batterydata/paper-abstracts huggingface dataset:
We report (electro-)chemically stable, high temperature resistant and fast wetting Li-ion battery separators produced through a phase inversion process using novel polyetherimides (PEI) based on bisphenol-aceton diphthalic anhydride (BPADA) and para-phenylenediamine (pPD). In contrast to previous studies using PEI based on BPADA and meta-phenylenediamine (mPD), the separators reported herein show limited swelling in electrolytes and do not require fillers to render sufficient mechanical strength and ionic conductivity. In this work, the produced 15–25 μm thick PEI-pPD separators show excellent electrolyte compatibility, proven by low degrees of swelling in electrolyte solvents, low contact angles, fast electrolyte wicking and high electrolyte uptake. The separators cover a tunable range of morphologies and properties, leading to a wide range of ionic conductivities as studied by Electrochemical Impedance Spectroscopy (EIS). Dynamic Mechanical Analysis (DMA) demonstrated dimensional stability up to 220 °C. Finally, single layer graphite/lithium nickel manganese cobalt oxide (NMC) pouch cells were assembled using this novel PEI-pPD separator, showing an excellent capacity retention of 89.3% after 1000 1C/2C cycles, with a mean Coulombic efficiency of 99.77% and limited resistance build-up. We conclude that PEI-pPD is a promising new material candidate for high performance separators.
The development of new materials is required to improve the energy density of Li-ion batteries. A new graphite type with optimised physical–chemical characteristics has been studied and developed to improve negative electrode performance. Lithium ion charge and discharge acceptance have been improved by the enhanced intrinsic properties of the material. The new material has higher efficiency electrode porosity/tortuosity, and increases electrical conductivity. This allows better charge performance at low temperatures and discharge performance at high rates. Combined with an optimised electrolyte composition, it also gives low and reproducible fading, good discharge performance in very low temperature conditions, and long term storage at high temperatures. Due to this and other design modifications that will be discussed, a 22% improvement in energy density is obtained in the new generation of Saft Li-ion medium prismatic cells (MP).
TiO2 mesoporous single crystals (MSCs) with diverse constructions in a controllable fashion are successfully fabricated by a new template-free method for the first time, using oxalic acid (OA) as the pore-forming agent and morphological controller. Unlike the seeding-template based growth mechanism, the TiO2 MSCs in the present work may involve a process of oriented aggregation and crystallographic fusion of primary nanocrystals. The structural control of TiO2 MSCs can be easily realized by tailoring growth conditions, such as Ti-source concentration and OA dosages. Moreover, the TiO2 MSCs shows substantial improvement in lithium specific capacity from 0.2C to 10C in comparison to the reference TiO2 nanoparticle. The high-rate performance was further improved by fabricating MSCs/graphene oxide nanocomposites, and specific capacity of the composite at the rate of 20C is as high as 90mAhg−1. This new template-free strategy may open up new and exciting opportunities for the preparation of other MSCs, and makes important applicatory significance for the structure design of high-rate lithium ion battery anodes.
Carbon–carbon (C–C) composite has been investigated as an anode for lithium-ion battery systems. The composite electrode delivers high reversible capacity and very low irreversible capacity loss. The test results of lithium-ion cells made with the C–C composite anode show many advantages, such as excellent performance and enhanced safety. The performance improvement is achieved because of strong mechanical integrity (cycle life) and absence of binder (shelf life) in C–C composite. The enhancement in safety comes from high thermal conductivity, fire retardant characteristics and an acceptable ability to overcharge and overdischarge.
