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In this research, we demonstrate a new method for reducing the shuttle effect by confining polysulfide in separator area through the use of polyimide (PI) separator with reversible adsorption functions in lithium-sulfur batteries. As a comparison, the cells with polypropylene (PP) separators which have no function to adsorb dissoluble polysulfide show a result that the content of sulfur on lithium anode surface is increased up to 63.94% after 100th cycles with the content of N-methyl-N-butylpiperidinium bis-(trifluoromethylsulfonyl) imide (PP14TFSI) in the mixture electrolyte increasing. This result illustrates that the migration and reaction between dissolved polysulfide in PP14TFSI and lithium cannot be neglected although the solubility of polysulfide is slight in PP14TFSI solvent. However, when PI separators are introduced, besides improving the wettability with PP14TFSI-based electrolytes, experimental results also show that the PI separator has a reversible adsorption function to dissoluble polysulfide which is used to confining polysulfide in separator area to a certain extent due to the abundant nitrogen-, oxygen-containing functional groups in PI skeleton. What’s more, PI separator can decreases the sulfur content on lithium surface after cycling to 17.92% which decreases greatly than that with PP separator and improves its electrochemical performance.
We first report the exceptional cycleability of SnO2 anodes by atomic layer deposition (ALD) over directly on stainless steel substrates without any capacity fade for 500 cycles. Perfect choice of cycling potential (5–800mV vs. Li) and synthesis condition yielded such performance with reversible capacity of 646mAhg−1 at current density of 5μAcm−2. Further, SnO2 undergoes the conversion reaction along with alloying reaction enables higher capacity than alloying reaction, however, experiencing severe capacity fade during cycling. Obtained results on SnO2 anodes by ALD technique certainly influence the impact on the development of solid-state, thin film and 3D Li-ion batteries.
The volume changes of polyaniline thick films (∼200 μm) upon redox switching in different acidic media were studied using voltammetric experiments with simultaneous microscopical observation. The area occupied by the polymer film in the microscope images was measured and used to compute the film volume and its variations. It is found that these films are considerably swelled by the electrolyte. During continuous potential cycling the film shows smooth volume changes, decreasing slightly at the beginning of the cycle, followed by a steeper increase in the last part of the positive scan; the volume changes show hysteresis and dependence on the electrolyte anion. When the polymer is completely reduced and relaxed the dimensional changes in the subsequent positive scan show, depending on the electrolyte, a small overall volume increase. During the negative scan the volume changes are similar in both cases, showing essentially two steps as the stationary positive scans. The results suggest that the volume changes are governed by several factors: ion and water exchange with the electrolyte, Coulombic repulsion between charged sites in the polymer backbone, anion–polymer interactions, and a structural change of the polymer backbone. With the aid of IR measurements, the influence of the different anions is interpreted in terms of their interaction with the polymer chain.
A low molecular weight gel electrolyte was formed by the self-assembly of a low molecular weight gelator in aqueous solution electrolyte and used in a Ni/MH cell. When the temperature was below 348 K, the low molecular weight gel electrolyte was used as a solid. The high ionic conductivity (1.51×10−2 S cm −1 ) and a stable electro- chemical window of the gel electrolyte were confirmed at 303 K. A Ni/MH cell was fabricated with the low molecular weight gel electrolyte, and its charge-discharge and capacity retention characteristics were measured. The deflection of the cell with gel electrolyte was smaller than that of the cell with aqueous solution electrolyte. Therefore, the gel electrolyte had good electrochemical properties while solving the problem of solution leakage.
