batterydata/paper-abstracts huggingface dataset:
We have successfully prepared three dimensional carbon nanotube foams (CNTF) by a simple environmental-friendly method. However, the as-grown CNTF shows a high electrical conductivity but a reduced specific surface area which limits its application as electrode materials in energy storage devices. In this work, the as-grown CNTF has been activated by using certain concentration of KOH aqueous solution. The results indicate that activation can enlarge the specific surface area by producing new pores with sizes from micropore to macropore, but give no important change in shape and size of the CNTF. We take the activated CNTFs as electrodes for supercapacitors and lithium-ion batteries respectively, and find that activation can clearly enhance the specific capacities and rate properties due to the enhanced specific surface area and hierarchical porous structures. The activated three dimensional CNTF materials can also be used as supporters for other active materials indicating a potential application prospects.
Electronic and ionic conductivities of active materials are the fundamental properties in determining the dynamical behavior and rate performance of batteries, yet, they are typically hard to be distinguished due to the convolution of the two conduction processes, the complexity of the dynamic responses in composite electrodes, and other extrinsic factors such as porosity and interfacial effects. Herein, we report a simple and reliable method that combines the electrochemical impedance spectroscopy with direct-current polarization to accurately resolve the electronic and ionic conductivities of conventional layered cathode materials for Li-ion batteries, including LiCoO2 and LiNi1-x-yMnxCoyO2. A significant increase in the electronic conductivity was observed with the increasing Ni content, accompanied by a large decrease in the activation energy. Meanwhile, a similar variation trend in Li+ conductivity was observed, together with a large decrease in the Li+ hopping barrier. These can be attributed to the variations in electronic structure and defect chemistry, the apparent lattice expansion with incorporating Ni, especially along the c-axis, as well as a weakened Li+-transition metal interaction via decreasing the Mn4+ content.
Adopting inorganic solid electrolytes (ISEs) is a promising approach to assemble batteries using Li metal anodes because of their superior Li-ion conductivity and high mechanical strength. This approach greatly improves the energy density and the safety of batteries. However, lithium dendrites still can pierce the bare ISE because of inhomogeneous current distributions at interfaces, leading to serious short circuits. This work proposes to reduce the interfacial resistance and prevent lithium dendrite growth simultaneously through in situ formation of interlayers enabled by a conversion reaction of MoS2 layers coated on a bare Li6.5La3Zr1.5Ta0.5O12 (LLZO) pellet. The interfacial resistance is reduced to only 14 Ω cm2, with the overpotential decreasing notably. The critical current density of cells is improved from 0.7 mA cm−2 to 2.2 mA cm−2. Furthermore, short circuits are significantly suppressed above the critical current density with the potential diverging quickly. The cell can be recovered to some extent by applying an inverse potential for a short time. The comparison between XPS and XAS measurements reveals that the nanoscale thin MoS2 layer in contact with the Li anode can be converted into an interlayer composed of Mo and Li2S through the conversion reaction. The sluggish kinetics of the conversion reaction resulting from the poor electronic conductivity makes the in situ-formed interlayer kinetically stable, which can hinder further reaction of MoS2 with Li effectively. Moreover, the in situ reaction could suppress the local tip electric field effect efficiently and make the current distribution more even. This study provides a new strategy to optimize the interface of anodes by screening for more candidates which undergo a conversion reaction.
Li2Zn0.6Cu0.4Ti3O8 anode material was synthesized by a sol-gel method and the precursor calcinations. The sample is characterized by X-ray diffraction patterns (XRD), scanning electron microscope (SEM), Transmission Electron microscopy(TEM), galvanostatic charge-discharge tests, cyclic voltammetry (CV) tests, and electrochemical impedance spectroscopy (EIS). The results shows the nanoparticles were high crystalline and their size was found to be ca. 50–100nm. The electrochemical measurements indicate that the anode material made of Li2Zn0.6Cu0.4Ti3O8 displayed a highly reversible capacity and excellent cycling stability. The initial charge capacities of Li2Zn0.6Cu0.4Ti3O8 are 239.5mAhg−1, 225.8mAhg−1, 217.4mAhg−1,190.5mAhg−1 and 171.6mAhg−1 at 50mAg−1, 100mAg−1, 300mAg−1, 500mAg−1 and 1000mAg−1,respectively. After 50 cycles, the charge capacity of 196.3mAhg−1, 190.1mAhg−1, 177.3mAhg−1, 161.5mAhg−1 and 154.8mAhg−1 could be retained. This indicates that the Li2Zn0.6Cu0.4Ti3O8 material is a promising anode material for lithium-ion batteries.
