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LiNi0.8Co0.15Al0.05O2 cathode powders with fine size and spherical shape were prepared by solid-state reaction method using the Ni–Co–Al–O precursor powders with fine size and spherical shape. The Ni–Co–Al–O precursor powders with fine size and filled inner structure were prepared by spray pyrolysis from the spray solution with drying control chemical additive (DCCA), citric acid and ethylene glycol. The one LiNi0.8Co0.15Al0.05O2 cathode powder with fine size and spherical shape was formed from the one precursor powder with spherical shape and filled morphology. The mean size of the spherical shape LiNi0.8Co0.15Al0.05O2 cathode powders was 1.1μm. The initial discharge capacity of the LiNi0.8Co0.15Al0.05O2 cathode powders prepared from the spray solution with citric acid, ethylene glycol and DCCA was 200mAhg−1. The cycle properties of the cathode powders prepared from the spray solution with and without additives were compared.
Individuals who drive under the influence (DUI) of alcohol may be at greater risk for neurocognitive impairment because of their exposure to multiple sources of neurological risk. This could contribute to the persistence of DUI behaviour and influence the effectiveness of remedial interventions. The objectives of this study were to clarify the neurocognitive characteristics of DUI recidivists and the nature of potential impairments, and to explore relationships between these characteristics and the frequency of past DUI convictions. One hundred male recidivists were evaluated for visuospatial constructional abilities and visual memory, verbal fluency, attention skills, cognitive flexibility, spatial planning, and verbal and movement inhibition. Results indicated that a majority of recidivists showed signs of neurocognitive impairment on several dimensions. Impairment was most marked on visuospatial constructional abilities and visual memory. In contrast to previous studies, no participants were found to have impulse control problems. Measures of memory and cognitive efficiency were significantly associated with the frequency of past convictions. Finally, exploratory analyses of two potential sources of impairment, alcohol exposure and head trauma, suggested the role of excessive alcohol use as the most obvious associated factor. Overall, the findings indicate that neurocognitive impairments are a common feature in recidivists and may contribute to DUI persistence. Development of a DUI-specific neurocognitive assessment and greater understanding of how neurocognitive status influences DUI risk could lead to remediation strategies better adapted to the individual characteristics of recidivists.
Ni-rich LiNi0.8Co0.1Mn0.1O2 cathode material possesses advantages of high capacity and low cost, but the rapid capacity decline and power degradation during cycle process at high cut-off voltage limits its large-scale industrialization. Meanwhile, LiVPO4F modified with carbon based hybrid is relatively stable and has excellent electrochemical properties at higher cut-off voltage of 4.4–4.5 V. Based on the idea of secondary modification for cathode material, the LiVPO4F hybrid is used to modify LiNi0.8Co0.1Mn0.1O2 to obtain LiVPO4F-LiNi0.8Co0.1Mn0.1O2 composites. The presence of the LiVPO4F hybrid maintains interfacial stability, suppresses irreversible side reactions and sustains a relatively rapid charge transfer under high voltage. The LiVPO4F modified LiNi0.8Co0.1Mn0.1O2 composites delivers a discharge specific capacity of 140.0 mAh g−1 at high rate of 20 C, and achieves a cycle retention rate of 83.38% at 4.5 V after 150 cycles, revealing that good rate capability and cycling performance of LiNi0.8Co0.1Mn0.1O2 is improved-achieved by surface modification of LiVPO4F even at high cut-off voltage of 4.5 V.
Antimony-carbon nanocomposites are known anode materials for lithium- and sodium-ion batteries that can display an attractively stable cyclic behaviour in half-cells. They can also be used for potassium-ion batteries but a similar stability is not achieved, and electrode failure (abrupt capacity decay) is noted. Here, we probe the failure mechanism in potassium cells using samples with varied Sb particle sizes and weight fractions. A smaller particle size and extra carbon result in a failure in a later cycle. Mechanical degradation is the main reason for capacity drop; the phenomena associated with unstable solid electrolyte interphase are less critical. A number of strategies (an electrolyte additive, the type of a binder and adding an extra alloying element to composites) are explored. The choice of a binder affects the nature of decay and may lead to longer cycling. The inclusion of phosphorus in the nanocomposite coupled with an alternative binder appears to be more effective in improving the cyclic stability; a capacity of above 400 mAh g−1 is achieved in the first 50 cycles. The results demonstrate that the stability of alloying-dealloying anode materials in potassium-ion batteries can be influenced by optimising the composition of these materials and altering a binder.
