batterydata/paper-abstracts huggingface dataset:
High cost, scarcity, and detrimental environmental effect of the noble-metal based catalysts have prompted the seek of less expensive, more benign, and earth abundant substitutes for energy conversion and storage. Here, we demonstrate a novel multifunctional electrocatalyst constructed by pyrolysis of the complex of polyaniline (PANI) and metal organic framework [Co-based MOF; zeolitic imidazolate framework (ZIF-67)]. The resultant PANI/ZIF-67 complex unveiled excellent electrocatalytic activities towards oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) in alkaline medium. It was found that the catalytic activities of the PANI/ZIF-67 complex towards ORR, OER and HER could be tuned by simple changing the weight ratio of PANI to the MOF. Further, we tested the material as an air electrode for a primary zinc-air battery, demonstrating an open-circuit potential of 1.42V and a peak power density of ~ 45mWcm−2 - both are superior to those of its counterpart of the Pt/C air-electrode. The excellent multifunctional catalytic activities of the PANI/ZIF-67 are mainly attributed to the synergistic combination of cobalt nanoparticles, Co3O4, and nitrogen doped carbon from the PANI/ZIF-67 complex after pyrolysis.
This study reports the development of multiwalled carbon nanotube (MWCNT)-LiMn2O4 nanocomposites by a facile sol–gel method. The elemental compositions, surface morphologies and structures of the nanocomposites are characterized with a view to their use as cathode materials for Li-ion batteries. The results indicate that the nanocomposite consists of LiMn2O4 nanoparticles containing undamaged MWCNTs. The nanocomposites show high cycle performance with a remarkable capacity retention of 99% after 20 cycles, compared with LiMn2O4 nanoparticles with a 9% loss of the initial capacity after 20 cycles. Measurements of a.c. impedance show that the charge-transfer resistance of the nanocomposites is much lower than that of spinel LiMn2O4. A cyclic voltammetry study further confirms higher reversibility of the nanocomposites compared with LiMn2O4 particles. The enhanced electrochemical performance of the nanocomposites is attributed to the formation of conductive networks by MWCNTs that act as intra-electrode wires, thereby facilitating charge-transfer among the spinel LiMn2O4 particles.
A photocatalyst that uses optical radiation — which makes up 43% of solar energy — has been developed at the National Institute of Advanced Industrial Science and Technology, Japan. A reliable source of hydrogen is one of the key aims of energy production — as hydrogen releases lots of energy when it burns and the only has water as a by-product. Previous catalysts only responded to ultraviolet radiation, which accounts for just 4% of the Sun's energy
Manganese (Mn) is an essential nutrient; however, overexposure can be neurotoxic. Recent evidence suggests that exposure to Mn from drinking water could be neurotoxic; however, research is hampered by the lack of consensus on a reliable biomarker of Mn exposure. Naturally high concentrations of Mn can occur in groundwater, particularly for private, unregulated water systems. This study aimed to investigate the association between exposure to Mn from drinking water with a relatively low Mn content (median of 2.9 μg/L; range, undetectable–8,340 μg/L) and Mn in toenails from women collected at two time points: during and after pregnancy. Mn concentrations in the paired toenail samples gathered during the second to third trimester of pregnancy and 2 weeks postpartum were correlated (r = 0.47, p < 0.001, n = 596). Among women consuming drinking water Mn in the highest tertile (i.e., > 9.8 μg/L) significant positive correlations were found between water Mn and toenails Mn (r = 0.31 and r = 0.38, for toenail samples collected during pregnancy and postpartum, respectively), whereas little to no correlation was observed at lower water concentrations. Overall, our data suggest that maternal toenail samples are a reliable environmental Mn exposure biomarker and reflect exposure from drinking water.