The health measures within the Standard Shiftwork Index (SSI) do not require responses to be anchored to a specific time frame or shift context. Thus, the validity and sensitivity of these measures, as indicators of the relative impact of different types of shifts (or shift-schedules), are questionable. This study examined self-reports of gastrointestinal and cardiovascular symptoms. Modified versions of the SSI health measures were administered to a sample of 28 rotating shiftworkers to obtain: (1) reports of general, non-shift-specific symptoms; (2) reports of symptoms generally experienced when on the day and night shift (shift-dependent reports); and (3) reports of symptoms obtained immediately following completion of a set of day and night shifts (shift-cycle-dependent reports). Symptom frequencies were reported differentially for day and night shift. General, non-shift-specific reports represented an approximate average of these reports. Furthermore, self-reports of symptoms varied depending on when in the shift-cycle they were reported; night shift symptoms were greater than those on day shift. No differences were detected between retrospective reports of shift-dependent symptoms and reports made immediately following completion of a set of shifts. The implications of the findings were discussed in relation to the formatting of the SSI health measures. Relevance to industry This study is relevant to researchers and managers who require accurate measurement tools to assess and/or develop work schedules that minimize the impact of shiftwork on the health of workers.
Linear sweep and cyclic voltammetry were used for electrochemical characterization of the Pt/sodium-β′′-Al2O3 system and investigation of the phases formed upon electrochemical pumping of sodium ions to the Pt catalyst-electrode under conditions of propane combustion or under mixtures of O2 or CO2 with helium, at temperatures between 320 and 480 °C. The number, position and magnitude of the peaks in the obtained voltammograms were found to depend on gas phase composition, temperature, and pre-scan (initial polarization) conditions. The results showed that under conditions of propane combustion more than one sodium phases can be formed as a result of electrochemical pumping of sodium ions to the Pt catalyst. The related electrochemical reactions and the identity of these sodium phases, which correspond mainly to carbonate or bicarbonate phases but also to oxide phases, are discussed on the basis of the obtained results and those of former studies.
Although hydrogel electrolytes have attracted considerable attentions due to high water retention and low leakage, their vulnerability and low conductivity still pose challenges in large-scale applications. In this work, a mechanically strong and highly conductive poly (acrylic acid) (PAA) electrolyte reinforced by cellulose nanofibrils (CNFs) is developed via versatile blending followed by polymerization. As a result of physical entanglement and hydrogen bonding, the mechanical strength of the PAA electrolyte is enhanced from 0.656 to 1.875 MPa at a CNF loading of 3 wt%, and the dimensional swelling is suppressed to half of its original level. The ionic conductivity of the composite electrolyte is improved by 100% due to excellent ion-transfer paths created by the hydroxyl groups exposed on the surfaces of CNFs. Furthermore, the CNF/PAAs exhibit preferable elasticity and flexibility with the maximum elongation at break reaching greater than 600%. These electrolytes are able to maintain the initial ionic conductivity even after being stretched to 100% elongation for 500 circles. After assembling with an air cathode and an aluminum anode, the as-prepared Al−air battery show good discharging performance, demonstrating promises for applications in portable and flexible electronic devices.