This paper outlines new work in cross-cultural psychology largely drawn from Nisbett, Choi, and Smith (Cognition, 65, 15–32, 1997); Nisbett, Peng, Choi, & Norenzayan, Psychological Review, 108(2), 291–310, 2001; Nisbett, The Geography of Thought: How Asians and Westerners Think Differently...and Why. New York: Free Press 2003), Ji, Zhang and Nisbett (Journal of Personality and Social Psychology, 87(1), 57–65, 2004), Norenzayan (2000) and Peng (Naive Dialecticism and its Effects on Reasoning and Judgement about Contradiction. University of Michigan, Ann Arbor, Michigan 1997) Peng and Nisbett (Cross-Cultural Similarities and Differences in the Understanding of Physical Causality. Paper presented at the Science and Culture: Proceedings of the Seventh Interdisciplinary Conference on Science and Culture, Frankfort, K. Y. 1996), and Peng, Ames, & Knowles (Culture and Human Inference: Perspectives from three traditions. In: D. Matsumoto (Ed.), Handbook of Cross-Cultural Psychology (pp. 1–2). Oxford: Oxford University Press 2000). The paper argues that the findings on cultural influences on inference-making have implications for teaching and education generally, and specifically for the debate on conceptions and misconceptions of Asian students studying in western tertiary institutions around the world. The position defended is that, while there seems to be compelling empirical evidence for intercultural differences in thought patterns, these patterns are, for the most part, insignificant in everyday exchanges, though language and culture might subtlety modulate our inference-making at the margins. Linguistic determinism however is not defended. Nonetheless, the evidence provides food for thought, and it needs to inform the recent debates about international students studying overseas.
Managed artificial recharge (MAR) is a well-established practice for augmentation of depleted groundwater resources or for environmental benefit. At the St-André MAR site in the Belgian dune area, groundwater resources are optimised through re-use of highly treated wastewater by means of infiltration ponds. The very high quality of the infiltration water sets this system apart from other MAR systems. The low total dissolved solid (TDS) content in the infiltration water (less than 50 mg/L) compared to the dune aquifer (500 mg/L) triggers a number of reactions, increasing the TDS through soil-aquifer passage. Multi-component reactive transport modelling was applied to analyse the geochemical processes that occur. Carbonate dissolution is the main process increasing the TDS of the infiltration water. Oxic aquifer conditions prevail between the infiltration ponds and the extraction wells. This is driven by the high flow velocities, leaving no time to consume O2 between the ponds and extraction wells. Cation exchange is important when infiltration water is replaced by native dune water or when significant changes in infiltration-water quality occur. The seasonal variation of O2 and temperature in the infiltration water are the main drivers for seasonal changes in the concentration of all major ions.
Cerebrovascular disease is often associated with cognitive impairment. Owing to evolving definitional criteria, however, it has proved difficult to determine the frequency of vascular cognitive disorders in the general population. In this review, Ola Selnes and Harry Vinters review the current state of knowledge in the field of vascular cognitive impairment, emphasizing the neuropathologic and neurocognitive aspects.
A benzoquinone polymer is synthesized by the polymerisation of hydrobenzoquinone and formaldehyde, followed by oxidation process using a hydrogen peroxide to convert hydroquinone to quinone. As prepared materials are characterized with FTIR, 1H-13C CPMAS NMR, pyrolysis coupled with gas chromatography (GC) and mass spectrometer (MS), TGA-MS analysis, EDX, elemental analysis, XRD, SEM and TEM microscopies and BET nitrogen adsorption. The benzoquinone polymer shows an excellent electrochemical performance when used as a positive electrode material in Li-ion secondary batteries. Using an electrolyte consisting 1 M bis(trifluoromethane)-sulfonimide lithium salt dissolved in 1,3-dioxolane and dimethoxyethane in a vol. ratio 1:1 (1 M LiTFSI/DOL + DME = 1:1) a stable capacity close to 150 mAh/g can be obtained. Compared to other electroactive materials based on benzoquinones it has a supreme capacity stability and is prepared by a simple synthesis using easily accessible starting materials. Further improvements in the capacity value (up to the theoretical value of 406 mAh/g) can be foreseen by achieving a higher degree of oxidation and by modification of polymerization process to enhance the electronic and ionic conductivity.
Highly nonlinear structures and constituent materials and hazardous experiment situations have resulted in a pressing need for a numerical mechanical model for lithium-ion battery (LIB). However, such a model is still not well established. In this paper, an anisotropic homogeneous model describing the jellyroll and the battery shell is established and validated through compression, indentation, and bending tests at quasi-static loadings. In this model, state-of-charge (SOC) dependency of the LIB is further included through an analogy with the strain-rate effect. Moreover, with consideration of the inertia and strain-rate effects, the anisotropic homogeneous model is extended into the dynamic regime and proven capable of predicting the dynamic response of the LIB using the drop-weight test. The established model may help to predict extreme cases with high SOCs and crashing speeds with an over 135% improved accuracy compared to traditional models. The established coupled strain rate and SOC dependencies of the numerical mechanical model for the LIB aims to provide a solid step toward unraveling and quantifying the complicated problems for research on LIB mechanical integrity.
