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Spherical Al-substituted γ-NiOOH as an individual positive electrode material for a new type of alkaline primary/rechargeable Zn-NiOOH battery was prepared by the chemical oxidation of spherical Al-substituted α-Ni(OH)2. The spherical Al-substituted γ-NiOOH was characterized by XRD, SEM, FT-IR, TGA-DTG, TPD-MS and HT-XRD. The tap density and average nickel oxidation state were measured. Its electrochemical performance and storage stability were also investigated. The results show that the as-prepared spherical Al-substituted γ-NiOOH has remarkably higher specific discharge capacity and superior storage stability in alkaline electrolyte compared to spherical β-NiOOH.
The present study shows a novel method for the synthesis of uniformly-shaped poly(othophenylediamine) (PoPD) nanofibers by chemical oxidative polymerization method for application towards smart corrosion resistance coatings. Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) studies confirm morphology of PoPD with three dimensional (3D) networked dendritic superstructures having average diameter of 50–70nm and several hundred meters of length. UV–vis and FTIR spectral results shows the formation of PoPD nanofibers containing phenazine ring ladder-structure with benzenoid and quinoid imine units. Thermogravimetric analyses (TGA) of PoPD nanofibers possess good thermal stability. The anti-corrosion behavior of PoPD nanofibers on 316L SS was investigated in 3.5% NaCl solution using potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) measurements. The PoPD coated 316L SS exhibits higher corrosion potential when compared to uncoated specimen. EIS studies, clearly ascertain that PoPD nanofiber coatings exhibits excellent potential barrier to protect the 316L SS against corrosion in 3.5% NaCl.
A cathode was prepared by sealing a carbon supported sulfur electrode inside a composite ion-selective net made of carbon, binder and lithiated ionomer to restrict shuttling of polysulfide anionic species. As a result, the soluble polysulfide anions become unable to escape from the composite ion-selective films due to the electrostatic repulsion between the immobilized single ion conducting ionomers and the polysulfides with no dead angles. Experimentally, lithiated 4,4′-difluoro bis(benzene sulfonyl)imide and PEG200 were copolymerized to form a polyether based single ion conducting polymer. The ionic conductivity of the blend film made of ionomer and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) at a mass ratio of 1:1 is 0.57 mS cm−1 at room temperature. The battery capacity with the sealed sulfur electrode is 1412 mAh g−1 at 0.5 C, 1041 mAh g−1 at 1.0 C, 873 mAh g−1 at 2.0 C and 614 mAh g−1 at 5.0 C, significantly better than the results with lithiated Nafion especially at high C rates. In addition, a long cycling test at 2 C for 500 cycles gives rise to a stable capacity of 800 mAh g−1. The intrinsic electrostatic repulsion between polysulfide anions and the negatively charged electrolyte film, together with the overall sealed electrode configuration, is responsible for blocking the shuttling of polysulfides effectively.
The binding and catalyzing of soluble polysulfide species to prevent their shuttles and accelerate the polysulfides conversion kinetics is essential to achieve lithium-sulfur batteries with high rate capability and superior cycling stability. Here, earth-abundant and eco-friendly pyrite FeS2 supported on N-doped porous carbon sheets is firstly demonstrated to act as a reliable adsorbent and active electrocatalyst towards polysulfide redox reaction with the aid of theoretical calculation and a series of fundamental experiments, which results in fast conversion kinetics of polysulfide. A detailed dissolution-capture-transformation mechanism is proposed on the tri-phase interface among pyrite FeS2, conductive N-doped porous carbon sheets and polysulfide species. On this tri-phase interface, the soluble polysulfide species can be chemically anchored and subsequently transform to Li2S efficiently catalyzed by pyrite FeS2, while the porous N-doped porous carbon sheets serve as highly conductive substrates for the nucleation of Li2S deposition. Consequently, the lithium-sulfur batteries with the composite cathodes exhibits excellent electrochemical rate capability (475 mAh g−1 at 5 C) and cycling stability (783 mAh g−1 after 160 cycles). The merits of low cost, eco-friendly feature combined with high activity towards polysulfides conversion reaction endows the pyrite FeS2 a promising electrocatalyst in realizing advanced lithium-sulfur batteries.