Controlling the crystallographic structure in olivine lithium phosphates is crucial for obtaining superior electronic (J. Electrochem. Soc., 2002, 149, A1184-A1189) and ionic conductivities (Electrochem. Solid-State Lett., 2006, 9, A352-A355; Electrochem. Solid-State Lett., 2006, 9, A439-A442; Nat. Mater., 2002, 1, 123-128), and stability, for use as cathodes in lithium batteries. Here, we report a completely new approach to enhance Li+ extraction and transport in LiCoPO4 through Fe doping. We show that preferential Fe occupation of the 4c sites suppresses 4a–4c antisite mixing of Li and Co, thereby stabilizing the olivine structure by compensating for the Co-encapsulating oxygen octahedron shrinkage due to Co2+ oxidation during Li+ extraction. The structural stabilization gives rise to ∼10% higher charge capacity at a two-fold lower resistance than the undoped counterparts besides accelerating the intercalation/extraction kinetics. Our findings provide key atomistic-level insights that pave the way for the rational design and realization of new types of metal-doped cathode materials for lithium batteries and related applications.
Demand-side flexibility from smart appliances and passenger electric vehicles has been increasingly regarded in recent years as an effective measure to reduce peak loads and to aid system balancing. While numerous studies have been undertaken to investigate the benefits of demand-side flexibility, most have either focused only on the power sector or provided a snapshot for a future year or day. The influence of interactions between sectors in the long-term under energy transition pathways has therefore been under explored. This paper presents a novel modelling approach in a whole energy systems model, UK TIMES, to investigate the benefits of demand-side flexibility from smart appliances and passenger electric vehicles, including the reduction in the costs of moving to a low carbon economy. This analysis shows that demand-side control increases system flexibility, enabling the integration of high levels of low carbon power, such as nuclear and wind, whilst reducing the requirements for storage. By 2050, the peak load is reduced by around 7 GW (9%), and cumulatively about 30.9 billion GBP saved with the help of this demand-side flexibility. This approach could be integrated into other energy systems models to improve the representation of this important flexibility mechanism.
Small, stand-alone, direct methanol fuel cells (DMFCs) that have no auxiliary liquid pumps and gas blowers/compressors are known as passive DMFCs. The devices are ideal for powering portable electronic devices, as this type of fuel cell uniquely has a simple and compact system and no parasitic power losses. This article provides a comprehensive review of experimental and numerical studies of heat and mass transport in passive DMFCs. Emphasis is placed on the mechanisms and key issues of the mass transport of each species through the fuel cell structure under the influence of passive forces. It is shown that the key issue regarding the methanol supply is how to feed high-concentration methanol solution but with minimum methanol crossover through the membrane so that both the system specific energy and cell performance can be maximized. The key issue regarding the oxygen supply is how to enhance the removal of liquid water from the cathode under the air-breathing condition. For water transport, the aim is to transport the water produced on the cathode through the membrane to the anode by optimizing the design of the membrane electrode assembly so that the fuel cell can be operated with pure methanol and with minimum flooding at the cathode. The heat loss from a passive DMFC is usually large and it is therefore critically important to reduce this feature so that the fuel cell can be operated at a sufficiently high temperature, which critically affects the cell performance.
Organic cathode materials have owned wide range of research interests for lithium ion batteries (LIBs) owing to their higher theoretical storage capacities, safety advantage, desirable fabrication at molecular level and significant sustainability. However, the dissolution of active materials into electrolyte results in short cycle life and low rate capacity which are inevitable obstacles to the industrialization. The organic species in carbon materials like active carbon, carbon nanotubes and graphene, cannot be stabilized in electrolytes due to their weak interactions. Here, we report a novel organic cathode design to fabricate long-cycle life LIBs. The organic cathode relies on the ionic interactions between positively charged N,N′-bis(2-N,N-dimethylaminoethyl)-3,4,9,10-perylenebis(dicarboximides) (PDI) and negatively charged graphene oxide (GO). In this design, the carbon matrices can load significant amount of organic molecules and can develop the interactions with electrolytes for a long time. The exclusive design can assemble the organic PDI LIBs with reversible capacity higher than 81 mA h g-1 with excellent cyclability at 25 mA g−1. Moreover, the reversible capacity is sustained up to 28.4 mA h g-1 at a higher current rate 500 mA h g-1. The current investigations confirmed that the proposed strategy can be effective for hundreds of organic materials which have been ignored in past owing to their poor cyclability, and now these can be reinvestigated under the consideration of ionic interactions.
