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Even though organic molecules with well-designed functional groups can be programmed to have high electron density per unit mass, their poor electrical conductivity and low cycle stability limit their applications in batteries. Here we report a facile synthesis of π-conjugated quinoxaline-based heteroaromatic molecules (3Q) by condensation of cyclic carbonyl molecules with o-phenylenediamine. 3Q features a number of electron-deficient pyrazine sites, where multiple redox reactions take place. When hybridized with graphene and coupled with an ether-based electrolyte, an organic cathode based on 3Q molecules displays a discharge capacity of 395 mAh g−1 at 400 mA g−1 (1C) in the voltage range of 1.2–3.9 V and a nearly 70% capacity retention after 10,000 cycles at 8 A g−1. It also exhibits a capacity of 222 mAh g−1 at 20C, which corresponds to 60% of the initial specific capacity. Our results offer evidence that heteroaromatic molecules with multiple redox sites are promising in developing high-energy-density, long-cycle-life organic rechargeable batteries.
Si nanoparticle–graphene hybrids are fabricated by covalent immobilization and subsequent heating in a H2 + Ar atmosphere. The absence of a graphite (002) peak in X-ray diffraction shows that the hybrid synthesized by this approach prevents graphene nanosheets re-agglomerating. Transmission electron microscopy shows a homogeneous distribution of Si nanoparticles on the graphene. Galvanostatic charge/discharge tests demonstrate that the Si nanoparticle–graphene hybrid has much better charge capacity retention than pristine Si nanoparticles and a Si nanoparticle/graphene mixture. The relationship of the capacity to the weight ratio of Si nanoparticles and graphene in the hybrid has been investigated. The results reveal that the hybrid of with a weight ratio 15:1 (Si:G) exhibits the most stable cycle performance, which retains 92.7% capacity of the 1st cycle after 50 charge/discharge cycles. The 1st Li+ insertion capacity is 1297 mAh g−1, and the 50th Li+ insertion capacity is 1203 mAh g−1.
MgCo2O4 nanoneedles were introduced on the surface of micro and mesoporous silicon carbide flakes (SiCF) to synthesize a supercapacitor with high capacitive performance, made of hybrid electrode materials. Based on the synergistic effect between electric double layer capacitive contributions of SiCF and faradic reaction of MgCo2O4, the SiCF/MgCo2O4 electrode shows outstanding energy storage performance, exhibiting a 310.02 C g−1 of specific stored charge capacity at 5 mV s−1 with high capacity retention ratio over wide range of scan rates (83.2% at 500 mV s−1). Furthermore, in conjunction with a capacitive SiCF negative electrode in a quasi-solid-state PVA-KOHKI gel electrolyte, it resulted in a unique redox-active flexible solid-state asymmetric supercapacitor device. It delivers outstanding capacitive performance (specific stored charge capacity of 185.88 C g−1 at 5 mV s−1), with maximum energy density of 41.308 Wh kg−1 at 464.72 W kg−1 of power density, surpassing many recently reported flexible supercapacitors. Moreover, the ability to operate 3-V green light-emitting diodes (LED) at bending state also indicates its possibility for practical application. Therefore, these novel electrode materials with unique redox-active solid state electrolyte may find promising applications in flexible energy storage devices in future.
ABSTRACT A new ionic liquid (IL) based on a “neutral” ligand, 4-propylpyridine, is obtained via complexation with AlCl3. It is found that the asymmetric cleavage of AlCl3 generates AlCl2 + and AlCl4 −, and the former is coordinated by 4-propylpyridine to produce the Al-containing cations ([AlCl2(4-Pr-Py)2]+). The AlCl3/4-propylpyridine IL with a molar ratio of 1.3/1 is highly fluidic with a viscosity of 42.8mPas and an ionic conductivity of 5.0×10−4 S/cm at room temperature. In contrast to conventional ILs for electroplating aluminum in which the electrochemically active species are Al-containing anions (for example Al2Cl7 −), this new IL has an Al-containing cation as the electroactive species, which is beneficial to electrodeposition of aluminum.