Prebiotic oligosaccharides are demonstrated to confer a wide spectrum of physiological benefits during pregnancy. In view of this, focused attempts are being directed towards understanding their role as modulators of brain chemistry and behavior. Epidemiological studies have identified that exposure to neurotoxins during prenatal/early life can profoundly impact neurodevelopment/function. In this context, we have tested the hypothesis that a combination of prebiotic supplements during gestation has the propensity to attenuate acrylamide (ACR) induced oxidative impairments, mitochondrial dysfunction and neurotoxicity in maternal and fetal brain of rats. To achieve this, pregnant dams given oral supplements of a combination of fructo- and xylooligosaccharides (FOS + XOS, 3 g/kg/day) during gestation days (GD 0–19) were exposed to ACR (200 ppm in drinking water, GD 6–19). The behavioral analysis revealed that ACR dams fed prebiotics displayed higher exploratory behavior in the open field test. The prenatal evaluation showed that ACR-induced decrements of placental/fetal weights were markedly restored with prebiotic feeding. Prebiotics significantly offset markers of oxidative stress, restored enzymic antioxidants, cholinergic and mitochondrial function in the maternal and fetal brain. Concomitantly, prebiotics restored ACR-induced depletion in the levels of dopamine and γ-aminobutyric acid in the maternal cortex that positively correlated with cecal bacterial numbers. Collectively, these data suggest that prenatal prebiotic oligosaccharide supplements protect developing brain against oxidative stress-mediated neurotoxicity. While the underlying mechanism/s by which prebiotics abrogate the impact of neurotoxicants in the developing brain merits further studies, we speculate that it may be mediated predominantly through attenuation of oxidative stress and proliferation of enteric microbiota.
By using the Seebeck effect to produce electrical voltage, thermoelectric as a highly scalable, stationary and silent heat engine has undergone a state of vigorous research. Starting with the review on thermoelectric generators, it shows that thermoelectric is gaining more attention since the past decade. Generally, the research conducted on the thermoelectric generators concentrate on the material development, mathematical and numerical model development as well as the application of thermoelectric generators. For this article, attention is given to the application research of the thermoelectric generators. From the survey conducted, most of the application research carried out is based on intermittent electrical power generation (e.g. the direct use of solar energy available or waste heat recovery). Hence, it opens an opportunity for the research on the application of thermoelectric generators by utilising a heat source that is continuously ready for thermal-electrical energy conversion, such as phase change material, geothermal heat or solar pond. In the later section, the review is continued by introducing solar pond, a facility that has been used as a supply of low-grade heat source at the remote area or industrial process heating. The research on the fundamentals of solar pond and its applications, but not limited to, the power generation has also been summarised. The ultimate idea of this review is to provide an insight that a thermal-storage based heat source (e.g. in this review, the solar pond) could be useful for small-scale electric power generation, despite its ordinary function as low-grade heat source provider via heat extraction.
A novel surface modification strategy that could convert lithium residues on the Ni-rich material surface into a lithium ion conductor coating layer was investigated. Various analysis techniques, such as high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS), were used to confirm the formation of an amorphous lithium lanthanum titanate (LLTO) coating layer with a thickness below 10nm. 1 mol% LLTO modified LiNi0.6Co0.2Mn0.2O2 exhibits the optimized electrochemical performance, with 87.2% capacity retention after 200 cycles at 0.5C, and excellent rate performance compared with that of the pristine LiNi0.6Co0.2Mn0.2O2. The cycling performance at higher charging voltage (4.5V) and storage characteristics against moisture and air are also improved significantly after LLTO modification. The enhanced electrochemical performance could be attributed to the high ionic conductivity of LLTO and the uniformity of the coating layer. It can not only suppress the interfacial resistance increasing, but also stabilize the crystal structure of the cathode material during charge-discharge cycling.
Co3O4 powders are synthesized by a controllable microwave process in the presence of nonionic surfactants characterized by various structures. The influence of the surfactant structure on the charge storage performance of Co3O4 –based electrode is commented through the specific surface area and morphology of Co3O4 powder. In the absence of surfactants, Co3O4 layers are self-organized into microspheres. When linear PEG 2000 or Triton X100 polymers are used as surfactants, Co3O4 microspheres unfold into particles. However, a nanorods-like morphology is obtained with the multi-branched Tween 20 surfactant. Such a unique architecture exhibits remarkable electrochemical performance with high capacity and suitable cycle life after 2000 cycles in 3 M KOH aqueous solution. Increasing the specific surface area results in the improvement of the electrochemical performance. The specific capacity values deduced from cyclic voltammetry experiments are found to increase in the following order: Co3O4 -without surfactant (60 mAh g−1) < Co3O4-Triton X100 < Co3O4-PEG 2000 < Co3O4-Tween 20 (126 mAh g−1). The exceptional charge storage performance of Co3O4 elaborated with Tween 20 is also confirmed galvanostatically in term of high capacity retention. It shows that 70% of the capacity is maintained upon a gradual increase of the applied current density from 5 to 15 A g−1.
