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The effect of cathode particle size on cell potential was investigated using a voltage prediction method from the Coulomb potential created by the atoms of a cathode active material. LiNiO2 was selected as a typical cathode of an ordered rock salt structure. From the calculation, it was found that the voltage changes when the size becomes less than about 10nm. The voltage increased with decreasing in-plane size, and decreased with decreasing the number of layers.
In this paper, Li4Ti5O12 (LTO) hollow microspheres with the shell consisting of nanosheets have been synthesized via a hydrothermal route and following calcination. Because of the favorable transport properties of this hollow structure, it is the rate performance at high current densities which is exceptional. When the LTO hollow microspheres were used as the anode material in lithium ion battery, they exhibited superior rate performance and high capacity even at a very high rate (131mAhg−1 at 50C).
Publisher Summary This chapter discusses the applications of process hazard analyses on industrial facilities. The bulk of process hazard analyses will be a Hazard and Operability (HAZOP), What-If, or a Preliminary Hazard Analysis (PHA) review. PHA, HAZOP, and Security Vulnerability Analysis (SVA) reviews are generally organized and conducted in a similar fashion. The HAZOP review is more detailed and structured, while the PHA and What-If approach, which are also applied in SVAs, are typically broader, and free flowing PHA is primarily an initial hazard identification and evaluation tool in capital project proposals prior to HAZOP or other quantitative reviews later detailed design phases. The basic facilities that can be considered for a PHA and What-If review are basic fluid/gas transfer, storage, or separation systems, such as wellheads, tank batteries, pipelines (gathering and trunk), production test facilities, subsea (template) production facilities, drilling operations, wireline and workover operations, pumping stations, multistage separation systems (gas/oil/water), gas compression systems for sales, water injection systems, tank farms, liquid loading facilities (truck, rail, ship), marketing terminals, and unmanned offshore facilities. A HAZOP review method is suggested for the process when more complex facilities are under study. These facilities contain processes that typically are complex in nature, have chemical processes containing volatile hydrocarbons and toxic chemicals, or have high employee concentrations. SVAs will generally be applicable to all types of facilities; however, there will be more concern to apply its review to highly visible, valuable, and important facilities or operations. During the changes at a facility a multitude of different changes may occur, therefore the company’s management of change (MOC) procedures should define the type of analysis required by the change.
Structural changes for a series of nickel based layer structured cathode materials during heating from 25 to 450°C in the presence of electrolyte were studied using time-resolved X-ray diffraction (XRD). These samples were electrochemically delithiated to Li0.33NiO2, Li0.27Ni0.8Co0.15Al0.05O2, and Li0.2Ni0.5Mn0.5O2. The structural changes of all these three samples follow a same trend, first convert from a layered structure to a disordered spinel structure, then the disordered spinel phase transforms to the NiO-like phase as the temperature increases. However, the onset temperature of the thermal decomposition reactions strongly depends on the nickel content of the material. The lower the nickel content, the higher the decomposition temperature. At the end of heating at 450°C, the metallic nickel structure was observed only for Li0.33NiO2 sample.
Two types of nitrogen-doped graphene sheets (NGS) synthesized by a facile hydrothermal method are used to immobilize sulfur via an in situ sulfur deposition route. The structure and composition of the prepared nitrogen doped graphene/sulfur (NGS/S) composites are confirmed with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Scanning electron microscope (SEM) and Transmission electron microscope (TEM) images shows the porous sulfur particles are well wrapped by NGS. Compared with graphene/sulfur (GS/S) composite, the NGS-1/S composite with high loading (80 wt%) of sulfur presents a remarkably higher reversible capacity (1356.8 mAh g−1 at 0.1 C) and long cycle stability (578.5 mAh g−1 remaining at 1 C up to 500 cycles). Pyridinic-N rich NGS-1/S exhibits a better electrochemical performance than pyrrolic-N enriched NGS-2/S. The improvement of electrochemical properties could be attributed to the chemical interaction between the nitrogen functionalities on the surface of NGS and polysulfide as well as the enhanced electronic conductivity of the carbon matrix.
