batterydata/paper-abstracts huggingface dataset:
The molecular dynamics (MD) computer simulation technique has been used to study the effect of an amorphous intergranular film (IGF) present in a polycrystalline cathode on Li transport. The solid electrolyte is a model lithium silicate glass while the cathode is a nanocrystalline vanadia with an amorphous V2O5 IGF separating the crystals. Thin (∼1 to a few nanometer thick) IGFs are known to be present in most polycrystalline oxide materials. However, the role of such a film on Li transport in oxide cathodes has not been addressed. Current scanning probe microscopy (SPM) studies have shown that the orientation of the layered nanocrystalline vanadia crystals near the cathode/solid electrolyte interface is not optimized for Li ion transport. While the precise structure of the material between the crystals has not been identified, initially it can be initially considered as likely to be a thin non-crystalline (amorphous) film. This is based on the ubiquitous presence of such a structure in other polycrystalline oxides. Also, and with more relevance to the materials used in thin film batteries, an amorphous film can be expected to form between nanocrystals that crystallized from an amorphous matrix, as would be the case in a deposited thin film cathode. Consistent with simulations of Li transport in amorphous vanadia, the current simulations show that Li ions diffuse more rapidly into the amorphous intergranular thin film than into the layered vanadia with the (001) planes parallel to the cathode/electrolyte interface.
The performance of a liquid electrolyte composed of lithium bis-fluorosulfonyl imide (LiSFI) in a 1:1 volume of ethylene carbonate and dimethyl carbonate is evaluated for use in lithium ion batteries. Imide salts offer the benefits of higher thermal stability and could provide a safer alternative to LiPF6 which is prone to the formation of HF. However, the most studied lithium imide salt, lithium bis(trifluoromethanesulfonyl) imide, is well known to have a problem with corrosion of aluminum which is commonly used as the cathode current collector. Consequently, the corrosion properties of liquid electrolytes based on lithium bis-fluorosulfonyl imide are also investigated.
Electrosynthesis of benzoquinone from phenol was investigated in acetonitrile–water mixtures on α-PbO2 and β-PbO2 electrodes. The influence of water concentration, electrolysis potential, initial phenol concentration and temperature on benzoquinone production was also studied. Different electrocatalytic activities of α and β structures of PbO2 were determined.
The biogenic iron oxide/hydroxide materials possess useful combination of physicochemical properties and are considered for application in various areas. Their production does not require special investments because these compounds are formed during cultivation of neurophilic iron bacteria. Bacteria from genus Leptothrix develop intensively in the Sphaerotilus-Leptothrix group of bacteria isolation medium and feeding media of Fedorov and Lieske. These media are different in their composition which determined the present study as an attempt to clear up the reasons that define the differences in the composition of the laboratory-obtained biomasses and the natural biomass finds. FTIRS, Mössbauer spectroscopy, and XRD were used in the research. Comparative analysis showed that the biomass and control samples contain iron compounds (α-FeOOH, γ-FeOOH, β-FeOOH, γ-Fe2O3) in different ratios. The biomass samples were enriched in oxyhydroxides of higher dispersion. Organic residuals of bacterial origin, SO4, CO3, and PO4 groups were registered in the biogenic materials.
The hierarchical carbon cloth supported Li4Ti5O12@NiCo2O4 branched nanowire (NW) arrays were fabricated as the flexible, binder-free anode for lithium-ion batteries. The novel composite exhibits greatly improved specific capacity and rate capability as well as excellent cyclic stability compared to carbon cloth supported Li4Ti5O12 NW arrays. The results clearly demonstrate that branched growth of NiCo2O4 NWs on the surface of Li4Ti5O12 NWs on carbon cloth enhances lithium diffusion. The superior electrochemical performance is ascribed to the unique architecture as well as the synergetic effect of good flexibility and high conductivity of carbon cloth, almost zero volume change during charge/discharge process of Li4Ti5O12, and high capacity and conductivity of NiCo2O4. This novel anode possesses high potential for applications in high-performance, flexible lithium-ion batteries.