Recent metabolic engineering efforts have generated microorganisms that can produce biofuels, including bio-jet fuels, however these fuels are often toxic to cells, limiting production yields. There are natural examples of microorganisms that have evolved mechanisms for tolerating hydrocarbon-rich environments, such as those that thrive near natural oil seeps and in oil-polluted waters.
High-energy-density batteries have been a long-standing target toward sustainability, but the energy density of state-of-the-art lithium-ion batteries is limited in part by the small capacity of the positive electrode materials. Although employing the additional oxygen-redox reaction of Li-excess transition-metal oxides is an attractive approach to increase the capacity, an atomic-level understanding of the reaction mechanism has not been established so far. Here, using bulk-sensitive resonant inelastic X-ray scattering spectroscopy combined with ab initio computations, we demonstrate the presence of a localized oxygen 2p orbital weakly hybridized with transition metal t2g orbitals that was theoretically predicted to play a key role in oxygen-redox reactions. After oxygen oxidation, the hole in the oxygen 2p orbital is stabilized by the generation of either a (σ + π) multiorbital bond through strong π back-donation or peroxide O22− through oxygen dimerization. The multiorbital bond formation with σ-accepting and π-donating transition metals can thus lead to reversible oxygen-redox reaction.
A synthesis method consisting of a mechanical ball milling activation process followed by a sintering heating treatment is proposed to obtain MnSn2 as anode material for Li-ion batteries. This two-step approach strongly reduces the amount of βSn impurities and provides a better material morphology. This improves the electrochemical performances, even at high C-rate, as shown from the comparison between electrode materials obtained with and without this preliminary activation process. The electrochemical reactions have been followed at the atomic scale by in situ 119Sn Mössbauer spectroscopy. The first discharge is a restructuring step that transforms the pristine material into Mn/Li7Sn2 nanocomposite which should be considered as the real starting material for cycling. The delithiation of this nanocomposite is characterized by two plateaus of potential attributed to the de-alloying of Li7Sn2 followed by the back reaction of Mn with poorly lithiated Li x Sn alloys, respectively. The composition and the stability of the solid electrolyte interphase were characterized by X-ray photoelectron spectroscopy.
NiO, NiS and NiO–NiS nanocomposite thin films have been successfully fabricated by pulsed laser deposition. Their electrochemical properties are evaluated by galvanostsic cycling and cyclic voltammograms. Compared with NiO and NiS thin films, NiO–NiS nanocomposite thin film shows an improved electrochemical performance with a reversible specific capacity around 500mAhg−1 and good cyclability. Scanning electron microscopy, high-resolution transmission electron microscopy and selected area electron diffraction measurements are employed to study the electrochemical reaction mechanism of NiO–NiS nanocomposite electrode. These results reveal that NiO and NiS in the mixture films react with lithium separately and could be reversibly reproduced.
Energy crisis and environmental issues have encouraged the adoption of electric vehicle as an alternative transportation option to the conventional internal combustion engine vehicle. Recently, the development of smart grid concept in power grid has advanced the role of electric vehicles in the form of vehicle to grid technology. Vehicle to grid technology allows bidirectional energy exchange between electric vehicles and the power grid, which offers numerous services to the power grid, such as power grid regulation, spinning reserve, peak load shaving, load leveling and reactive power compensation. As the implementation of vehicle to grid technology is a complicated unit commitment problem with different conflicting objectives and constraints, optimization techniques are usually utilized. This paper reviews the framework, benefits and challenges of vehicle to grid technology. This paper also summarizes the main optimization techniques to achieve different vehicle to grid objectives while satisfying multiple constraints.
This paper presents a critical appraisal of renewable energy options for Malian modern energy technologies. A critical review of different renewable energies is presented, some comparisons between the country and other Saharan countries are listed. The study shows that Mali energy is very poor compared with other Saharan countries and the level of firewood energy is very high and the one of modern energy is very low. The study also shows that only 10% of Malians have access to electricity, the rest depend on wood, charcoal, kerosene, and petrol for their energy needs. In term of renewable energy used, Mali's balance is better than some Saharan countries. That way can be appreciated just for the new promotion and sustainability of renewable energy policy targets of the country. As a poor Country Mali can more exploit it renewable energies to combat the poverty and especially in rural zone with very low rate of electricity about 1%. The utilization of the renewable energies can also be a good opportunity to fight the desertification and dryness in Mali which is about 60% of Malian territory.