Organic/inorganic hybrid membranes based on (3-glycidoxypropyl) trimethoxysilane (GPTMS) and ethylene glycol diglycidyl ether (EGDE), have been prepared by sol-gel method and organic polymerization as solid electrolytes for Li-ion batteries. Lithium bis(trifluoromethane)sulfonamide (LiTFSI) was used as Li salt. FTIR and Raman spectroscopies were used to confirm the hybrid structure formation and the interactions between Li ions and hybrid network. An Arrhenius-like temperature dependence of ionic conductivity was observed for solid hybrid electrolyte membranes, suggesting that the diffusion of charge carriers was assisted by the segmental motions of the organic network. The Li-ion transfer number was determined and correlated with their ionic conductivities. Maximum ionic conductivities for the solid hybrid electrolyte membrane with LiTFSI and a [Li+]/[O]=0.10 (class II hybrid) of 2.6×10−5 S/cm was obtained at room temperature. A good value of electrochemical stability window (7V) and an excellent high rate performance after 500 cycles make these hybrids materials a promising electrolyte candidate for all-solid-state lithium battery applications.
Mesoporous Li4Ti5O12 is prepared via ball-milling assisted solid-state reaction with titanyl sulfate and LiOH as precursors. Different from previous reports, the solid-state reaction route generates mesopores in Li4Ti5O12 by removing the impurities after the high-temperature synthesis process. This technique ensures the formation of well-defined mesoporous structure and ultrafine nanoparticles with the size of around 8 nm. The as-prepared sample shows good rate and cycle performance. At the current density of 1750 mA g−1 (10 C), high initial discharge capacity of 174.5 mAh g−1 can be obtained, which can be retained at 143.4 mAh g−1 after 50 cycles. This facile ball-milling assisted solid-state reaction could be a practical way for the mass synthesis of mesoporous Li4Ti5O12 as high-performance anodes.
The application of Li–O2 batteries is hindered by severe parasitic reactions in battery cycling. Here the authors show that the highly reactive singlet oxygen is the main cause for the electrolyte and carbon electrode degradation on discharge and charge.
Concentrated solar energy provides a virtually unlimited source of clean, non-polluting, high-temperature heat. This article reviews the underlying principles of concentrating solar radiation and describes the latest technological advances and future prospects of solar thermal power and thermochemical fuel production.
Extension of battery life and dissipation of heat from components with high power density are significant challenges in mobile computing platforms. A power architecture suitable for the integration of low voltage, low power renewables into the bus is described in this paper as an innovative, green approach to help both of these issues. The architecture is both scaleable and flexible in order to accommodate the intermittent nature of the renewable energy sources. A new charge pump based boost scheme with fully asynchronous control is utilized as the enabling building block to meet the stringent power dissipation and efficiency requirements of this application. The resulting power electronics do not contain magnetic components and can be integrated into an LSI chip.
The present paper describes results of the experimental investigation of a small-scale mono-hull model boat propelled by a localised flexural wave propagating along the plate of finite width forming the boat's keel. Forward propulsion of the boat was achieved through flexural wave propagation in the opposite direction, which is similar to the aquatic propulsion used in nature by stingrays. The model boat under consideration underwent a series of tests both in a Perspex water tank and in an experimental pool. In particular, the forward velocity of the boat has been measured for different frequencies and amplitudes of the flexural wave. The highest velocity achieved was 32cm/s. The thrust and propulsive efficiency have been measured as well. The obtained value of the propulsive efficiency in the optimum regime was 51%. This indicates that the efficiency of this type of aquatic propulsion is comparable to that of dolphins and sharks (around 75%) and to that of a traditional propeller (around 70%). In contrast with a propeller though, the wave-like aquatic propulsion has the following advantages: it does not generate underwater noise and it is safe for people and marine animals.
