batterydata/paper-abstracts huggingface dataset:
Graphene and N-doped graphene have been widely used for improving the cycling performance of silicon based anode for advancing lithium-ion battery's performance due to their capabilities in suppressing the volume expansion of Si nanoparticles which is responsible for the rapid and irreversible degradation. While it is known that there are pyridinic and pyrrolic nitrogen motifs in the N-doped graphene, there have been no studies of the controllability and optimization of their ratio during N-doping and how it influences on the battery performance. We demonstrate here for the first time that the pyridinic-to-pyrrolic nitrogen ratio is not only controllable in N-doped graphene but also there is an optimal ratio for the enhancement of battery performance. The pyrrolic type N as the major doping form in Nano-Si@NG is shown to deliver a reversible capacity of 950 mA h g−1 over 100 cycles in Li-ion battery performance test, a much better capacity retention than that of bare Si nanoparticle. The degree and type of N-doping in the nanocomposite were shown to be two dominated factors influencing the lithium storage properties, which was supported by X-ray photoelectron spectroscopy (XPS) identification of three types of N-doping structures. The result is further substantiated by density functional theory (DFT) calculation of the energy barrier for diffusion of Li ion in the nanocomposite structure, revealing the smallest diffusion barrier for the pyrrolic type N-doped graphene. Implications of these findings to the design of Nano-Si-based Li-ion battery with high capacity and improved cycle life are also discussed.
Aim The aim of this study was to evaluate the restoration of gastrointestinal motility after NOTES using capsule endoscopy (CE). Materials and Methods Twenty adult Yorkshire pigs were randomly assigned to four groups: transgastric NOTES (gNOTES), transrectal NOTES (rNOTES), transvaginal NOTES (vNOTES), and laparoscopy (LAP). At the end of a 30-min peritoneoscopy with identification of seven predetermined organs, an array of eight receivers and the recorder were attached to the abdominal wall. The CE was delivered into the antrum with the help of an endoscope and a polypectomy snare. Animals were kept alive for 14 d. Results Median time for surgery was longer in gNOTES (56 min, range 47–63) and vNOTES (54 min, range 44–79) than in LAP (32 min, range 32–33; P < 0.05 and P < 0.01) and in rNOTES (45.5 min, range 33–56) (P = ns). This increase was related to a larger incision and longer closure times. Images from the CE were successfully retrieved in 19 cases. The CE was retained in the stomach in all animals in gNOTES (459 min; range 360–600), but only in one animal in rNOTES and vNOTES and in none in the LAP group. Failure of passage of the CE beyond the stomach was associated with gNOTES and longer closure of the incision. Animals in the gNOTES group gained less weight than the others and this change was statistical significant when compared with vNOTES animals (1.7 kg, range –1.98 to 4.5 versus 8.4 kg, range 5.8 to 11.45; P < 0.01). Conclusion Gastric emptying is delayed after gNOTES peritoneoscopy compared with rNOTES, vNOTES, and LAP and this effect is associated with less weight gain.
Dendritic morphology evolution during zinc electrodeposition is a major roadblock in the development of rechargeable zinc anodes in alkaline zinc batteries. In the present work, we report the use of branched polyethylenimine (PEI, M.W.=800g/mol) as an effective electrolyte additive for suppressing dendrite formation during zinc electrodeposition from typical alkaline electrolytes used in secondary zinc batteries. Dendrite suppression is characterized as a function of the PEI concentration via ‘live’ observation of the dendrite propagation using an in-situ optical microscopy setup. Steady-state and transient electrochemical polarization measurements on a rotating disk electrode, combined with electrochemical quartz crystal microgravimetry and ex-situ scanning electron microscopy, reveal the mechanism by which PEI suppresses dendrites, i.e., PEI adsorption on the zinc surface leading to suppression of the zinc electrodeposition kinetics. Our work presents a comprehensive characterization of the role of polymeric additives, such as PEI, in suppressing dendritic growth during alkaline zinc electrodeposition.
