batterydata/paper-abstracts huggingface dataset:
The development of high-performance and new-structure electrode materials is vital for the wide application of rechargeable lithium batteries in electric vehicles. In this work, we design a special composite electrode structure with the macroporous three-dimensional graphene areogel framework supporting mesoporous LiFePO4 nanoplate. It is realized using a simple sol-gel deposition method. The highly conductivity graphene nanosheets assemble into an interconnected three-dimensional macroporous areogel framework, while LiFePO4 grows along the graphene nanosheets and generates a mesoporous nanoplate structure. In comparison with LiFePO4, this unique sandwich nanostructure offers a greatly increased electronic conductivity thanks to the framework of graphene nanosheets. Also, the bimodal porous structure of the composite remarkably increases the interface between the electrode/electrolyte and facilitates the transport of Li+ throughout the electrode, enabling the superior specific capacity, rate characteristic and cyclic retention.
A facile twice-hydrothermal method is developed for large-scale growth of NiCo2S4 nanotube array on Ni foam with robust adhesion. As-prepared materials are characterized by SEM, XRD and EDS. It can be observed that NiCo2S4 nanotubes directly grow on Ni foam with an average inner-diameter of ∼55nm, external-diameter of 100nm, and length of ∼2μm. When evaluated as a binder-free anode for LIBs, NiCo2S4 nanotube array exhibits outstanding lithium-storage performance that includes high special capacity, excellent cyclic stability and desirable rate capability. At 0.2C rate, NiCo2S4 nanotube array delivers the average discharge capacity of 720mAhg−1 during 50 cycles that slightly surpasses its theoretical capacity of 703mAhg−1. When the current comes back to 0.2C after rate measurements, NiCo2S4 nanotubes can still stably deliver the discharging capacity of 652mAhg−1, reaching 92.7% of that at the initial 0.2C. Cyclic Voltammetry (CV) measurements reveal that NiCo2S4 nanotube array contains two sets of electrochemical reaction behavior come from Ni and Co. The unique NiCo2S4 nanotube array exhibits great potential as an anode material for high-performance Lithium-ion batteries.
Highly crystalline nano-sized lithium manganese oxide particles were fabricated by spray pyrolysis. The resultant particles had well-developed facet planes in a transmission electron microscopy (TEM) image and electron diffraction pattern from a single particle also showed clear diffraction spots, indicating that the prepared particles were highly crystalline. The mean crystallite size estimated from X-ray diffraction peaks was ca. 18nm, which was in good agreement with the diameter of the particles observed in the TEM image. These particles were gathered on platinum mesh and their electrochemical properties were investigated. The mean crystallite size increased with an increase in annealing temperature, which influenced the electrochemical lithium insertion/extraction properties of the particles. In particular, samples annealed at 773K showed different kinds of lithium extraction/insertion properties in the cyclic voltammogram (CV), and only a couple of broad redox peaks were observed at around 0.8V (versus Ag/AgCl) between 0.4 and 1.0V. It is suggested that lithium distribute randomly in the sample annealed at 773K sample due to the effects of grain boundaries, which resulted in different kinds of phase transition reactions.
Non-aqueous lithium-oxygen battery is considered as the next-generation battery because it has the highest theoretic energy density among all rechargeable batteries. But its discharge product Li2O2 is difficult to be oxidized back in the charge process, which causes high charge overpotential, serious electrolyte decomposition and poor cyclability. An effective way to solve this problem is adding redox mediator (RM) in the electrolyte to catalyze the charge reaction via redox shuttle process. However, the reaction kinetics between the oxidized RM and Li2O2 is seldom reported. Here, taking iodine species as the model RM, we find that the efficiency of the solution phase catalysis is limited by the reaction rate between the oxidized RM and Li2O2, which is largely dependent on the electrolyte solvent. Protic solvents, such as water and alcohols lead to high reaction rate because of the hydrogen bond-assisted solvation of Li2O2. However, too high proton activity may also bring unwanted peroxide disproportionation. Among a series of alcohols, n-butanol is found to show proper proton activity and significantly promote the efficiency of the redox shuttle process. To prove the electrochemical mechanisms, this paper also introduces a Li2O2-graphite cell to evaluate the reversibility of cathodic reaction. Comparing with conventional cycling tests with excess lithium metal anode, the Li2O2-graphite configuration can eliminate the “fake reversible capacity” caused by parasitic cathodic reactions, and thus is more reliable.
