batterydata/paper-abstracts huggingface dataset:
Carbon materials are widely used in supercapacitors because of their high surface area, controlled porosity and ease of processing into electrodes. The combination of carbon with metal oxides results in hybrid electrodes with higher specific capacitance than pure carbon electrodes, which has so far limited the energy density of supercapacitors currently available commercially. However, the preparation and processing of carbon/metal oxide electrodes into supercapacitors of different structures and configurations, especially for miniaturized electronics, has been challenging. Here, we demonstrate a simple one-step process for the synthesis and processing of laser-scribed graphene/RuO2 nanocomposites into electrodes that exhibit ultrahigh energy and power densities. Hydrous RuO2 nanoparticles were successfully anchored to graphene surfaces through a redox reaction of the precursors, graphene oxide, and RuCl3 using a consumer grade LightScribe DVD burner with a 788nm laser. This binder-free, metal current collector-free graphene/RuO2 film was then used directly as a hybrid electrochemical capacitor electrode, demonstrating much-improved cycling stability and rate-capability with a specific capacitance up to 1139Fg− 1. We employed these hybrid electrodes for building aqueous-based symmetric and asymmetric cells that can deliver energy densities up to 55.3Whkg−1, placing them among the best performing hybrid electrochemical capacitors. Furthermore, this technique was used for the direct writing of interdigitated hybrid micro-supercapacitors in a single step for the first time, with great potential for miniaturized electronics. This simple approach provides a general strategy for making a wide range of composite materials for a variety of applications.
When hydroelectric power systems became widespread, associated developments for energy storage, using pumped water, soon followed. Many other methods of storage have since been considered. Today's interest in other renewables, notably wind energy has led to assertions that, because it is intermittent, wind can make no contribution to the firm power on a power system (i.e., it has no capacity credit) but that storage can make it viable. Here we show that such assertions about intermittent renewables like wind are false – they can and do make contributions to firm power and storage has no special contribution to make for them. However, their main contribution is to fuel saving and storage is counter-productive for that because the losses in the storage and regeneration round-trip would represent a waste of fuel that had already been saved. More importantly, the energy being stored comes from those generators that were the last ones brought on line to supply the extra energy that is being stored, which would be the first to be shut down if the storage stopped, e.g., because the store was full or had broken down. These will be (marginally) the most expensive generation on line, the (marginally) cheapest generation always having being used first. Renewables have no fuel costs, so their (marginal) cost is zero, which must always make them (marginally) the cheapest power on the system, whenever they are available. So they will always be the last to be shut down or stored. When storage is installed, grid-connected intermittent renewables like wind energy will never be stored unless nothing else is available.
In this work, a micro-carbon/nano-silicon hybrid material is synthesized via a scalable and practical solid-state process for rechargeable Li-ion battery anodes. The carbon encapsulated silicon composite is produced by a two-step thermal reduction of commercial wheat flour. This silicon-carbon hybrid demonstrates a stable gravimetric capacity of ca. 1500mAhg−1 Si (equivalently, 700mAhg−1 composite mass) from galvanostatic cycling for 90 cycles at a cycling rate of C/20. Multi-rate cycling shows the silicon-carbon hybrid performs with stable gravimetric capacities of 830mAhg−1 at C/10 and 300mAhg−1 at 1C. After prolonged cycling, the carbon-silicon hybrid further demonstrates superior mechanical and electrochemical resilience when compared to unencapsulated silicon electrode: greater composite conductivity (ca. 4 times larger at full lithiation), lower electrode deformation, and less SEI formation.
All-solid-state lithium batteries (ASSLBs) with solid electrolytes have attracted great attention for the replacement of traditional lithium batteries with liquid electrolytes due to their advantages such as high safety, excellent electrochemical cycling property and long-term stability. To date, various solid electrolytes including oxide, sulfide and polymer and organic-inorganic hybrid electrolytes have been developed for ASSLBs. Especially, the strategies to improve electrochemical performance especially ionic conductivity and stability of solid electrolytes have been widely studied. However, nowadays, ASSLBs are still not commercialized and used in our daily life. In this article, the situations of the solid electrolytes are critically reviewed, the main challenges and future prospective for the development of solid electrolytes are given and the utmost limits of those state-of-the-art solid electrolytes are analyzed. In addition, the electrode/electrolyte interface modification techniques to make ASSLBs achieving the excellent performance are evaluated. It is expected to provide a guidance for the development of novel solid electrolytes with higher ionic conductivity and environmental stability for ASSLBs.