Background Data on paediatric deep brain stimulation (DBS) is limited, especially for long-term outcomes, because of small numbers in single center series and lack of systematic multi-center trials. Objectives We seek to systematically evaluate the clinical outcome of paediatric patients undergoing DBS. Methods A German registry on paediatric DBS (GEPESTIM) was created to collect data of patients with dystonia undergoing DBS up to the age of 18 years. Patients were divided into three groups according to etiology (group 1 inherited, group 2 acquired, and group 3 idiopathic dystonia). Results Data of 44 patients with a mean age of 12.8 years at time of operation provided by 6 German centers could be documented in the registry so far (group 1 n = 18, group 2 n = 16, group 3 n = 10). Average absolute improvement after implantation was 15.5 ± 18.0 for 27 patients with pre- and postoperative Burke-Fahn-Marsden Dystonia Rating scale movement scores available (p < 0.001) (group 1: 19.6 ± 19.7, n = 12; group 2: 7.0 ± 8.9, n = 8; group 3: 19.2 ± 20.7, n = 7). Infection was the main reason for hardware removal (n = 6). 20 IPG replacements due to battery expiry were necessary in 15 patients at 3.7 ± 1.8 years after last implantation. Discussion Pre- and postoperative data on paediatric DBS are very heterogeneous and incomplete but corroborate the positive effects of DBS on inherited and acquired dystonia. Adverse events including relatively frequent IPG replacements due to battery expiry seem to be a prominent feature of children with dystonia undergoing DBS. The registry enables collaborative research on DBS treatment in the paediatric population and to create standardized management algorithms in the future.
Amorphous carbon and graphene co-modified LiFePO4 nanocomposite has been synthesized via a facile polyol process in connection with a following thermal treatment. Various characterization techniques, including XRD, Mössbauer spectra, Raman spectra, SEM, TEM, BET, O2-TPO, galvano charge-discharge, CV and EIS were applied to investigate the phase composition, carbon content, morphological structure and electrochemical performance of the synthesized samples. The effect of introducing way of carbon sources on the properties and performance of LiFePO4/C/graphene composite was paid special attention. Under optimized synthetic conditions, highly crystalized olivine-type LiFePO4 was successfully obtained with electron conductive Fe2P and FeP as the main impurity phases. SEM and TEM analyses demonstrated the graphene sheets were randomly distributed inside the sample to create an open structured LiFePO4 with respect to graphene, while the glucose-derived carbon mainly coated over LiFePO4 particles which effectively connected the graphene sheets and LiFePO4 particles to result in a more efficient charge transfer process. As a result, favorable electrochemical performance was achieved. The performance of the amorphous carbon-graphene co-modified LiFePO4 was further progressively improved upon cycling in the first 200 cycles to reach a reversible specific capacity as high as 97 mAh·g−1 at 10 C rate.
This paper proposes an adaptive multistage constant current–constant voltage (MCCCV) strategy for charging electric vehicles in different situations. First, a high-fidelity thermoelectric-aging coupling model based on a resistor–capacitor pair electrical model, a thermal network model, and a semiempirical aging model is constructed. Second, an adaptive MCCCV charging strategy involving optimization of the charging current using particle swarm optimization is developed. It can satisfy the preference of users for reducing the charging time or the battery degradation. Finally, three charging strategies based on the Pareto boundary curve of the battery charging time–state of health are developed: a fast-charging strategy for motorway driving, a minimum-aging charging strategy for family use, and a balanced charging strategy for daily use. Additionally, according to the Pareto boundary, the effects of key factors on the optimization of the charging strategy are analyzed and compared. The results show that the balanced charging strategy is 3.60% better than the 0.5C constant current–constant voltage (CCCV) charging strategy recommended by the battery manufacturer with regard to aging loss. Moreover, the charging time is reduced by 37%. Compared with the traditional CCCV charging strategy, the proposed adaptive MCCCV charging strategy has good application prospects with regard to both the charging time and the battery degradation.
