batterydata/paper-abstracts huggingface dataset:
Herein, we present a new strategy for the mass production of high-quality reduced graphene oxide (RGO) with a surface area of 354 m2 g−1 using high pressure hydrogen as a reducing agent under hydrothermal conditions. The high pressure used is solely generated from the packing of the gas cylinder itself and a pressure meter could simply fulfil the role of monitoring pressure. The reduction process is green without chemical wastes produced. Comparing to other reported methods, the significant advancements of our strategy lie not only in the high-quality RGO with high C/O ratio, conductivity and surface area, but also in the most environment-friendliness and cost-effectiveness, which make the large scale fabrication feasible. Moreover, clean noble metal nanocrystals such as Pt could be easily in situ deposited onto the surface of RGO nanosheets when noble metal salts are introduced into the system. In particular, the prepared RGO and Pt/RGO show exceptional electrochemical performances in supercapacitors and lithium oxygen batteries because of their clean electrochemical surface, good conductivity and large surface area. Our results reveal that the obtained RGO have a specific capacitance of 884.4 F g−1 at a current density of 0.5 A g−1, and the Pt/RGO electrode can deliver discharge–charge capacities of 1000 mAh g−1 for 40 cycles with a high round-trip efficiencies of 74.9% at 50 mA g−1 when used as Li–O2 battery electrodes.
MgTi, Mg0.5Ni0.5Ti and MgTi0.5Ni0.5 alloys doped with 10wt.% Pd were prepared by high energy ball milling and evaluated as hydrogen storage electrodes for Ni–MH batteries. X-ray diffraction analyses indicated that the Mg0.5Ni0.5Ti and MgTi0.5Ni0.5 alloys could be monophased or composed of a nanoscale mixture of MgTi+NiTi and MgTi+MgNi phases, respectively. Their hydrogen storage characteristics were investigated electrochemically in KOH electrolyte. No activation step was observed during the cycling of the Mg–Ti–Ni electrodes in contrast to that observed with the MgTi electrode. The highest hydrogen discharge capacity was obtained with the MgTi0.5Ni0.5 electrode (536mAhg−1) compared to 401 and 475mAhg−1 for the Mg0.5Ni0.5Ti and MgTi electrodes, respectively. The ternary Mg–Ti–Ni alloys showed a better cycle life with an average capacity decay rate per cycle lower than 1.5% compared to ∼7% for the binary MgTi electrode. The Mg–Ni–Ti electrodes also displayed a much higher discharge rate capability than the binary MgTi electrode, especially with the Mg0.5Ni0.5Ti electrode. The origin of this was established on the basis of the anodic polarization curves, where a substantial decrease of the concentration overpotential (reflecting a higher hydrogen diffusivity) was observed for the Mg0.5Ni0.5Ti electrode.
Nowadays nickel-rich LiNixCoyMn1-x-yO2 (0.5 < x < 1) cathode materials attract great research interests due to their high specific capacity in lithium ion batteries. However, poor cycling performance and serious safety concerns trade off their benefits. Here, we present an effective etching-induced coating strategy for surface modification of LiNi0.8Co0.1Mn0.1O2 cathode materials by LiAlO2. Hydrolysis of AlCl3 creates H+ to etch the hydroxide precursor of LiNi0.8Co0.1Mn0.1O2 and to induce oriented deposition of Al(OH)3 layer on surface of the hydroxide precursor, which is transformed into uniform γ-LiAlO2 coating on the LiNi0.8Co0.1Mn0.1O2 particles after the subsequent lithium impregnating and annealing. The 2.2 wt% LiAlO2-coated LiNi0.8Co0.1Mn0.1O2 cathode delivers a high rate capacity of 135.2 mAh g−1 at 10 C and long cyclability with capacity retention of 85.8% after 200 cycles at 0.5 C. In addition, the thermal stability of LiAlO2-coated LiNi0.8Co0.1Mn0.1O2 is significantly improved. The enhanced battery performances are due to partial Al3+ doping and Li+ conductive LiAlO2 coating layer that provides well-connected networks for Li+ transport, improves the structural stability and prevents core materials from the attack by side products.
