batterydata/paper-abstracts huggingface dataset:
To increase the energy density of supercapacitors to approach that of batteries, the current research is always directed towards the cathode materials, whereas the anode materials are rarely studied. In the present work, single-crystalline Fe2O3 nanoparticles directly grown on graphene hydrogels are investigated as high performance anode materials for supercapacitors. During the formation of the graphene/Fe2O3 composite hydrogels, flexible graphene sheets decorated with Fe2O3 particles are self-assembled to form interconnected porous microstructures with high specific surface area, which strongly facilitate charge and ion transport in the full electrode. Infrared spectra show that hydrogen bond is formed between C–OH on graphene hydrogels and Fe2O3. Benefits from the combined graphene hydrogels and Fe2O3 particles in such a unique structure are that the graphene/Fe2O3 composite electrode exhibits an ultrahigh specific capacitance of 908Fg−1 at 2Ag−1 within the potential range from −1.05 to −0.3V, and an outstanding rate capability (69% capacity retention at 50Ag−1). Furthermore, the cycling performance is clearly much better for the graphene/Fe2O3 composite hydrogels than that for pure Fe2O3 sample. These findings open a new pathway to the design and fabrication of three-dimensional graphene hydrogel composites as anode materials in the development of high-performance energy-storage systems.
The National Index of Violence and Harm (NIVAH) tracks levels of violence and harm in the United States and identifies trends over the study period 1995–2003. NIVAH is comprised of nineteen variables in the areas of interpersonal, intrapersonal, institutional and structural violence and harm as experienced by people in the U.S. Two composite indexes are formed to describe overall trends in the realms of personal and societal violence. In addition to describing the Index’s construction and most recent conclusions, various methodological issues and their impacts on index findings are investigated.
The search for low cost and high activity bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) is a research priority in the development of rechargeable metal-air batteries. Manganese oxides are the current favorite, but their native activity needs to be substantially improved before they can be considered as the substitute of noble metals. We discovered phosphate modification as an effective strategy to increase the bifunctional oxygen activity of MnO2 in ORR and OER. Specifically, the half-wave potential of phosphate-promoted α-MnO2 (PMO) for ORR is 0.85 V vs. RHE, ∼70 mV more positive than α-MnO2 and the same as the benchmark 20 wt% Pt/C catalyst. The OER potential to maintain 10 mA cm−2 of current density is 1.63 V, ∼40 mV more negative than α-MnO2 and about the same as the benchmark 20 wt% Ir/C catalyst (1.60 V). The potential difference between ORR (at −3 mA cm−2) and OER (at 10 mA cm−2) is 0.79 V, a standard measure of bifunctional oxygen activity, notably surpasses the performance of α-MnO2 (0.91 V) and the noble metals (0.95 V for Pt/C and 0.93 V for Ir/C). Additional electrochemical measurements and density functional theory calculations suggest that the promoted bifunctional activity of PMO is due to the dual-affinity of phosphate for O and OH groups, which assists O2/OH adsorption in ORR/OER.
In spite of the many studies performed since the beginning of the last century, the Fe electrode, used as negative of both Ni/Fe and Fe/Air batteries, still poses several problems. For instance, according to the current literature, the following points are still not clear: (i) whether and how the depth of discharge affects electrode performance; (ii) what pathway the discharge follows, generally assumed as it is to involve consecutive Fe → FeII and FeII → FeIII oxidation; (iii) why, at room temperature, only a minor fraction of the large theoretical capacity can be exploited. The present paper shows that deep discharges do increase Fe electrode performance, since they induce a transitory inhibition of hydrogen evolution. Likewise, Fe/Metal oxide composite electrodes have shown that the formation of FeIII in discharge can take place directly from Fe, when the discharging rate applied is no longer compatible with the increase in electrode resistance due to oxidation products. Fe/Intermetallic compound composite electrodes have been studied as possible routes for increasing the efficiency of Fe capacity: useful indications have been gained as regards the compatibility of Fe with an IMC for charge storage.