In this study, nano-polyanline and manganese oxide nanometer tubular composites (nano-PANI@MnO2) were prepared by a surface initiated polymerization method and used as electrochemical capacitor electrode materials; and the effect of aniline amount on the microstructure and electrochemical performance was investigated. The microstructures and surface morphologies of nano-PANI@MnO2 were characterized by X-ray diffraction, scanning electron microscopy and fourier transformation infrared spectroscope. The electrochemical performance of these composite materials was performed with cyclic voltammetry, charge–discharge test and electrochemical impedance spectroscopy, respectively. The results demonstrate that the feed ratio of aniline to MnO2 played a very important role in constructing the hierarchically nano-structure, which would, hence, determine the electrochemical performance of the materials. Using the template-assisted strategy and controlling the feed ratio of aniline to MnO2, the nanometer tubular structure of nano-PANI@MnO2 was obtained. A maximum specific capacitance of 386 F/g was achieved in aqueous 1 mol/L NaNO3 electrolyte with the potential range from 0 to 0.6 V (vs. SCE).
The amount of natural gas resources accessible via proven production technology and existing infrastructure is declining. Therefore, smaller and less accessible gas fields are considered for commercial exploitation. The research project Enabling production of remote gas builds knowledge and technology aiming at developing competitive remote gas production based on floating LNG and chemical gas conversion. In this project, scenarios are used as basis for directing research related to topics that affect the overall design and operation of such plants. Selected research areas are safety, environment, power supply, operability and control. The paper summarises the scenario building process as a common effort among research institutes and industry. Further, it documents four scenarios for production of remote gas and outlines how the scenarios are applied to establish research strategies and adequate plans in a multidisciplinary project. To ensure relevance of the scenarios, it is important to adapt the building process to the current problem and the scenarios should be developed with extensive participation of key personnel.
Intelligent Transportation Systems (ITS) aim to improve safety, mobility and environmental performance of road transport. The INSIGMA project provides a fresh look at the possible innovations in this field, by enhancing the functionality and accuracy of ITS in urban environments. This paper describes the architecture, sensors, processing algorithms, output modules and advantages of the developed system. A comparison of existing ITS systems has been provided as background. Special attention has been given to performance and privacy issues, as the system includes social aspects such as location monitoring.
We demonstrate the significance of nanostructuring on the reversible Li-insertion into octahedral sites of the nickel substituted spinel Li[Ni0.5Mn1.5]O4. One dimensional nanofibers (50–250 nm diameter) of the Li[Ni0.5Mn1.5]O4 were prepared by a single spinneret electrospinning and their performance was compared with powders synthesized via a conventional solid state approach. Li-diffusion coefficient of electrospun fibers was an order of magnitude higher (5.8 × 10−11 cm2 s−1) than that of conventional powders (1.22 × 10−12 cm2 s−1). Galvanostatic studies revealed a much improved capacity and rate performance for electrospun fibers. The fibers delivered a reversible capacity of ∼87 mAh g−1 after 150 cycles at 1C rate compared to negligible capacity for solid-state prepared material. Finally, the performance of this nanostructured spinel phase as an anode in aqueous rechargeable Li-ion system was demonstrated to require a strongly alkaline electrolyte.
Two new functionalized ILs based on pyrazolium cations and bis(trifluoromethylsulfonyl)imide anions (TFSI−) were synthesized and characterized. Their physicochemical and electrochemical properties, including melting point, thermal stability, density, viscosity, conductivity, and electrochemical window were investigated. The two ILs had low melting points and wide electrochemical windows. Behaviors of lithium redox, chemical stability against lithium metal, and charge–discharge cycle performance of lithium battery were also examined for the two IL electrolytes with 0.4molkg−1 LiTFSI. The IL electrolytes showed good chemical stability against lithium metal, and Li/LiFeO4 cells using the two IL electrolytes without additives owned good capacity and cycle property at the current rate of 0.1C.
