batterydata/paper-abstracts huggingface dataset:
Achieving high yields in the production of bulk chemicals is an important goal for the chemical industry. We investigated the influence of the metal on the catalytic performance of M/MgCuCr2O4 (M=Cu, Ag, Pd, Pt, Au) catalysts to better understand the metal–support synergy for the aerobic oxidation of ethanol. Pt/MgCuCr2O4 and Pd/MgCuCr2O4 are more active and less selective for ethanol oxidation than the other catalysts, mainly because they can dehydrogenate and then cleave the carbon–carbon bonds in ethanol at relatively low temperature. Because of the facile oxidation of Cu0 and Ag0 under aerobic oxidation conditions, Cu/MgCuCr2O4 and Ag/MgCuCr2O4 are less active for ethanol oxidation. On contrary, Au/MgCuCr2O4 is a very active, selective and stable catalyst for sustainable production of acetaldehyde, achieving 96% selectivity at full ethanol conversion (space–time–yield up to 583galdehyde gAu −1 h−1) at 250°C. Low gold loading and high gold dispersion are important to enhance the Au0–Cu+ synergy and the catalytic efficiency of Au/MgCuCr2O4.
Our living environment has an abundance of energies in the forms of light, thermal, mechanical (such as vibration, sonic wave, wind, and hydraulic), magnetic, chemical, and biological. Harvesting these types of energies is of critical importance for long-term energy needs and sustainable development of the world. Over the years, rationally designed materials and technologies have been developed for converting solar and mechanical energies into electricity. Photovoltaic relies on approaches such as inorganic pn junctions, organic thin films, and organic–inorganic heterojunctions. Mechanical energy generators have been designed based on principles of electromagnetic induction and piezoelectric effect. Innovative approaches have to be developed for conjunctional harvesting of multiple types of energies using an integrated structure/material so that the energy resources can be effectively and complimentarily utilized whenever and wherever one or all of them are available. We give a review on the hybrid cells that are designed for simultaneously harvesting solar and mechanical, and chemical and mechanical energies using nanotechnology. The two energy harvesting approaches can work simultaneously or individually, and they can be integrated in parallel and series for raising the output current and voltage, respectively. Innovative approaches have been demonstrated for developing integrated technologies for effectively scavenging available energies in our environment around the clock.
X-ray tomography is used to investigate material redistribution and effects of electrochemical reactions in a zinc-air battery in-situ. For this, a special battery set-up is developed which meets tomographic and electrochemical requirements. The prepared batteries are discharged and some of them have partially been charged. To analyse the three-dimensional structure of the zinc and air electrode a tomographic measurement is made in charge and discharge condition without disassembling the battery. X-ray tomography gives the opportunity to detect and analyse three different effects within the cell operation: tracking the morphology and transformation of zinc and air electrode, monitoring electrolyte decomposition and movement, finding electrical misbehaviour by parasitic reactions. Therefore, it is possible to identify the loss of capacity and major problems of cyclability. The electrolyte strongly reacts with the pure zinc that leads to gassing and a loss of electrolyte. The loss prevents a charge carrier exchange between the anode and the cathode and reduces the theoretical capacity. One of the chemical reaction produces hydroxylated zinc, namely zincate. The most crucial problems with cyclability are affected by zincate movement into the catalyst layer. This assumption is confirmed by finding pure zinc areas within the catalyst layer.
Cyclic voltammetry experiments at various electrolyte solution concentrations (0.001–0.1 M) and scan rates (1 to 5 mV s−1) have been performed to study the electrical double layer (edl) formation in nanostructured carbon aerogel. The results show that carbon aerogel is a good edl capacitor and can be further divided into mesoporous and microporous capacitors. According to the experiments, the mesoporous capacitor shows a fast charging/discharging response and is only minimally affected by the electrolyte concentration and scan rate. Therefore, the specific capacitance of the mesoporous capacitor is found to be constant over a wide range of applied electrical potentials. On the other hand, the microporous capacitor shows a slow charging/discharging response and its capacitance strongly depends on the electrolyte concentration and potential. Unlike previous experiments, in which only a flat minimum was observed at the point of zero charge (pzc), in the current study, a deep minimum is observed near the pzc at low electrolyte concentration if a slow scan rate is used. This unique feature is a result of edl overlapping in the micropores and is consistent with the predictions by the Gouy–Chapman model employed in this study. Based on this behavior, a new approach is suggested for pzc measurements of solid porous materials for which a large portion of the surface area is in the micropore region.