Electrochemical intercalation studies are used to characterize a series of ionic liquids composed of a variety of cationic and anionic species. Electrochemically, the ionic liquids are characterized by cyclic voltammograms and charge–discharge experiments for the intercalation and de-intercalation of the various cationic and anionic species into graphite. X-ray structure analysis is also performed to determine the relationship between the electrochemical behaviour of the ionic liquids, and the formation of intercalated graphitic compounds. Two different types of imidazolium cations are studied, specifically the di- and trisubstituted imidazolium. These cations are paired with the following anions: tetrafluoroborate, hexafluorophosphate, bis(trifluoromethanesulfonyl)imide, bis(perfluoroethanesulfonyl)imide, nitrate and hydrogen sulfate. Results indicate stronger intercalation chemistry for the trisubstituted imidazoliums, correlating with the greater charge–discharge efficiencies found for these types of ionic liquids. Many of the anions exhibit very poor charge–discharge efficiencies, correlating to very poorly formed graphite intercalates. The exception to this is the hydrogen sulfate intercalate, which had low charge–discharge efficiencies but formed a well defined graphite intercalate. Only the imide based anions exhibited both high charge–discharge efficiencies and the formation of a clearly defined graphite intercalate.
Within the field of photocatalytic water splitting there are several strategies to achieve the goal of efficient and cheap photocatalytic water splitting. This work examines one particular strategy by focusing on monolithically stacked, two-photon photoelectrochemical cells. The overall aim of the analysis is to compare the relative merits of two fundamentally different designs: one, where the photoanode is the large bandgap material (light-facing side), and the other, where the photocathode is the large bandgap material. Even though the former design is often shown in the literature, the present analysis shows that the latter design has several advantages. This is particularly true when considering designs that incorporate protection layers to protect the photoabsorbers. A high throughput computational screening was used to filter materials databases in search of candidates with the correct properties. These results show that without protective layers there are scarcely any materials which seem viable as photoabsorbers whereas with protection layers there are significantly more candidates. Since the protection layer (and redox catalysts) on the light facing side should not interfere with light absorption, this is the more difficult side to optimize. Nevertheless, by using TiO2 as a transparent cathode protection layer in conjunction with known H2 evolution catalysts, protection is clearly feasible for a large bandgap photocathode. This suggests that there may be promising strategies for photocatalytic water splitting by using a large bandgap photocathode and a low bandgap photoanode with attached protection layers.
VRLA Refined™ lead produced and marketed by Pasminco since 1997 is a very high purity lead with guaranteed low levels of the gassing elements but with optimum bismuth content that produces oxide of finer particle size, higher acid absorption and imparts outstanding electrical performance and endurance especially under conditions of deep cycling. VRLA batteries suffer dry-out, self-discharge, negative plate capacity loss and poor cycle life unless special lead is used for the grids and active material. This paper addresses the lead used for active material.
In order to improve low-temperature performance of ethylene carbonate (EC)+tetrahydropyran (THP) (5:5) electrolyte with 1 mol dm −3 lithium bisperfluoroethylsulfonyl imide (LiN(SO2C2F5)2) as solute, propylene carbonate (PC) solvent was mixed with this electrolyte. It was found that the electrochemical properties of the resultant ternary electrolytes depended strongly on the solvent composition and 1 mol dm−3 (LiN(SO2C2F5)2)/EC+PC+THP (3:3:4) electrolyte had not only promising freezing point of −36°C but also high lithium cycling efficiency of 95.2%. Furthermore, lithium cycling efficiency was improved to 99.0% by decreasing lithium deposition current density to 0.2 mA cm−2. At the temperature ranging from 25 to −10°C, Li/LiMn2O4 coin cell with 1 mol dm−3 (LiN(SO2C2F5)2)/EC+PC+THP (3:3:4) electrolyte showed the satisfactory cycling performance. Thermal tests further disclosed that this ternary electrolyte showed good thermal stability even with the existence of lithium metal.