This paper presents a personal view of the status and research needs of the MCFC and other molten-salt fuel cells. After an overview of current MCFC performance, compared with performance and cost of other fuel cells, improvements in power density and lifetime as well as cost reduction are identified as key priorities to accelerate the commercialization of the MCFC. In spite of its unfavorable public image (compared to, in particular, PEMFC and planar SOFC) MCFC technology has progressed steadily and cost reduction has been significant. Large-scale commercialization, especially in the distributed generation and cogeneration market, remains a possibility but its chances are highly dependent on a forceful and consistent energy policy, for example taking into account the externalities associated with various modes of electric power production from fossil fuels. In spite of steady improvements in performance, important defects in fundamental knowledge remain about wetting properties, oxygen reduction kinetics, corrosion paths and control mechanisms. These must be addressed to stimulate further simplification of design and find solutions to lifetime issues. Recently, alternative concepts of molten-salt fuel cells have been capturing attention. The direct carbon fuel cell (DCFC), reviving an old concept, has caught the attention of energy system analysts and some important advances have been made in this technology. Direct CO and CH4 oxidation have also been a focus of study. Finally, the potential of nanotechnology for high-temperature fuel cells should not be a priori excluded.
LiFePO4 nanopowders (50 nm) were prepared through a simple hydrothermal process. Poly vinylidene fluoride (PVDF): LiFePO4 complex membranes as solid polymer electrolytes were characterized. X-ray diffraction (XRD) and differential scanning calorimetric (DSC) studies show a decrease in crystalline size and crystallinity of the polymer PVDF with increasing LiFePO4 concentration. Scanning electron micrographs show smaller spherical domains in the dry film with increased LiFePO4 nanopowder content. Impedance measurements suggest that the ionic conductivity of (PVDF + LiFePO4) increases with increased temperature and lithium powder concentration.
Research on nanostructured fuel cell electrodes has recently been growing significantly. Although improvements on the charge capacity and lifetime of nanostructured electrodes have been frequently reported, an analytical evaluation of the energy loss of nanostructured fuel cells is still lacking. In this communication, an electrochemical cell is designed and analyzed to measure the gas diffusivities through electrodes. With the measured gas diffusivities, the correlation between the concentration polarization energy loss and the important parameters associated with nanoscale electrodes in gas–fuel based fuel cells, such as temperature, and the porosity of the electrodes, can be efficiently analyzed.
Summary The aim of the study was to compare anthropometric and physical performance data of players who were selected for a Victorian elite junior U18 Australian rules football squad. Prior to the selection of the final training squad, 54 players were assessed using a battery of standard anthropometric and physical performance tests. Multivariate analysis (MANOVA) showed significant (p <0.05) differences between selected and non-selected players when height, mass, 20-m sprint, agility and vertical jump height were considered collectively. Univariate analysis revealed that the vertical jump was the only significant (p <0.05) individual test and a near significant trend (p =0.07) for height differentiating between selected and non-selected players with medium effect sizes for all other tests except endurance. In this elite junior football squad, physical characteristics can be observed that discriminate between players selected and non-selected, and demonstrates the value of physical fitness testing within the talent identification process of junior (16–18 years) players for squad and/or team selection. Based on MANOVA results, the findings from this study suggest team selection appeared to be related to a generally higher performance across the range of tests. Further, age was not a confounding variable as players selected tended to be younger than those non-selected. These findings reflect the general consensus that, in state-based junior competition, there is evidence of promoting overall player development, selecting those who are generally able to fulfil a range of positions and selecting players on their potential.