Increasing usage and recent accidents due to Lithium ion (Li-ion) batteries exploding or catching on fire has inspired research on the thermal management of these batteries. In cylindrical 18650 cells, heat generated during the charge/discharge cycle must dissipate to the surrounding through its metallic case due to the poor thermal conductivity of the jelly roll, which is spirally wound with many interfaces between electrodes and the polymeric separator. This work develops a technique to measure the thermal resistance across the case-separator interface, which ultimately limits heat transfer out of the jelly roll. Commercial 18650 batteries are discharged and opened using a battery disassembly tool, and the 25 μm thick separator and the 200 μm thick metallic case are harvested to make samples. A miniaturized version of the conventional reference bar method (ASTM D5470) combined with infrared thermal microscopy to map the temperature profile including the interfacial temperature jumps enables measurement of the interfacial thermal conductance across a range of case temperatures and interface pressures. The mean thermal conductance across the case-separator interface is 670 ± 275 W/(m2 K) and no significant temperature or pressure dependence on is observed.
In recent decades, several dozen colleges and universities have instituted loan-reduction initiatives (LRIs), such as “no-loan” programs. Institutions frequently cast such initiatives as efforts to increase socioeconomic diversity on campus. Using a difference-in-differences analytic strategy with national institution-level data, we examine the effect of LRI adoption at 54 institutions on three sets of outcomes: student borrowing, admission metrics, and campus diversity. Our analysis suggests LRIs decreased institution-level borrowing rates at private institutions, with no detected change at public institutions. Consistent with stated program goals, LRI adoption increased the number of Pell Grant recipients at both public and private institutions. However, adopting LRIs at public institutions reduced racial/ethnic diversity, suggesting possible trade-offs for LRI adoption in terms of student body diversity.
A novel type of porous TiO2 nanobelts anchored with Sn3O4 nanosheets (TiO2 nanobelts @Sn3O4 nanosheets) core-shell composites were developed via two-step hydrothermal methods. The structure, morphology, formation mechanism and electrochemical performance of the porous TiO2 nanobelts coated with mixed transition-metal oxides Sn3O4 nanosheets core-shell composites were researched. The results illustrated that the Sn3O4 nanosheets were uniformly anchored on the surface of the porous TiO2 nanobelts, which were almost perpendicular to the porous TiO2 nanobelts. The composites as anode materials exhibited more remarkable electrochemical performances than the Sn3O4 nanosheet and the porous TiO2 nanobelts, in terms of the cycling performance and rate capability. The initial discharge capacity was 1513.7 mAh/g and the reversible capacity was 659 mAh/g after 50 cycles. This study perhaps inspired the designing of other transition metal oxide-based anode materials with desirable electrochemical performance for applications of lithium ion batteries.
Surface modification of the electrode improved the performance of the LiNiO2 electrode charged to 4.6V. An amorphous carbon thin film was uniformly deposited on the electrode surface using dc plasma chemical vapor deposition. This surface treatment suppressed electrolyte decomposition during the charge process. When a coin-type cell using this electrode was charged to 4.6V, the charge–discharge efficiency was 84% in the first cycle and 96–98% through the second to fifth cycles. This treatment suggests a new approach to the development of the positive electrode for lithium-ion secondary batteries.
This paper proposes a novel control strategy for a charging station which provides reflex-based fast charging service for electric vehicles through a number of connection ports. Reflex method has distinct advantages compared to other bulk charging methods. It applies a three-stage charge sequence, a positive, negative, and zero battery current for each cycle. Due to uninterrupted drastic changes in the battery currents during the cycles of this method, the charging station encounters an important power quality issue in which phasor of the AC-side terminal current changes significantly and level of the delivered power to the batteries has considerable variations. An ultra-capacitor is connected to it according to a particular topology and then, is controlled according to the novel control strategy in order to resolve the power quality problem.