The electrochemical behavior of FeCp2 +/FeCp2 (Cp−, cyclopentadienyl), FeCl4 −/FeCl4 2−, FeBr4 −/FeBr4 2− and Fe(CN)6 3−/Fe(CN)6 4− couples was studied in the hydrophobic room-temperature ionic liquids based on bis(trifluoromethylsulfonyl)imide (TFSI−) with 1-n-butyl-1-methylpyrrolidinium (BMP+) and other quaternary ammonium cations. The cyclic voltammetric data indicated that these complexes were stable in BMPTFSI and that the redox reactions between trivalent and divalent iron species of these complexes are electrochemically reversible. The diffusion coefficients of these complexes were found to be affected mainly by the size of the species. On the other hand, the redox potential of Fe(CN)6 3−/Fe(CN)6 4− couple depended on organic cations reflecting the difference in the acceptor properties of the organic cations.
Multifunctional façade components have nowadays become a significant research topic as a step towards developing energy-efficient buildings. This paper presents the performance evaluation of an experimental setup of a real fully decentralized façade-integrated photovoltaic (PV) system installed in a prototype façade, for direct DC power use. The goal of this evaluation was to test the system's ability to fulfill a pre-designed daily electrical load of 925Wh corresponding to a three-people office space under 100% decentralization. This was achieved by studying the operation under different weather conditions and the impact of the system design and components on its overall output. The evaluation of both the actual and theoretical system outputs indicates poor actual system performance in terms of low energy yield and unacceptable load fulfillment factor, which did not exceed 0.95. At the same time it revealed underutilized system potential which could be exploited theoretically with a proper system configuration. The results in this paper conclude that decentralized façade integrated PV systems can completely satisfy their designated applications if properly-designed and implemented, and provides a methodology which could be used in designing similar systems. Satisfactory fulfillment is shown to be achieved by having 30% additional PV and 9 times bigger storage capacities in this system.
Background Impairments to body systems contribute to mobility limitations. The objective of this study was to determine whether impaired gait coordination, as measured by the Phase Coordination Index (PCI), is significantly associated with mobility limitations in older adults, even after adjusting for other gait features. Methods We conducted a cross-sectional analysis of performance-based measures of mobility in older adults (N=164) 77–101years of age, participants in the population-based MOBILIZE Boston Study. Mobility outcomes included the Short Physical Performance Battery (SPPB) and each of its three components. Multivariable linear regression models, adjusting for age and gender, were used to examine the associations of PCI and the coefficients of variation of stride length, width and time, stance time, and step width with each outcome. Results PCI accounted for more variance in SPPB score (R2 =0.21), gait speed (R2 =0.17), chair rise score (R2 =0.10), and balance score (R2 =0.09) than any of the other gait measures. Impaired gait coordination was significantly associated with performance on the SPPB and each of its component tasks, even after accounting for gait measures previously linked to mobility tasks (all P<0.05). In multivariable linear regression modeling PCI accounted for an additional 9% of the variance in SPPB score (P<0.001), after accounting for the other gait variables, age, and gender. Conclusions This study shows that impaired gait coordination is associated with poorer mobility performance in older adults, independent of other gait variables previously linked to mobility tasks.
A single-metal redox flow battery employing manganese(III) acetylacetonate in tetraethylammonium tetrafluoroborate and acetonitrile has been investigated. Cyclic voltammetry was used to evaluate electrode kinetics and reaction thermodynamics. The MnII/MnIII and MnIII/MnIV redox couples appeared to be quasi-reversible. A cell potential of 1.1V was measured for the one-electron disproportionation of the neutral MnIII complex. The diffusion coefficient for manganese acetylacetonate in the supporting electrolyte solution was estimated to be in the range of 3–5×10−6 cm2 s−1 at room temperature. The charge–discharge characteristics of this system were evaluated in an H-type glass cell. Coulombic efficiencies increased with cycling suggesting an irreversible side reaction. Energy efficiencies for this unoptimized system were ∼21%, likely due to the high cell-component overpotentials.
