batterydata/paper-abstracts huggingface dataset:
We present a new concept of the hybrid electrochemical capacitor technology in which a poly(2,2,6,6-tetramethylpiperidinyloxy methacrylate) nitroxide polyradical/activated carbon composite (PTMA–AC) is used as the positive electrode material and activated carbon is used as the negative electrode material. On the positive electrode, both reversible reduction and oxidation of nitroxide polyradical and non-faradic ion sorption/de-sorption of activated carbon are involved during charge and discharge process. The capacity of the composite electrode is 30% larger than that of the pure activated carbon electrode. A hybrid capacitor fabricated by the PTMA–AC composite positive electrode and the activated carbon negative electrode shows a good cycling life, it can be charged/discharged for over 1000 cycles with slight capacity loss. The hybrid capacitor also has a good rate capability, it maintains 80% of the initial capacity even at the high discharge current of up to 20C.
In spite of latest research achievements, the development of energy storage devices with high power density and safety remains an urgent task. Among others, lithium-ion batteries are most promising power sources due to its good energy density and low self-discharge. The performance of lithium batteries depends on physicochemical characteristics of materials, which used as electrodes. Recently, among new materials, a special attention is paid to TiO2(B) owing to its high potential of lithium insertion/extraction (∼1.5 V vs. Li/Li+) and pseudocapacitive energy storage mechanism. However, the commercial application of bronze titania has been hampered to date by its poor electronic conductivity and lattice stresses during lithiation/delithiation. This review highlights recent progress in TiO2(B) modifying with a most promising ways, including morphology tailoring, hybridization, and doping. The main important achievements in this area are summarized and discussed in detail.
Sn–Co alloy thin films with high IR reflectivity were prepared by electroplating on a copper substrate and served as anodes of lithium ion battery. The interfacial properties of the Sn–Co alloy anode in an electrolyte of 1M LiPF6/EC+DMC (1:1, vol.%) during discharge/charge (or lithiation/delithiation) processes were investigated by using in situ microscope Fourier transform infrared reflection spectroscopy (in situ MFTIRS). The results demonstrated that the solvation/desolvation reactions of lithium ions with solvent molecules in discharge/charge processes vary with the concentration of both solvated and free solvent molecules, leading to the shift of CO, C–O and C–H IR bands. The effect of solvation/desolvation, which provides a possibility to probe the lithiation/delithiation processes by in situ MFTIRS, is observed and analyzed clearly. The solid electrolyte interphase (SEI) layer on a cycled Sn–Co alloy anode has also been investigated by ex situ MFTIRS, which determined that the main chemical composition of the SEI layer is ROCO2Li. The current studies are of significance in understanding the interfacial reactions involving in lithium ion battery at molecular level.
Vanadium oxide has attracted interest for energy storage applications due to its high theoretical capacitance and stable layered structure. The low electronic conductivity, of V2O5 necessitates combining with conducting materials, typically carbon. However combining with conductive carbon materials may require binders, which compromise the active surface. In this study, V2O5 nanowire (VNWs)–graphene composite flexible paper electrodes were prepared without using binders. Graphene introduces conductivity and electric double layer capacitance (EDLC) to the composite. Graphene sheets were prepared using an alkaline deoxygenation process (hGO), which is a green alternative to traditional hydrazine reduction. Coin cell type supercapacitors were assembled using the hGO–VNW paper electrodes as the anode and spectracarb fiber cloth as the cathode in a two-electrode cell configuration. Electrochemical studies for different compositions of VNWs on hGO are reported. The composite electrode hGO–VNW120, showed balanced EDL and pseudocapacitance as well as an energy density of 38.8 Wh kg−1 at a power density of 455 W kg−1. The maximum power density of 3.0 kW kg−1 was delivered at a constant current discharge rate of 5.5 A g−1. The device prepared using hGO–VNW120 anode showed a specific capacitance of 80 F g−1.