The present study reports on the direct synthesis of LiFePO4 nanoparticles and graphene nanosheets to form a composite cathode (LFP/GNs) in a one-step microwave-assisted polyol reaction. The polyol reaction induced by microwave irradiation for a few minutes produces nanocrystalline LFP and graphene nanosheets simultaneously from lithium, iron and phosphorus and carbon (5 wt% of graphite oxide) sources, respectively, used as starting precursors. Powder X-ray diffraction (XRD), electron microscopy, and atomic force microscopy (AFM) studies on microwave-reacted sample obtained using just graphite oxide confirms the formation of graphene nanosheets separately. Whereas, electron microscopy studies on the LFP/GNs composite reveals that olivine nanoparticles of average sizes ranging between 5 and 20 nm are well-dispersed on the graphene nanosheets. Electrochemical measurements reveal that the LiFePO4/GNs nanocomposite cathodes registered enhanced discharge capacities (79 and 108 mAh g−1 for the as-prepared and annealed composite cathodes, respectively) at 32 C rates with good capacity retention capabilities. The AC impedance measurements confirm that the enhanced cathode properties of the LFP/GNs nanocomposite are ascribed to the improved electronic conductivity of the graphene nanosheets and the nano-sized particles. The slightly better electrochemical properties of the annealed LFP/GNs are attributed to its higher crystallinity.
Capacity fading of lithium ion batteries (LIBs) is a huge hurdle for their commercial utilization that may be reduced by the insertion of high quality anode material. Herein, we introduce high-graphitized graphene foam (GF) as anode material, which can be helpful for minimizing the loss of specific capacity during electrochemical reactions. GF shows excellent results when employed as anode in LIBs with high capacity values of 497mAhg−1 along with very low capacity fading (∼0.00578% at a current density of 200mAg−1).
Nowadays, renewable energy systems are taking place than the conventional energy systems. Especially, PV systems and wind energy conversion systems (WECS) are taking a big role in supplying world's energy necessity. Efficiency of such types of renewable energy systems is being tried to be improved by using different methods. Besides conventional methods, intelligent system designs are seem to be more useful to improve efficiency of renewable energy systems. However, artificial neural networks (ANN) have many usage areas in modeling, simulation and control of renewable energy systems. ANNs are easy to use and to implement renewable energy system designs. In this paper, artificial neural network applications of PV, WECS and hybrid renewable energy systems which consist of PV and WECS are presented. Usage of neural network structures in such types of systems have been motivated.
Gel polymer electrolyte (GPE) and composite gel polymer electrolyte (CGPE) have been widely employed to improve the safety and cycling performance of rechargeable lithium and lithium-ion batteries. In order to determine whether this approach is applicable to lithium/sulfur (Li/S) battery, we examine the effect of CGPE on the cycling and storage performances of Li/S cells by comparing a 50PEO-50SiO2 (wt.%) composite coated separator (C-separator) with a pristine separator (P-separator). Results show that the composite coating significantly enhances the wettability of liquid electrolyte on the separator and that resulting CGPE can tightly glue the separator and electrode together. In comparison with the P-separator, the C-separator offers Li/S cells similar capacity retention and rate capability; however it greatly affects the specific capacity of sulfur. The analysis on the impedance spectrum of a lithium polysulfide (PS) solution reveal that the reduction of sulfur specific capacity is due to the high viscosity of the CGPE and the strong adsorption of SiO2 filler to the PS species, which trap PS species in the separator and hence reduce the utilization of sulfur active material. Therefore, the benefits of the GPE and CGPE to the Li/S batteries can be taken only at the expense of sulfur specific capacity.
