batterydata/paper-abstracts huggingface dataset:
Graphitic carbon fiber felt (GCFF) with a crystalline graphitic carbon structure was facilely prepared by a combination of electrospinning and graphitization (2800 °C heat treatment) and was used as an interlayer between the cathode and separator in Li-S batteries. This GCFF interlayer trapped the polysulfides on the cathode side and increased the utilization of sulfur by suppressing the shuttle phenomenon. Also, the GCFF was shown to be able to act as an upper current collector to reduce the charge-transfer resistance owing to the high crystallinity of the graphitic carbon fibers. The sulfur cathode with the GCFF interlayer showed a high specific initial discharge capacity of 1280.14 mAh g−1 and excellent cycling stability (1004.62 mAh g−1 after 100 cycles) at 0.2 C. Also, an image of the glass fiber (GF) separator on the anode side confirmed the presence of an SEI after 200 cycles, which apparently resulted from stable Li deposition on the Li metal because of the low or medium concentration of sulfur in the electrolyte solution. Our observations should contribute to elucidating the key features of complex three-dimensional carbon fabrics with crystalline graphitic structures that allow them, when inserted as interlayers, to markedly improve the performance of rechargeable batteries.
In this work, we studied the hydrogen storage properties of some La0.1Sr0.9Co1−y Fe y O3−δ perovskite oxides for the application in Ni–H batteries. Sr-doped La0.1Sr0.9FeO3−δ (LSF), La0.1Sr0.9CoO3−δ (LSC) and La0.1Sr0.9Co0.8Fe0.2O3−δ (LSCF) oxides were synthesized by conventional solid state method and were selected as anode materials for Ni–H battery. Their electrochemical hydrogen charge/discharge properties of oxide electrodes were investigated and exchange current density and proton diffusivity were calculated using linear polarization measurement and the potential-step method, respectively. X-ray photoelectron spectroscopy (XPS) analysis was used to show the changes in oxidation states of transition metal ions during charging/discharging process. The proton diffusion rates for LSF, LSC and LSCF were 6.73×10−17, 1.45×10−16 and 2.16×10−16 cm2 s−1, respectively.
Hybrid structures of carbon nanofibers (CNFs) and activated carbon (AC) have been fabricated using natural potato starch as the substrate for in situ growth of the CNFs. Iron nitrate was used as both the activation agent and the catalyst precursor. The AC was derived from potato starch and the CNFs grew from the surface of AC. The hybrid structure has a large specific surface area (approximately 1930m2 g−1) and exhibits excellent electrochemical properties as supercapacitor for electrode materials. Its capacitance reaches a peak value of 268Fg−1 with an excellent cyclical ability, which is attributed to the unique hybrid structure, large specific surface area, and the high electron conductivity of CNFs grown in situ with AC. These low cost, eco-friendly CNF/AC hybrid structures are promising for energy storage.
The iron-containing electrode material is a promising candidate for low-cost Na-ion batteries. In this work, the electrochemical properties of Fe3O4 nanoparticles obtained by simple hydrothermal reaction are investigated as an anode material for Na-ion batteries. The Fe3O4 with alginate binder delivers a reversible capacity of 248mAhg−1 after 50 cycles at a current density of 83mAg−1 (0.1C), while the electrode using polyvinylidene fluoride binder shows a gradually capacity fading to 79mAhg−1 after 50 cycles. The high electrochemical performance can be ascribed to both the nano size of Fe3O4 and excellent binding ability of alginate binder which can buffer large volume change. The mechanism of conversion reaction for Fe3O4 is also tracked by combining electrochemical impedance spectroscopy analysis and magnetization measurement after electrochemical cycling. Finally, the Na-ion full cell consisting of the Fe3O4-alginate anode and the Na3V2(PO4)3/graphene cathode is assembled to demonstrate performance of the Fe3O4 anode for Na-ion batteries.