Separators have drawn substantial attention because of their important role in achieving the safety and good electrochemical performance of lithium-ion batteries. In this study, we report a new type of composite membrane prepared by a combination of fluorinated polypropylene (PP) nonwoven fabric, poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) and SiO2 nanoparticles. 2, 2, 3, 3, 4, 4, 5, 5-Octafluoropentyl methacrylate (OFPMA) is first grafted on the surface of PP nonwoven by plasma treatment to improve the nonwoven’s adhesion with PVdF-HFP. Two kinds of composite separators have been prepared by using the different PP nonwovens together with PVdF-HFP and SiO2 nanoparticles. They were separately designated as PHS for commercially raw PP nonwoven system and PHS-n for OFPMA-modified PP nonwoven systems (n means plasma treatment time). The morphology, electrolyte uptake, ionic conductivity and electrochemical properties of the composite separators have been analyzed by scanning electron microscope (SEM) analysis, impedance measurement, charge-discharge cycle and C-rate tests, respectively. The results indicate that PHS-10 composite separator using the modified PP nonwoven treated by plasma for 10min exhibits much better properties than PHS separator, including an improved mechanical property, thermal stability, electrolyte uptake (290wt%) and ionic conductivity (1.76mScm−1). More importantly, the LiFePO4/Li half-cell assembled with PHS-10 composite separator displays a good C-rate performance, which shows an enhancement in the chemical stability and discharge capacity. The capacity keeps above 150mAhg−1 after 100 charge–discharge cycles. These performances endow this composite membrane as a promising candidate for high-performance lithium-ion battery separators.
To meet the rapid development of flexible, portable, and wearable electronic devices, extensive efforts have been devoted to develop matchable energy storage and conversion systems as power sources, such as flexible lithium-ion batteries (LIBs), supercapacitors (SCs), solar cells, fuel cells, etc. Particularly, during recent years, exciting works have been done to explore more suitable and effective electrode/electrolyte materials as well as more preferable cell configuration and structural designs to develop flexible power sources with better electrochemical performance for integration into flexible electronics. An overview is given for these remarkable contributions made by the leading scientists in this important and promising research area. Some perspectives for the future and impacts of flexible energy storage and conversion systems are also proposed.
In this work, electrochemical performance and parasitic losses are combined in an overall system-level efficiency metric for a high performance, all-vanadium redox flow battery. It was found that pressure drop and parasitic pumping losses are relatively negligible for high performance cells, i.e., those capable of operating at a high current density while at a low flow rate. Through this finding, the Equal Path Length (EPL) flow field architecture was proposed and evaluated. This design has superior mass transport characteristics in comparison with the standard serpentine and interdigitated designs at the expense of increased pressure drop. An Aspect Ratio (AR) design is discussed and evaluated, which demonstrates decreased pressure drop compared to the EPL design, while maintaining similar electrochemical performance under most conditions. This AR design is capable of leading to improved system energy efficiency for flow batteries of all chemistries.
We outline the analysis of performance of redox flow batteries (RFBs) using polarization curves. This method allows the researcher immediate access to sources of performance losses in flow batteries operating at steady state. We provide guidance on ‘best practices’ for use of this tool, illustrated using examples from single cells operating as vanadium redox batteries.
Lithium iron phosphate/carbon (LiFePO4/C) microspheres with an excellent multiple conductive network are synthesized using iron (III) acrylate as both iron and carbon sources. The innermost network is constructed by a uniform carbon layer on the surface of LiFePO4 primary nanoparticles, which derives from the carbonation of in-situ polymerized polyacrylic acid (PAA) layer. Moreover, the acetylene black added in spay drying process fills the voids among primary nanoparticles to construct the second conductive network. Finally, the carbon from optimized content sucrose used as binder and linker can interconnect primary nanoparticles together to form the third network. In addition, subtle mesoporous structure is formed inside the multiple carbon conductive network. The highly speed electron transfer and lithium ion transportation can be achieved simultaneously for LiFePO4/C microspheres. All these features contribute to their great rate performance (163.1mAhg−1 at 0.1C and 126.5 mAh g−1 at 5C) and outstanding cycling stability (95.3% of capacity retention after 1000 cycles at 5C/5C). The well-designed LiFePO4/C microspheres with unique structure are very promising cathode materials for rechargeable lithium ion power batteries.