Children with severe or profound intellectual and motor disabilities often present problems of balance and ambulation and spend much of their time sitting or lying, with negative consequences for their development and social status. Recent research has shown the possibility of using a walker (support) device and microswitches with preferred stimuli to promote ambulation with these children. This study served as a replication of the aforementioned research and involved five new children with multiple disabilities. For four children, the study involved an ABAB design. For the fifth child, only an AB sequence was used. All children succeeded in increasing their frequencies of step responses during the B (intervention) phase(s) of the study, although the overall frequencies of those responses varied largely across them. These findings support the positive evidence already available about the effectiveness of this intervention approach in motivating and promoting children's ambulation. Practical implications of the findings are discussed.
Objectives The aim of this study was to determine the extent of autonomic dysfunction in patients with clinically isolated syndrome (CIS) by using a standardized battery of autonomic tests in the form of the Composite Autonomic Scoring Scale (CASS). Methods This was a prospective, cross sectional study which included 24 consecutive patients who were diagnosed with CIS and 17 healthy controls. In all participants, heart rate and blood pressure responses to the Valsalva maneuver, heart rate response to deep breathing and blood pressure response to passive tilt were performed. In 16 patients, Quantitative Sudomotor Axon Reflex Test (QSART) and catecholamine measurement was performed. Results The proportion of CIS patients with pathological adrenergic index was statistically significantly higher compared to healthy controls (12 vs 2, p =0.018), while there was no difference in cardiovagal index between groups. Five patients had a sudomotor index of 1 (in 4 there was hypohydrosis <50% and in 1 persistent foot hyperhidrosis). When combining adrenergic, cardiovagal and sudomotor index into CASS, 8 patients (50%) had evidence of autonomic dysfunction, 7 mild and one moderate. Conclusion Sympathetic nervous system is frequently affected in CIS patients. Significance CASS is able to detect autonomic nervous system dysfunction in CIS patients.
Recent progress is reported in preparing membrane/electrode assemblies for polymer electrolyte fuel cells based on radiation-grafted FEP-g-poly(styrenesulfonic acid) membranes. MEAs with an improved interface between the membrane and commercially available gas diffusion electrodes were obtained by Nafion®-coating of the membrane and hot-pressing. These improved MEAs showed both, performance data comparable to those of MEAs based on Nafion® 112 and an operation lifetime in H2/O2 fuel cells of more than 2000 h at 60°C and 500 mA cm−2 current density.
Rechargeable energy storage systems with high energy density and round-trip efficiency are urgently needed to capture and deliver renewable energy for applications such as electric transportation. Lithium–air/lithium–oxygen (Li–O2) batteries have received extraordinary research attention recently owing to their potential to provide positive electrode gravimetric energies considerably higher (∼3 to 5×) than Li-ion positive electrodes, although the packaged device energy density advantage will be lower (∼2×). In light of the major technological challenges of Li–O2 batteries, we discuss current understanding developed in non-carbonate electrolytes of Li–O2 redox chemistry upon discharge and charge, oxygen reduction reaction product characteristics upon discharge, and the chemical instability of electrolytes and carbon commonly used in the oxygen electrode. We show that the kinetics of oxygen reduction reaction are influenced by catalysts at small discharge capacities (Li2O2 thickness less than ∼1 nm), but not at large Li2O2 thicknesses, yielding insights into the governing processes during discharge. In addition, we discuss the characteristics of discharge products (mainly Li2O2) including morphological, electronic and surface features and parasitic reactivity with carbon. On charge, we examine the reaction mechanism of the oxygen evolution reaction from Li2O2 and the influence of catalysts on bulk Li2O2 decomposition. These analyses provide insights into major discrepancies regarding Li–O2 charge kinetics and the role of catalyst. In light of these findings, we highlight open questions and challenges in the Li–O2 field relevant to developing practical, reversible batteries that achieve the anticipated energy density advantage with a long cycle life.
We have investigated a set of sodium cobaltates (NaxCoO2) samples with various sodium content (0.67 ≤ x ≤ 0.75) using Nuclear Quadrupole Resonance (NQR). The four different stable phases and an intermediate one have been recognized. The NQR spectra of 59Co allowed us to clearly differentiate the pure phase samples which could be easily distinguished from multi-phase samples. Moreover, we have found that keeping samples at room temperature in contact with humid air leads to destruction of the phase purity and loss of sodium content. The high sodium content sample evolves progressively into a mixture of the detected stable phases until it reaches the x = 2/3 composition which appears to be the most stable phase in this part of phase diagram.