A two-dimensional layered Sb2Se3-based amorphous composite (a–Sb2Se3/C) is synthesized using a simple solid-state ball-milling process, and its potential for Li- and Na-ion batteries is evaluated. Ex situ extended X-ray absorption fine structure analyses clearly indicate the electrochemical reaction mechanisms of Sb2Se3 and a–Sb2Se3/C as anodes for Li- and Na-ion batteries. During Li- and Na-insertion, the Sb2Se3 and a–Sb2Se3/C electrodes are converted into the final phases of Li3Sb/Na3Sb and Li2Se/Na2Se, respectively. During Li- and Na-extraction, the Li3Sb/Na3Sb and Li2Se/Na2Se in the Sb2Se3 electrode are converted into Sb and Se, showing a non-recovery reaction, whereas a recovery to the original Sb2Se3 in the a–Sb2Se3/C electrode occurs after full Li and Na extraction. Owing to the interesting conversion/recovery reaction, the a–Sb2Se3/C electrode exhibits excellent electrochemical performance, such as high reversible capacities (Li-ion battery: 662 mAh g−1; Na-ion battery: 407 mAh g−1), a long cycle life with highly reversible capacities (Li-ion battery: 662 mAh g−1 and 1,205 mAh cm−3, respectively, after 100th cycle; Na-ion battery: 378 mAh g−1 and 688 mAh cm−3, respectively, after 50th cycle), and high rate capabilities (Li-ion battery: 623 mAh g−1 and 1,133 mAh cm−3 at 3C; Na-ion battery: 270 mAh g−1 and 492 mAh cm−3 at 2C).
A nanocomposite of MoO3 coated with polypyrrole (PPy) was prepared as an anode material for ARLBs. When nanochain LiMn2O4 is used as the cathode, the ARLB can deliver an energy density of 45 Wh kg−1 at 350 W kg−1 and even maintain 38 Wh kg−1 at 6 kW kg−1 in 0.5 M Li2SO4 aqueous electrolyte, corresponding to an good rate capability. In addition, its cycling behavior is greatly improved compared with the virginal MoO3. Our findings provide valuable clues to improve the comprehensive performance of ARLBs for practical application. This unique performance demonstrates that this battery will be of great promise as a power source for large power devices such as power loading and the storage of solar and wind energies.
The paper deals with application of giant magnetostrictive materials for power harvesting from vibration. Mathematical modelling and design of magnetostrictive electric generators (MEG) are considered. The mathematical model, original MEG and test rig have been developed for simulation and experimental study of conversion of mechanical energy of vibration into electrical energy using Terfenol-D as an active material. Simulation and experimental results have confirmed functionality of designed MEG. Generator using Terfenol-D rod with 50mm in length and 15mm in diameter has shown efficiency of the transduction processes up to 25% with maximum power generation up to 240W.
Environmental issues and the prospect of an energy crisis inspire humans to exploit wind power. However, with the increase of wind power penetration level, operating power systems securely and reliably is a serious challenge due to the inherent nature of wind power intermittency. Wind power intermittency has been the major barrier for large scale wind power integration. This paper reviews past research on wind power intermittency, including its impacts on power system, how it is measured, and mitigation solutions. It has been found that as wind power integration increase, the system reverses and costs consequently increase, while the system reliability and CO2 reductions decrease. In order to mitigate wind power intermittency, studies on intermittency measurements and mitigation solutions are necessary. Existing measurements of wind power intermittency are summarized firstly. Considering the limitations of existing methods, new definitions and metrics are proposed based on our study. Then, various wind power intermittency mitigation solutions are comprehensively reviewed, including wind farms, generation-side, demand-side and energy storage. In the final part of this paper, the further work on wind power intermittency is discussed in detail. In summary, wind power intermittency can be effectively mitigated using various technological and managerial approaches based on an in-depth understanding of intermittency.