Introduction This study measures the levels of various markers of oxidative stress and inflammation in blood samples from first-episode psychosis (FEP) patients, and examines the association between these peripheral biomarkers and cognitive performance at 6months after treatment. Methods Twenty-eight FEP patients and 28 healthy controls (matched by age, sex and educational level) had blood samples taken at admission for assessment of total antioxidant status, superoxide dismutase (SOD), total glutathione (GSH), catalase (CAT), glutathione peroxidase, lipid peroxidation, nitrites and the chemokine monocyte chemoattractant protein-1 (MCP-1). A battery of cognitive tests was also applied to the healthy controls and those FEP patients who were in remission at 6months after the acute episode. Results FEP patients had significantly lower levels of total antioxidant status, catalase and glutathione peroxidase, compared with the healthy controls. Regression analyses found that MCP-1 levels were negatively associated with learning and memory (verbal and working), nitrite levels were negatively associated with executive function, and glutathione levels were positively associated with executive function. Conclusion Our results suggest an association between certain peripheral markers of oxidative stress and inflammation and specific aspects of cognitive functioning in FEP patients. Further studies on the association between MCP-1 and cognition are warranted.
Side-chain-type polymer architectures have been extensively studied for development of highly conductive fuel cell membranes. However, the commonly used rigid, hydrophobic spacers (between the ionic end-group and polymer backbone) limit self-assembly of ionic side-chains and, therefore, ion transport. Herein, we report a flexible, hydrophilic side-chain-type anion exchange membrane (AEM), where ethylene oxide spacers are incorporated into imidazolium-containing cationic side-chains. AFM and SAXS analysis confirm that the flexible spacers facilitate self-assembly of the ionic side-chains to form continuous conducting channels. Most importantly, both in situ FTIR spectroscopy and molecular dynamic theory simulations indicate that the ethylene oxide spacers are capable of hydrogen bonding to both H2O molecules and hydrated OH− ions. This unique auxiliary function facilitates both ion and H2O transport during fuel cell operation. The resultant AEM exhibits a peak power density of 437 mW cm−2 at 65 °C when tested in a H2/O2 single-cell anion-exchange membrane fuel cell, which is among the highest reported for comparable side-chain-type AEMs.
Polycrystalline samples of CrSb2 have been obtained by direct synthesis and allowed to react with lithium in electrochemical cells of the type: Li∣LiPF6(EC:DEC)∣CrSb2. The cathode contained graphite additives to improve the electrical conductivity of the solid during the first steps of discharge. The discharge of the cell under galvanostatic intermittent titration and continuous discharge at C/4 revealed a main process at ca. 0.6 V leading to the simultaneous destruction of the CrSb2 structure and formation of lithium antimonide, without direct evidence of the topotactic formation of a ternary compound containing lithium. The galvanostatic cycling of the cells reveal capacities above 300 mA h g−1 during the first few cycles and a progressive loss of capacity on prolonged cycling. The performance of the cells shows a significant improvement from the use of pure antimony electrodes, due to the presence of the metallic side product chromium.
The proliferation, cell cycle exit and differentiation of progenitor cells are controlled by several different factors. The chromodomain protein mortality factor 4-like 1 (Morf4l1) has been ascribed a role in both proliferation and differentiation. Little attention has been given to the existence of alternative splice variants of the Morf4l1 mRNA, which encode two Morf41l isoforms: a short isoform (S-Morf4l1) with an intact chromodomain and a long isoform (L-Morf4l1) with an insertion in or in the vicinity of the chromodomain. The aim of this study was to investigate if this alternative splicing has a function during development. We analysed the temporal and spatial distribution of the two mRNAs and over-expressed both isoforms in the developing retina. The results showed that the S-Morf4l1 mRNA is developmentally regulated. Over-expression of S-Morf4l1 using a retrovirus vector produced a clear phenotype with an increase of early-born neurons: retinal ganglion cells, horizontal cells and cone photoreceptor cells. Over-expression of L-Morf4l1 did not produce any distinguishable phenotype. The over-expression of S-Morf4l1 but not L-Morf4l1 also increased apoptosis in the infected regions. Our results suggest that the two Morf4l1 isoforms have different functions during retinogenesis and that Morf4l1 functions are fine-tuned by developmentally regulated alternative splicing. The data also suggest that Morf4l1 contributes to the regulation of cell genesis in the retina.