Here we report novel zinc ion conducting polymer electrolytes based on oligomeric polyether/PVDF-HFP blends with or without the incorporation of a small amount of organic carbonates. Their thermal properties, ionic conductivity and electrochemical properties are characterized and the effect of different Zn salts and incorporation of a small amount of organic carbonates are investigated. These polymer electrolyte membranes exhibit essentially no or very low volatility, high thermal stability, high ionic conductivity, wide electrochemical stability window, acceptable interfacial resistance with zinc, and the capability for reversible Zn plating/stripping. Particularly promising are electrolyte systems based on the combination of low lattice energy zinc imide salt and a special co-solvent of oligomeric poly(ethylene glycol) dimethyl ether (PEGDME) mixed with a small amount of ethylene carbonate (EC), dimensionally stabilized with PVDF-HFP. Such novel polymer electrolyte membranes could lead to the development of new kinds of electrochemical energy storage devices based on zinc electrochemistry, including solid-state, thin-film rechargeable zinc/air cells envisaged.
Ferrocene compounds are promising redox shuttles for application in dye-sensitized solar cells (DSCs). Chemical modification of the cyclopentadienyl rings is easily achievable affording almost unlimited variation of the redox properties. This allows fine-tuning of the driving force for dye-regeneration and optimization of the energy conversion efficiency of DSCs. Herein, six ferrocene derivatives have been chosen for investigation which cover the large redox potential range of 0.85 V, by virtue of simple alkylation and halogenation of the cyclopentadienyl ring, and enable improved matching of the energy levels of the sensitizer and the electrolyte. Although the focus of this work was to examine the effect of the redox potential on charge transfer processes, DSCs were fabricated which achieved high energy conversion efficiencies of over 5%. Charge transfer reactions were studied to reveal the dependence of the dye regeneration rate, recombination losses and recombination pathways on the reaction driving force. An increase in redox potential led to a higher efficiency due to higher open circuit potentials until a threshold is reached. At this threshold, the driving force for dye regeneration (18 kJ mol−1, ΔE = 0.19 V) becomes too small for efficient device operation, leading to rapid recombination between the oxidized dye and electrons in the TiO2 conduction band. As a result of this work guidelines can be formulated to aid the selection of redox couples for a particular sensitizer in order to maximize the utilization of incident solar energy.
Li2CoSiO4 has been prepared successfully by a solution route or hydrothermal reaction for the first time, and its electrochemical performance has been investigated primarily. Reversible extraction and insertion of lithium from and into Li2CoSiO4 at 4.1V versus lithium have shown that this material is a potential candidate for the cathode in lithium ion batteries. At this stage reversible electrochemical extraction was limited to 0.46 lithium per formula unit for the Li2CoSiO4/C composite materials, with a charge capacity of 234mAhg−1 and a discharge capacity of 75mAhg−1.
The 2LiFePO4·Li3V2(PO4)3/C samples are synthesized through spray drying method. Glucose and oxalic acid are used as collaborative carbon sources to improve the electrochemical performance of 2LiFePO4·Li3V2(PO4)3/C composites. XRD results reveal the LiFePO4·Li3V2(PO4)3/C samples are composed of orthorhombic LiFePO4 and monoclinic Li3V2(PO4)3 phases. SEM results reveal that the nano-spherical Fe4(VO4)4·5H2O are about 80 nm and the 2LiFePO4·Li3V2(PO4)3/C composites possess a micro-nano spherical morphology with carbon coating layer. The samples show the best electrochemical performance when the mass ration of glucose and oxalic is 6:4, it can deliver a capacity of 147.6 mAh g−1, 145.0 mAh g−1, 134.1 mAh g−1 and 123.0 mAh g−1 at the rates of 0.1C, 1C, 5C and 10C, respectively.
Oriented nanochannel niobium pentoxide (Nb2O5) films with different geometries were prepared via the anodization of Nb foils, and the electrochemical lithium storage kinetics for batteries and hybrid supercapacitors were investigated using cyclic voltammetry. The morphology and crystal structure of the nanoporous Nb2O5 films were examined by X-ray diffraction analysis and scanning and transmission electron microscopies. Analyses of the cyclic voltammograms indicated that the film morphology, including the pore size and film thickness, significantly affects the Li insertion and extraction kinetics. Furthermore, electronic transport through the nanochannel film appears to become a major limiting factor for reversible lithium storage as both the potential sweep speed and film thickness increase. To enhance the electrochemical lithium storage kinetics in the ordered nanochannel Nb2O5 films, the use of a conductive material coating and phase transformation are suggested.