E-cigarettes are gaining popularity in the U.S. as well as in other global markets. Currently, limited published analytical data characterizing e-cigarette formulations (e-liquids) and aerosols exist. While FDA has not published a harmful and potentially harmful constituent (HPHC) list for e-cigarettes, the HPHC list for currently regulated tobacco products may be useful to analytically characterize e-cigarette aerosols. For example, most e-cigarette formulations contain propylene glycol and glycerin, which may produce aldehydes when heated. In addition, nicotine-related chemicals have been previously reported as potential e-cigarette formulation impurities. This study determined e-liquid formulation impurities and potentially harmful chemicals in aerosols of select commercial MarkTen® e-cigarettes manufactured by NuMark LLC. The potential hazard of the identified formulation impurities and aerosol chemicals was also estimated. E-cigarettes were machine puffed (4-s duration, 55-mL volume, 30-s intervals) to battery exhaustion to maximize aerosol collection. Aerosols analyzed for carbonyls were collected in 20-puff increments to account for analyte instability. Tobacco specific nitrosamines were measured at levels observed in pharmaceutical grade nicotine. Nicotine-related impurities in the e-cigarette formulations were below the identification and qualification thresholds proposed in ICH Guideline Q3B(R2). Levels of potentially harmful chemicals detected in the aerosols were determined to be below published occupational exposure limits.
This study measured the accuracy and precision of four commercial dental radiometers. The intra-brand accuracy was also determined. The light outputs from 14 different curing lights were measured three times using four brands of dental radiometers and the results were compared to two laboratory-grade power meters that were used as the “gold standard”. To ensure proper representation, three examples of each brand of dental radiometer were used. Data collected was analyzed using ANOVA, with 95% confidence intervals, comparing the laboratory-grade meters to the dental radiometers. Bioequivalence was established where the confidence interval for the irradiance values was within ±20% of the “gold standard” reading. Forest plots were used to highlight bioequivalence values. The two laboratory-grade meters differed by less than 0.6%. Overall, all three examples of the Bluephase and SDI radiometers as well as two examples of the LEDRadiometer and one CureRite meter were bioequivalent to the gold standard. However, the type of curing light measured had a significant effect on the accuracy of the radiometer. There was significant variability of the irradiance readings between radiometer brands, and between irradiance values recorded by the three samples of each brand studied. This made it impossible to definitively rank the radiometer brands for accuracy. Within the ±20% bioequivalence limits of this study, there was a clinically significant difference in the irradiance readings between radiometer brands and the choice of curing light affected the results. There was also significant variation in irradiance readings reported by different examples of the same brand of radiometer. Whether in clinical practice or in research, dental radiometers should not be used when either the irradiance or energy delivered needs to be accurately known.
Incorporation of carbonate repeating units in a poly(ε-caprolactone) (PCL) backbone used as a host material in solid polymer electrolytes is found to not only suppress crystallinity in the polyester material, but also give higher ionic conductivity in a wide temperature range exceeding the melting point of PCL crystallites. Combined with high cation transference numbers, this electrolyte material has sufficient lithium transport properties to be used in battery cells that are operational at temperatures down to below 23 °C, thus clearly demonstrating the potential of using non-polyether electrolytes in high-performance all-solid lithium polymer batteries.
Kinetic and mass transport properties were investigated for the oxygen reduction reaction in Nafion 117 and a sulfonated poly (arylene ether sulfone) membrane (SPES-40, 40% sulfonated groups/repeat unit) under 1 atm oxygen pressure, 100% relative humidity in a temperature range of 303–343 K using a solid-state electrochemical cell. Kinetic parameters were obtained using slow-sweep voltammetry while mass transport parameters, the diffusion coefficient (D) and solubility (C), were obtained using chronoamperometry at a Pt (microelectrode)/proton exchange membrane (PEM) interface. Oxygen reduction kinetics was found to be similar for both Nafion® 117 and SPES-40 membrane at the Pt microelectrode interface. The temperature dependence of O2 permeation parameters showed same trends for both the membranes studied, there was an increase in D and a concomitant decrease in C. Despite lower equivalent weight and hence higher water content SPES-40 exhibited relatively close values of D with Nafion® 117. The results are discussed in the context of their different microstructures. Values of C showed a closer relationship to water content and the percent volume of aqueous phase in the respective membranes. The values of overall oxygen permeability were significantly higher in Nafion® 117, with a higher positive slope in its variation with temperature.