In this paper, a hierarchical coordinated charging framework for PEVs across multiple aggregators is proposed. First, each aggregator computes its aggregate charging load boundaries based on customer charging requirements and local transformer capacity limits. With the load boundaries of aggregators, a linear optimization model is then solved at the distribution system operator (DSO) level to generate the preferred charging curve for each aggregator. Finally, each aggregator intelligently allocates the charging power suggested by the DSO based on a fast heuristic algorithm. Case studies on four aggregators following different charging strategies are carried out. Simulation results indicate this charging coordination framework successfully achieves electricity cost minimization and system peak load controlling. Moreover, considering that part of profits of aggregators might be compromised by participating in charging coordination, a simple but clear compensation mechanism for aggregators is designed.
A practical universal modeling and simulation approach is presented in this paper to show that accurate battery pack simulation can be achieved if cell-to-cell variations were taken into account. A generic equivalent circuit model was used in the approach with parameters deduced from cell testing with proper protocols, which could come from live cell monitoring in a control circuitry. Using a single cell model, which was validated against experimental data and demonstrated with validity of high accuracy in predicting cell performance, we showed that such a high accuracy in single cell model is essential for a high fidelity pack simulation. It is also important to derive statistical confidence intervals accurately from experiments to characterize intrinsic cell-to-cell variations in capacity and internal resistance, which need to be considered in the pack model. If parameters for each individual cell were correctly approximated and used in the pack model, the accuracy in the prediction of pack performance could be significantly improved.
Carbon coated LiFePO4 particles were first synthesized by sol–gel and freeze-drying method. These particles were then coated with La0.7Sr0.3MnO3 nanolayer by a suspension mixing process. The La0.7Sr0.3MnO3 and carbon co-coated LiFePO4 particles were calcined at 400°C for 2h in a reducing atmosphere (5% of hydrogen in nitrogen). Nanolayer structured La0.7Sr0.3MnO3 together with the amorphous carbon layer forms an integrate network arranged on the bare surface of LiFePO4 as corroborated by high-resolution transmission electron microscopy. X-ray diffraction results proved that the co-coated composite still retained the structure of the LiFePO4 substrate. The twin coatings can remarkably improve the electrochemical performance at high charge/discharge rates. This improvement may be attributed to the lower charge transfer resistance and higher electronic conductivity resulted from the twin nanolayer coatings compared with the carbon coated LiFePO4.
Silicon is the most promising high capacity anode material to replace graphite for developing next generation high energy density Li-ion batteries. In this approach, patterned amorphous and microcrystalline Si thin film electrodes (a-Si and μc-Si) have been prepared by rf-sputtering and etched further by a reactive ion etching (RIE) system to form square-shape microcolumn electrodes with controllable size (5 × 5 μm width, 500 nm height, aspect ratio of width/height is 10:1) and array distance (5 μm). It has been found that the volume expansion and contraction of a-Si and μc-Si are anisotropic, about 180% along vertical direction and 40% along lateral direction. The total volume variation changes linearly with the increase of lithium insertion content up to ∼310% for a-Si and ∼300% for μc-Si. It occurs nearly reversibly. In addition, it is observed that the original square-shape Si column transforms into the dome-like appearance after lithium insertion and changes into bowl shape after lithium extraction gradually. Radial-like curved cracks are formed after 5−10 cycles and the neighboring Si columns tend to merge together when the distance of the columns is less than 1 μm.
To ensure safety for humans, it is essential to characterize the genotoxic potential of new chemical entities, such as pharmaceutical and cosmetic substances. In a first tier, a battery of in vitro tests is recommended by international regulatory agencies. However, these tests suffer from inadequate specificity: compounds may be wrongly categorized as genotoxic, resulting in unnecessary, time-consuming, and expensive in vivo follow-up testing. In the last decade, novel assays (notably, reporter-based assays) have been developed in an attempt to overcome these drawbacks. Here, we have investigated the performance of two in vitro reporter-based assays, Vitotox and ToxTracker. A set of reference compounds was selected to span a variety of mechanisms of genotoxic action and applicability domains (e.g., pharmaceutical and cosmetic ingredients). Combining the performance of the two assays, we achieved 93% sensitivity and 79% specificity for prediction of gentoxicity for this set of compounds. Both assays permit quick high-throughput analysis of drug candidates, while requiring only small quantities of the test substances. Our study shows that these two assays, when combined, can be a reliable method for assessment of genotoxicity hazard.
Because of the rise in renewable energy use, the redox flow battery (RFB) has attracted extensive attention as an energy storage system. Thus, many studies have focused on improving the performance of the felt electrodes used in RFBs. However, existing analysis cells are unsuitable for characterizing felt electrodes because of their complex 3-dimensional structure. Analysis is also greatly affected by the measurement conditions, viz. compression ratio, contact area, and contact strength between the felt and current collector. To address the growing need for practical analytical apparatus, we report a new analysis cell for accurate electrochemical characterization of felt electrodes under various conditions, and compare it with previous ones. In this cell, the measurement conditions can be exhaustively controlled with a compression supporter. The cell showed excellent reproducibility in cyclic voltammetry analysis and the results agreed well with actual RFB charge-discharge performance.