Background Patient-reported outcomes (PROs) can be part of an electronic routine outcome monitoring (eROM). eROM can improve patient involvement, treatment outcomes and simplify scientific data assessment. Available studies on eROM focus on its evaluation only and lack a detailed description of the prior implementation procedure. Objective The aim was to implement an eROM assessment at a division of Psychosomatic Medicine and provide a detailed description of the implementation procedure. Methods According to the Replicating Effective Program concept the project consisted of 4 phases: pre-condition (1), pre-implementation (2), implementation (3) and maintenance and evolution (4) mainly focusing the description of the implementation procedure and a short evaluation. Results We describe the actions taken during the implementation procedure and steps which were taken to overcome identified barriers. All decisions were carried out based on the Participatory Action Research process. A core set consisting of sociodemographic and clinical data and a comprehensive questionnaire battery covering symptoms, functioning parameters and psychological constructs was implemented. In total 164 patients, took part in the eROM assessment from June 2015 to December 2016. The evaluation showed that eROM was appreciated by health-care professionals (85.2%) and patients (70.2%) alike. The majority of patients (89.4%) and health-care professionals (85.7%) experienced no delays in daily clinical routine due to eROM. Conclusion The detailed description of the implementation process can guide institutions planning to implement eROM into their daily clinical routine. Focusing scientific efforts on the implementation process is essential since this influences all further steps such as evaluation and acceptance.
Herein, we developed a highly conductive and lightweight membrane substrate based on the ethylene–vinyl acetate copolymer (EVA), carbon nanotubes (CNTs) and lens wiping paper, and demonstrated its implementation as high-performance mechanical support for MnO2 in supercapacitors. The 45 s-MnO2/EVA/40 wt%CNT electrode exhibited a high capacitance (0.126 F cm−2 at 0.5 mA cm−2) with excellent flexibility. Furthermore, the fabricated devices based on these 45 s-MnO2/EVA/40 wt%CNT electrodes exhibited excellent flexibility and stability (85% of its initial capacitance retained after 800 bending cycles) and achieved a high energy density of 9.4 Wh kg−1 at 6780 W kg−1.
Battery packs usually consist of multiple individual cells in a series connection, thus the worst cell defines the pack's performance. All cells do age individually causing a spread in cell performance. We will show that not only the local operating conditions, but also variances from within the cell manufacturing process influence the variation of aging trends. By an experiment with 48 cells from a mass production line it can be found that the aging spread cannot be neglected. Using data mining algorithms a dependency between initial cell performance and cycle lifetime is identified. The resulting linear regression model can predict the lifetime and can therefore be used to classify cells into different batches before battery pack production.
Toward a carbon neutral renewable energy conversion and storage device, we present a novel bio-inspired microbial supercapacitor, utilizing unique pseudocapacitance formed by exoelectrogen, a specific species of bacteria named Geobacter spp. grown on single-layer graphene film and 3D graphene-scaffold electrodes. Charging and discharging the microbial supercapacitor were performed by regulating the respiration of the exoelectrogen. Substantially high maximum current and power densities, 531.2A/m2 (1,060,000A/m3) and 197.5W/m2 (395,000W/m3), respectively, are marked. The microbial supercapacitor demonstrates high cycle stability of over 1 million. A specific capacitance of 17.85±0.91mF/cm2 is demonstrated, which is 4.4 fold to 2 orders of magnitude higher than previously reported supercapacitors having graphene-based electrodes, suggesting a promising alternative energy storage device. Furthermore, the microbial supercapacitor was used to deduce quantitative kinetic parameters of extracellular electron transfer (EET) by fitting discharging curves of the supercapacitor, which is critical to fully understand the EET of Geobacter spp. and determining the rate-limiting mechanism. At the initial-stage biofilm, the acetate turnover is the slowest among individual EET steps, whereas for fully-grown stage biofilm, kinetics of both acetate turnover and electron transfer from inside exoelectrogen to extracellular redox cofactors are rate-limiting. Our results also suggest cytochrome c may not be the main electron storage units of a microbial supercapacitor, regardless of initial- or fully-grown stage biofilms.