In this study TiS2 is chosen as a model electrode material to investigate the relationship between the electrochemical and mechanical performance of layered cathodes for Na-ion batteries. Employing NaFP6 in EC/DMC as the electrolyte allowed for the most promising electrochemical properties recorded in the literature, namely a reversible capacity of 203 mAh g−1 at 0.2 C and 88 mAh g−1 at 10 C with a capacity retention of 92% over 50 cycles. Despite this promising performance the capacity still decayed during long term cycling. In-situ x-ray diffraction and high-resolution transmission electron microscopy imaging revealed that TiS2 underwent a large expansion of 17.7% along the c direction and irreversible phase transformations took place during the sodiation/de-sodiation process, which lead to severe mechanical strains and intragranular cracks. In comparison, the mechanical stability of TiS2 in Li-ion cells was significantly higher. The experimental results are interpreted within a continuum mechanics model which revealed that the maximum effective von Mises stress that is present at the interface between the ion-intercalated TiS2 and pristine TiS2 is about four times higher during sodiation than lithiation indicating that the electrode is more susceptible to failure/fracture during sodiation.
The aim of this paper is to characterize spent zinc–carbon and alkaline batteries. Characterization is essential to any process devoted to recovering the valuable materials contained in the batteries. In particular, the status of zinc and manganese has been established to permit treating only the zinc and manganese-bearing components in a recovery process, thus using smaller equipments and reducing both the material to treat and the energy consumption. At present, in fact, industrial processes treat the spent batteries as a bulk, only performing a preliminary separation with physical methods followed by a pyro- or hydrometallurgical process to recover zinc and manganese. Characterization has been carried out by chemical analysis, TGA/DTA analysis, XRPD and SEM analysis after having dismantled the batteries into the single components. Zinc and manganese are well separated in alkaline batteries while in zinc–carbon batteries the two metals are mixed, thus rendering difficult a preliminary separation by picking up the components containing the two metals separately.
Effective delivery of healthcare services requires availability of adequate infrastructure, diagnostic medical equipment, drugs and well-trained medical personnel. In Nigeria, poor funding and mismanagement often characterize healthcare service delivery thereby affecting coverage and quality of healthcare services. Therefore, the state of service delivery in Nigeria’s health sector has come under some persistent criticisms. This paper analyzed service readiness of Primary Health Care (PHC) facilities in Nigeria with focus on availability of some essential drugs and medical equipment.
Structural characteristics and electrochemical properties of non-graphitizable carbons were investigated. The carbons were obtained by heat-treating the oxidized graphitizable carbon precursors with various molar ratios of aromatic compounds and cross-linking agent. The discharge profiles of the non-graphitizable carbons heat-treated at 600°C had one plateau discharge region at 1.0 V vs. Li/Li+, which is similar to graphitizable ones heat-treated at the temperature. However, the discharge profiles of the non-graphitizable carbons heat-treated above 800°C exhibited two plateau discharge regions at 0.2 and 1.0 V vs. Li/Li+. The discharge capacities of the non-graphitizable carbons increased with an increase of cavity volume, which was controlled by molar ratios of aromatic compound and cross-linking agent. The structural parameters proposed were measured to compare with each other, and it was found that they showed good correlation.
This paper presents an original sizing method for Energy Storage Systems (ESS) based on directly matching their capabilities – as specified by their energy-power Safe Operation Area (SOA) in the Energy-Power (EP) plane – with the energy and power demand required to accomplish their missions. Starting from the system requirements and from an energy management strategy, the power demanded by a set of representative operating scenarios and its associated energy are calculated and represented as trajectories in the EP plane. The objective is to size the ESS such as its SOA contains these trajectories. Comparison between different technologies of Energy Storage Devices (ESDs) is possible using this SOA characterization. Special attention should be paid to compare specific SOAs across devices. Diverse energy management strategies can be synthesized in the EP plane where they can be compared and analyzed. The sizing method converges extremely fast and is suitable for its integration in an optimization loop. The method allows to determine directly and efficiently the technology and the size most appropriate (in terms of indicators such as mass or cost) to a given EP demand. In the paper, three different technologies (SuperCapacitor, Li-Ion and H 2 ∕ O 2 batteries) are characterized and compared in terms of sizing synthesis.