The role of energy in overall social and economical developments is well recognized. However, most energy providers are reluctant to venture in rural regions of developing countries. These regions are generally characterized by: low-income populations, minimum access to electricity, rare access to financial services or loans. In this paper we present the potential of rice husk for rural electrification in Cambodia. Rice husk is locally abundant at almost no cost, with a production over 9.3 million tons paddy rice in 2014 for a total population of about 15 million people. The conversion of rice husk into electricity through gasification or thermally generated electricity is a well-known technology. Rice husk can contribute in a sustainable manner to grant access to electricity to Cambodian rural population and is more reliable and competitive with reference to other renewable energy sources of electricity. The present investigation focuses on the study of self-sustaining energy service model to provide grid quality power to rural populations without the need of subsidies. In Cambodia, many rice mills are operating in rural and semi-urban areas. Some of these mills are now using rice husk for electricity production for industries and rural households, generally for lighting at low cost. We believe that the power systems focusing on both power requirements for the industry such rice mills and power requirements for the people living in the neighboring villages/rural areas at affordable tariff could become the most appropriate solution for the sustainable rural electrification. Along with the potential of rice husk for rural electrification in Cambodia, we present a financially viable business model to provide the grid quality power to rural population without grant or subsidy.
SOI CMOS device and circuit technologies operating at low voltages dedicated for ultralow power applications are reviewed. It is important to improve energy efficiency while maintaining an acceptable speed performance in ultralow power applications for long-life battery operation, or using harvested power. Major obstacles for the low voltage operation of CMOS are large characteristic variability and small on–off ratio of transistors. The solution to this issue involves using a fully depleted silicon-on-insulator (FDSOI) transistor with back bias control. The current status of the device, and circuit technology development of FDSOI with back bias, is presented.
Herein, the influence of the dopant concentration and the effect of varying the amount of the carbon coating for the electrochemical properties of Co-doped SnO2 as lithium-ion anode material are presented. Pure SnO2 and three different doping ratios of Co-doped SnO2 (Sn0.95Co0.05O2, Sn0.90Co0.10O2, and Sn0.85Co0.15O2) were synthesized and characterized regarding their structure, morphology, and electrochemical behavior. The results reveal that the Co content has a significant impact on the specific capacity and cycling stability, rendering Sn0.90Co0.10O2 as the sample with the best electrochemical performance among these three dopant ratios. The impact of the carbon coating content was explored for two different concentrations, i.e., 16 wt% (Sn0.90Co0.10O2-C16%) and 50 wt% (Sn0.90Co0.10O2-C50%), reflecting that the carbon coating as such and concerning the eventual amount has a significant influence on the cycling stability, coulombic efficiency, and rate capability.
Biomass (fallen leaves) was used directly as carbon source to synthesize Ce doped and C coated Li4Ti5O12 (LTO) in alkaline ballmilling medium. The unique porosity structure of fallen leaves and their trace amount of S elements can improve the Li ions migration ability and stability by coating a loose layer consisted of carbon quantum dots and inducing the interaction between S2 − and PF6 −. The alkaline medium can transform different species into unified hydrate form leading to the pre-arranged six-coordinate and four-coordinate lithium precursor and perfect crystal structure LTO. The capacity of obtained LTO reaches 169.4 mAh/g, 156.1 mAh/g, 141.5 mAh/g at 0.5 C, 5 C and 10 C, respectively and the capacity can maintain almost 100% even after 300 cycles at 10 C.
Cation (Mg and Al)-substituted spinel were synthesized using metal oxide precursor by co-precipitation method. XRD revealed that the prepared substituted spinel has spinel structure with Fd3m space group. In order to compensate the decreased initial capacity of cation-substituted spinel, partial anion (F) substitution was also carried out. The cycling performance of all the substituted spinel was improved, compared to the Li1.05Mn1.95O4 at 55°C. Li1.05Al0.1Mn1.85O3.95F0.05 showed better capacity retention than the other substituted spinels. Both cation and anion substitution appeared to be effective for improving the cycling performance of spinel material at elevated temperature.