Electrical power generation is changing dramatically across the world because of the need to reduce greenhouse gas emissions and to introduce mixed energy sources. The power network faces great challenges in transmission and distribution to meet demand with unpredictable daily and seasonal variations. Electrical Energy Storage (EES) is recognized as underpinning technologies to have great potential in meeting these challenges, whereby energy is stored in a certain state, according to the technology used, and is converted to electrical energy when needed. However, the wide variety of options and complex characteristic matrices make it difficult to appraise a specific EES technology for a particular application. This paper intends to mitigate this problem by providing a comprehensive and clear picture of the state-of-the-art technologies available, and where they would be suited for integration into a power generation and distribution system. The paper starts with an overview of the operation principles, technical and economic performance features and the current research and development of important EES technologies, sorted into six main categories based on the types of energy stored. Following this, a comprehensive comparison and an application potential analysis of the reviewed technologies are presented.
Organosulfides (R–Sn–R) exhibit a high theoretical capacity and low cost, but suffer from sluggish kinetics and poor reversibility. Here, we demonstrate an effective and universal strategy to improve their redox activity by replacing one organic functional group with an allyl (A) to form asymmetric allyl-substituted organosulfides (R–Sn–A). This promotes the cleavage of the A–S bond owing to facile generation of allyl radials, thereby improving the reduction kinetics and capacity. We verified the formation of asymmetric organosulfides by gas-chromatography–mass spectrometry and show that the allyl-activation strategy is universal to a series of functional groups. We successfully increased the discharge potential (up to 280 mV) and discharge capacity (up to 200%) of the organosulfide compared to its symmetric counterpart. A highly-concentrated liquid electrolyte (5 M) with a volumetric capacity of 224 A h L−1 was realized, demonstrating a substantial improvement in volumetric capacity compared to other reported liquid electrolytes to date. This strategy revitalizes organosulfides for high-energy and low-cost energy storage applications.
The flexible plant postulated in this study would produce four types of batteries for electric-drive vehicles – a hybrid (HEV), 10-mile range and 40-mile range plug-in hybrids (PHEV), and a 150-mile range battery-electric (EV). The annual production rate of the plant is 235,000 battery packs (HEV: 100,000; PHEV10: 60,000; PHEV40: 45,000; EV: 30,000). The cost savings per battery pack calculated with the Argonne BatPaC model for this flex plant vs. dedicated plants range from 9% for the EV battery packs to 21% for the HEV packs including the battery management systems (BMS). The investment cost savings are even larger, ranging from 21% for EVs to 43% for HEVs. The costs of the 1.0-kWh HEV batteries are projected to approach $714 per unit and that of the EV batteries to approach $188 per kWh with the most favorable cell chemistries. The best single indicator of the cost of producing lithium-manganate spinel/graphite batteries in a flex plant is the total cell area of the battery. For the four batteries studied, the price range is $20–24 per m2 of cell area, averaging $21 per m2 for the entire flex plant.
The purpose of this study was to compare the performance of the automated detection versus the manual scoring from the ApneaLink™ device to diagnose obstructive sleep apnoea syndrome (OSAS).
Rational design of non-noble metal catalysts with an electrocatalytic activity comparable or even superior to Pt is extremely important for future fuel cell-based renewable energy devices. Herein, we demonstrate a new concept that a metal–organic framework (MOF) can be used as a novel precursor to in situ encapsulate Co@Co3O4@C core@bishell nanoparticles (NPs) into a highly ordered porous carbon matrix (CM) (denoted as Co@Co3O4@C–CM). The central cobalt ions from the MOF are used as a metal source to produce Co metal cores, which are later transformed into a fancy Co@Co3O4 nanostructure via a controlled oxidation. The most notable feature of our Co@Co3O4@C–CM is that the highly ordered CM can provide much better transport pathways than the disordered pure MOF derived nanostructure that can facilitate the mass transport of O2 and an electrolyte. As a result, the well-designed Co@Co3O4@C–CM derived from the MOF shows almost identical activity but superior stability and methanol tolerance for the ORR relative to the commercial Pt/C in alkaline medium. Our work reports a novel Co@Co3O4@C nanostructure from a MOF for the first time and also reveals the important role of the introduction of a highly ordered carbon matrix into the MOF derived catalyst in enhancing the ORR activity and stability. To the best of our knowledge, the Co@Co3O4@C–CM is the most efficient non-noble metal nanocatalyst ever reported for the ORR.