Previous molecular studies on the termite Reticulitermes flavipes have revealed that two hexamerin proteins serve an important status quo role in the regulation of juvenile hormone (JH)-dependent caste differentiation. Here, we report sequence data and other experimental evidence suggesting how these two hexamerins function in achieving caste regulation. The two hexamerin genes, named Hex-1 and Hex-2, encode highly unique sequence features relative to the 100+ other known insect hexamerins. These features include a long hydrophobic tail and prenylation motif in Hex-1, and a long hydrophilic insertion plus several putative protease cleavage sites in Hex-2. Both hexamerin genes are primarily expressed in fat body tissue, but only Hex-2 expression is substantially induced by JH. SDS–PAGE showed that the hexamerin proteins constitute a major proportion of total soluble termite protein. Also, although each protein occurs in both the membrane and soluble protein fractions, Hex-2 has stronger membrane affinity. Anti-JH antiserum specifically recognizes hemolymph-soluble Hex-1 protein, supporting that the unique prenylation site in Hex-1 facilitates covalent JH binding to the primary amino acid chain. Finally, increased ratios of Hex-2 to Hex-1 transcription occur in caste phenotypes and developmental stages that differentiate in response to rising JH titers. Two main conclusions can be taken from these studies. First, elevated ratios of Hex-2 to Hex-1 expression are associated with caste phenotypes that differentiate in response to rising JH titers (i.e., workers, presoldiers and soldiers). Second, due to their unique structural features and other observed characteristics, our findings support the hypothesis that the two hexamerins participate in the regulation of caste-differentiation by modulating JH availability.
This essay discusses the reciprocal relationship between progress and technology. It demonstrates that progress cannot be separated from technological improvements because improvements are believed to be the result of progress, and technological improvements cannot be conceived without progress because progress is believed to be the result of improvements. The idea of technological progress lies deep in the historical past, and can be found as early as the Greeks. Thinkers, such as Bacon, Descartes and Marx, who gave their support to the idea of progress in reference to technology, are analyzed, as are other significant factors, such as the cultural and historical importance of Christianity, which introduced both an eschatological interpretation of history and a linear conception of time. In conjunction with the ideas discussed above, technological progress is sustained by its own mythology, which extends and perpetuates the idea of progress indefinitely into the future.
In this study, three identical LiNixCoyAl1−x−yO2, (NCA) batteries are evaluated to understand the impact of high rate discharge on the rate of capacity fade. The first of the three cells is repeatedly discharged in a pulse width modulated (PWM) manner at a frequency of 10 kHz, duty cycle of 50%, and peak rate of 83C (250 A). The second cell is repeatedly discharged at a constant current (CC) rate of 25C (75 A) while the third cell, which serves as the control cell, is discharged at its nominal CC rate of 1C (3 A). All three cells are recharged using a 1C CC recharge procedure to minimize the impact of recharge on cell aging. Novel and commercially procured battery cyclers are used to experimentally discharge and recharge the cells. Periodic baseline measurements, in which both capacity and electrochemical impedance spectroscopy (EIS) measurements show that the degradation mechanisms are enhanced under high rate pulse discharge cycling conditions. EIS modeling points to breakdown in the integrity of the anodic side double layer and increased charge transfer resistance as the largest contributors to impedance evolution in the cell.