Publisher Summary The starting point of power sources for electric vehicles is the lead-acid battery. Because of their relatively low power density, compared with other types of battery which are available, other types of batteries are alsoconsidered for this application. The low power density of the lead-acid system puts severe limitations on the range that can be achieved between battery charges, although the restrictions regarding acceleration and maximum speed are not as limiting as they once were. The lead-acid battery is not dismissed lightly as a power source for electric vehicles. It is, in fact, the only type of battery being used in large-scale prototype vehicle trials. Chloride Batteries UK are currently conducting several such trials. Further, nickel-cadmium batteries are used extensively in France for electric vehicle propulsion, example by Renault and Peugeot. The nickel-zinc system is another viable candidate for electric vehicle propulsion based on its high energy density and power density.
Background: Recently, genome-wide significant risk variants for psychotic disorders have been discovered that afford an opportunity to establish neural mechanisms linked to genetic risk for schizophrenia and bipolar disorder through an imaging genetics approach. Methods: We use an imaging genetics approach in a sample of healthy German volunteers of German descent and a replication sample of similar ethnicity, recruited and assessed with a cognitive and resting fMRI and structural imaging battery in the context of the BMBF-founded MooDs project. Results: ZNF804A and CACNA1C impact on cortical-subcortical connectivity with emphasis on hippocampus and prefrontal cortex. Cognitively specific and global abnormalities can be dissociated, indicating structural (maturational?) components and connectivity aspects relating to the specific type of information processed (working memory, theory of mind, episodic memory, emotional regulation). Discussion: Genome-wide significant variants impact on the brain connectome, partially recapitulating phenotypes observed in patients at risk and with overt disease. Disturbances of connectivity are likely part of the core neurogenetic risk architecture of schizophrenia.
In the present paper, a nonwoven material is presented, which improves the mechanical behaviour and safety of current polymer electrolytes/separators in Li–polymer batteries. The nonwoven material thereby acts as a support material of the separating polymer electrolytes. It helps to improve mechanical properties, safety and processibility of the current polymers. The presented nonwoven material consists of fine polyester fibres and has a thickness of below 20μm. The mechanical strength values are in the range of 20N/5cm with low values of elongation at tension values, which are relevant in battery production. It is electrochemically stable against a Li battery environment and can tolerate temperatures up to 180°C with low values of thermal shrinkage. The wet-laid material is homogeneous regarding pore size distribution. Average pore sizes are in the range of 20–30μm. On the other hand, the material's porosity is in the range of 55–65%, which is high enough to be filled with gel electrolytes also of increased viscosity. Due to the labyrinth-like structure of the nonwoven material, pin-holes do not occur. An outlook is given, how such a material could also improve separators for proton exchange membrane (PEM) fuel cells.
This work is devoted to an extension of the continuum elasticity model combined with the classical lattice-gas (LG) model that recently appeared in the literature and described guest ion insertion into various host materials. The extension involves two important aspects: (i) derivation of intercalation isotherms with four different elastic parameters with the purpose to find their critical combination, leading to first-order phase transitions, and (ii) quantitative treatment of the first-order phase transition reactions controlled by slow external kinetics. This analysis helps to understand properly an important issue of the mechanism of electrochemically driven first-order phase transitions in various ion-insertion electrodes often disregarded in the literature: whatever the concerned electrochemical characteristics are measured, the underlying (often hidden, in practice) kinetic limitations must be considered. The analysis described herein refers to the dependence of the (chemical) differential intercalation capacitance, C dif, and of the chemical diffusion coefficient, D, on the concentration of Li-ions in graphite in the course of electrochemical lithiation/delithiation of these electrodes.