Perovskite oxide catalysts have emerged as the most promising bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts for electrochemical energy conversion and storage. In this work, a new type of oxygen-deficient BaTiO3−x has been synthesized using a sol–gel method followed by a reductive heat treatment at 1300°C in vacuum. The prepared perovskite nanoparticles have an average particle size on the order of 100nm with uniform size distribution. X-ray diffraction shows that this perovskite catalyst consists of a significant amount of hexagonal BaTiO3−x . State-of-the-art IrO2 nanoparticles were also prepared in this work, which were used for reference and has excellent OER activity. Importantly, the oxygen-deficient perovskite catalysts exhibited high catalytic activity simultaneously for the ORR and the OER in alkaline electrolyte. The more challenged OER activity measured with the perovskite exceeds the IrO2 catalyst at relatively low potentials (<1.6V) evidenced by a much reduced onset potential (1.32V) and increased current density. In order to clearly elucidate the structure of the oxygen-deficient BaTiO3−x catalysts, X-ray and neutron diffraction experiments were further carried out, indicating that the hexagonal phase in the best performing BaTiO3−x catalyst is oxygen-deficient with a stoichiometry of BaTiO2.76. The oxygen vacancies in the perovskite crystal structure may lead to vastly enhanced electrocatalytic activity toward the ORR and OER. This work demonstrates a new type of highly efficient perovskite bifunctional catalyst for electrochemical energy technologies relying on oxygen electrocatalysis.
A freestanding sulfur/dehydrogenated polyacrylonitrile/multiwalled carbon nanotube composite (S/DPAN/MWCNT) was prepared by a simple vacuum filtration of a mixture of S/DPAN composite and MWCNT suspensions, and studied as a cathode for high performance lithium-sulfur batteries. SEM and EDS analysis revealed uniform distribution of sulfur in a conductive pyrolyzed polyacrylonitrile host matrix with MWCNT integrated into the composite. Self-weaving MWCNT create an electronically conductive network and reinforce structural stability of the system, leading to an outstanding electrochemical performance of the composite cathode. Binder/current collector-free composite cathode exhibits high capacities of 1450mAhg−1 at 0.2 C and 930mAhg−1 at 2 C charge-discharge rates. A high discharge capacity of 1250mAhg−1 is achieved after 260 cycles at 0.2 C with a coulombic efficiency around 100%.
The ongoing technical improvements in architecture design with improved features of mobile or smartphones do not automatically guarantee user acceptance, because technical and commercial aspects primarily drive the development of mobile communication systems and devices. Especially in early stages of technology development, user preferences and values are not adequately considered, which might even have a negative impact on acceptance issues. The aim of this study was the implementation of a quantified understanding of user needs in terms of values into the system design process of cell-phone processors. Moreover, we aimed for an extension of the engineering’s trade-off analysis by using conjoint analysis in order to investigate trade-offs between specific device characteristics. Finally, our aim was the evaluation of empirically based user-oriented research methods. Results of the first study revealed that battery life, speech quality, signal quality and data-transmission rate are the most important device characteristics. Results from conjoint analysis indicated a clear trade-off between battery life and the three other characteristics. Moreover, this research demonstrated that technology acceptance research benefits considerably from an interdisciplinary and multi-method approach. Besides, implementing the users’ preferences into early stages of the product development process offers several advantages concerning effectiveness as well as economic aspects of development.
Cubic Spinel MnCo2O4/graphene sheets (MCO/GS) nanocomposites are synthesized by a facile hydrothermal method with a subsequent annealing process. Nano-sized MnCo2O4 particles are evenly embedded in paper-like graphene sheets, possessing a unique nanoparticles-on-sheets hybrid nanostructure, with particle size around 20–50 nm. Owing to the special nanoparticles-on-sheets structures, MCO/GS nanocomposites have an outstanding electrochemical performance for rechargeable energy storage devices. As an anode material for lithium-ion batteries, MCO/GS electrodes exhibit high reversible discharge capacities (1350.4 mAh g−1 at the initial rate of 100 mA g−1), excellent rate capability (462.1 mAh g−1 at a current rate of 4000 mA g−1) and outstanding cycling performance (584.3 mAh g−1 at 2000 mA g−1 after 250 cycles). Meanwhile, as an anode material for sodium-ion batteries, MCO/GS electrodes also exhibit comparably promising electrochemical characteristics. Greatly improved electrochemical properties can be assigned to the special advantageous nanostructures. Besides, the existence of graphene sheets is beneficial to the transportation of ions/electrons during battery operation. The outstanding electrochemical performance demonstrates that the lithium/sodium storage capability of MCO/GS nanocomposites is highly promising for high-capacity batteries.