Mn3O4/Fe3O4 nanoflowers with controllable components are simply fabricated through one step etching of the Mn5Fe5Al90 ternary alloy. The as-made hierarchical flower-like structure with interconnected voids consists of a packed array of uniform regular hexagon-like nanoslices. Based on the simple dealloying strategy the target metals are directly converted to uniform nanocomposite composed of Mn3O4 and Fe3O4 species. With the unique hierarchical flower-like structure and the synergistic effects between Mn3O4 and Fe3O4, the nanocomposite exhibits higher performance as anode material for lithium ion batteries than that of pure Mn3O4 and Fe3O4 anodes. The Mn3O4/Fe3O4 nanocomposite deliver much higher discharge capacity and lower initial irreversible loss than Mn3O4 anode. The Mn3O4/Fe3O4 anode material also shows an excellent cycling stability at the high rate of 1500mAg−1 with outstanding rate capability. With the advantages of simple preparation and excellent electrochemical performance, Mn3O4/Fe3O4 nanoflowers manifest great application potential as anode material for lithium ion batteries.
Optimal electrode compression can efficiently reduce electrode contact resistance and enhance species mass transfer so that the performance of vanadium redox flow battery (VRFB) is consequently improved. New designs of VRFB with a serpentine flow field on the current collector and compressed thin electrodes are investigated to increase its power density. In this study, the intrusion ratio, porosity, strain–stress, area specific resistance, hydrodynamic characteristics, and charge/discharge performance of VRFBs are comprehensively characterized under different compression ratios (CRs) which can be adjusted by changing the assembly force. Then, VRFBs using carbon felts with different CRs are tested by experiments, and the influence of electrode compression on VRFB cell performance is quantitatively evaluated. The in-homogeneous compression of carbon felt electrode in a VRFB with a flow field leads to a non-uniform porosity distribution of the electrodes under the channel, intrusion, and rib regions. The intrusion ratio, local average porosity, and permeability at different CRs are obtained. The Kozney–Carman constant of carbon fiber felt is modified by measuring the flow pressure drop through the electrode. The charge/discharge curves are acquired and the corresponding energy efficiencies are calculated under different CRs. It is shown that the charge/discharge time increases with the CR, and the energy efficiency can be improved to a maximum of 19.4% when the CR varies from 0.3% to 41.8%.
Mn cation trapping by polymeric aza-15-crown-5 ethers is an effective means for mitigating the consequences of Mn dissolution in Li-ion batteries. Mn cations trapping was investigated in lithium manganese oxide (LMO) spinel–graphite (GR) cells containing 1 M LiPF6 in ethylene carbonate (EC):diethyl carbonate (DEC) 1:2 v/v. A commercial polyolefin separator membrane coated with poly[divinylbenzene-(vinylbenzyl-aza-15-crown-5)-vinylbenzylchloride)] effected a 39% reduction in capacity loss rate during cycling at 50 °C with 100% depth of discharge (DOD) at C/5 rate. Simultaneously, a 50–60% reduction in the Mn deposited at the negative electrode, and a 6× to 10× increase in the Mn on the coated separator were observed for cells with coated separators, over baseline cells with plain separators. X-ray absorption near-edge spectroscopy (XANES) yielded average oxidation states near +3 for Mn cations in graphite electrodes and separators from cycled cells, suggesting that Mn metal or in oxidation state +2 can only be minor fractions of the Mn existing outside the positive electrode. We discuss the implications of these results for choosing an optimal chelating agent. We also show that the cation chelating polymer reported here is compatible with existing manufacturing processes for Li-ion battery separators.
Objective The nature of the relationship between physiological and subjective responses in phobic subjects remains unclear. Phobics have been thought to be characterized by a heightened physiological response (physiological perspective) or by a heightened perception of a normal physiological response (psychological perspective). Method In this study, we examined subjective measures of anxiety, heart rate (HR), and cardiac autonomic responses to flight-related stimuli in 127 people who applied for fear-of-flying therapy at a specialized treatment center and in 36 controls without aviophobia. Results In keeping with the psychological perspective, we found a large increase in subjective distress (η 2=.43) during exposure to flight-related stimuli in the phobics and no change in subjective distress in the controls, whereas the physiological responses of both groups were indiscriminate. However, in keeping with the physiological perspective, we found that, within the group of phobics, increases in subjective fear during exposure were moderately strong coupled to HR (r=.208, P=.022) and cardiac vagal (r=.199, P=.028) reactivity. In contrast to predictions by the psychological perspective, anxiety sensitivity did not modulate this coupling. Conclusion We conclude that subjective fear responses and autonomic responses are only loosely coupled during mildly threatening exposure to flight-related stimuli. More ecologically valid exposure to phobic stimuli may be needed to test the predictions from the physiological and psychological perspectives.