The nominal LiMn2O4 and Li-doped spinels with different oxygen stoichiometry were prepared and investigated for capacity fading upon cycling at elevated temperatures. The discharge plateau at 3.2V originating from oxygen defects in manganese spinels is observed to grow very quickly to nearly a maximum scale in initial 15 cycles at 60°C. Meanwhile, the majority of capacity fading is lost. Therefore, the quick capacity fading in the initial stage is associated with the increase of oxygen deficiencies or oxygen loss upon cycling. It is proposed that the oxygen loss is originated from the decomposition of instable spinel phases that containing little Li cations on the 8a sites ([□1]8a[Mn2−x ]16d[O4−δ □ δ ]32e, etc.), which are formed upon charging to the upper voltage limit. This phenomenon is much severe for nominal LiMn2O4 spinels with oxygen deficiencies. After partial substitution of Mn with Li, part of the Li cations on the 8a sites will be retained upon charging to the upper voltage limit. Thereafter, the cycling performance can be improved for the stabilized spinel phases formed upon charging.
Diffusion-induced stress and volumetric expansion under potentiostatic operation are investigated with an axisymmetric finite element model taking account of plastic yielding, coupling effects between diffusion and stress, diffusion from the edge surface, and concentration dependence of material properties. Significant differences on stresses, displacements, and fracture energies between purely elastic and elastic–plastic materials are found. Plasticity based on von-Mises criterion has no effect on concentration variation. The critical regions for fracture are the edge surface, and the regions near the edges on both the top surface and the interface.
A 1D electrochemical, lumped thermal model is used to explore pulse power limitations and thermal behavior of a 6Ah, 72 cell, 276V nominal Li-ion hybrid-electric vehicle (HEV) battery pack. Depleted/saturated active material Li surface concentrations in the negative/positive electrodes consistently cause end of high-rate (∼25C) pulse discharge at the 2.7Vcell−1 minimum limit, indicating solid-state diffusion is the limiting mechanism. The 3.9Vcell−1 maximum limit, meant to protect the negative electrode from lithium deposition side reaction during charge, is overly conservative for high-rate (∼15C) pulse charges initiated from states-of-charge (SOCs) less than 100%. Two-second maximum pulse charge rate from the 50% SOC initial condition can be increased by as much as 50% without risk of lithium deposition. Controlled to minimum/maximum voltage limits, the pack meets partnership for next generation vehicles (PNGV) power assist mode pulse power goals (at operating temperatures >16°C), but falls short of the available energy goal. In a vehicle simulation, the pack generates heat at a 320W rate on a US06 driving cycle at 25°C, with more heat generated at lower temperatures. Less aggressive FUDS and HWFET cycles generate 6–12 times less heat. Contact resistance ohmic heating dominates all other mechanisms, followed by electrolyte phase ohmic heating. Reaction and electronic phase ohmic heats are negligible. A convective heat transfer coefficient of h =10.1Wm−2 K−1 maintains cell temperature at or below the 52°C PNGV operating limit under aggressive US06 driving.
The electrochemical peculiarities of classical redox systems with solid-state reagents (non-soluble quinones, intercalation compounds of graphite) as well as polyaniline-type conducting polymers have been considered. The conducting polymers show a significant non-faradaic component of the electrochemical mechanism. The essential differences of faradaic and non-faradaic systems in equilibrium behavior, trends of galvanostatic charge–discharge curves and cyclic voltammograms have been shown, and criteria for the identification of these mechanisms are proposed. Our investigations of the current-producing mechanism for the polyaniline electrode have shown that at least within a narrower range of potentials ΔE n from 0.30–0.40 to 0.80–0.90 V versus SHE (depending on pH value) the ‘capacitor’ model of ion electrosorption/desorption in well conducting emeraldine salt phase is more preferable. Nevertheless, such a model should take into account the transport of both anions and protons (cations in a general case). Besides the possibilities of redox processes at the limits and beyond this range of potentials ΔE n should be taken into account. At the same time, these processes can lead to the fast formation of thin passive layers of new poorly conducting phases (leucoemeraldine salt, leucoemeraldine base, etc.) near the current collector. The formation of such phases, even in a small amount, rapidly inhibits and discontinues the electrochemical process.