Summary The purpose of this study was to examine the physiological correlates of the Yo–Yo intermittent recovery test level 1 (Yo–Yo IR1) in basketball players. Twenty-two male basketball players (means±S.D., body mass 72.4±11.4kg, height 181.7±6.9cm, age 16.8±2.0 years) were tested for maximal oxygen uptake (VO2max), ventilatory threshold (VT) and running economy (RE) on a motorized treadmill. Lower limb explosive strength and anaerobic-capacity was assessed using vertical jumps (CMJ), 15m shuttle running sprint (15mSR) and line drill (LD), respectively. The same test battery was replicated after an experimental basketball game in order to assess selective effect of fatigue on physical performance. Pre to post-game CMJ (40.3±5.7 versus 39.9±5.9cm) and 15mSR (5.80±0.25 versus 5.77±0.22s) performances were not significantly different (p >0.05). LD performance decreased significantly post-game (from 26.7±1.3 to 27.7±2.7s, p <0.001). Yo–Yo IR1 performances (m) were significantly related to VO2max (r =0.77, p =0.0001), speed at VO2max (r =0.71, p =0.0001) and %VO2max at VT (r =−0.60, p =0.04). Yo–Yo IR1 performance was significantly correlated to post-game LD decrements (r =−0.52, p =0.02). These findings show that Yo–Yo IR1 may be considered as a valid basketball-specific test for the assessment of aerobic fitness and game-related endurance.
The effect of bismuth (Bi) for both VO2 +/VO2+ and V3+/V2+ redox couples in vanadium flow batteries (VFBs) has been investigated by directly introducing Bi on the surface of carbon felt (CF). The results show that Bi has no catalytic effect for VO2 +/VO2+ redox couple. During the first charge process, Bi is oxidized to Bi3+ (never return back to Bi metal in the subsequent cycles) due to the low standard redox potential of 0.308V (vs. SHE) for Bi3+/Bi redox couple compared with VO2 +/VO2+ redox couple and Bi3+ exhibit no (or neglectable) electro-catalytic activity. Additionally, the relationship between Bi loading and electrochemical activity for V3+/V2+ redox couple was studied in detail. 2wt% Bi-modified carbon felt (2%-BiCF) exhibits the highest electrochemical activity. Using it as negative electrode, a high energy efficiency (EE) of 79.0% can be achieved at a high current density of 160mA/cm2, which is 5.5% higher than the pristine one. Moreover, the electrolyte utilization ratio is also increased by more than 30%. Even the cell operated at 140mA/cm2 for over 300 cycles, the EE can reach 80.9% without obvious fluctuation and attenuation, suggesting excellent catalytic activity and electrochemical stability in VFBs.
Much work has focused on the effects of metal-contaminated sediment on benthic community structure, but effects on ecosystem functions have received far less attention. Decomposition has been widely used as an integrating metric of ecosystem function in lotic systems, but not for lentic ones. We assessed the relationship between low-level sediment lead (Pb) contamination and leaf-litter decomposition in a lentic system. We measured 30-day weight loss in 30 litter-bags that were deployed along a Pb-contamination gradient in a cypress-forested lake. At each deployment site we also quantified macrobenthos abundance, dissolved oxygen, water depth, sediment organic content, sediment silt/clay content, and both total sediment and porewater concentrations of Cd, Cu, Ni, Pb and Zn. Principal components (PC) analysis revealed a negative relationship between Pb concentration and benthic macroinvertebrate abundance, and this covariation dominated the first PC axis (PC1). Subsequent correlation analyses revealed a negative relationship between PC1 and percent leaf-litter loss. Our results indicate that leaf-litter decomposition was related to sediment Pb and benthic macroinvertebrate abundance. They also showed that ecosystem function may be affected even where sediment Pb concentrations are mostly below threshold-effects sediment quality guidelines—a finding with potential implications for sediment risk assessment. Additionally, the litter-bag technique used in this study showed promise as a tool in risk assessments of metal-contaminated sediments in lentic systems.