Porous graphene-doped carbon/Fe3O4 (GN@C/Fe3O4) nanofibers are synthesized via in-situ electrospinning and subsequent thermal treatment for use as lithium-ion battery anode materials. A polyacrylonitrile (PAN)/polymethyl methacrylate (PMMA) solution containing ferric acetylacetone and graphene oxide nanosheets is used as the electrospinning precursor solution. The resulting porous GN@C/Fe3O4 nanofibers show unique dark/light banding and a hierarchical porous structure. These nanofibers have a Brunauer–Emmett–Teller (BET) specific surface area of 323.0m2/g with a total pore volume of 0.337cm3/g, which is significantly greater than that of a sample without graphene and C/Fe3O4 nanofibers. The GN@C/Fe3O4 nanofiber electrode displays a reversible capacity of 872 mAh/g at a current density of 100mA/g after 100 cycles, excellent cycling stability, and superior rate capability (455mA/g at 5A/g). The excellent performance of porous GN@C/Fe3O4 is attributed to the material’s unique structure, including its striped topography, hierarchical porous structure, and inlaid flexible graphene, which not only provides more accessible active sites for lithium-ion insertion and high-efficiency transport pathways for ions and electrons, but also accommodates the volume change associated with lithium insertion/extraction. Moreover, the zero-valent iron and graphene in the porous nanofibers enhance the conductivity of the electrodes.
Silicon-graphite composite electrode is one of the most practical solution for next generation high performance lithium ion batteries. Electrode geometry design is a new strategy to improve the electrochemical performances. Herein, we report a unique hierarchical structure of Si@alginate microcapsule-graphite composite anode, in which Si microcapsules are prepared by wrapping of calcium cross-linked alginate. The Si@alginate microcapsules are uniformly dispersed in graphite anode with the widely adopted CMC and SBR binder. The new geometry of electrode architecture has locally different binder systems, which enables both Si and graphite run in their optimized binder environment. The cross-linked alginate capsule effectively confines the volume change and prevents aggregation of the Si nano-particles, which contribute to a significant improvement of the electrochemical performances. At a weight ratio of 3:7 between Si and graphite, the composite electrode exhibits a reversible capacity of 916 mAh g−1 and a capacity retention of 92.4% after 200 cycles. The new strategy for hybrid anode represents a promising avenue for the mass production of high performance Si-graphite composite anode in the future.
The incorporation of additives designed to sacrificially react on the surface of cathode materials of lithium ion batteries has been investigated. Addition of low concentrations of inorganic additives including lithium bisoxalatoborate (LiBOB), lithium difluorooxalatoborate (LiBF2(C2O4)), and tetramethoxy titanium (TMTi) to 1M LiPF6 in 1:1:1 EC/DEC/DMC improves the capacity retention of Li/Li1.17Mn0.58Ni0.25O2 cells cycled to 4.9V vs. Li. Surface analysis of the cathode materials (XPS and IR) suggests that structure of the cathode surface film is modified by the presence of the additives resulting in a decrease in detrimental electrolyte oxidation reactions on the cathode surface.
In the current study, an environmental benign process namely mechanochemical approach was developed for cobalt and lithium recovery from spent lithium-ion batteries (LIBs). The main merit of the process was that neither corrosive acid nor strong oxidant was applied. In the proposed process, lithium cobalt oxide (obtained from spent LIBs) was firstly co-grinded with various additives in a hermetic ball milling system, then Co and Li could be easily recovered by a water leaching procedure. It was found that EDTA was the most suitable co-grinding reagent, and 98% of Co and 99% of Li were respectively recovered under optimum conditions: LiCoO2 to EDTA mass ratio 1:4, milling time 4h, rotary speed 600r/min and ball-to-powder mass ratio 80:1, respectively. Mechanisms study implied that lone pair electrons provided by two nitrogen atoms and four hydroxyl oxygen atoms of EDTA could enter the empty orbit of Co and Li by solid-solid reaction, thus forming stable and water-soluble metal chelates Li-EDTA and Co-EDTA. Moreover, the separation of Co and Li could be achieved through a chemical precipitation approach. This study provides a high efficiency and environmentally friendly process for Co and Li recovery from spent LIBs.