Coating the members of the olivine family LiMPO4 with conductive carbon is difficult, excepted in the case MFe. To overcome this difficulty, we found possible to coat LiMnPO4 with a thin layer of LiFePO4 to take benefit of the catalytic reaction of Fe with C, so that a 3nm-thick layer of carbon can be deposited at the surface of this composite. We find that the electrochemical properties of the carbon-coated LiFePO4–LiMnPO4 composite are improved with respect to the carbon-coated LiMn2/3Fe1/3PO4 solid solution with comparable Fe/Mn ratio. Therefore, the use of a LiFePO4 as a buffer layer between the high-density cathode element (like LiMnPO4) and the carbon layer opens a new route to improve the performance of the olivine family as the active element of the cathode for Li-ion batteries.
In recent research, both soil (root-zone) and air temperature have been used as predictors for the treeline position worldwide. In this study, we intended to (a) test the proposed temperature limitation at the treeline, and (b) investigate effects of season length for both heat sum and mean temperature variables in the Swiss Alps. As soil temperature data are available for a limited number of sites only, we developed an air-to-soil transfer model (ASTRAMO). The air-to-soil transfer model predicts daily mean root-zone temperatures (10cm below the surface) at the treeline exclusively from daily mean air temperatures. The model using calibrated air and root-zone temperature measurements at nine treeline sites in the Swiss Alps incorporates time lags to account for the damping effect between air and soil temperatures as well as the temporal autocorrelations typical for such chronological data sets. Based on the measured and modeled root-zone temperatures we analyzed the suitability of the thermal treeline indicators seasonal mean and degree-days to describe the Alpine treeline position. The root-zone indicators were then compared to the respective indicators based on measured air temperatures, with all indicators calculated for two different indicator period lengths. For both temperature types (root-zone and air) and both indicator periods, seasonal mean temperature was the indicator with the lowest variation across all treeline sites. The resulting indicator values were 7.0°C±0.4SD (short indicator period), respectively 7.1°C±0.5SD (long indicator period) for root-zone temperature, and 8.0°C±0.6SD (short indicator period), respectively 8.8°C±0.8SD (long indicator period) for air temperature. Generally, a higher variation was found for all air based treeline indicators when compared to the root-zone temperature indicators. Despite this, we showed that treeline indicators calculated from both air and root-zone temperatures can be used to describe the Alpine treeline position.
The purpose of this study, determination of the science teacher candidates’ views on electronic waste pollution. Science teachers’ views on the data of electronic waste pollution. The participants of the study were determined with a purposive sample which enables researcher to choose the ones who are believed to find to solutions to the problems of the researcher. Total 75 teacher candidates that first, second and third grade from uludag university and different universities are participated to study during the 2013-2014 academic year, summer school courses. Data were collected open-ended questions which developed by the researchers. Students were answered the related seven open ended questions in almost 30minutes. The qualitative data obtained from the study were analyzed using a phenomenological method. According to results of the study it was determined that teachers candidates are not sufficiently knowledgeable about the electronic waste and damages to the environment and human health. It was recommended that teachers candidates need to be aware of this issue.
A new strategy involving the addition of a cationic surfactant, cetyl trimethyl ammonium bromide (CTAB), has been found to influence the electrochemical properties of nickel hexacyanoferrate film greatly. Nickel hexacyanoferrate surface films deposited by potential cycling procedure in the presence and absence of CTAB are compared for ion transport characteristics using cyclic voltammetry. CV parameters in 0.1 M KCl+0.1 M HCl both in the presence and absence of CTAB, switching time obtained from chronoamperometry and diffusion coefficient values obtained from double pulse chronocoulometry and cyclic voltammetry are presented and discussed.