Lithium-sulfur battery is one of the most promising alternative power sources, but the polysulfide shuttle between the anode and cathode induces low Coulombic efficiency, low utilization of the sulfur cathode, and severe degradation of cycle life. Herein, the polysulfide shuttle was tuned by the loading of sulfur and electrolyte in a Li-S cell. A lithium-sulfur cell with a high initial discharge capacity of 1053 mAh g−1 at a high rate of 1 C and an ultralow decay rate of 0.049%/per cycle during 1000 cycles was obtained by using carbon nanotube@sulfur cathode and suppressing polysulfide shuttle to a shuttle factor of 0.02 by matching the sulfur/electrolyte loading. The use of matching the sulfur/electrolyte loading is a facile way to tune the shuttle of polysulfide, which provides not only new insights to the energy chemistry of Li/S batteries, but also important principle to assemble a Li/S cell with recommend loading for their commercialization application in portable mobile devices and electric vehicles.
One of the most critical factors for lifetime and operability of ad-hoc and sensor networks is the limited amount of available energy. To this respect, minimizing the interference in the network (i.e., the overlapping of signals at network nodes) has certainly a positive effect, because it induces a reduction of the number of conflicting transmissions, and then results in an overall saving of energy consumption. Along this direction, in this paper we study the computational hardness of several interference minimization problems which arise while supporting some classic network communication patterns such as broadcasting (one-to-all), gossiping (all-to-all), and symmetric gossiping (symmetric all-to-all). In particular, concerning the non-approximability results, we prove that for any of the above communication patterns, the prominent problem of minimizing the maximum interference experienced by any node in the network is hard to approximate within better than a logarithmic factor, unless NP admits slightly superpolynomial time algorithms. On a positive side, we show that any approximation algorithm for the problem of minimizing the total transmission power assigned to the nodes in order to guarantee any of the above communication patterns, can be transformed, by maintaining the same performance ratio, into an approximation algorithm for the problem of minimizing the total interference experienced by all the nodes in the network.
In this paper, a series of sulfonated poly(ether ether ketone) (SPEEK) hybrid membrane doped by the different amount of sulfonated graphene oxide (SGO) nanosheets are prepared by solution-casting method. The membrane structure, physicochemical property and cell performance of vanadium redox flow battery (VRB) have been characterized through FT-IR, SEM, XPS, and single-cell test system, etc. The incorporation of SGO in SPEEK improves the water uptake, ion exchange capacity and proton conductivity of the hybrid membrane, and effectively reduces the swelling degree and the vanadium ion permeability. In the single cell performance test, the energy efficiency of the SPEEK/SGO-3 hybrid membrane is 81.1%, which is higher than that of SPEEK (76.0%) and Nafion 117 membrane (73.8%). And, a longer self-discharge time (56.6 h) against Nafion 117 (23.5 h) and SPEEK (32.8 h) membrane is shown. In addition, the incorporated SGO nanofillers don't improve the chemical stability of SPEEK membrane soaked by 1.5 M V5+ solution although they block the vanadium ion permeation. Then, the durability for SPEEK/SGO hybrid membranes should be further explored for VRB system.
In order to achieve a profound understanding of the production process of electrodes for lithium-ion batteries, methods to determine the (intermediate) product quality are a necessity. Therefore, a new, fast and easy to use two point method to determine the relative resistivity of dry electrodes has been established. The method is used to determine process-induced changes in the electrode’s structure. A materials testing machine is used to ensure a homogeneous and constant mechanical stress during the analysis. By applying a direct current and measuring the voltage drop the electron transport characteristic along the whole electrode cross-section, taking all battery relevant resistances into account, can be determined. The result is an easy to compare relative resistivity value including coating resistance, contact resistance between coating and adhering current collector as well as the contact resistances between sample and probe. Process-induced changes are clearly visible in the results. The influence of the main testing parameters – contact stress and applied current – is determined. To cross-check the results, an established ‘powder probe’ method is used to confirm the relative resistivity changes caused by calendering. Slight calendering of LiNiMnCoO2 cathodes leads to an increase in electrode resistivity as conductive pathways are broken by the applied shear forces. However, increasing the cathode density to 2.95g/cm3 decreases resistivity by one third compared to uncalendered electrodes by re-establishing and shortening electrical pathways. Furthermore, a relative resistivity of anodes produced with a high energy powder mixing step is measured and shows that applying too much stress to the carbon black leads to a loss in long range conductivity, resulting in electrodes with an increased resistivity of up to 50%.