This article presents a review of the colloidal and liquid-crystalline properties of vanadium pentoxide suspensions from a physicist's perspective. The processes occurring during the synthesis of these suspensions are first discussed. Then, the liquid-crystalline properties of V2O5 sols and gels are described. These nematic phases are easily aligned by weak magnetic fields or by alternative electric fields. The delicate interplay between repulsive hardcore and electrostatic interactions and van der Waals attractions defines the (concentration, ionic strength) phase diagram that includes an isotropic phase, a uniaxial nematic phase, a biaxial nematic gel state and a flocculated state. Deuterium NMR spectroscopy of D2O molecules gives information on the rotational dynamics of the nematic phase. Finally, various applications of these colloidal suspensions in the fields of hybrid organic/inorganic materials, mesoporous solids, and of the structures of biomolecules, are reviewed.
Kindergarten to third grade mathematics achievement scores from a prospective study of mathematical development (n =306) were subjected to latent growth trajectory analyses. The four corresponding classes included children with mathematical learning disability (MLD, 6% of sample), and low (LA, 50%), typically (TA, 39%) and high (HA, 5%) achieving children. The groups were administered a battery of intelligence (IQ), working memory, and mathematical-cognition measures in first grade. The children with MLD had general deficits in working memory and IQ and potentially more specific deficits on measures of number sense. The LA children did not have working memory or IQ deficits but showed moderate deficits on these number sense measures and for addition fact retrieval. The distinguishing features of the HA children were a strong visuospatial working memory, a strong number sense, and frequent use of memory-based processes to solve addition problems. Implications for the early identification of children at risk for poor mathematics achievement are considered.
A comparative discussion of the electrochemical and spectroelectrochemical properties of poly(o-phenylenediamine) POPD, an aromatic diamine, is presented. In situ conductance measurements show that POPD shows some conductance around the redox peak potentials, i.e.=−0.02< E SCE <0.00V. In situ UV–vis and Raman spectroelectrochemical results suggest that radical cations of polyaniline (PANI)-like segments in POPD backbone might be responsible for imparting conductance to this otherwise nonconducting polymer (as commonly supposed in the literature). The presence of radical cations was confirmed by in situ Raman spectra showing a band at 1390cm−1 characteristic of a C–N+-stretching vibration having an intermediate single/double bond character and being coupled to quinoid rings/polaronic form of PANI segments in the polymer. Results also reveal that POPD shows a close correlation between its electrochemical and spectroelectrochemical properties in the range of −0.02< E SCE <0.00V, and provide support for the suggested presence of doped PANI-like segments in said potential range.
The publisher regrets that incorrect information was uploaded within the supplementary data found in Appendix A. This has now been corrected. The publisher would like to apologise for any inconvenience caused.
The delivery of cathodes with both high capacity and excellent cycling stability is a great challenge in the development of sodium-ion batteries (SIBs) for energy storage systems. Here, we exploited a novel potassium-ion-intercalated layered iron/manganese-based material (K0.7Fe0.5Mn0.5O2). On the basis of advanced in situ and ex situ X-ray diffraction analysis, we confirm that K0.7Fe0.5Mn0.5O2 can provide highly reversible layer spacing variations and an ultra-stable skeleton structure during the sodiation/desodiation processes. As a result, K0.7Fe0.5Mn0.5O2 displays superior performance, with both high capacity and superior cycling stability, as a cathode for SIBs. A high discharge capacity of 181mAhg−1 is achieved at 100mAg−1. Remarkably, even when cycled at high rate of 1000mAg−1, 85% of the initial discharge capacity is maintained after 1000 cycles. These results indicate that K0.7Fe0.5Mn0.5O2 is a promising candidate for high-capacity and long-life SIBs. Additionally, this work will provide a unique insight into the development of high-performance cathodes for energy storages.