A novel V2O5@PANI composite nanowires were prepared by simply stirring in sodium nitrate solution and in-situ chemical oxidation polymerization methods. The V2O5@PANI composite nanowires display excellent optical and electrochemical properties, such as multicolor ranging from black, pale yellow, light yellow to dark green, outstanding cycling stability for 1000 cycles and fast switching time of bleaching and coloration (1.5 and 2.3 s, respectively). These outstanding performances are attributed to the synergistic effect between PANI encapsulated and original V2O5 nanobelts. The study offer a new synthesis strategy for fabricating inorganic-organic composite materials in optical and electrochemical fields. The morphology and structure of the composite were characterized by scanning electron microscopy, high-resolution transmission electron microscopy and X-Ray photoelectron spectroscopy.
We investigated the effect of coating Fe- and Ni-substituted Li2MnO3 cathodes (Li1.23Mn0.46Fe0.15Ni0.15O2, LMFN) with Sm oxide (Sm2O3). The cells with LMFN and Sm2O3-coated LMFN cathodes respectively showed 85% and 90% capacity retention and generated 4.3 and 1.6 mlg−1 of gas during 50 cycles, which verified that the Sm2O3 coating was effective. Observations with a scanning transmission electron microscope equipped with an energy dispersive X-ray spectroscopy analyzer showed that the Sm2O3 uniformly coated the LMFN. Synchrotron radiation X-ray absorption spectroscopy indicated that the Sm2O3 coating had little effect on the valence and/or electronic state of the Mn, Fe, and Ni during cycles. However, hard X-ray photoemission spectroscopy indicated that the Sm2O3 coating disturbed solid electrolyte interphase growth originating from the chemical reaction with the electrolyte solution and cathode electrode. The irreversible redox reactions of oxygen ions were also considerably suppressed. We believe that the improvements in cell properties had by using the Sm2O3-coated LMFN cathode will contribute to the development of next-generation storage devices.
The improvement of lead-acid batteries with respect to charge acceptance and cycle life in partial state of charge operations due to carbon additives in negative electrodes is state of the art. However, there is still a lack of knowledge about the mechanisms which generate these enhancements. Especially the influence of the physicochemical connection between the carbon additives and the surrounding lead skeleton has not been investigated in much detail yet, but seems to play an important role. Therefore, we developed a new method for characterizing the degree of interaction between lead and carbon additives with focus on graphite materials. By potentiostatic deposition of lead on graphite electrodes, we observe a correlation between the deposition overpotential and the number density of nucleation sites. Chronoamperometry is used to calculate the number density of nucleation sites on graphite electrodes which is in accordance with microscopic observations. We found that expanded graphite exhibits a significantly higher number of nucleation sites than synthetic graphite. Finally, a correlation between this number density of nucleation sites and the integration of the graphite particles in real lead electrodes is observed. Thus, the technique can be used to predict the integration of different graphite particles into the negative active material.
This study utilizes a Taguchi-based particle swarm optimization algorithm to search an optimal four-stage constant current charge pattern for delivering the maximum capacity to provide long runtimes within the shortest charging time. The goal is to maximize the cost function for the applied charge pattern based on the charging time and discharge capacity ratio that both share the same weight. The discharge capacity ratio is defined as the total capacity of a cell discharged at a constant current of 0.3 C using the four-stage constant current charging strategy until reaching the preset voltage of 3.0 V to the one employs the constant current constant voltage charging method. The charging time is the overall charging duration of the 4SCC charging process. Sanyo UR14500P batteries in the cylindrical shape with a nominal voltage of 3.7 V and a rated capacity of 840 mAh are tested. In the tests, the optimal 4SCC sequence of 1.262 C, 1.082 C, 0.662 C and 0.258 C is allowed to charge the battery up to 94.7% of the nominal capacity for 67 min, and the constant current constant voltage charging arrangement of 0.7 C to 4.2 V and the cut-off of 0.05 C are used to charge the battery up to 99.5% of the nominal capacity in 119 min.