Flexible Li-ion batteries have shown great promise in powering wearable electronic devices due to their high energy/power densities and long cycling time. However, coordinating the promising electrochemical performance and flexibility for different applications is still a big challenge. Herein, we report a highly conductive graphene-modified mesoporous anatase TiO2 (M-TiO2-GS) hierarchical film electrode for flexible Li-ion battery anode via a two-step vacuum filtration method. In such a hierarchical film electrode, the down-layer composed of bare graphene component provides ideal mechanical flexibility and electronic conductivity, and the hybrid top-layer composed of both graphene and active M-TiO2 guarantees effective Li+ and electrons transport pathways and acts as the active layer for energy storage. The designed M-TiO2-GS film electrode delivers a reversible capacity of 205 and 76 mAh g−1 at rates of 0.5C and 20C, respectively, and high capacity retention of ∼70.5% after 3500 cycles at 5C. When packed in flexible cells, the M-TiO2-GS electrode can also maintain a highly reversible capacity and outstanding cycling stability in both flating and benting conditions. This work may provide a promising anode candidate for the next-generation flexible LIBs and the developed two-step filtration method can be readily applied to other flexible electrodes.
Municipal waste landfills contain numerous sources of mercury which could be emitted to the atmosphere. Their generation of methane by anaerobic bacteria suggests that landfills may act as bioreactors for methylated mercury compounds. Since our previous study at a single Florida landfill, gaseous inorganic and methylated mercury species have now been identified and quantified in landfill gas at nine additional municipal landfills in several regions of the US. Total gaseous mercury occurs at concentrations in the μgm−3 range, while methylated compounds occur at concentrations in the ngm−3 range at all but one of the landfill sites. Dimethylmercury is the predominant methylated species, at concentrations up to 100ngm−3, while monomethyl mercury was generally lower. Limited measurements near sites where waste is exposed for processing (e.g. working face, transfer areas) suggest that dimethylmercury is released during these activities as well. Although increasing amounts of landfill gas generated in the US are flared (which should thermally decompose the organic mercury to inorganic mercury), unflared landfill gas is a potentially important anthropogenic source of methylated mercury emissions to the atmosphere.
With the limited but ongoing usage of perfluorooctane sulfonate (PFOS), the health effects of both PFOS and its alternatives are far from being understood. Long-term potentiation (LTP) was evaluated in rats after exposure to PFOS and its alternatives, aiming to provide some evidence about their potential to affect cognitive ability. Different dosages of PFOS and alternative chemicals, including perfluorohexane sulfonate (PFHxS), perfluorobutane sulfonate (PFBS) and chlorinated polyfluorinated ether sulfonate (Cl-PFAES), were given to rats via acute intracerebroventricular injection. The field excitatory postsynaptic potential (fEPSP) amplitude of the input/output functions, paired-pulse facilitations, and LTP in vivo were recorded. PFOS and its alternatives inhibited LTP in varying degrees, without significant effects on the normal synaptic transmission. In addition, PFHxS and Cl-PFAES exhibited comparable potential to PFOS in disturbing LTP. The results suggested that acute exposure to PFOS and its alternatives impaired the synaptic plasticity by a postsynaptic rather than a presynaptic mechanism. Besides, the fEPSP amplitude of the baseline was reduced by Cl-PFAES but not by other compounds, indicating that Cl-PFAES might act in a different mode. Providing some electrophysiological evidence and the potential mechanism of the neurotoxicity induced by PFOS and its alternatives, the present study addresses further evaluation of their safety and health risks.
Invasive crayfish are spreading rapidly across Europe, where they are replacing the native crayfish species and impacting negatively on some other biota. Freshwater crayfish and many benthic fishes share similar habitat and food requirements and hence potentially compete for resources. In this study, we investigated impacts of the introduced signal crayfish (Pacifastacus leniusculus) on fish in stony littoral habitats of two large boreal lakes. We compared the littoral fish community composition and the densities of two common benthic fish species between sites with and without crayfish. To evaluate whether signal crayfish share the same food resources as benthic littoral fish or change their feeding habits, we used mixing models and trophic niche estimates based on analyses of stable isotopes of carbon and nitrogen. Both the community composition of littoral fish and the densities of benthic fish species were similar at sites with and without signal crayfish. Even though stable isotope signatures indicated strong dietary overlap between crayfish and benthic fish, the use of food sources and trophic niche widths of fish were not noticeably different between crayfish sites and non-crayfish sites. Our results suggest that, at current densities, the non-native signal crayfish does not have significant impacts on benthic fish in the stony littoral habitats of large boreal lakes.