The effect of surface functionalization of aminophenyl and bromophenyl groups on carbon-coated LiFePO4 and the electrochemical properties of composite electrode containing these materials are reported. The functionalization was performed by spontaneous reduction of the corresponding in situ generated diazonium ions. The resulting chemically grafted LiFePO4/C materials were characterized by energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) to confirm the presence of the surface organic species. XRD analyses indicated the cathode material was partially oxidized. Thermogravimetric and elemental analyses revealed the loading of grafted molecules was between 0.2 and 1.1 wt.% depending on the reaction conditions. Interestingly, the electrochemical performances of the modified LiFePO4/C are not adversely affected by the presence of either aminophenyl and bromophenyl groups at the carbon surface, and in fact the grafted LiFePO4/C displayed slightly superior discharge capacity at the highest C rate investigated for a low loading of organic molecules.
La15Fe10−x Ni70Mn5B x (x = 0, 1, 1.5, 2, 3) hydrogen storage alloys are prepared using a vacuum induction-quenching furnace. A structure analysis shows that the boron-free alloy is composed of a La0.99Mn0.32Ni4.71 phase and an (Fe, Ni) phase and that the alloys containing boron consist of the La0.99Mn0.32Ni4.71, (Fe, Ni) and La3Ni13B2 phases. As the x increase, the parameter a of the La0.99Mn0.32Ni4.71 and La3Ni13B2 phases increases, while the c decreases. The relative abundance of the La3Ni13B2 phase and the gather degree of the (Fe, Ni) phase increase with increasing x. Electrochemical testing shows that the boron content has an unapparent effect on the alloy electrodes' activation property. The maximum discharge capacity of the alloy electrodes is stable (approximately 310 mAh g−1) when x increases from 0 to 2. The cycling capacity retention rate at the 50th cycle monotonically increases from 56.6% (x = 0) to 76.7% (x = 3). The high-rate dischargeability of the alloy electrodes first increases with increasing x from 0 to 1.5 and then decreases until x increases to 3. The HRD is controlled by the hydrogen diffusion rate in the bulk of the alloy (x = 0–1.5) and the charge-transfer reaction of hydrogen on the alloy electrode surface (x = 1.5–3).
Linear poly(ethylenimine) (LPEI) is an NH-containing analog of poly(ethylene oxide) (PEO). Various groups (e.g. CH3) can be attached to the nitrogen atoms in order to decrease the crystallinity and eliminate hydrogen bonding of the host polymer. This paper focuses on linear poly(N-methylethylenimine), LPMEI, with dissolved lithium triflate (LiTf) and sodium triflate (NaTf). These electrolytes were investigated using infrared spectroscopy, differential scanning calorimetry (DSC), and impedance measurements of the conductivity. A spectroscopic comparison of LPMEI containing LiTf and NaTf over a composition range of 5:1 to 20:1 (nitrogen:cation) shows that contact ion pairs are the predominant species in both systems except for the 5:1 NaTf sample, where the “free” triflate ions are the predominant species. Furthermore, there is an increase in the degree of ionic association with increasing salt concentration in the LiTf systems. The effect of salt concentration on the glass transition temperature (Tg) of the polymer host was examined using DSC. In LPMEI, Tg occurs at −91°C and increases to 3°C at a 5:1 (N:Li) composition. Conductivity measurements of the LPMEI:LiTf system over a composition range of 5:1 to 20:1 are compared with the LPEI:LiTf systems for temperatures between 25 and 60°C. In addition, X-ray powder diffraction (XRD) show a significant presence of crystalline domains in the LPMEI:NaTf samples.
Proton-conducting metal-organic frameworks (MOFs) could be used as the electrolytes in proton exchange membrane fuel cells but chemically stable materials that perform well at low humidity are still sought. Here the authors prepare a stable, structurally flexible MOF that maintains high proton conductivity under a wide range of humidity.