The self-discharge mechanism of LiNi1/3Co1/3Mn1/3O2 cathode for lithium ion battery at high potential (4.5 V) has been understood through physical and electrochemical characterizations including charge/discharge test, electrochemical impedance spectroscopy (EIS), inductively coupled plasma atomic emission spectrometer (ICP-AES), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). It is found that the charged LiNi1/3Co1/3Mn1/3O2 cathode to 4.5 V suffers seriously self-discharge. After storage for 8 days, the potential of the cathode charged to 4.2 V remains stable, while that of the charged cathode to 4.5 V decreases from 4.5 to 1.0 V, The characterizations, from SEM, TEM, ICP-AES, and XRD, demonstrate that this self-discharge results from the interaction between charged LiNi1/3Co1/3Mn1/3O2 and electrolyte, which causes the dissolution of transition metals from LiNi1/3Co1/3Mn1/3O2 and the successive decomposition of the electrolyte.
A cytochrome P450 (CYP) enzyme, 3’-daidzein hydroxylase, CYP105D7 (3’-DH), responsible for daidzein hydroxylation at the 3’-position, was recently reported. CYP105D7 (3’-DH) is a class I type of CYP that requires electrons provided through electron transfer proteins such as ferredoxin and ferredoxin reductase. Presently, we constructed an artificial CYP in order to develop a reaction host for the production of a hydroxylated product. Fusion-mediated construction with the reductase domain from self-sufficient CYP102D1 was done to increase electron transfer efficiency and coupling with the oxidative process. An artificial self-sufficient daidzein hydroxylase (3’-ASDH) displayed distinct spectral properties of both flavoprotein and CYP. The fusion enzyme catalyzed hydroxylation of daidzein more efficiently, with a kcat/Km value of 16.8 μM-1 min-1, which was about 24-fold higher than that of the 3’-DH-camA/B reconstituted enzyme. Finally, a recombinant Streptomyces avermitilis host for the expression of 3’-ASDH and production of the hydroxylated product was developed. The conversion that was attained (34.6%) was 5.2-fold higher than that of the wild-type.
The aim of this work is to present an optimization methodology for the installation capacity of a stand-alone hybrid generation system, taking into consideration the cost and reliability. Firstly, on the basis of derived steady state models of a wind generator (WG), a photovoltaic array (PV), a battery and an inverter, the hybrid generation system is modeled for the purpose of capacity optimization. Secondly, the power system is analyzed for determining both the system structure and the operation control strategy. Thirdly, according to hourly weather database of wind speed, temperature and solar irradiation, annual power generation capacity is estimated for the system match design in order that an annual power load demand can be met. The capacity determination of a hybrid generation system becomes complicated as a result of the uncertainty in the renewable energy together with load demand and the nonlinearity of system components. Aimed at the power system reliability and the cost minimization, the capacity of a hybrid generation system is optimized by application of an adaptive genetic algorithm (AGA) to individual power generation units. A total cost investigation is made under various conditions, such as wind generator power curves, battery discharge depth and the loss of load probability (LOLP). At the end of this work, the capacity of a hybrid generation system is optimized at two installation sites, namely the offshore Orchid Island and Wuchi in Taiwan. The optimization scheme is validated to optimize power capacities of a photovoltaic array, a battery and a wind turbine generator with a relative computational simplicity.
In this paper, in-situ nanomechanical measurement and ex-situ morphology study were conducted to investigate the surface roughness effects of current collectors on the performance of thin film silicon anodes. The in-situ analysis quantifies electrochemical processes and associated mechanical stress such as silicon-lithium alloy formation during charge and discharge. Upon lithiation, after SEI formation (approximately below 0.35 V), both α-Si films deposited on the pristine and FeCl3-etched copper experience elastic deformation with a rapid rise of a compressive stress. The films begin to deform plastically after the stress reaches compressive yield strength. Upon delithiation, the α-Si on the pristine copper has shown to have stress dissipation at a tensile stress of 0.28 GPa. However, the tensile stress of the α-Si on the FeCl3-etched copper continues until the stress reaches 0.4 GPa at the end of delithiation. In addition, the silicon anode was found to form small islands on roughened current collector (instead of peel-off from flat current collector), indicating the design of the current collector may play an important role in the performance of lithium ion battery.