The degree of crystallinity, morphology and electrochemical properties of a nanocomposite formed by stabilized alpha-Ni(OH)2 nanoparticles and bentonite nanoflakes is strongly influenced by the vacuum drying process, either at room temperature or by freeze-drying (lyophilization). Alpha-Ni(OH)2 nanoparticles induced the formation of intercalation nanocomposites exhibiting higher structural organization than in the precursor clay. Also, lyophilization process preserved the structure of the nanocomposites in aqueous suspension and/or induced the disaggregation of nanoflakes, producing materials with lower degree of crystallinity, larger interlamellar distances and electrochemically more active than those obtained by conventional vacuum drying. In fact, the lyophilized materials exhibited more than twice as large density of current for electrocatalytic oxidation of methanol (37 against 14 mA cm−2) indicating its potentiality for development of sensors and fuel cells.
Poly(aniline-co-3-amino-4-hydroxybenzoic acid) was synthesized using cyclic voltammetry. The monomer concentration ratio and applied potential strongly affect the copolymerization rate and electrochemical properties of the copolymer. The results from the infrared spectrum (IR) and X-ray photoelectron spectroscopy (XPS) of the copolymer demonstrate that 3-amino-4-hydroxybenzoic acid units are incorporated into the copolymer chain and that SO4 2− ions can be doped into the copolymer film during the electrochemical copolymerization. The scanning electron microscopy (SEM) micrograph proves that the copolymer film has a nanostructured network of mass interwoven fibers with a diameter of 10–50nm. The copolymer obtained at the optimum conditions exhibits excellent redox activity in a 0.30M Na2SO4 aqueous solution (pH 11.0), which is superior to that of polyaniline itself. The improvement can be attributed to the synergistic effect of the COOH and OH functional groups in the copolymer chain.
Abstract In material science, ferroelectric materials, called smart materials, which possess multifunctional properties like dielectric property, piezoelectric, and pyroelectric properties, have great potential interest among the researchers. These materials possess spontaneous polarization when placed in an external electric field. All ferroelectrics are piezoelectric materials in which the dipole moments are already aligned in the absence of external electric field or can be aligned in the presence of an external electric field. Moreover, these materials are electrostrictive materials with good dielectric, pyroelectric properties, and piezoelectric properties. Here our focus is on the piezoelectric property of the smart materials and applicability in the field of biomedical field.
Research into the development of direct methanol alkaline fuel cell (DMAFC) using an anion exchange polymer electrolyte membrane is described. The commercial membrane used had a higher electric resistance, but a lower methanol diffusion coefficient than Nafion® membranes. Fuel cell tests were performed using carbon supported Pt catalyst, and the effect of temperature, methanol concentration, methanol flow rate, air pressure and Pt loading were investigated. It was found that the cell performance improved drastically with a membrane assembly electrode (MEA) which did not include the gas diffusion layer on the anode, because of lower reactant mass transfer resistance. To give suitable cathode performance, humidification of the air and a subtle balance between the air pressure and water transport is required.
Carbon fiber yarns (CFY) are promising as a new type of flexible building blocks for the construction of flexible architectures for the energy storage applications. The main hurdle with CFY is how to make them high energy and power capable by using economically and environmentally viable materials. Here, we report reduced graphene oxide (rGO) and Prussian blue (PB) coated CFY, derived from a facile electrochemical process at room temperature for supercapacitor electrodes. The PB coated CFY and rGO coated CFY electrodes exhibit the excellent gravimetric capacitance of 339 F/g and 160.2 F/g, respectively, in aqueous KCl electrolyte in three-electrode cell configuration. When we coupled these electrodes inside the flexible plastic tube and separated by the electrolyte wet filter paper in order to construct flexible architecture, the resulting device delivers excellent specific energy of 52.1 Wh/kg and 26.5 Wh/kg with offering specific power of 3100 W/kg and 14400 W/kg respectively, under a wide operating potential of 1.8 V with excellent rate capability. The device shows high tolerance towards bending, and retained its efficiency to the capacitance after being bent at an angle of 360° for 200 bending cycles.
A unique in-situ morphology transition from multiwall carbon nanotubes (MWCNT) to graphene nanosheets (GNS) upon Li intercalation results in enormous increase in capacity of SnO2/MWCNT composites anode during cycling. The anode capacity increases from 330mAhg−1 to 500mAhg−1 which is more than 50% of its initial capacity when cycled at a current density of 200mAg−1. Further when the sample is cycled at a high current density of 500mAg−1 the composite sample shows a stable capacity of 400 mAhg−1 for 100 cycles which is attributed to the complete transition of MWCNT to GNSs as confirmed from the high resolution transmission electron microscope (HRTEM) images. First principles density functional theory calculations have been carried out to validate possibility of this morphological transition upon Li intercalation and the results agree well with the experimental findings.