LiNi1/3Co1/3Mn1/3O2 cathode materials have been coated with Al2O3 nano-particles using sol–gel processing to improve its electrochemical properties. The X-ray diffraction (XRD) pattern of the as-prepared Al2O3 nano-particles was indexed to the cubic structure of the γ-Al2O3 phase and had an average size of ∼4nm. The XRD showed that the structure of LiNi1/3Co1/3Mn1/3O2 was not affected by the Al2O3 coating. However, the Al2O3 coatings on LiNi1/3Co1/3Mn1/3O2 improved the cyclic life performance and rate capability without decreasing its initial discharge capacity. These electrochemical properties were also compared with those of LiAlO2-coated LiNi1/3Co1/3Mn1/3O2 cathode material. The electrochemical impedance spectroscopy (EIS) was studied to understand the enhanced electrochemical properties of the Al2O3-coated LiNi1/3Co1/3Mn1/3O2 compared to uncoated LiNi1/3Co1/3Mn1/3O2.
Hard carbon has attracted enormous attentions as electrode materials for various energy storage devices owing to its low cost, abundant sources and high theoretical capacitances/capacities. However, it still suffers poor electrical conductivity and unsatisfying rate performance. Herein, N/S co-doped ultrathin carbon nanosheet is reported as high performance electrode material for both supercapacitors and sodium-ion batteries. The symmetric supercapcitors assembled with the as-synthesized materials (1.0 M Na2SO4 as electrolyte) deliver a high energy density of 24.5 Wh kg−1 at a power density of 500 W kg−1 within a wide voltage range of 0–2.0 V. When being served as anode for sodium-ion batteries, the electrode exhibits a high reversible capacity (371.2 mAh g−1 @ 0.1 A g−1) and superior rate capability (180.9 mAh g−1 @ 10.0 A g−1). Besides, the as-fabricated electrodes display stable cycling performance in both energy storage systems. Subsequent mechanism studies further shed light on the excellent electrochemical performance.
Machine learning is a specific application of artificial intelligence that allows computers to learn and improve from data and experience via sets of algorithms, without the need for reprogramming. In the field of energy storage, machine learning has recently emerged as a promising modelling approach to determine the state of charge, state of health and remaining useful life of batteries. First, we review the two most studied types of battery models in the literature for battery state prediction: the equivalent circuit and physics-based models. Based on the current limitations of these models, we showcase the promise of various machine learning techniques for fast and accurate battery state prediction. Finally, we highlight the major challenges involved, especially in accurate modelling over length and time, performing in situ calculations and high-throughput data generation. Overall, this work provides insights into real-time, explainable machine learning for battery production, management and optimization in the future.
SiO2–non-graphitizable carbon composites were prepared by pyrolysis of a mixture of ethyl cellulose and nano-sized SiO2. The composite electrode showed high reversibility in insertion and/or extraction reactions of Li ions at potentials below 1 V with little hysteresis after the 2nd cycle, whereas a large irreversible capacity was observed in the 1st cycle. This reversible capacity increased with increasing SiO2 content above 5 wt%. Li ion transfer at the interface between a composite electrode and an electrolyte was studied by ac impedance spectroscopy. In the Nyquist plots, a semi-circle that was assigned to charge-transfer resistance (Rct) because of Li ion transfer across the interface between the composite electrode and electrolyte appeared at potentials below 1 V. The values of Rct decreased with increasing SiO2 content. These results indicate that both a decrease in Rct and an increase in reversible capacity can be achieved by use of SiO2–non-graphitizable carbon composite electrodes; this would lead to Li-ion batteries with higher power and energy density.
This study implements a possible use of the state of charge (SOC) instead of the charge voltage limit (Vlimit) to control the charging process for a four-stage constant current charging strategy. To determine the charging current in each stage, an iterative optimization procedure based on Taguchi method is employed to find near-optimal values. To control the change of the charging stage and terminate the charging process, the Coulomb counting method combined with battery’s open circuit voltage estimation is adopted for SOC estimation. Tests of Sanyo 840 mA h, 3.6 V lithium-ion (Li-ion) batteries have been conducted with a Keithley 2230-30-1 triple power supply and a Prodigit 3332 F dual electronic load. The implemented charger has an input voltage of 12 V, output currents of 1.176 A, 0.840 A, 0.588 A, and 0.336 A, as well as an output voltage ranged from 0.168 V to 0.588 V. By performing the experiments, the proposed charging strategy has shorter charging time than the equivalent constant current constant voltage (CCCV) and the Vlimit-based charging methods. However, it yields a slightly lower charging efficiency than the equivalent CCCV and pulse current charging methods.