A new approach for scalable synthesis of three-dimensional graphene (3d-G) with the assistant of silica is reported. Silica is generated on the surface of graphene oxide through a facile solution reaction. Graphene coated by silica is reduced through thermal reduction. 3d-G can be obtained after the subsequent etching process. The structures and morphologies of samples are investigated. It is demonstrated that the agglomeration of individual graphene sheets during the thermal reduction is effectively avoided under the perfect protection of silica. The electrochemical studies of the material show a significant enhancement in the specific capacity and rate capability of the lithium ion battery over commercially available graphite electrodes due to its unique 3D cross-linked graphene architecture. This method enables us to develop a facile and effective approach to scalable preparation of graphene.
Copper sulfide (CuS) nanorods with the size of sub-10 nm are synthesized via a facile sol–gel method without post–thermal treatment. The as-prepared CuS nanorods are characterized by X-ray diffraction, transmission electron microscope, and energy dispersive X-ray spectroscopy as hexagonal covellite CuS. The as-prepared CuS nanorods utilized as anode material exhibit a high reversible capacity and excellent cycling stability up to 250 cycles, as well as high Coulombic efficiency. The unique structure of the CuS nanorods should be responsible for their excellent electrochemical performance.
The performance and thermal response of large-scale GS-Yuasa LEV50 50-Ah NMC automotive battery cells were investigated via simulation. To evaluate local transient temperature distributions, the Dualfoil model was coupled to local energy-balance equations. At similar C rates the difference between maximum and minimum temperature in the LEV50 was found to be higher than that in an 18650 cell with identical chemistry. Unlike thinner prismatic lithium ion batteries, the temperature variation through the cell thickness in the large-format cell was not negligible (∼5 °C at 4C discharge). Because of the non-uniform temperature distribution within the jellyroll, the risk of lithium plating at high charging rates and low ambient temperatures may be greater toward the jellyroll exterior. Simulations of thermal abuse (oven test) of the large cell showed a delayed thermal response relative to the 18650, but also indicated a lower onset temperature for thermal runaway.
Although previous research has identified a number of interesting aspects of future thinking in adults, little is known about the developmental trajectory and coherence of future-oriented behaviors during early childhood. The primary goal of this study was to explore these issues by administering a battery of tasks assessing different aspects of future thinking, including mental time travel, delay of gratification, planning, and prospective memory, to 72 preschoolers. Results revealed that performance on all of the tasks increased significantly between 3 and 5years of age. Although most tasks were correlated, suggesting “behavioral” coherence, many of these significant correlations dropped out once age and receptive vocabulary were controlled. These results are discussed with respect to theories about, and measurement of, future orientation.
Li4Ti5O12 was synthesized by a modified and facile sol–gel method with ethylene diamine tetraacetic acid (EDTA) and citric acid (CA) as a bi-components chelating agent. The raw precursor and powders further calcined at various temperatures and holding time were characterized by XRD, FT-IR, TG, BET and SEM. Nano-scale Li4Ti5O12 oxides, with a high phase purity and good stoichiometry, can be obtained at a calcination temperature of 750 °C and higher. The Li4Ti5O12 nanoparticle shows a network morphology with high dispersion, which reached a capacity of 164 and 108 mAh g−1 at 1C and 10C discharge rate, respectively. The result of the cycling performance shows a high capacity maintenance ratio of 97% at 1C and 25 °C after 1000 cycles. Electrochemical lithium intercalation/extraction performance is also evaluated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) at room temperature.
Transient analytical solutions are presented for the overpotential and the voltage for a porous electrode that includes both double-layer charging and a faradaic reaction. In addition, a simplified dynamic model is developed for the same process based on a second order, three-parameter polynomial approximate model. The effects of the parameters such as dimensionless exchange current density, conductivity ratio and applied current density on the voltage and overpotential distribution are presented. Also, using the exact transient solution an expression for the dimensionless interfacial current density is derived and the effects of the parameters mentioned above are presented.
In this study, the formation of an artificial primary solid electrolyte interphase on a fresh Li surface, via reaction with 1-pentylamine (PA), is reported, allowing removing the influence of the metal electrode’s prior history. Electrochemical impedance spectroscopy, galvanostatic cycling, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) are used in order to investigate the effect of PA as solid electrolyte interphase precursor on Li metal. It is shown that pretreating native SEI-free Li metal surfaces with 1M PA in n-pentane sharply decreases the electrode impedance and overpotential with respect to the treatment with only n-pentane. The treatment with 1M PA in n-pentane results in surface roughening, but no increase of dendrite formation upon cycling. However, the use of higher PA concentration (5M) increases impedance and overpotential and leads to dendrite growth.