The choice of the transmission power levels adopted in Wireless Sensor Networks (WSNs) is critical to determine the performance of the network itself in terms of energy efficiency, connectivity and spatial reuse, since it has direct impact on the physical network topology. In this paper, a cooperative, lightweight and fully distributed approach is introduced to adaptively tune the transmission power of sensors in order to match local connectivity constraints. To accurately evaluate the topology control solution, a small-scale testbed based on MicaZ sensor nodes is deployed in indoor and outdoor scenarios. Practical measures on local and multi-hop connectivity, convergence time and emitted power are used to compare the proposed approach against previous solutions. Moreover, mathematical programming formulations of the topology (power) control problem are introduced to assess the optimality of the distributed algorithm. Finally, simulation analysis complements the experimental evaluation in large-scale static and mobile WSN scenarios, where a testbed implementation becomes unfeasible.
As the penetration of weather-dependent embedded generation grows, the variations in apparent demand experienced by distribution network operators will become more extreme. A method for the autonomous control of domestic electricity demand and microgeneration is proposed using the established, but underdeveloped, radio teleswitch technology. The disadvantages of cost or carbon-emission based optimisation using this method are discussed and an alternative approach based on minimisation of exergy loss is described. Results obtained from a computer model demonstrate its potential contribution to the balancing of electricity supply and demand.
Background: The purpose of the present study was to characterize the association between cognition, clinical symptoms and social functioning and anatomical cerebral deficits in a sample of schizophrenia outpatients using voxel-based morphometry (VBM). Methods: Participants were 6 schizophrenia outpatients and 8 matched (sex ,age) healthy comparison subjects. Both patients and healthy controls were assessed using VBM. Cognitive status was assessed by standardised neuropsychological test battery. Psychopathology was evaluated using the Positive and Negative Syndrome Scale (PANSS). Social functioning was assessed using Life Skills Profile (LSP). Results: (preliminar results) Decreased gray matter volume was observed in schizophrenia patients in left medial temporal gyrus, left insula and bilateral superior temporal gyri (uncorrected data). Discussion: These preliminar findings revealed volume loss in the the left medial temporal gyrus, left insula and bilateral superior temporal gyri in schizophrenia outpatients.
Habitual coffee consumption has been associated with lower risk of type 2 diabetes and cardiovascular disease. Since these diseases are main determinants of functional limitations, we have tested the hypothesis that coffee intake is associated with lower risk of physical function impairment, frailty and disability in older adults. We focused on women and those with obesity, hypertension or type 2 diabetes because they are at higher risk of functional limitations.
A series of Tantalum-doped lithium titanate (Ta-doped Li4Ti5O12) samples have been successfully synthesized by one step solid-state method using TiO2, Li2CO3, and Ta2O5 as raw materials. The Li4Ti5O12 with only 0.1 at% Ta doping (Li4Ti4.995Ta0.005O12) exhibits higher rate capability and better cyclic stability than the pristine Li4Ti5O12. Li4Ti4.995Ta0.005O12 could deliver 95.1 mAh g−1 at 10C with much lower overpotential (216.1 mV) while the pristine Li4Ti5O12 delivers only 50.4 mAh g−1 at 10C with higher overpotential of 392.2 mV. As indicated by XRD, HRTEM and electrochemical characterizations, Ta doping in Li4Ti5O12 would enlarge the lattice parameter of the Li4Ti5O12, and facilitate the Li+ diffusion during the charge/discharge process. In addition, the higher charge compensation of the stoichiometric reduction of Ti4+ to Ti3+ by introducing Ta increases the electronic conductivity of Li4Ti5O12. The improved ionic conductivity and electronic conductivity are beneficial to the electrochemical performance of Li4Ti5O12. As a result, Ta doping is a new strategy for enhancing the electrochemical performance of Li4Ti5O12.