Photovoltaic (PV) materials are increasingly being incorporated into the construction of new buildings for generating electrical power and are used to replace conventional building materials in parts of the building envelope such as the roof, skylights, or facades. Also photovoltaic systems may be retro it - integrated into existing buildings. The advantage of integrated photovoltaic systems over the non-integrated systems is that their initial cost can be offset by reducing the cost of the materials and labo r that would normally be spent to construct the part of the building that is replaced. This study examines the effect of air flow on a building integrated PV-panel. It is shown that in summer, the maximum temperature of a PV-panel of 3 m in height is experienced for an east facing surface and reaches 77°C early in the mornin. The maximum temperature for a south facing panel is 51°C and that for a west fac ng surface is 58°C. The air velocity in the air-gap between the PV-panel and the building wall is an important factor. It is shown that for an air-gap width of 0.02 m, an air velocity of 0.5 m s–1 can lower the mean temperature of the panel from 77°C to 39°C, allowing for a significant increase in its efficiency. Finally the air-gap width is varied for a steady elocity of 0.2 m s–1, and it is shown that the temperature of the building wall varies from 23.7°C for a width of 0.01 m to 20°C for a width of 0.05 m.
This paper describes the glycine-nitrate-based solution combustion synthesis of LiNi0.5Mn1.5O4 as a high-voltage cathode material for lithium-ion batteries. The morphology, size, and crystallinity of the products were dependent on the synthesis conditions like glycine amount and calcination temperature and duration, as investigated in particular by X-ray diffraction and scanning electron microscopy, which likewise influenced their electrochemical properties. The electrochemical performance was characterized by galvanostatic charge-discharge cycling. The product obtained at a glycine/nitrate ratio of 1, which was calcined at 800°C for 24h, indicated the best charge-discharge cycling performance. The sample showed an initial discharge capacity of 124.9 mAh/g and could retained 97.20% of the capacity after 50 cycles at a charge-discharge rate of 1C. The sample also exhibited a good high-rate capability, indicating a high discharge capacity of 98 mAh/g at a rate of 10C.
Power generation and storage in electronics require flexible, thin micro-electrochemical energy storage/conversion systems. Micro-supercapacitors (μSCs) with double-layer capacitance carbon electrodes are attracting much attention for their capability of delivering short power pulses with high stability over repeated charge/discharge cycling. Supersonic Cluster Beam Deposition (SCBD) is an effective strategy for the development of nanostructured, binder-free porous carbon electrodes on temperature sensitive substrates including polymers. We exploited SCBD for the development of a flexible, planar μSC featuring nanostructured carbon (ns-C) electrodes deposited on a plastic Mylar substrate and N-trimethyl-N-propyl-ammonium bis(trifluoromethanesulfonyl) imide (N1113TFSI) ionic liquid electrolyte. The electrochemical performance at different temperatures of the μSC which operates at 3V above RT up to 80°C with a capacitance density approaching 10Fcm−3 and delivering maximum specific energy and power densities of 10mWhcm−3 and 8-10Wcm−3 with long cycling stability over 2×104 cycles is here reported and discussed.
This paper aims to examine the sustainability and environmental performance of PV-based electricity generation systems by conducting a thorough review of the life cycle assessment (LCA) studies of five common photovoltaic (PV) systems, i.e., mono-crystalline (mono-Si), multi-crystalline (multi-Si), amorphous silicon (a-Si), CdTe thin film (CdTe) and CIS thin film (CIS), and some advanced PV systems. The results show that, among the five common PV systems, the CdTe PV system presents the best environmental performance in terms of energy payback time (EPBT) and greenhouse gases (GHG) emission rate due to its low life-cycle energy requirement and relatively high conversion efficiency. Meanwhile, the mono-Si PV system demonstrates the worst because of its high energy intensity during the solar cells’ production process. The EPBT and GHG emission rate of thin film PV systems are within the range of 0.75–3.5 years and 10.5–50g CO2-eq./kWh, respectively. In general, the EPBT of mono-Si PV systems range from 1.7 to 2.7 years with GHG emission rate from 29 to 45g CO2-eq./kWh, which is an order of magnitude smaller than that of fossil-based electricity. This paper also reviews the EPBT and GHG emission rates of some advanced PV systems, such as high-concentration, heterojunction and dye-sensitized technologies. The EBPT of high-concentration PV system is lower, ranging from 0.7 to 2.0 years, but the CO2 emission rate of dye-sensitized PV system is higher than the ones of other PV systems at the moment. The LCA results show that PV technologies are already proved to be very sustainable and environmental-friendly in the state of the art. With the emerging of new manufacturing technologies, the environmental performance of PV technologies is expected to be further improved in the near future. In addition, considering the existing limitations in the previous LCA studies, a few suggestions are recommended.