Wireless Sensor Networks (WSN) are large networks of tiny sensor nodes that are usually randomly distributed over a geographical region. The network topology may vary in time in an unpredictable manner due to many different causes. For example, in order to reduce power consumption, battery operated sensors undergo cycles of sleeping–active periods; additionally, sensors may be located in hostile environments increasing their likelihood of failure; furthermore, data might also be collected from a range of sources at different times. For this reason multi-hop routing algorithms used to route messages from a sensor node to a sink should be rapidly adaptable to the changing topology. Swarm intelligence has been proposed for this purpose, since it allows the emergence of a single global behavior from the interaction of many simple local agents. Swarm intelligent routing has been traditionally studied by resorting to simulation. The present paper aims to show that the recently proposed modeling technique, known as Markovian Agent Model (MAM), is suited for implementing swarm intelligent algorithms for large networks of interacting sensors. Various experimental results and quantitative performance indices are evaluated to support this claim. The validity of this approach is given a further proof by comparing the results with those obtained by using a WSN discrete event simulator.
Tin (IV) oxide, SnO2 films have been successfully synthesized in argon gas using a magnetron sputtering device. The morphology, structure, optical, photoluminescence, and photoresponse features of the samples have been analyzed via field electron scanning electron microscope, X-ray diffractograms, UV–Vis spectrometer, and spectro fluorophotometer. Compact nano grained morphologies with tetragonal structure and high absorbance were obtained. Increasing the annealing temperature led to a slight rise in the bandgap energies of the deposited samples. SnO2 films exhibited good photoluminescence features with increasing photoresponse with time as the annealing temperature reduced. The films can be potentially applied to optical and solar cell devices.
This paper introduces the 2012 round of the Egypt Labor Market Panel Survey (ELMPS), a publicly-available nationally representative longitudinal household survey. We describe the key characteristics of the ELMPS, including the samples and questionnaires for each round. Additionally, we examine the attrition processes observed in the panel and discuss the creation of weights to correct for attrition. We compare our data to other statistical sources for Egypt to evaluate the sample’s representativeness. To demonstrate how the ELMPS allows for an improved understanding of the labor market, we compare unemployment trends using the ELMPS and other data on unemployment in Egypt.
Solution processing via roll-to-roll (R2R) coating promises a low cost, low thermal budget, sustainable revolution for the production of solar cells. Poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3′′′-di(2-octyldodecyl)-2,2′;5′,2′′;5′′,2′′′-quaterthiophen-5,5-diyl)], PffBT4T-2OD, has recently been shown to achieve high power conversion efficiency (>10%) paired with multiple acceptors when thick films are spun-coat from hot solutions. We present detailed morphology studies of PffBT4T-2OD based bulk heterojunction films deposited by the volume manufacturing compatible techniques of blade-coating and slot-die coating. Significant aspects of the film morphology, the average crystal domain orientation and the distribution of the characteristic phase separation length scales, are remarkably different when deposited by the scalable techniques vs. spun-coat. Yet, we find that optimized blade-coated devices achieve PCE > 9.5%, nearly the same as spun-coat. These results challenge some widely accepted propositions regarding what is an optimal BHJ morphology and suggest the hypothesis that diversity in the morphology that supports high performance may be a characteristic of manufacturable systems, those that maintain performance when coated thicker than ≈200 nm. In situ measurements reveal the key differences in the solidification routes for spin- and blade-coating leading to the distinct film structures.
Potassium-ion batteries are attracting great attention as a promising alternative to lithium-ion batteries due to the abundance and low price of potassium. Herein, the phosphorus/carbon composite, obtained by a simple ball-milling of 20 wt% commercial red phosphorus and 80 wt% graphite, is studied as a novel anode for potassium-ion batteries. Considering the high theoretical specific capacity of phosphorus and formation of stable phosphorus-carbon bond, which can alleviate the volume expansion efficiently, the phosphorus/carbon composite exhibits a high charge capacity of 323.5 mA h g−1 after 50 cycles at a current density of 50 mA g−1 with moderate rate capability and cycling stability. By the X-ray diffraction analysis, the alloying–dealloying mechanism of phosphorus is proposed to form a KP phase. Meanwhile, prepotassiation treatment is conducted to improve the low initial coulomb efficiency.