The sulfonic acid group exhibits considerable ion affinity. The present work therefore synthesizes, a core-shell composite material having a sulfonated polyaniline shell, and a bamboo-derived porous carbon core loaded with sulfur. The thin, homogeneous shell has a thickness of approximately 20 nm. This composite is employed as a cathode material in Li-S batteries and the electrochemical properties of these devices are systematically investigated. This cathode (containing 64.0 wt% S) exhibits a higher initial discharge capacity (1484 mAh g−1 at 0.1 C), improved cycling stability (853 mAh g−1 after 100 cycles at 0.1 C), and remarkable rate performance (810.2, 682.7 and 353.0 mAh g−1 at 2, 3 and 5 C, respectively). These values are superior to those obtained using a polyaniline shell. Electrochemical impedance spectroscopy and density functional theory calculations are used to elucidate the internal mechanisms of the sulfonated polyaniline shell during cycling. The calculated results demonstrate that the shell possesses extremely high electron and Li ion conductivities, and so enhances the redox reaction kinetics during long-term cycling. It also physically confines and chemically anchors polysulfides, thus limiting the shuttle effect. This cathode design is expected to assist in the future commercialization of Li-S batteries.
Many security problems in smartphones and other smart devices are approached from an anomaly detection perspective in which the main goal reduces to identifying anomalous activity patterns. Since machine learning algorithms are generally used to build such detectors, one major challenge is adapting these techniques to battery-powered devices. Many recent works simply assume that on-platform detection is prohibitive and suggest using offloaded (i.e., cloud-based) engines. Such a strategy seeks to save battery life by exchanging computation and communication costs, but it still remains unclear whether this is optimal or not in all circumstances. In this paper, we evaluate different strategies for offloading certain functional tasks in machine learning based detection systems. Our experimental results confirm the intuition that outsourced computation is clearly the best option in terms of power consumption, outweighing on-platform strategies in, essentially, all practical scenarios. Our findings also point out noticeable differences among different machine learning algorithms, and we provide separate consumption models for functional blocks (data preprocessing, training, test, and communications) that can be used to obtain power consumption estimates and compare detectors.
Despite great interest in a Li–S battery, soluble polysulfides as charge/discharge intermediates pose an important challenge to realize commercial Li–S batteries. For building physical barriers to reduce a diffusional loss of those species, chemical surface-trap-sites have been proposed, but experimental evidence about the trapping interaction hasn't been reported. Here, highly crosslinked polymer-electrolyte coating layers with electron-donating groups were designed to bind lithium polysulfides. An ester group with a high spatial density was shown to be a strong candidate to bind lithium polysulfides. Spectroscopic evidence for the presence of lithium bonds between the lithium polysulfides and the electron-donating groups is reported for the first time. An electrochemical charge/discharge model is also proposed, which can explain the electrochemical behavior within the insulating polymer layer.
Bowl-like nanostructures of Pt/Pd bimetallic nanocrystals are prepared by employing Ag nanoparticles as a template and completely removing the residual Ag after the displacement. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations display that the thin walls of Pt/Pd nanobowls are composed of nanoparticles. X-ray diffraction (XRD) pattern demonstrates that Pt and Pd form the alloy in the nanobowls. The crystal structures of the nanobowls consist of [111], [200], [220] surfaces as revealed by both high-resolution TEM (HRTEM) and XRD results. The Pt/Pd nanobowls exhibit significant high electrocatalytic activities toward the methanol oxidation and oxygen reduction compared with the Pt/Pd nanospheres and Pt nanobowls.