Publisher Summary This chapter provides an introduction to fuel cells and discusses their modeling with a focus on polymer electrolyte membrane (PEM). Fuel cell modeling is relevant in addressing global power needs. It consists of a negatively charged electrode (anode), a positively charged electrode (cathode), and an electrolyte membrane. Hydrogen is oxidized on the anode and oxygen is reduced on the cathode. Protons are transported from the anode to the cathode through the electrolyte membrane, and the electrons are carried to the cathode over the external circuit. The interest in fuel cells has increased due to the fact that the use of fossil fuels for power has resulted in many negative consequences. Fuel cells are now closer to commercialization than ever, and they have the ability to fulfill all global power needs while meeting the efficacy and environmental expectations. PEM fuel cells are the most popular type of fuel cells that use hydrogen as the fuel. They also have many other fuel options, which range from ethanol to biomass-derived materials. These fuels can either be directly fed into the fuel cell, or sent to a reformer to extract pure hydrogen, which is then directly fed to the fuel cell.
The article presents a comparative analysis of the structural characteristics of absorptive glass mats manufactured by “Hollingsworth & Vose” (a 2.8 mm thickness) and “Bernard Dumas” (a 3.0 mm thickness) modified by impregnation with polymeric emulsions based on polyvinylidene fluoride, a polyvinylpyrrolidone styrene copolymer, and polytetrafluoroethylene, by means of standard contact porosimetry. The key study is influence of features of the porous structure on the compression properties, the rate of wicking, and the oxygen cycle efficiency in lead-acid battery mock-ups under several plate-group compression pressures. It is found that the treatment of the absorptive glass mat separators with polymeric emulsions leads to redistribution of their pores by size. An increased pressure in the electrode unit insignificantly changes the pore structure of the modified absorptive glass mat separators, and the oxygen cycle efficiency rises in comparison with unmodified separators.
Soluble nutrient flux is increasingly implicated in the degradation of receiving water quality. With high-frequency sensors, river discharge along with nitrate and orthophosphate concentrations were collected over 2 years. We examined how storms (16 events) affected the dissolved nutrient flux in two watersheds with contrasting landcover—urban and agricultural. The adjacent watersheds, both < 7 km2, had very similar soil, slope, relief, and physiography. Wastewater is conveyed outside of the watersheds minimizing this nutrient source. Cumulative nitrate and orthophosphate fluxes in the agricultural watershed were substantially higher than the urban watershed. In both watersheds, a disproportionate amount of discharge, higher orthophosphate concentrations and flux occurred during the highest flow events—approximately 50–70% of flux occurring in the highest 5% of daily discharge. The nitrate flux was dampened compared to discharge during storm events. Baseflow accounted for 66% of the nitrate flux and had higher or comparable concentrations than storm events. The pattern of flux and concentration within storm events also differed for the two solutes. Nitrate exhibited positive hysteresis (higher concentrations on the rising limb of the hydrograph) and magnification of flux during the first flush of storm runoff. In contrast, orthophosphate concentrations were lower on the rising limb and flux during the first flush of storm runoff was dampened. In addition to targeting source reductions, orthophosphate flux may require runoff reducing strategies (i.e., enhanced infiltration) from large runoff events. First flush stormwater management practices combined with enhancement/protection of groundwater nitrate sinks (e.g., riparian wetlands) may help reduce nitrate fluxes.