The management of concussion and mild traumatic brain injury is an area of clinical uncertainty for many sports medicine professionals. While recent studies suggest sex differences in neurocognitive function may exist, our understanding of the effects of menstrual cycle phase and oral contraceptive pill (OCP) use in healthy females is limited. The purpose of this study was to investigate whether there were changes in neurocognitive function, postural stability and self-reported symptoms between the early and late stages of the menstrual cycle, and also to identify whether performance across menstrual cycle would differ between females using OCP and eumenorrheic females not using OCP. Healthy college-aged females completed a standard concussion test battery including computerised assessment of neurocognitive function, postural stability and symptom status. Participants completed the counterbalanced testing design during the early and late phases of their menstrual cycle. No significant main effects or interactions for any neurocognitive function or postural stability outcome measure were observed. Eumenorrheic females endorsed a higher number of symptoms and reported an increased symptom severity score compared to females using OCP. Menstrual cycle phase had no effect on the total severity or the number of symptoms endorsed. These results suggest preseason neurocognitive and postural stability baseline tests are stable across the menstrual cycle, regardless of OCP use. Therefore, decreased performance on these measures following a suspected concussion is likely not attributable to menstrual cycle phase or use of OCP.
The processes involved in the reduction of an electrolytic manganese dioxide (EMD) were investigated and their exchange current densities were determined. The dQ/dE vs E curve was fitted by least squares minimisation with peaks based on the Nernst equation. The derivation of the peak model is described. In the potential range of 0.3 to - 0.4 V (vs Hg/HgO reference), nine processes were found to contribute to the overall reduction. Exchange current densities for three of the main processes were determined from the movement of the deconvoluted peaks during a series of constant current discharge experiments.
Patients with the depigmentation disorder vitiligo have low catalase expression/activities and constantly accumulate 10−3 M hydrogen peroxide (H2O2) in their skin. Such high concentrations of H2O2 oxidize L-methionine residues in proteins and peptides to (R and S)-methionine sulfoxide diasteriomers. In vivo FT-Raman Spectroscopy revealed the presence of methionine sulfoxide in the depigmented skin of patients with active vitiligo. In normal healthy human skin, methionine sulfoxide reductases A and B specifically reduce methionine sulfoxides (S) and (R), respectively, back to L-methionine consequently repairing oxidatively damaged proteins and peptides. In this report, we show that the expression/activities of MSRA and MSRB are significantly decreased in the epidermis of patients with vitiligo compared to healthy controls. Also, we used recombinant human MSRA and MSRB1 to show that both enzymes are deactivated by 10−3 M H2O2 by 85 and 40%, respectively. Structural modelling based on the crystal structure of human MSRA revealed that the active site of this enzyme is significantly altered after H2O2-mediated oxidation of L-methionine, L-tryptophan, and L-cysteine residues in its active site. Taken together, our results confirm that very important anti-oxidant enzymes are seriously affected in acute vitiligo.
Publisher Summary This chapter deals with the effect of coal usage on human health and the environment. Coal has played a significant role in the advancement of civilization and continues to be a major fuel source for at least the next quarter century. Coal mining has a direct impact on the environment, as it disturbs large areas of land and has the potential to affect surface water and groundwater in the case of surface mining. In some surface mines, the generation of acid mine drainage (AMD) is a major problem. Other significant impacts include fugitive dust emissions and disposal of overburden and waste rock. This chapter focuses on coal utilization, specifically combustion, which produces several types of emissions that adversely affect the environment, particularly ground level air quality. In addition, the generation of coal combustion by-products must be addressed, whether they are disposed of or reused. Moreover, this chapter discusses the environmental and health effects of these pollutants, along with other pollutants, such as carbon monoxide (CO), lead, and organic emissions. This chapter concludes that the impacts of mining, storage, handling, transportation, beneficiation, combustion by-products, and emissions from coal-fired power plants are presented with a focus on activities in the United States.