The present study explores H2V3O8 as high capacity cathode material for lithium-ion batteries (LIB's). Despite having high discharge capacity, H2V3O8 material suffers from poor electrochemical stability for prolonged cycle life. Ultra-long H2V3O8 nanobelts with ordered crystallographic patterns are synthesized via a hydrothermal process to mitigate this problem. The growth of the crystal is facile along [001] direction, and the most common surface is (001) as suggested by Wulff construction study. Electrochemical performance of H2V3O8 cathode is tested against Li/Li+ at various current rates. At 50 mA g−1current rate, it delivers a discharge capacity of 308 mAh g−1, whereas, at 3000 mA g−1, an initial discharge capacity of 144 mAh g−1 is observed and stabilized at 100 mAh g−1 till 500 cycles. Further, the density functional theory (DFT) based simulations study of both the pristine and lithiated phase of H2V3O8 cathode materials is undertaken. DFT study reveals the presence of hydrogen as hydroxyl unit in the framework of the host. In correlation, the magnetic property of vanadium atoms is examined in detail with through partial density of states (PDOS) calculation during three stage lithiation processes and evaluating various potential steps involved in lithium insertion.
The epidemiologic evidence for the carcinogenicity of lead is inconsistent and requires improved exposure assessment to estimate risk. We evaluated historical occupational lead exposure for a population-based cohort of women (n=74,942) by calibrating a job-exposure matrix (JEM) with lead fume (n=20,084) and lead dust (n=5383) measurements collected over four decades in Shanghai, China. Using mixed-effect models, we calibrated intensity JEM ratings to the measurements using fixed-effects terms for year and JEM rating. We developed job/industry-specific estimates from the random-effects terms for job and industry. The model estimates were applied to subjects’ jobs when the JEM probability rating was high for either job or industry; remaining jobs were considered unexposed. The models predicted that exposure increased monotonically with JEM intensity rating and decreased 20–50-fold over time. The cumulative calibrated JEM estimates and job/industry-specific estimates were highly correlated (Pearson correlation=0.79–0.84). Overall, 5% of the person-years and 8% of the women were exposed to lead fume; 2% of the person-years and 4% of the women were exposed to lead dust. The most common lead-exposed jobs were manufacturing electronic equipment. These historical lead estimates should enhance our ability to detect associations between lead exposure and cancer risk in the future epidemiologic analyses.
An integrated stress model is developed to study the cycling effect on the commercial Li x C6 electrode, which has bridged the stress/strain analysis with the battery internal multi-transport processes. A Li x C6-Li y Mn2O4 cell is utilized as a physical base, and the battery charging-discharging induced SEI film growth are included in the model development. The important factors including depth of discharge, charging-discharging rate, cooling conditions, end of battery charge voltage as well as the particle packing pattern are investigated in the cycling operation. Results show that both the thermal stress and the chemical stress increase with the battery cycling, and the maximum local stresses are present in the middle of the Li x C6 particles and the interfaces. The potential of fracture can be raised by the elevated battery temperature and lithium concentration gradient. A denser packed Li x C6 electrode can reduce the maximum local stress in the electrode particles, and can improve the stability of the electrode structure in the cycling by flattening the local stress/strain distribution.
Binder-free Ni(OH)2/carbon nanofiber composites used as supercapacitor electrodes were fabricated through the chemical precipitation of Ni(OH)2 on electrospun carbon nanofibers. These composites exhibited a hierarchical structure in which Ni(OH)2 nanoflakes connected with the carbon fiber network. We varied the annealing temperature to investigate the morphological progress and the subsequent electrochemical performance of the composite fibers. The hierarchical structure remained unchanged when the annealing temperature was lower than 300°C. At 350°C, most Ni(OH)2 was converted to NiO, and NiO peeled off from the fiber surface, forming NiO microparticles. Electrochemical measurements revealed that the specific capacity of the Ni(OH)2/carbon nanofiber composites increased with an increase in the annealing temperature and reached a maximum of 455C/g at 300°C. In addition, the Ni(OH)2/carbon nanofiber composites exhibited a favorable cycling stability after 2000 cycles without fading. The electrochemical performance of the composites was satisfactory because of the synergetic effect of the faradaic behavior of Ni(OH)2 and easily accessible electron transport in the carbon nanofiber network. At 350°C, the peeling off and aggregation of NiO microparticles caused a reduction in the specific capacity of the Ni(OH)2/carbon nanofiber composites.