We report the first attempt to retard the pulverization of an amorphous Li12Si7 anode by controlling the working voltage window. The suitable working voltage window for the amorphous Li12Si7 anode was determined to be 0.11−0.7V by analyzing the change in the charge transfer resistance using electrochemical impedance spectroscopy. After 100 cycles, the capacity retention of the Li12Si7 electrode cycled at 0.11−0.7V increased to 57.6% from the 18.2% capacity retention obtained for the electrode cycled at 0.02−2.0V, representing more than a 2-fold enhancement. SEM observations displayed the limited pulverization and fracture for the electrode cycled at 0.11-0.7V, which is the most important reason for the improved cycling stability. The methodology presented in this work can be extended to other electrode materials for Li-ion batteries that undergo large volume changes during lithiation/delithiation.
The design of Li-ion batteries with high energy storage capacities and efficiencies is a subject of increased research interest, being of key importance for their large-scale applications and further commercialization. However, conventional Li-ion batteries are expensive and have stability-related concerns, which limit their practical applications. In our search for cheaper and safer Li-ion batteries, we use a concentration gradient method to prepare LiNi0.9Co0.1–x Ti x O2 (0.02 ≤ x ≤ 0.05) cathode materials surface-enriched with Co and Ti that exhibit decreased oxygen loss and improved structural stability. The corresponding crystal structures and morphologies are analyzed by X-ray diffraction and field emission scanning electron microscopy, with the Ni, Co, and Ti concentration distributions determined by energy-dispersive X-ray spectroscopy. The material with the best performance (x = 0.04) exhibits a discharge capacity of 214 mAh g−1 in a charge/discharge voltage range of 3.0–4.3 V (vs. Li/Li+), and possesses an excellent 50-cycle capacity retention of 98.7%. Thermogravimetric analysis shows that partial substitution of Ni with the strongly oxophilic Ti solves the problem of oxygen loss observed in Ni-rich cathode materials such as LiNiO2.
Flexible supercapacitors with excellent performance are needed to meet the increasing demand for wearable and flexible electronics. The challenge remains to design exceptionally flexible supercapacitors with remarkable electrochemical properties. Natural nacre shows outstanding fracture toughness due to its alternating inorganic and organic layered structure and abundant interfacial interactions, providing an inspiration for designing flexible supercapacitors. Herein, we demonstrated nacre-inspired flexible supercapacitors via synergistic interfacial interactions of π-π conjugated bonds, hydrogen bonding, and electrostatic interaction between halloysite (HA)-polyaniline (PANI) nanocomposites and graphene oxide (GO) nanosheets. The resultant nacre-inspired HPA-rGO nanocomposite films demonstrate strong tensile strength (351.9 MPa), high electrical conductivity (397.0 S cm−1), and long cycle life with ~ 85% of capacitance retention after 10,000 cycles. Furthermore, the assembled all-solid-state supercapacitors (ASSSs) based on bioinspired HPA-rGO electrodes can not only display extraordinary flexibility with no decay of capacitance behavior after 5000 bending cycles, but also deliver remarkable mass energy density up to 16.3 Wh kg−1, outperforming other flexible graphene-based supercapacitors. This nacre-inspired strategy for designing flexible electrodes provides an avenue for the next-generation power source in the fields of aerospace and smart wearable electronics.
The goal of this work is to study electrical transport within multiphase structures of Li-ion electrodes through numerical microstructure reconstruction and direct evaluation. Li-ion battery electrodes at different compositions were numerically reconstructed mimicking the experimental fabrication process. Electrode material agglomeration and interfaces between components, as well as possible implication on battery performance were explored. Distribution of electrode phases (active material particles, binder, conducting phase carbon), and electrical conductivity were studied upon the reconstructed 3D microstructure. The electrical conductivity of the electrodes was estimated from the reconstructed electrode structures, and compared favorably with those measured experimentally using four-probe tests. It has been found that macro mass transport properties of the numerically reconstructed electrodes depend critically on nanoscale physical characteristics of electrode components and their contact. This work revealed the localized nanoscale electrode complexity and transport processes in great details, which are currently difficult to investigate experimentally or by alternative models.