The energy density of the lithium-ion capacitors are restricted by the low charge-storage capability of the capacitive electrodes. Fast redox reactions from the redox-active aqueous electrolytes can effectively boost the charge storage of the capacitive electrodes without sacrificing the power performance, but are limited by the narrow electrochemical stability window. The “water-in-salt” electrolytes can enlarge the electrochemical stability window by effectively passivating the electrodes, but on the other hand remarkably elevate the cost, impair the ion conductivity and sacrifice the functionality of free water. Herein, we energize the unexpected role of free water in the “water-in-salt” electrolytes as the solvent of high-potential redox-active species, combining with the lithium insertion/de-insertion reaction at the battery-electrode to constitute a bi-redox system for effectively boosting the energy density. In addition, the unexpected opposite shift of the bi-redox potentials resulted from the decreases of the electrolyte concentration leads to an increased discharging voltage plateau to 2.2 V, helping further increase energy density and reduce costs.
Stress is one of the biggest problems in modern society. It may not be possible for people to perceive if they are under high stress or not. It is important to detect stress early and unobtrusively. In this context, stress detection can be considered as a classification problem. In this study, it was investigated the effects of stress by using accelerometer and gyroscope sensor data of the writing behavior on a smartphone touchscreen panel. For this purpose, smartphone data including two states (stress and calm) were collected from 46 participants. The obtained sensor signals were divided into 5, 10 and 15 s interval windows to create three different data sets and 112 different features were defined from the raw data. To obtain more effective feature subsets, these features were ranked by using Gain Ratio feature selection algorithm. Afterwards, writing behaviors were classified by C4.5 Decision Trees, Bayesian Networks and k-Nearest Neighbor methods. As a result of the experiments, 74.26%, 67.86%, and 87.56% accuracy classification results were obtained respectively.
ABSTRACT Graphene-CdS quantum dots (QDs) hybrid materials were successfully prepared via one-step hydrothermal method. CdS QDs with average size of ∼6nm were dispersed on graphene sheets with high coverage through non-covalent bonding. Photocurrent and electrochemical impedance spectroscopy (EIS) results suggested that the best dosage of graphene oxide for graphene-CdS hybrid materials is 0.5% (G0.5-CdS). When G0.5-CdS QDs was used as photoanode materials in non-enzymatic sensor, and the sensor was used to detect glucose and displayed satisfactory analytical performance with good linear range from 0.1∼4mmol dm−3 with a detection limit of 7μmol dm−3 at a signal-to-noise ratio of 3. The sensor also possessed high selectivity and durability in trace detection of glucose.
The electrochemical performance of Li-ion batteries strongly depends on the interaction between atomic scale and micro scale phenomena in high capacity electrode materials such as silicon and sulfur. Local thermodynamic interactions between host and guest species on atomic-scale significantly influence transfer kinetics and deformation kinematics on the micro-scale. We propose a multi-scale model to characterize the electrochemical and mechanical response of an amorphous silicon thin film during discharge/charge cycling. In the atomic-scale simulation, the stress-dependent energy barrier for the migration of lithium and the molar excess Gibbs free energy were calculated using density functional theory. These atomic-scale effects account for the nonlinear lithium diffusion behavior in the continuum simulation. In the continuum simulation, we considered the coupled diffusion and large deformation model on the cell-scale to determine the non-equilibrium cell potential as a function of the surface lithium concentration using Butler-Volmer kinetics. We clearly show that Li macroscopic kinetics is significantly affected by the stress induced by the volumetric strain associated with diffusion and the mixing formation energy of Li x Si. Our simulation results demonstrate that the multi-scale model is consistent with experimental observations at different C-rates.
Obesity among adolescents is becoming increasingly prevalent and “food addiction” (addiction-like attraction to foods with high content of fat and refined carbohydrates) may be a potential contributor to this development. This study aimed to investigate the psychometric properties of the dimensional Yale Food Addiction Scale for Children version 2.0 (dYFAS-C 2.0) and to estimate the weighted mean score on the dYFAS-C 2.0 (as a measure of food addiction symptom load) among adolescents from the general Danish population.