New vanadate compounds having the molecular structure Li x Mg1−x V2−x Mo x O6 (0≤ x ≤1) were studied. Six samples were prepared by sol–gel process from precursor using the following ratios of x =0, 0.2, 0.4, 0.6, 0.8 and 1, respectively. These samples were labeled S1, S2, S3, S4, S5 and S6. The final process of firing occurred at 750°C for 18h in air. The prepared materials were characterized by XRD, SEM, IR, electron spin resonance (ESR) and magnetic measurements. The morphologies of S1, S2, S5 and S6 are prismatic as they have monoclinic crystal structures. S3 and S4 differ in the crystal morphology from the other previous samples due to their triclinic crystal lattice structure. IR spectra revealed that the bond lengths of the vanadyl groups ν VO, ν sy V–O and σ V–O increase in the same direction from S1 to S6. The data of the ESR explain the existence of V4+ beside V5+ in S1, S4 and S6 and also presence of Mo5+ with Mo6+ in S4 and S6. S4 exhibited better magnetic susceptibility and saturated magnetization than the other samples. The first specific discharge capacities of the samples were performed. S4 showed the maximum specific capacity of 265mAhg−1 in comparison with the other samples. Cyclic voltammogram of S4 exhibited the highest current intensity in comparison with the other samples. This sample showed two peaks at 0.53 and 1.3V versus Li/Li+ characterizing double de-insertions of two lithium atoms from Li1.6Mg0.4V1.4Mo0.6O6−x and Li0.6Mg0.4V1.4Mo0.6O6, respectively. Also, two additional peaks were characterized for the oxidation of Mo5+ to Mo6+ and V4+ to V5+ at 3.5 and 4V, respectively.
Germanium-based multimetallic-oxide materials have attracted significant attention as high-capacity anodes for next generation lithium-ion batteries (LIBs). However, they suffer from poor cyclic stability due to extreme volume expansion and reduced electrical conductivity after repeated cycles. To circumvent these issues, we propose that Ge-based multimetallic-oxide nanowires can be synthesized with electrically conductive carbon to significantly enhance the cyclic stability of the Ge-based anodes. We prepare conformal-carbon-coated Zn2GeO4 nanowires (NWs) using a microwave-induced hydrothermal method with subsequent thermal decomposition. The obtained carbon-coated Zn2GeO4-NW anode exhibits a discharge capacity of 485 mAh/g and a Coulombic efficiency (CE) of 98.4% after 900 cycles at 0.6C. Furthermore, these anodes exhibit outstanding rate-capability characteristics, even with an increased C-rate of 17.7C. This excellent electrochemical performance can be ascribed to the improved electron and ion transport provided and the structurally reinforced conductive layer comprising a conformal carbon layer. Therefore, it is expected that our approach can also be applied to other multimetallic-oxide materials, resulting in large, reversible capacities; excellent cyclic stabilities; and good rate capabilities for high-performance LIBs.
A micro-scale rod-like heterostructure derived from molybdenum-based metal organic framework (Mo-MOF) has been successfully prepared via subsequent annealing treatment, which assembled from N-doped carbon encapsulated MoSe2 nanosheets grown on the surface of MoO2 microrod (named as MoO2@MoSe2@NC). For this novel heterostructure, the MoO2 nanoparticles assembled into rod core not only serve as supporting substrate for facilitating the fast kinetics of Li+ cations inside the electrode but also protect the MoSe2 structure from restacking in the charge/discharge process. Moreover, the outer-layered MoSe2 nanosheets enable the fast lithium ion movement owing to its large interlayer spacing. Moreover, this unique rod-like core–shell structure composite could further effectively alleviate the structural strains caused by large volume expansion during charge/discharge process, thus leading to stable electrochemical performance when evaluated as anode material for lithium ion batteries. Electrochemical testing exhibits that the MoO2@MoSe2@NC heterostructure presents highly reversible capacity of 468 mAh g−1 at 0.5 A g−1 and superior rate capability (318 mAh g−1 even at 5.0 A g−1), which is attributed to the synergistic effect of N-doped carbon encapsulated MoSe2 nanosheets and MoO2 nanoparticles.