There is a large and growing literature on welfare state attitudes, most of which is built on random-sample population surveys with standardised closed-question items. This article criticises the existing survey instruments, especially those that are used within the International Social Survey Programme, in a novel approach with focus group data from Germany. The article demonstrates: firstly, these instruments underestimate the inconsistency (the degree to which attitudes logically contradict each other), the uncertainty (the degree to which individuals are unsure about what to think), the ambivalence (the simultaneous occurrence of positive and negative reactions) and non-attitudes towards welfare state activities that common people have. Secondly, the meaning of these items to respondents seems to vary to such an extent that inference based on such measures is questionable. Finally, the article concludes by suggesting some survey instruments that alleviate these measurement problems.
The paper presents the results of a controlled study that had the purpose to test the efficiency of a complex plan for the treatment of attention deficit hyperactivity disorder. This therapeutic plan combines metaphorical scenarios adapted for therapeutic intervention in small groups of hyperactive children with special groups of professional optimisation organised for the teachers of these children. The subjects were 40 children diagnosed with ADHD, combined type. One-way ANOVA showed that there is a significant difference between the four groups on each criterion (p<.05). Bonferoni Post-hoc multiple comparisons tests showed that this difference is due to the mean scores for the control group, significantly different from the experimental groups.
A new bifunctional redox flow battery (BRFB) system, V(III)/V(II)—l-cystine(O2), was systematically investigated by using different separators. It is shown that during charge, water transfer is significantly restricted with increasing the concentration of HBr when the Nafion 115 cation exchange membrane is employed. The same result can be obtained when the gas diffusion layer (GDL) hot-pressed separator is used. The organic electro-synthesis is directly correlated with the crossover of vanadium. When employing the anion exchange membrane, the electro-synthesis efficiency is over 96% due to a minimal crossover of vanadium. When the GDL hot-pressed separator is applied, the crossover of vanadium and water transfer are noticeably prevented and the electro-synthesis efficiency of over 99% is obtained. Those impurities such as vanadium ions and bromine can be eliminated through the purification of organic electro-synthesized products. The purified product is identified to be l-cysteic acid by IR spectrum. The BRFB shows a favorable discharge performance at a current density of 20mAcm−2. Best discharge performance is achieved by using the GDL hot-pressed separator. The coulombic efficiency of 87% and energy efficiency of about 58% can be obtained. The cause of major energy losses is mainly associated with the cross-contamination of anodic and cathodic active electrolytes.
Transition metal oxides are very promising electrode materials for lithium-ion batteries that operate through conversion reactions. Energy densities for conversion reactions are higher than for intercalation reactions, but most of transition metal oxides show poor cycling performance and reversibility due to the pulverization of active materials and subsequent volume changes. We here report a facile and scalable synthesis for realizing Li4Ti5O12-coated Fe/Fe3O4 hybrid nanocomposites in the form of one-dimensional nanofibers (C@Fe-Fe3O4/Li4Ti5O12 hybrid NFs). This is a new class of highly-reversible and safe anode material that can significantly reduce the lithium-ion diffusion length and improve strain tolerance during Li ion insertion/extraction. Its oxidation state was also impressively controlled through a carbothermal reaction during annealing. The precise oxidation state control of C@Fe-Fe3O4/Li4Ti5O12 hybrid NFs simultaneously enabled high capacity due to the conversion reaction of Fe3O4 as well as high reversibility and stability resulting from zero-strain characteristics and superb kinetics of Li4Ti5O12. This new electrode material appears promising for not only future energy systems but also various electronic devices.
The ability to interpret and predict other people's actions is highly evolved in humans and is believed to play a central role in their cognitive behavior. However, there is no direct evidence that this ability confers a tangible benefit to sensory processing. Our quantitative behavioral experiments show that visual discrimination of a human agent is influenced by the presence of a second agent. This effect depended on whether the two agents interacted (by fighting or dancing) in a meaningful synchronized fashion that allowed the actions of one agent to serve as predictors for the expected actions of the other agent, even though synchronization was irrelevant to the visual discrimination task. Our results demonstrate that action understanding has a pervasive impact on the human ability to extract visual information from the actions of other humans, providing quantitative evidence of its significance for sensory performance.