A novel hierarchical architecture of CoMoO4 nanoneedle with high electrochemical performance was synthesized using a facile one-step hydrothermal method. As the active electrode material in supercapacitors, it exhibited a large specific capacitance (1628.1 C g−1 at a current density of 2 mA cm−2), a high rate capability (874.8 C g−1 at 50 mA cm−2), and superior cycling stability (90.54% capability retention after 5000 cycles at 10 mA cm−2). Moreover, as an electrocatalyst for the oxygen evolution reaction (OER), the CoMoO4 nanoneedle exhibited an early onset potential of 1.37 V, a small Tafel slope of 66 mV Dec−1, and a low overpotential of 235 mV at the current density of 10 mA cm−2. The excellent electrochemical performance of the hierarchical CoMoO4 structure was attributed to its porosity and the characteristics of the 2D nanosheet subunits that possess many active reaction sites, rapid electron/ion transport, and high stability. The synthetic strategy used in the present study is simple, cost-effective, and generalizable. It can be used to develop effective electrode materials for large-scale energy storage and conversion applications.
Li[Li0.2Mn0.56Ni0.16Co0.08]O2 cathode materials with well-formed layered structure are synthesized by sol–gel process with different metal sources. Two normal metal salts (acetate and nitrate) are performed as the metal sources, and the effect of particle morphology on the electrochemical performance of the Li-rich layered oxide is investigated to show the importance of the choice of metal sources. Porosity with high specific surface area of 10.09m2 g−1 is only observed for the oxide powder synthesized with nitrate. Simultaneously, high discharge capacity of 247.8mAhg−1 and 135.5mAhg−1 are obtained at current densities of 200mAg−1 and 2000mAg−1, respectively. In addition, the results of electrochemical impedance spectroscopy (EIS) indicate that such porous morphology with good particle contact can efficiently reduce the impedance of the oxide electrode.
Sensitization, the prerequisite event in the development of allergic contact dermatitis, is a key parameter in both hazard and risk assessments. The pathways involved have recently been formally described in the OECD adverse outcome pathway (AOP) for skin sensitization. One single non-animal test method will not be sufficient to fully address this AOP and in many cases the use of a battery of tests will be necessary. A number of methods are now fully developed and validated. In order to facilitate acceptance of these methods by both the regulatory and scientific communities, results of the single test methods (DPRA, KeratinoSens™, LuSens, h-CLAT, (m)MUSST) as well for a the simple ‘2 out of 3’ ITS for 213 substances have been compiled and qualitatively compared to both animal and human data. The dataset was also used to define different mechanistic domains by probable protein-binding mechanisms. In general, the non-animal test methods exhibited good predictivities when compared to local lymph node assay (LLNA) data and even better predictivities when compared to human data. The ‘2 out of 3’ prediction model achieved accuracies of 90% or 79% when compared to human or LLNA data, respectively and thereby even slightly exceeded that of the LLNA.
The Li3V2(PO4)3/phosphorus-doped carbon (LVP/P-C) nanocomposites with multilevel structures (such as spheroidal, foam, prism and flower-like structures) are synthesized via one-pot in-situ synthesis using hybrid vanadium metal-organic frameworks (V-MOFs) as precursor. The structure and morphology of the LVP/P-C nanocomposites were characterized by scanning electron microscopy, transmission electron microscopy, Raman, X-ray diffraction and element mapping. The results show that the multilevel structures are generated from the assemblies of the hybrid surfactant templates in the glass fiber drawing wastewater (GFDW) and the hybrid V-MOFs. The structure of LVP/P-C nanocomposite is controlled by V-MOFs. The nanocomposites exhibit a long service life, a discharge capacity of 65 mA h g−1 at 10 C with 90% capacity retention after 1100 cycles. The high cycling stability is attributed to the multilevel structures, which is ideal for making rechargeable lithium ion batteries. More importantly, our results have demonstrated that GFDW can be transformed into treasure of multilevel structure nanocomposites for cheap Li ion batteries.
LiMn2O4 is used as the cathode material in large lithium ion batteries for industrial and other uses because of its low cost, excellent thermal stability, and other attributes. Nevertheless, LiMn2O4 has weak points including severe capacity, deterioration at high temperatures, and low energy density. To overcome these points we conducted our research and development with a focus on LiCo x Ni y Mn z O2 composite oxides (layered lithium manganese composite oxides). We developed an industrial synthesis technology for layered lithium manganese composite oxides, and employed them as the new cathode material for the EX25A, an industrial lithium ion battery. Compared with the lithium ion batteries that used LiMn2O4 as their cathode material, the EX25A has double cycle life characteristics at high-temperature (according to our standards), and is capable of large 10C discharges.