The aim of this study was to investigate whether it is possible to strengthen the rehabilitation of spatial hemineglect by combining standard training for spatial scanning with optokinetic stimulation. A simple randomized design was used: one group of neglect patients was treated with a combination of the two techniques, and a second group received only the standard treatment. Both treatments were given for six consecutive weeks and produced significant improvements. However, addition of the optokinetic stimulation did not improve the patients' performance. Also, none of the independent variables (i.e., presence/absence of hemianopia) predicted the positive effect occasionally observed in individual patients.
The effect of CeO2 coating on LiFePO4/C cathode material has been investigated. The crystalline structure and morphology of the synthesized powders have been characterized by XRD, SEM, TEM and their electrochemical performances both at room temperature and low temperature are evaluated by CV, EIS and galvanostatic charge/discharge tests. It is found that, nano-CeO2 particles distribute on the surface of LiFePO4 without destroying the crystal structure of the bulk material. The CeO2-coated LiFePO4/C cathode material shows improved lithium insertion/extraction capacity and electrode kinetics, especially at high rates and low temperature. At −20°C, the CeO2-coated material delivers discharge capacity of 99.7mAh/g at 0.1C rate and the capacity retention of 98.6% is obtained after 30 cycles at various charge/discharge rates. The results indicate that the surface treatment should be an effective way to improve the comprehensive properties of the cathode materials for lithium ion batteries.
Nanocomposites of Mn3O4 nanoparticles and graphene (GR) nanosheets – Mn3O4@GR can be made by growing Mn3O4 nanoparticles directly on the surfaces of GR in solvothermal reactions. The asymmetric supercapacitors constructed with Mn3O4@GR as positive and activated carbon (AC) as negative electrodes, respectively, show highly enhanced performances in energy storage. It was found that the electrolytes employed in constructing electrodes of the devices can influence the performances of Mn3O4@GR supercapacitors dramatically. Compared to their energy density in KOH electrolyte, the devices exhibit improved charge storage performances in Na2SO4 electrolyte. Furthermore, the charge storage abilities of the devices are closely related to the amount of Mn3O4 nanoparticles loaded onto the surface of GR nanosheets. The performances of Mn3O4@GR//AC asymmetric supercapacitors can be optimized by carefully tailoring the composition of electrode materials and adjusting the electrolytes for making the devices.
Electric power grids exhibit frequency fluctuations brought on by changes in demand, trading and intermittency of renewable sources. Schäfer et al. analyse fluctuations in real power grids from North America, Japan and Europe and find deviations from Gaussianity and substantial contributions due to trading.
In the last decade, an emerging three-dimensional (3D) printing technique named freeform 3D printing has revolutionized the biomedical engineering field by allowing soft matters with or without cells to be printed and solidified with high precision regardless of their poor self-supportability. The key to this freeform 3D printing technology is the supporting matrices that hold the printed soft ink materials during omnidirectional writing and solidification. This approach not only overcomes structural design restrictions of conventional layer-by-layer printing but also helps to realize 3D printing of low-viscosity or slow-curing materials. This article focuses on the recent developments in freeform 3D printing of soft matters such as hydrogels, cells, and silicone elastomers, for biomedical engineering. Herein, we classify the reported freeform 3D printing systems into positive, negative, and functional based on the fabrication process, and discuss the rheological requirements of the supporting matrix in accordance with the rheological behavior of counterpart inks, aiming to guide development and evaluation of new freeform printing systems. We also provide a brief overview of various material systems used as supporting matrices for freeform 3D printing systems and explore the potential applications of freeform 3D printing systems in different areas of biomedical engineering.