The Relationship of Indoor, Outdoor and Personal Air (RIOPA) Study was undertaken to evaluate the contribution of outdoor sources of air toxics, as defined in the 1990 Clean Air Act Amendments, to indoor concentrations and personal exposures. The concentrations of 18 volatile organic compounds (VOCs), 17 carbonyl compounds, and fine particulate matter mass (PM2.5) were measured using 48-h outdoor, indoor and personal air samples collected simultaneously. PM2.5 mass, as well as several component species (elemental carbon, organic carbon, polyaromatic hydrocarbons and elemental analysis) were also measured; only PM 2.5 mass is reported here. Questionnaires were administered to characterize homes, neighborhoods and personal activities that might affect exposures. The air exchange rate was also measured in each home. Homes in close proximity (<0.5 km) to sources of air toxics were preferentially (2:1) selected for sampling. Approximately 100 non-smoking households in each of Elizabeth, NJ, Houston, TX, and Los Angeles, CA were sampled (100, 105, and 105 respectively) with second visits performed at 84, 93, and 81 homes in each city, respectively. VOC samples were collected at all homes, carbonyls at 90% and PM2.5 at 60% of the homes. Personal samples were collected from nonsmoking adults and a portion of children living in the target homes. This manuscript provides the RIOPA study design and quality control and assurance data. The results from the RIOPA study can potentially provide information on the influence of ambient sources on indoor air concentrations and exposure for many air toxics and will furnish an opportunity to evaluate exposure models for these compounds.
Sulfonated poly(ether ether ketone) (S-PEEK) was synthesized by sulfonation of commercial PEEK. The S-PEEK membrane was prepared by casting from organic solution dissolving the polymer, and the polymer electrolyte was obtained by soaking the S-PEEK membrane in water or sulfuric acid solution. The effect of soaking solvent on the liquid uptake and the ionic conductivity of the polymer electrolyte has been investigated. The quasi-solid-state electric double layer capacitors (EDLCs) which consisted of activated carbon electrodes and polymer electrolyte were assembled, and their electrochemical characteristics were studied by cyclic voltammetry and charge–discharge cycle tests.
Li2Se–Sb2Se3 nanocomposites with a highly heterogeneous mixture have been fabricated by reactive pulsed laser deposition method. The electrochemical properties of the as-deposited Li2Se–Sb2Se3 thin film during the first charging and discharging have been investigated by the galvanostatic cycling and cyclic voltammetry measurements for the first time. By using ex situ X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and selected-area electron diffraction (SAED) measurements, the decomposition of Li2Se driven by Sb2Se3 under the electrochemical potential is revealed. In the first cycle, the oxidation peaks at 2.5V and 3.2V and the reduction peaks at 2.0V can be attributed to the decomposition and formation of Li2Se with the conversion reaction of Sb2Se3 into Sb2Se5. Our findings demonstrate that nanocomposite Li2Se–Sb2Se3 can possess very high electrochemical activity. These results present a special case of solid-state heterogeneous electrochemistry with both nanostructured binary materials.
CuInZnS-decorated graphene (CIZS@graphene) is prepared via a hydrothermal process and investigated as an anode material for lithium-ion batteries. CIZS@graphene exhibits an initial discharge capacity of 1623 mA.h g−1 at 100 mA g−1, and at a high rate of 2000 mA g−1 its reversible capacity is steadily increased from 389 mA h g−1 to 494 mA h g−1 in 480 cycles, demonstrating promising stable cycling performance at high rates. Electrochemical impedance spectroscopic studies show that charge-transfer resistances of CIZS@graphene reduces after cycling at high rates, justifying the excellent high-rate performance and stability of the CIZS@graphene anode.