is considerable interest in the development of polymers with targeted optical properties such as second-order optical nonlinearity, and in conducting polymers as electrode materials, as a route towards supercapacitors and as electroluminescent materials. Polymeric materials can also be used as an electrolyte in the design of compact batteries.

scholarly journals Spark channel dynamics in railgun switches in unipolar and oscillatory discharges

2019 ◽  
Vol 37 (2) ◽  
pp. 223-230 ◽  
Author(s):  
A.V. Kharlov
Keyword(s):  
Electrode Materials ◽  
Plasma Channel ◽  
Capacitor Bank ◽  
Electrode Erosion ◽  
Channel Dynamics ◽  
Unipolar Pulse ◽  
Wide Range ◽  
Unipolar Discharge ◽  
Consistent Treatment ◽  
Spark Channel

AbstractSpark gaps are often used to commute energy in the discharge of a capacitive storage to a load. In some applications, a unipolar pulse is not feasible, and an oscillatory (underdamped sinusoidal) regime must be realized for the discharge of the capacitor bank. Spark gaps, which were developed for unipolar discharge, cannot be directly employed in an under-damped (oscillatory) regime since at the transition of the current through zero, the spark channel could stop motion and ignite in the following half period. This work has two main objectives: (i) To develop and test a simulation model of spark channel motion in linear rail geometry, which must be valid for both the oscillatory and unipolar regimes of capacitor bank discharge; and (ii) to investigate arc motion and electrode heating, depending on the current and charge transfer, over a wide range of operation. A self-consistent treatment of plasma motion and electrode heating (taking into account the radiation of a plasma channel) is applied in the present paper, and it is shown that radiation can significantly impact on the temperature of the electrodes. Electrode ablation and the temperature dependence of the main thermal parameters are also taken into account. Stainless steel (Cr/Ni/Ti 18/10/0.6÷0.8), copper (Cu), chromium (Cr), tungsten (W), and molybdenum (Mo) are used here as electrode materials since these materials are widely used for the manufacture of electrodes. The results of numerical calculations are compared with experimental results, and conditions are defined for reduced electrode erosion.

scholarly journals Label-Free Electrochemical Biosensors for the Determination of Flaviviruses: Dengue, Zika, and Japanese Encephalitis

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4600 ◽  
Author(s):  
Ekaterina Khristunova ◽  
Elena Dorozhko ◽  
Elena Korotkova ◽  
Bohumil Kratochvil ◽  
Vlastimil Vyskocil ◽  
...  
Keyword(s):  
Japanese Encephalitis ◽  
Electrode Materials ◽  
Biological Fluids ◽  
Research Progress ◽  
Immunological Methods ◽  
Label Free ◽  
Viral Pathogens ◽  
Electrochemical Biosensing ◽  
Wide Range

A highly effective way to improve prognosis of viral infectious diseases and to determine the outcome of infection is early, fast, simple, and efficient diagnosis of viral pathogens in biological fluids. Among a wide range of viral pathogens, Flaviviruses attract a special attention. Flavivirus genus includes more than 70 viruses, the most familiar being dengue virus (DENV), Zika virus (ZIKV), and Japanese encephalitis virus (JEV). Haemorrhagic and encephalitis diseases are the most common severe consequences of flaviviral infection. Currently, increasing attention is being paid to the development of electrochemical immunological methods for the determination of Flaviviruses. This review critically compares and evaluates recent research progress in electrochemical biosensing of DENV, ZIKV, and JEV without labelling. Specific attention is paid to comparison of detection strategies, electrode materials, and analytical characteristics. The potential of so far developed biosensors is discussed together with an outlook for further development in this field.

Ti2P monolayer as a high performance 2-D electrode material for ion batteries

2020 ◽  
Vol 22 (33) ◽  
pp. 18480-18487
Author(s):  
Zishuang Cheng ◽  
Xiaoming Zhang ◽  
Hui Zhang ◽  
Heyan Liu ◽  
Xiao Yu ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electrode Material ◽  
High Performance ◽  
Electrode Materials ◽  
Storage Capacity ◽  
Ion Diffusion ◽  
Battery Electrode

Electrical conductivity, storage capacity and ion diffusion ability are three crucial parameters for battery electrode materials.

The photolysis of hexafluoroacetone

1956 ◽  
Vol 234 (1199) ◽  
pp. 476-488 ◽  
Keyword(s):  
Quantum Yield ◽  
Initial Step ◽  
Excited Molecule ◽  
Inert Gases ◽  
Wide Range ◽  
Electronically Excited ◽  
Photolytic Decomposition ◽  
Long Lifetime ◽  
The Stability ◽  
Excellent Source

The photolytic decomposition of hexafluoroacetone has been studied over a wide range of temperatures and pressures using light of wavelength 3130 Å. The initial step involves the production of CF 3 radicals, and the only products are C 2 F 6 and CO. The reaction is an excellent source of CF 3 radicals. The quantum yield diminishes with increasing pressure. A mechanism is suggested involving the participation of an electronically excited molecule of comparatively long lifetime, and the effect of various inert gases on the stability of this species is discussed.

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