In this study, the electrochemical behaviour of the Ce3+/4+ redox couple in methanesulfonic acid medium on various electrode substrates was investigated as a function of temperature. Carbon composite electrodes as well as platinum and platinum iridium coated electrodes were studied for their suitability in carrying out the Ce3+/4+ redox reaction. Cyclic voltammetry in 0.8moldm−3 cerium and 4.5moldm−3 methanesulfonic acid solution showed that elevated temperatures favoured the Ce3+/Ce4+ reaction on the various platinum and platinum–iridium coated substrates as well as on carbon composite surfaces. The latter electrodes showed better kinetics than the metal coatings but deteriorated badly under the high positive potentials required for the cerium reaction. The exchange current density (j o ), obtained through Tafel extrapolation, polarisation resistance and electrochemical impedance spectroscopy measurements, increased with temperature over the range 25°C to 60°C. The Pt–Ir coatings gave the largest j o at 60°C and appear best suited for use as the positive electrode in the Zn–Ce redox flow battery.
The field of quality-of-life (QOL) measurement grew out of attempts in the 1960s and 1970s to connect the ever-increasing levels of public expenditure on technology-based health care for chronic diseases with evidence of the benefits and harms to patients. Most of the concepts, methods, and standards for measuring QOL were derived from psychometrics, but the degree to which current tools adhere to these methods varies greatly. Despite the importance of QOL, patient-reported outcomes are not measured in most cardiovascular clinical trials. Lack of familiarity with QOL measures and their interpretation, and unrealistic expectations about the information these measures can provide, are obstacles to their use. Large clinical trials of revascularization therapy for coronary artery disease and medical treatments for heart failure show small-to-moderate QOL effects, primarily detected with disease-specific instruments. Larger treatment effects, seen in trials of device therapy for heart failure and ablation therapy for atrial fibrillation, have been detected with both generic and disease-specific instruments. A large gap remains between the parameters currently being measured in clinical research and the data needed to incorporate the 'patient's voice' into therapeutic decision-making.
Fe3 – x O4 raspberry shaped nanostructures/graphene nanocomposites were synthesized by a one-step polyol-solvothermal method to be tested as electrode materials for Li-ion battery (LIB). Indeed, Fe3 – x O4 raspberry shaped nanostructures consist of original oriented aggregates of Fe3 – x O4 magnetite nanocrystals, ensuring a low oxidation state of magnetite and a hollow and porous structure, which has been easily combined with graphene sheets. The resulting nanocomposite powder displays a very homogeneous spatial distribution of Fe3 – x O4 nanostructures at the surface of the graphene sheets. These original nanostructures and their strong interaction with the graphene sheets resulted in very small capacity fading upon Li+ ion intercalation. Reversible capacity, as high as 660mAh/g, makes this material promising for anode in Li-ion batteries application.
The flow battery module comprised of multi-stack is commonly constructed for use in large-scale electrical energy storage applications. In such a multi-stack module, the transport delay associated with electrolyte flow in the piping systems inevitably exists that can impose a significant impact on module design and operation performance. In this paper, a complete dynamic model incorporating transport delay is developed for the multi-stack vanadium flow battery module. Based on the model, the module performance and capacity utilization are comprehensively analyzed for different module designs and various operational conditions. Simulation results demonstrate that the transport delay can cause uneven concentration distributions along the piping and lead to a poor stack voltage uniformity in the module, which can subsequently result in premature voltage cut-off in operation and a degraded capacity utilization. Meanwhile, the analyses also prove that the transport delay and its negative effect on the module can be effectively reduced by optimizing the electrolyte feeding mode in addition to adopting a high variable flow rate and a small pipe radius. Such an in-depth simulation analysis considering the transport delay not only offers a cost-effective way to analyze a multi-stack flow battery system, but also provides a deep insight into design and optimization of the large-scale flow battery module that can allow both high system efficiency and superior capacity utilization to be achieved.
Background Noninvasive brain stimulation is a powerful way to modify excitability of the cerebral cortex in humans and is increasingly used to treat psychiatric disorders. The observed clinical effects are in the moderate range and it has been suggested that the efficiency of brain stimulation depends on the underlying cortical state. Objective To isolate and manipulate brain rhythms associated with cortical excitability. Methods In the first experiment electroencephalography (EEG) and transcranial magnetic stimulation (TMS) were interleaved to study associations between brain oscillations and the amplitude of the motor evoked potential (MEP) during isometric contraction. Results of the first experiment were used in a second experiment to selectively modulate cortical excitability levels by applying transcranial alternating current stimulation (tACS). Results A linear regression showed that MEP amplitude could be modeled by θ (4-7 Hz) and β (13-30 Hz) oscillations recorded over the left and right M1. Significant increases in cortical excitability were found after θ (5 Hz)-β (20 Hz) tACS as compared with baseline and α (10 Hz) tACS. Conclusions Scalp-recorded brain oscillations can serve as a proxy for the effective modulation of cortical excitability by mimicking natural brain rhythms using weak electric currents.