The effect of doping foreign metal ions into the LiMn2O4 spinel structure on the oxygen deficiency by high-temperature firing has been investigated. The degree of the oxygen deficiency in the Mg- and/or Al-doped spinel is very small even when fired at 1000°C, and then the oxygen deficiency nearly disappeared after low temperature annealing. Mg-doped Mn-spinels (Li1.05Mn1.94−x Mg x Ca0.01O4−z , 0≤ x ≤0.15) obtained at 1000°C contained a small oxygen deficiency amount when the x-value reached 0.03 or more. The annealing at 800°C then reduced the oxygen defect content in the Mg-doped spinels. The crystallinity of the spinels is improved by doping with a small amount of Ti. The storage performance of the coin-type cell at 60°C is improved about 1.6 times using both Mg- and Ti-doping, which would be due to the oxygen stoichiometric spinels with a low solubility by firing at high temperatures and/or by Ti-doping to increase the crystallinity.
The present analysis adds up to the discussion carried around the flexibilisation of the electricity networks, as means of higher diffusion of renewable energy sources (RES). Inspiring from innovation studies the paper proposes an economic rationale for considering RES technology manufacturers as investors in electricity networks. Moreover, the present analysis scrutinize the extent to which the various economic operators within specific segments of the power supply chain invest in a portfolio of research and development activities, among which the electricity grids and storage technologies. The intensity of these research investments was mapped across the European countries for the year of 2011. Their geographic distribution confirms the rationale of an analysis based on canonical correlation testing the associations between RES market diffusion and power network indicators. The analysis provides useful insights for specific technology, such as the one revealing PV market sensitivity to research investments in storage technologies, confirming a potential business model coupling the two technologies. Accommodating this pattern and enabling further diversification of research portfolios, the public incentives could be redesigned in order to address the flexibilisation of power networks.
Separation of the total Li/LiTFSI+MPPipTFSI/Li cell impedance into single contributions was performed with the use of electrochemical impedance spectroscopy (EIS). The structure of the electrode was observed by scanning electron microscopy (SEM). The charge transfer process occurs at a solid|solid Li+(SEI)→Li(metal) interphase (SEI is the solid electrolyte interphase). SEM images show that the structure of the electrode surface (and of the interphase) is grain-like. The kinetics of Li+ reduction in ionic liquids is interesting as the Li+ desolvation step (which takes place in classical solutions) does not take place which leads to a simpler process. Deconvolution of the EIS spectra indicates three resistances and corresponding three ln R = f(T −1) straight lines of different slopes, associated with the resistance of liquid electrolyte, SEI and the charge transfer process, respectively. Activation energy for the Li+ conduction process in the liquid electrolyte and solid SEI is 23 and 32kJmol−1, respectively. Activation energy for the charge transfer process Li+(SEI)→Li is 62kJmol−1 and the corresponding exchange current density at T =298K is 1.92×10−5 Acm−2. As the process occurs at the SEI|Li interphase, the concentration independent rate constant cannot be calculated.
In 2008, a group of clinicians, scientists, engineers, and industry representatives met to discuss advances in the application of engineering technologies to the diagnosis and treatment of patients with epilepsy. The presentations also provided a guide for further technological development, specifically in the evaluation of patients for epilepsy surgery, seizure onset detection and seizure prediction, intracranial treatment systems, and extracranial treatment systems. This article summarizes the discussions and demonstrates that cross-disciplinary interactions can catalyze collaborations between physicians and engineers to address and solve many of the pressing unmet needs in epilepsy.
The present study aims at developing a silicon/soft-carbon nanohybrid material for high performance lithium-ion battery (LIB). It is composed of micronized silicon coated with so-called “soft-carbon” dispersed in soft-carbon matrix at nanometer level. This material is characterized with abundant nanosized voids with diameter of ca. 70 nm and hard bulk skeletal structure. It exhibited a long cycle life of 163 charging and discharging cycles with a large capacity of 850 mAh/g and retention rate up to 90% of the initial capacity in a half cell with Li-metal counter electrode. For this new material, the volume expansion ratio was 6.9% at a capacity level of 1100 mAh/g. This electrode capacity is approximately three times larger than that of graphite-based electrode currently used in LIB. Furthermore, this electrode retained 80.9% of its capacity at 250 cycles in a full cell with a LiCoO2 counter electrode. Addition of 5 wt % fluoroethylene carbonate (FEC) to the electrolyte improved the retention up to 81.3% after 300 cycles. These results demonstrate the usefulness and high possibility of this material as the negative electrode of LIB.