Electrochemical double layer capacitors (EDLCs) are conceived as high power devices. Generally, power improvement is mainly related to lowering the device impedance (P max = V 2/4R). However, the supercapacitor impedance is the sum of several contributions (electrolyte, active material, contact between the active material and the current collector, electrode porosity). In this work we demonstrate that the resistance at the interface between the electrode and the current collector and as well the diffusion resistance can be properly controlled during the electrode preparation. In our preparation method the electrodes are compacted by using a hot-press device. During the electrode fabrication parameters such as temperature and pressure are systematically modulated in order to find the best condition for increasing the contact between the electrode and the current collector while maintaining good electrode porosity.
The ambient dissipated energy such as the vast scale of mechanical energy in the agricultural system (e.g., leaf swing energy) and the writing motion existing extensively in our daily life are underutilized. Herein, to address these issues and overcome the limitations of conventional batteries, we fabricated a highly flexible and effective triboelectric nanogenerator (TENG) based on MXene and polydimethylsiloxane (PDMS) composite (PDMS/MXene) film and laser-induced graphene (LIG) electrode. The introduction of conductive and electronegative MXene into PDMS to fabricate porous film, not only enhances the electrical conductivity but also increases the triboelectronegativity. As a result, the output performance is significantly improved, 7-fold greater than the pure flat PDMS-based TENG. The developed TENG with excellent performance, considerable adhesion, and outstanding flexibility was successfully applied for harvesting leaf swing energy and being used as a writing board to collect writing energy. Furthermore, we developed a MXene-based TENG array acting as a self-powered sensor for handwriting recognition. In this regard, MXene-enabled TENG possesses a great promising in harvesting mechanical energy from the agricultural field (e.g., leaf swing energy) and human activities (e.g., writing), moreover, it can further be applied in writing or tactile sensing for pad, robotics, and man-machine interaction field.
We investigated an electrochemical reaction on the cathode surface of an overcharged Li[Ni0.45Co0.18Mn0.25Al0.12]O2/Li system at the molecular level by using Raman, X-ray absorption spectroscopy (XAS), and 2D hetero-spectral correlation analyses. Changes in the Raman spectra during the overcharging process showed that variations in the local atomic environment occurred with increasing extraction of Li+ ions. XAS spectra obtained during the overcharging process showed that oxidized transition metals coexisted with inoxidizable transition metals. Additionally, synchronous 2D hetero-spectral Raman/XAS correlation spectra clearly elucidated the correlation between the Raman and XAS bands, confirming their band assignments.
The performance of 2,5-dimethoxy-1,4-benzoquinone (DMBQ) as an active material for rechargeable lithium batteries was investigated. A positive-electrode that incorporated DMBQ showed an initial discharge capacity of 312mAhg−1 with an average voltage of 2.6V vs. Li+/Li. This discharge capacity corresponds to a benzoquinone-based two-electron redox behavior, and is more than twice that of the conventional positive-electrode material lithium cobalt oxide (LiCoO2). Furthermore, the positive-electrode with DMBQ showed fair cycle-life performance. Theoretical quantum calculations based on the density functional theory (DFT) were also performed to clarify the mechanism of the electrochemical properties of the solid state of DMBQ.
During the preschool years, children’s development of skills like language and communication, executive functions, and socioemotional comprehension undergo dramatic development. Still, our knowledge of how these skills are enhanced is limited. The preschool contexts constitute a well-suited arena for investigating these skills and hold the potential for giving children an equal opportunity preparing for the school years to come. The present study compared two pedagogical methods in the Swedish preschool context as to their effect on language and communication, executive functions, socioemotional comprehension, and early math. The study targeted children in the age span four-to-six-year-old, with an additional focus on these children’s backgrounds in terms of socioeconomic status, age, gender, number of languages, time spent at preschool, and preschool start. An additional goal of the study was to add to prior research by aiming at disentangling the relationship between the investigated variables.