Three different, innovative approaches have been taken to develop photovoltaic (PV) integrated electrochromic (EC) devices for smart-window applications. These are: (i) a stand-alone, side-by-side PV-powered EC window; (ii) a monolithically integrated PV-EC device; and (iii) a novel photoelectrochromic device based on a dye-sensitized TiO2 solar cell. The compatibility of PV-EC devices has been analyzed, and the potential for large energy savings for building applications has been suggested. The first monolithic, amorphous-silicon based, PV-powered electrochromic window is described in detail. The device employs a wide bandgap a-Si1−x C x /H n–i–p PV cell as a semitransparent power source, and a Li y WO3/LiAlF4/V2O5 EC device as an optical-transmittance modulator. The EC device is deposited directly on top of a PV cell that coats a glass substrate. The a-Si1−x C x /H PV cell has a gap of 2.5 eV and a transmittance of 60–80% over a large portion of the visible light spectrum. Our prototype 16-cm2 PV-EC device modulates the transmittance by more than 60% over a large portion of the visible spectrum. The coloring and bleaching times of the EC device are approximately 1 min under normal operating conditions (±1 V). A brief description of photoelectrochromic windows based on a combination of dye-sensitized TiO2 and WO3 EC-layer is also given.
Currently, safety issue on Li-ion battery caused by thermal stability is one of the main factors that restricts its developmental application. In this paper, from a perspective of heat generation, we present a method to estimate remaining capacity of single Li-ion battery. Sample entropy (SampEn) is employed for the calculation of surface temperature in charging process and the relationship between SampEn and capacity fading in aging process is built. Considering various factors of capacity attenuation, an intelligent estimation approach is proposed by the combination of SampEn and particle filter (PF).
Biomass waste-derived carbon materials are considered as high promising electrode materials in rechargable batteries since their wide sources, low costs and abundant reserves on earth. However, the structural design of these materials is still highly needed to further develop their applications in energy storage fields. In this work, peanut skin is choosen as the precursor to construct graphene-like nanosheets on the surface of porous carbon framework via a sulfuric acid-assisted hydrothermal process with following activation technique. Electrochemical results reveal this unique structure could provide high rate capacity (243 mAh·g−1 at 5 A g−1) and stable cycling performance (681 mAh·g−1 at 0.1 A g−1 after 100 cycles) in Li-ion battery and promising Na-ion storage cycling performance (233 mAh·g−1 at 0.5 A·g−1 after 450 cycles) as anodes materials. Further contrastive research indicates these promoted performance are mainly attributed to the graphene-like nanosheets in this composite structures. These sheets remarkbly enhance both of the intercalation and surface adsorption of Li-ion with high charge transfer ability, finally facilitating both of the pseudocapacitance and diffusion controlled process during the charge/discharge test. This work provides new choices for the design of nanostructures in other low cost carbonaceous materials with promoted applications in energy storage fields.
The Li metal anode has high theoretical specific capacity and low redox potential, making it suitable as an anode material for next-generation Li ion-based batteries (LIBs); however, challenges remain due to its unstable solid electrolyte interphase (SEI). In this study, we applied graphene-coated aramid attached to an uncoated aramid separator fabricated using a simple painting method to a Li metal anode to address the issues caused by the unstable SEI via fluorinated metathesis on a conjugated carbon network (CCN). The graphene-coated surface was partially fluorinated in a specific solvent environment, and as the Li+ ions were plated, the fluorinated surface induced formation of LiF as a chemically stable SEI component. Additionally, we demonstrated the successful application of fluorinated metathesis using other CCN materials, such as carbon black and activated carbon. The experimental results indicated that the CCN materials induced LiF via fluorination, and that the negative functionalities and lattice structure of the CCN materials affected the fluorination. These results demonstrated the effectiveness of this novel method for stabilizing a Li metal surface using a graphite pencil.
We report a Density Functional Theory (DFT) study on the electrochemical deposition process of Mg. We studied the impact of the thermodynamics and the kinetics to the morphologies of the deposited phases. Our analysis showed that the free energy difference between high dimensional and low dimensional phases was higher for Mg than for Li as a result of the stronger MgMg bond strength. On the other hand, the migration barriers of Li and Mg showed close values. These findings indicated that the electrochemically deposited Mg essentially prefers to form crystalline layers in comparison with Li due to the intrinsic thermodynamic properties. It suggested that Mg anode provides not only high energy densities, but also the potential to avoid the issues caused by the growth of dendrites.