One-step electrochemical synthesis of polypyrrole-vanadium oxide (PPy-VOx) composites was performed on the Vanadium-intercalated pencil graphite (PG) surface in an acetonitrile solution with the presence of carboxymethyl cellulose (CMC). Both intercalated surface and composite coating were characterized using SEM-EDX Spectroscopy and X-Ray Diffraction (XRD) techniques. The capacitive properties of the coating were elaborated in an H2SO4/water medium using galvanostatic charge–discharge, potential cycling, and electrochemical impedance spectroscopy methods in comparison with the coatings prepared without additives. While V-intercalation provides a significant increase in the specific capacitance, the carboxymethyl cellulose enhances the cyclic performance of the composite. The improvement at the capacitance of the composite may be due to the homogenous distribution as well as the synergetic effect between PPy and VOx. The capacitive properties were studied in aqueous solutions of H2SO4 and Li2SO4, and in an acetonitrile solution of HBF4/TBABF4. The specific capacitance value of the composite coating on the V-intercalated pencil graphite was determined as 204 F g−1 in an acetonitrile solution of HBF4/TBABF4 for a mass loading of 10.0 mg cm−2 at 2.0 A g−1, when the capacitance of bare graphite was subtracted. The two-electrode supercapacitors composed of both asymmetric and symmetric configurations were also prepared and examined in an acetonitrile/adiponitrile solution of HBF4/TBABF4. The charge–discharge results for asymmetric supercapacitor reveal that the PPy-VOx-CMC composite coating (20 mg cm−2) on V-intercalated graphite paper represents a high energy density of 18 Wh.kg−1 and a high power density of 0.43 kW kg-1 at 0.5 A g−1, as well as a stable cycle life at the potential range of 1.2 V.
Highly energy density olivine LiMn0.7Fe0.3PO4/C composite was synthesized by coprecipitation method followed by ball milling. The composite was characterized by elemental analysis, XRD, SEM, TEM and its electrochemical property was also studied. This electrode presents an enhanced electrochemical intercalation performance of lithium ions, a narrow particle size distribution, and an excellent electrochemical performance. Especially, the coprecipitation method reduces Mn dissolution into the electrolyte, a common problem in LiMnPO4 which influence its energy density, due to the homogeneous distribution of transition metals. The electrochemical performance of LiMn0.7Fe0.3PO4/C and the Mn dissolution rate with long term cycles were investigated by CV and EIS to further understand the intrinsic properties of the high Mn content LiMn0.7Fe0.3PO4/C materials. Our results indicate that homogeneous distribution of Mn and Fe is very important to achieve a higher energy density.
The performance of a divided, parallel-plate zinc–cerium redox flow battery using methanesulfonic acid electrolytes was studied. Eight two and three-dimensional electrodes were tested under both constant current density and constant cell voltage discharge. Carbon felt and the three-dimensional platinised titanium mesh electrodes exhibited superior performance over the 2-dimensional electrodes. The charge and discharge characteristics of the redox flow battery were studied under different operating conditions and Zn/Ce reactant, as well as methansulfonic acid concentration. The cell performance improved at higher operating temperatures and faster electrolyte flow velocities. The number of possible cycles increased at reduced states of charge. During 15min charge/discharge per cycle experiment, 57 cycles were obtained and the zinc reaction was found to be the limiting process during long term operation.
0.7LiFePO4·0.3Li3V2(PO4)3/C composites (LFVP/C) were synthesized via spray-drying technique followed by solid-state reaction approach using polyethylene glycol (PEG) and glucose as carbon sources. The samples were characterized by X-ray diffraction (XRD), X-ray absorption fine-structure spectroscopy (XAFS) and Raman spectroscopy. The results show that the bi-phase composite structure of LFVP/C contains olivine LiFePO4 (LFP) and monoclinic Li3V2(PO4)3 (LVP). The lower intensity ratio of the I D/I G and A sp 3 / A sp 2 for PEG-200 indicates the formation of higher degree of graphitized carbon during the process, which would enhance the electronic conductivity. The composite obtained using PEG-200 as carbon source show excellent rate performance, delivering the discharge capacity of 120mAh/g at the current density of 1.5A/g.