Na-deficient O3-type materials Na0.8Ni0.4−x Co2x Ti0.6−x O2 (x =0, 0.05, 0.1, and 0.15) were synthesized by a simple solid-state reaction and investigated as cathode materials for room-temperature sodium-ion batteries. Among these materials, O3-Na0.8Ni0.3Co0.2Ti0.5O2 exhibits excellent cycle stability and good rate capability. It delivers an initial capacity of 84mAh/g in the voltage range of 2.5–4.2V at a current rate of 0.1C. Approximately 95% of the capacity is maintained after 90 cycles, and the Coulombic efficiency reaches nearly 99% after the initial cycles. At a current rate of 1C, the capacity retention is 81% of the initial capacity. These results indicate that Co-substitution can improve the cycle stability during the course of sodium extraction and insertion.
Vagus nerve stimulation (VNS) is an established neurostimulation therapy used to treat refractory epilepsy. The effect of acute or chronic VNS on the postictal state as a separate entity is seldom reported in clinical or experimental studies. Apart from its antiseizure effects, VNS has several other beneficial effects. These effects may be of particular benefit for patients with postictal neuropsychiatric symptoms. The hypothesized mechanisms underlying the initiation and sustainment of the postictal phase, to some extent, overlap with mechanisms involved in the seizure-suppressing effects of VNS as well as other neurological and psychotropic effects of VNS. Both the clinical symptoms and the basic research hypotheses of the postictal state show similarities with clinical effects induced by VNS and its underlying mechanisms of action.
A three-dimensional Sn electrode is fabricated by the electrodeposition of Sn on a porous Cu foam substrate that consists of grape-like Cu nanodeposits. It is revealed from the XRD results that a small amount of Cu6Sn5 is formed at the interface of Sn deposits and the Cu foam, thereby forming Sn–Cu6Sn5/Cu foam electrode. The electrode shows better cyclic performance and higher charge capacity than the Sn electrode electrodeposited on a smooth Cu foil does. The improved electrochemical performances of the Sn–Cu6Sn5/Cu foam electrode is due to the fact that the porous Cu foam accommodates the volumetric expansion of Sn–Cu6Sn5, and hence inhibits the pulverization or delamination of the active materials from the substrate. Furthermore, ex situ XRD analysis and SEM observation demonstrate that Sn deposits electrodeposited on the Cu foam are gradually blended with the Cu deposits, causing the transformation of Sn into Cu6Sn5. The phase transformation of Sn into Cu6Sn5 enhances the bonding force between the Sn and the Cu foam, and reducing the volume changes of active materials during cycling.
The development of non-precious metal electrocatalysts for renewable energy conversion and storage is compelling but greatly challenging due to low activity of the existing catalysts. Herein, the ultrathin NiAl-layered double hydroxide nanosheets (NiAl-LDH-NSs) are prepared by simple liquid-exfoliation of bulk NiAl-LDHs and first used as ethanol electrooxidation catalysts. The ultrathin two-dimensional (2D) structure ensures that the LDH nanosheets expose a greater number of active sites. More importantly, much Ni(III) active species (NiOOH) in the ultrathin nanosheets are formed by the exfoliation process, which play an authentic catalytic role in the ethanol oxidation reaction (EOR). The presence of NiOOH remarkably improves the reactivity and electrical conductivity of LDH nanosheets. These synergistic effects lead to strikingly more than 30 times enhanced EOR activity of NiAl-LDH-NSs compared to bulk NiAl-LDHs. The obtained electrocatalytic activity is also much better than those of most Ni- and LDH-based EOR catalysts reported to date. In addition, the ultrathin NiAl-LDH-NS electrocatalyst also exhibits good long-term stability (maintain 81.8% of the original value after 10000 s). This study not only provides a highly competitive EOR catalyst, but also opens new avenues toward the design of highly efficient electrode materials that have various potential applications in supercapacitor, Ni-MH battery and other electrocatalytic systems.