Ratios used in financial analysis suffer from several drawbacks, and the tools – ranging from linear least-squares regressions to neural networks – suggested as alternatives also have serious disadvantages. We propose an alternative approach, based on quantile regression techniques, which exploits financial information in a more efficient way, not achievable by conventional tools. Our proposal is applied to the ROA (return on assets) ratio, this being one of the most popular ratios among both economic analysts and researchers. An empirical analysis is carried out on real data. Results indicate that the quantile approach provides a more accurate assessment of the financial position of the firm.
In those with symptoms indicative of obstructive sleep apnea (OSA), respiratory-specific health-related quality of life (HRQL) may be an important patient-centered outcome. The aim of this study was to assess the associations between sleepiness, fatigue, and impaired general and respiratory-specific HRQL among persons with suspected OSA.
ABSTRACT V2O5/mesoporous carbon composite has been prepared by an ultrasonically assisted method followed by a sintering process. The as-prepared V2O5/mesoporous carbon material containing 90wt% V2O5 shows better electrochemical performance, with capacity of 163mAhg−1 after 100 cycles at the current density of 500mAg−1, as well as better charge/discharge rate capability for lithium storage than V2O5 nanoparticles. The improved electrochemical performance indicates that the V2O5/mesoporous carbon composite could be used as a promising cathode material for lithium ion batteries.
A novel NiCo2O4/N-doped carbon nanowebs serving as a bifunctional electrocatalyst, consisting of hollow NiCo2O4 nanospheres and N-doped carbon nanowebs are prepared through a liquid-phase synthesis method accompanied by subsequent heat treatment. The N-doped carbon nanowebs mainly contribute to the high activity for oxygen reduction reaction, whereas the NiCo2O4 nanospheres act as an active phase for oxygen evolution reaction. The electrocatalytic performance is promoted by the synergistic effect between NiCo2O4 and N-doped carbon nanowebs. Benefiting from the hollow and N-doped structure with merits of more activity sites, fast charge and mass transport, the NiCo2O4/N-doped carbon nanowebs exhibit an excellent bifunctional catalytic activity, high selectivity of the apparent 4e− pathway, small ΔE values and long-term durability. Rechargeable Zn-air batteries using NiCo2O4/N-doped carbon nanowebs as catalyst display a lower overpotential, a high capacity (826.9 mAh g−1), a high energy density (954.2 Wh Kg−1) and long-term stability (600 cycles at 5 mA cm−2), when compared to commercial Pt/C + Ir/C. Furthermore, the NiCo2O4/N-doped carbon nanowebs is directly used as air catalyst in flexible Zn-air batteries, which also exhibit superior flexibility and cycling stability. This work provide a new method for developing highly efficiency electrocatalyst, rechargeable and flexible Zn-air batteries.
An electrical generator has been integrated with a locally produced, biomass-fed clay cooking stove in rural Malawi. The generator produces small amounts of electricity based on the thermoelectric effect. Five demonstrator stoves were deployed into a rural community in the Balaka district for up to 6months. This study investigates the power generation performance of the devices over the first 80days of the field trial. It was determined that the users were able to charge mobile phones, lights and radios from the generator stoves. The power generating performance of the stoves deteriorated slightly over the 80day period. The was due to the effects of thermal cycling on the generator system as a whole which caused eventual drying out of the thermal paste and a loosening of the clamping nuts which reduces clamping pressure and power output. One stove failed due to a mechanical problem. It was found that the power produced significantly exceeded the power consumed in most cases, which indicates an over-supply. It appears that 3Wh is sufficient to meet the average daily electrical power requirements for the participants in this study. The data obtained from the field trial has been used to inform a redesign of the device for a second field trial.
One dimensional MnO2/titanium nitride nanotube coaxial arrays have been designed for a high performance electrochemical capacitive energy storage system based on the concept of fabricating an efficient, fast charge separation network. This nanostructured composite material was prepared by electrodepositing mesoporous MnO2 into TiN nanotube arrays (TiN NTA), which are prepared by anodization of a Ti foil substrate and subsequent nitridation using ammonia annealing. The electrodeposited mesoporous MnO2 inside the electrically conductive framework of a TiN nanotube has been found to show high specific capacitance (681.0 F g−1 at 2 A g−1), excellent rate capability (55% capacitance retention from 2 to 2000 mV s−1), and a long cycle life (3% capacitance loss after 1000 cycles). These results demonstrate that this coaxial composite nanostructure is very promising for high performance supercapacitors.