In this work, a CoSb-nanocrystal/graphene hybrid nanostructure has been synthesized by a facile one-pot in situ solvothermal route. X-ray diffraction and X-ray photoelectron spectroscopy analyses show that the formation of CoSb alloy (CoSb or CoSb2) and the reduction of graphite oxide occur simultaneously during the one-pot solvothermal process. Scanning electron microscopy and transmission electron microscopy observations indicate that quasi-spheric CoSb (or CoSb2) nanoparticles with a size of 10–30nm are uniformly anchored on graphene, forming a unique layered structure. The presence of graphene prevents the nanoparticles from aggregating. The attached alloy nanoparticles also hinder the restacking of the graphene sheets. The electrochemical measurements have shown that CoSb-nanocrystal/graphene nanocomposites exhibit improved electrochemical Li-storage properties compared with bare CoSb alloy, due to the combined buffering, confining and conducting effects of the in situ introduced graphene.
Polyoxometalates with multiple redox reactions have been reported as electron/ion sponges for lithium-ion storage applications. Here we introduce a vanadium-based polyoxometalate, Na7H2[PV14O42] (NPV), as an anode material for Lithium-ion batteries (LIBs). NPV exhibits a high reversible capacity up to 687 mA h g−1 at 100 mA g−1 with a good capacity retention of ~80% after 150 cycles. In operando synchrotron X-ray absorption near edge structure reveals the change of the valences of vanadium from V4+ to V1.87+, indicating that it can transfer at least 30 electrons per molecule which leads to high capacity. In operando synchrotron X-ray diffraction confirms the crystal structure of NPV electrode converts to amorphous during charge/discharge processes. Therefore, the charge storage mechanism of NPV could be further proposed that Li ions insert into amorphous NPV electrode continuously and react with [PV14O42]9- molecules, and [PV14O42]9- is like an electron/ion sponge which can store at least 30 electrons.
A nickel sulfide/conductive carbon composite electrocatalyst was synthesized and used as counter electrode (CE) material for dye-sensitized solar cells (DSSCs). This material demonstrates superior electrocatalytic activity in the reduction of triiodide to iodide and has a high power conversion efficiency of 8.15% compared with that of the DSSC with commercial Pt-coated CE (η =8.29%).
This paper assesses the impact of being attractive and not being native on the gender gap in the opportunity of obtaining a job in Italy. To do so, we propose a field experiment that consists in sending 9680 fictitious curricula vitae to real firms looking for employees. We estimate an Heckit model in order to consider different response from firms and then to calculate the probability to receive a callback. We show that gender gap in opportunity of receiving a callback is a very important issue and this gap is affected by interaction with both attractiveness and not being italian natives, especially for the most qualified jobs.
CO2 electrolysers store electricity as CO or other chemical fuels, but can suffer from carbon deposition at the electrodes. Skafte et al. identify a mechanistic route to inhibiting carbon build-up in ceria-based electrolysers and build a cell that operates beyond the thermodynamic carbon deposition threshold.
Recently, nickel ferrite with high theoretical capacity over the other metal oxide has been applied as electrode material for batteries and supercapacitors. However, owing to the serious aggregation and low specific surface area, the electrochemical performance of nickel ferrite (NiFe2O4) should be in urgent need of improvement. Here, we report the synthesis of unique molybdenum dioxide (MoO2) and nickel ferrite composite (MoO2/NiFe2O4) material via a facile strategy for the first time. The composite material presents a nanosheets-nanocrystals heterostructure. When evaluated as an electrode for hybrid supercapacitor in an alkaline solution, the MoO2/NiFe2O4 composite material presents a greatly enhanced specific capacity (2105 mA h/g at 4 A/g), which is better than those of individual component and exceeds some of the reported MoO2 and NiFe2O4 based electrodes. The capacity retention of MoO2/NiFe2O4 composite is about 81.1% after 1900 cycles. Such composite material also has great potential in other energy storage and conversion system.