We report the performance of a hydrogen–chlorine electrochemical cell with a chlorine electrode employing a low precious metal content alloy oxide electrocatalyst for the chlorine electrode: (Ru0.09Co0.91)3O4. The cell employs a commercial hydrogen fuel cell electrode and transports protons through a Nafion membrane in both galvanic and electrolytic mode. The peak galvanic power density exceeds 1 W cm−2, which is twice previous literature values. The precious metal loading of the chlorine electrode is below 0.15 mg Ru cm−2. Virtually no activation losses are observed, allowing the cell to run at nearly 0.4 W cm−2 at 90% voltage efficiency. We report the effects of fluid pressure, electrolyte acid concentration, and hydrogen-side humidification on overall cell performance and efficiency. A comparison of our results to the model of Rugolo et al. [Rugolo et al., J. Electrochem. Soc., 2012, 159, B133] points out directions for further performance enhancement. The performance reported here gives these devices promise for applications in carbon sequestration and grid-scale electrical energy storage.
We have investigated the change in the electronic structure of Li x Mn0.5Fe0.5PO4 through the charge process, especially in the transition metal partial DOS using X-ray absorption and resonant photoemission spectroscopy measurements. The oxidation reaction between Fe2+ and Fe3+ proceeds while the 0.5 Li ions are extracted from LiMn0.5Fe0 .5PO4. Moreover, comparing resonant photoemission spectra of Li x Mn0.5Fe0.5PO4 with those of Li x FePO4, we have found that both spectral line-shapes are almost identical, suggesting that the strong localization of the Fe 3d states in the LiMn0.5Fe0.5PO4 system. On the other hand, in Mn 2p–3d X-ray absorption and resonant photoemission spectra, the Mn oxidation reaction from Mn2+ to Mn3+ partially occurs and Mn 3d states of Li x Mn0.5Fe0.5PO4 remain almost unchanged through the charge reaction. Reflecting the difference in the strength of the interaction between the transition metal Fe or Mn ions and the oxygen ions, it is suggested that although the oxidation from Fe2+ to Fe3+ proceeds largely on Fe ions during the charge reaction from x = 1.0 to 0.5, the charge compensation for the electron exchange mainly occurs not only at the Mn ions but also at the poly-anion sites during the charge reaction from x = 0.5 to 0.
Complex hydrides such as LiBH4 and LiNH2 exceed the gravimetric hydrogen density of transition metal hydrides by one order of magnitude. However, hydrogen in complex hydrides is covalently bound and arranged in subunits e.g. [NH2]− and [BH4]− with a fixed stoichiometry. Along this line of thought, these compounds can be considered as ordinary ionic compounds. The corresponding pseudo-binary phase diagram comprises a great variety of phases with a high ionic mobility of Li-cations as well as pseudo-anions as measured by diffusion gradients. Using this equilibrium preparation method, we are able to discriminate between stable and meta-stable phases such as Li2BH4NH2 formed during high-energy ball-milling. We identify Li2BH4NH2 as a mobile intermediate during phase formation. Hydrogen desorption as relevant for their potential use as hydrogen storage does not take place below 200 °C as measured by gravimetry. In particular amides, but also borohydrides emit hydrogen, and nitrogen and boron, respectively, containing species (NH3 and BHx, respectively). We probe the bulk and surface exchange of hydrogen in such subunits in LiNH2 and Li2BH4NH2 by hydrogen–deuterium experiments. In contrast to bulk exchange, surface exchange processes occur at very low temperatures – lower than a significant decomposition rate but coincidentally with the appearance of Li2NH comprising high ionic conductivity. The rate limiting step is thus the bulk transport – in agreement with the empirical correlation that the mobility of ions is linked to the hydrogen desorption kinetics of a material (P. A. Anderson et al., Faraday Discuss., 2011, 151, 271–284). However, the bulk transport of ionic species competes with the diffusion of neutral species such as ammonia, being the origin of the unwanted emission of NH3. These results are discussed with respect to the ionic mobility of borohydride and amide materials.