Recently, the organic/inorganic hybrid materials with flexibility, thermal, and chemical stabilities are extensively studied for the application of temperature tolerant polymer electrolyte fuel cells. This paper reports the preparation and properties of sol–gel derived proton conducting organic/inorganic materials based on zirconia bridged hydrocarbon phosphotungstic acids. The materials are molecular hybrids where linear hydrocarbons such as trimethylene glycols (TMGs) or octamethylene glycols (OMGs) are covalently bonded to zirconia interface to form macromolecular organic/inorganic networks. The hybrid materials become proton conducting polymer electrolytes by the addition of 12-phosphotungstic acids. The hybrid materials showed high thermal stability, and high protonic conductivity of 4×10−3 Scm−1 under saturated humidity condition at 150°C. The materials can be expected to be used for the application of temperature tolerant polymer electrolyte fuel cell.
We employed 2D/3D X-ray computed tomography in conjunction with microzone analysis to study the failure mechanisms of lithium-ion battery packs at low temperatures. A nondestructive X-ray computed tomography strategy confers the direct and comprehensive observation of the hard-swelling of lithium-ion battery packs at low temperatures. X-ray computed tomographic images indicate that severe wrinkles occur in the electrode components, thus shedding light on the evolution of the failure process, which provides a valid secondary analysis of the failure mechanisms without damaging the battery pack. Combined with the results of the microzone analysis, swelling failure can be attributed to the generation of Li dendrites, volume expansion and delamination of the active materials. These processes can be caused by the slow electrochemical kinetics of the active materials at low temperatures.
In this work, dimethylacetamide (DMAc) was investigated as an electrolyte film-forming additive to improve the cyclic stability of high voltage Lithium-rich layered nickel manganese cobalt oxide (LLO) cathode at room (25°C) and elevated (55°C) temperature. At 0.5C rate, addition of 1% DMAc slightly decreases the initial discharge capacity of LLO from 187 to 179mAhg−1 at room temperature and 255 to 246mAhg−1 at elevated temperature, while significantly improves the capacity retention of LLO from 65.8% to 80.2% after 200 cycles at room temperature and from 21.1% to 66.7% after 150 cycles at elevated temperature. The mechanism of DMAc improving the cyclic stability of LLO was investigated via theoretical calculation and experimental characterizations, which demonstrated that DMAc oxidized preferential to the STD (1.0M LiPF6 in a mixed solvent of ethylene carbonate/ethyl methyl carbonate/diethyl carbonate) electrolyte, generating a thin and uniform film on the LLO surface. This film effectively suppresses the subsequent decomposition of STD electrolyte and further degradation of spinel phase converted from the layered structure of LLO, resulting in improved cyclic stability of LLO at room and elevated temperature.
Highly ordered mesoporous β-MnO2 (HMM) was prepared using KIT-6 templates, and mesoporous β-MnO2/S (HMM/S) composites with four sulfur content were synthesized by thermally treating a mixture of sublimed sulfur and HMM for use as cathode in Li–S batteries. The results of thermal gravimetric analysis, Brunauer–Emmett–Teller measurements, X-ray diffraction, environmental scanning electron microscopy and transmission electron microscopy for samples of HMM and HMM/S material indicate that HMM has a highly ordered pore structure and highly crystalline walls, facilitating electrolyte flooding of these pores within the cathode. The mesopores of HMM contain the majority of the sulfur mass, and effectively suppress the diffusion of polysulfide species into the electrolyte. The thin (nm scale) walls of HMM ensure short diffusion distances for Li+ on intercalation in charge/discharge cycles. Electrochemical experiments show that HMM/S composites with low sulfur content exhibit high discharge capacities and good cycling stability.