Two-dimensional (2D) “graphene-like” inorganic materials, because of the short lithium ion diffusion path and unique 2D carrier pathways, become a new research focus of the lithium storages. Some “graphene-like” binary compounds, such as, MnO2, MoS2 and VO2 ultrathin nanosheets, have been synthesized by the peeling method, which also exhibit enhanced lithium storage performances. However, it still remains a great challenge to synthesize widely-used lithium-containing ternary oxides with “graphene-like” nanostructures, because the lithium-containing ternary oxides, unlike ternary layered double hydroxides (LDH), are very hard to be directly peeled. Herein, we successfully synthesized ultrathin Li3VO4 nanoribbons with a thickness of about 3nm by transformation from ultrathin V2O5·xH2O nanoribbons, moreover, we achieved the preparation of ultrathin Li3VO4 nanoribbon@graphene sandwich-like nanostructures (LVO/G) through the layer-by-layer assembly method. The unique sandwich-like nanostructures shows not only a high specific reversible capacitance (up to 452.5mAhg−1 after 200 cycles) but also an excellent cycling performance (with more than 299.2mAhg−1 of the capacity at 10C after 1000 cycles) as well as very high rate capability. Such template strategy, using “graphene-like” binary inorganic nanosheets as templates to synthesize lithium-containing ternary oxide nanosheets, may be extended to prepare other ternary oxides with “graphene-like” nanostructures.
The V2O3/reduced graphene oxide (V2O3-rGO) 3D gels are synthesized by a hydrothermal reaction and annealing process, using graphene oxide and NH4VO3 as raw materials. The V2O3 nanoparticles with the size of 4–10nm are homogeneously and closely anchored onto the graphene foam. When used as anode material for lithium-ion batteries, the V2O3-rGO 3D gel exhibits high capacity (786mAhg−1 at 0.07Ag−1), good cycle stability (350mAhg−1 at 1.86Ag−1 after 1000 cycles) and excellent rate capability (192mAhg−1 at 37.2Ag−1) as well as distinguished electrochemical properties at a wide temperature range of 0–75°C. The desirable electrochemical performance should be attributed to the high content of V2O3, the nanoscale size of V2O3 and the 3D porous graphene network.
The wind energy potential at four different sites in Ethiopia – Addis Ababa (09:02N, 38:42E), Mekele (13:33N, 39:30E), Nazret (08:32N, 39:22E), and Debrezeit (8:44N, 39:02E) – has been investigated by compiling data from different sources and analyzing it using a software tool. The results relating to wind energy potential are given in terms of the monthly average wind speed, wind speed probability density function (PDF), wind speed cumulative density function (CDF), and wind speed duration curve (DC) for all four selected sites. In brief, for measurements taken at a height of 10m, the results show that for three of the four locations the wind energy potential is reasonable, with average wind speeds of approximately 4m/s. For the fourth site, the mean wind speed is less than 3m/s. This study is the first stage in a longer project and will be followed by an analysis of solar energy potential and finally the design of a hybrid standalone electric energy supply system that includes a wind turbine, PV, diesel generator and battery.
Various activated carbons from the PICA Company have been tested in supercapacitor cells in order to compare their performances. The differences measured in terms of specific capacitance and cell resistance are presented. Porosity measurements made on activated carbon powders and electrode allowed a better understanding of the electrochemical behaviour of these activated carbons. In this way, the PICACTIF SC carbon was found to be an interesting active material for supercapacitors, with a specific capacitance as high as 125F/g.