A fluorinated electrolyte mixture, containing 1 M LiPF6/fluoroethylene carbonate:bis (2,2,2-trifluoroethyl) carbonate (1:1 w:w) with prop-1-ene-1,3-sultone as an electrolyte additive exhibited promising cycling and storage performance in Li(Ni0.4Mn0.4Co0.2)O2/graphite pouch type Li-ion cells tested to 4.5 V. The prop-1-ene-1,3-sultone additive was added to help control gas evolution in the fluorinated electrolyte cells, which was improved but still problematic even with the additive. Cells with the fluorinated electrolyte demonstrated higher impedance in early cycles compared to cells with carbonate solvents and state of the art additives. Symmetric cells were used to show this high impedance originated at the negative electrode/electrolyte interface. Nevertheless, in charge–discharge cycling tests to 4.5 V, cells with the fluorinated electrolyte and 1, 2 or 3% prop-1-ene-1,3-sultone additive, outperformed all non-fluorinated electrolytes with all additives tested. With further work, these, or other fluorinated carbonates, coupled with appropriate additives, may represent a viable path to NMC/graphite cells that can operate to 4.5 V and above.
Redox flow batteries (RFBs) are enjoying a renaissance due to their ability to store large amounts of electrical energy relatively cheaply and efficiently. In this review, we examine the components of RFBs with a focus on understanding the underlying physical processes. The various transport and kinetic phenomena are discussed along with the most common redox couples.
Publisher Summary Welding in the context of this chapter is the joining of two or more pieces of metal so that the parts to be joined merge with one another forming a homogeneous whole across the connection. Welding a metal requires the introduction of energy that can be as heat directly or in a form that will convert to heat where it is required. The chapter describes the principal features of the welding processes applied to the materials that are most commonly used in structural, mechanical, and process plant engineering—namely, steels and aluminum alloys. It reviews manual metal arc welding, submerged arc welding, and gas shielded welding. In manual metal arc welding, the welder holds in a clamp or holder, a length of steel wire, coated with a flux consisting of minerals, called a welding electrode or rod; the holder is connected to one pole of an electricity supply. The metal part to be welded is connected to the other pole of the supply and as the welder brings the tip of the rod close to it, an arc starts between them. Submerged arc welding uses a continuous bare wire electrode and a separate flux added over the joint separately in the form of granules or powder. The arc is completely enclosed by the flux so that a high current can be used without the risk of air entrainment or severe spatter but otherwise the flux performs the same functions as the flux in manual metal arc welding.
The self-discharge of Zn anode material is identified as a main factor that can limit the energy density of alkaline Zn–air batteries. Al2O3 has most positive effect on controlling the hydrogen evolution reaction accompanied by corroding Zn anode among various additives. The overpotential for hydrogen evolution is measured by potentio-dynamic polarization analysis. Al-oxide with high overpotential for hydrogen evolution reaction is uniformly coated on the surface of Zn powders via chemical solution process. The morphology and composition of the surface-treated and pristine Zn powders are characterized by SEM, EDS, XRD and XPS analyses. Aluminum is distributed homogeneously over the surface of modified Zn powders, indicating uniform coating of Al-oxide, and O1s and Al2p spectra further identified surface coating layer to be the Al-oxide. The Al-oxide coating layer can prevent Zn from exposing to the KOH electrolyte, resulting in minimizing the side reactions within batteries. The 0.25 wt.% aluminum oxide coated Zn anode material provides discharging time of more than 10 h, while the pristine Zn anode delivers only 7 h at 25 mA cm−2. Consequently, a surface-treated Zn electrode can reduce self-discharge which is induced by side reaction such as H2 evolution, resulting in increasing discharge capacity.