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NiCo2O4 and NiMn x Co2−x O4−y (x ≤1.0) have been synthesized by a co-precipitation method, and the effects of Mn substitution for Co on the microstructural and electrochemical properties pertaining to the supercapacitor applications have been studied. Spinel structure is retained when a quarter of Co of the spinel is substituted with Mn (i.e., x =0.5), where the Mn ions predominantly occupy the octahedral sites of the spinel lattice. The presence of Mn significantly suppresses crystal growth upon thermal treatment but tends to cause severe crystallite agglomeration. Electrodes of the materials exhibit nearly ideal electrochemical capacitor behavior in neutral electrolyte solution (1M KCl(aq)). Mn substitution greatly enhances the specific capacitance of the spinel, giving gravimetric and superficial specific capacitances of ca. 110Fg−1 and ca. 380μFcm−2, respectively for x =0.5 powder. The capacitance enhancement is attributed to the facile charge-transfer characteristic of the Mn ions, as revealed by in situ X-ray absorption near-edge structure analysis.
This paper represents an assessment of the main ageing phenomena in electrical double-layer capacitors (EDLCs). In this study the cycle life of the EDLC cells with a rated capacitance of 1,600 F has been investigated at different ambient temperatures and current rates. From the experimental results we can observe that the impact of the high ambient temperature is significant on the cycle life of the cells. Moreover, the results also show the negative impact of the current rate. The internal resistance tests showed that the increase of the resistance is much higher than the decrease of the capacitance. Thus, the ageing of the EDLC during cycling was clearly non-linear. Further the EIS measurements indicated the higher increase of the imaginary part of the impedance at low frequencies during cycling, which indicates the capacitance fade.
It is highly challenging but imperative to develop highly efficient, low-cost and environmentally friendly bifunctional electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, we successfully prepared hierarchically porous Ni3S2 nanorod array foam through a simple hydrothermal process assisted by the pretreatment with HCl. The resulting hierarchically porous Ni3S2 nanostructures exhibits excellent catalytic activity and stability towards both HER and OER with low overpotential of 200mV and 217mV at current density of 10mAcm−2 for HER and OER, respectively, which are among the best non-noble metal HER/OER electrocatalysts reported in literatures. The as-prepared bifunctional electrocatalyst for both HER and OER could act as the promising electrode materials for water splitting.
This research has designed a new hybrid-electric system, which is characterized by two mechanisms: internal-combustion engine energy-distribution mechanism and dual energy-integration mechanism. The internal-combustion engine energy-distribution mechanism comprises a first pulley-set and a second pulley-set, whereby it is possible to adjust its radius ratio and change the output load according to the road-surface, output speed and corresponding load to maintain an optimal operating state of engine for a given generator rotational-speed. In this way, the engine can function in its optimal state. For a dual energy-integration mechanism, any power source can be individually actuated by the electric motor and the power transmitted from the internal-combustion engine energy-distribution mechanism. Moreover, a one-way clutch can prevent the actuated power source from reversion, so any output power source will not be affected by any inactive power. Also, two input power-sources can be integrated into a bigger power source via the dual energy-integration mechanism, thus resulting in twice the output energy and obtaining the necessary tractive power. A dynamic equation is therefore derived from this system to obtain the flow direction for the power source. Furthermore, dynamic equations of various system components can be established by the modularized software Matlab/simulink, and fuzzy logic is used to control and develop this system's dual energy-integration mechanism as a control strategy. It can be learnt from the system simulation that, after the engine's energy is distributed by the controller of the dual energy-integration mechanism, subjected to a deceleration ratio of the first pulley-set of the internal-combustion engine distribution mechanism and added to the generator torque transmitted from the second pulley-set, the engine can maintain an optimum state under various operating conditions.
The carbon nanotubes (CNT) show promising electrochemical characteristics particularly for electrochemical energy storage. The electrochemical double-layer (ECDL) capacitor is a new type of capacitor with features intermediate between those of a battery and a conventional capacitor. ECDL capacitors have been made using various types of CNT and activated carbon (a-C) as electrode material. The specific capacitance per surface area of the electrodes depends on the thickness and the specific surface area of the active material. The CNT electrodes show a specific capacitance from 0.8 and 280mFcm−2 and 8 to 16Fcm−3, respectively. Increasing the mass density also helps to increase the capacitance. Commercially available activated carbon (a-C) electrodes were also tested in order to study their specific capacitance as a function of their physical properties. The various a-C electrodes have specific capacitance per surface area ranging from 0.4 to 3.1Fcm−2 and an average specific capacitance per volume of 40Fcm−3 due to their larger mass density.
Introduction Neurocognitive dysfunction is believed to be a core feature of schizophrenia and is increasingly recognized as a common symptom dimension in bipolar disorder. Despite a copious literature on neurocognition in these disorders, the relationship amongst neurocognition, symptoms, and diagnosis remains unclear. We examined neurocognitive functioning in a cross-diagnostic sample of patients with psychotic disorders. Based on previous findings, it was hypothesized that neurocognitive functioning would be impaired in all three patient groups, and that groups would be similarly impaired on all neuropsychological measures. Additionally, we predicted that negative symptoms but not positive, general, or mood symptoms, would be associated with neurocognitive functioning. Method Neurocognitive functioning and symptoms were assessed in participants with schizophrenia (n= 25), schizoaffective disorder (n =29), or bipolar disorder with psychosis (n =31), and in healthy controls (n =20). Results Neurocognitive functioning was significantly impaired in all patient groups, and groups did not differ by diagnosis on most measures. A series of linear regressions revealed that negative symptoms (but no other clinical symptom) predicted poorer executive functioning across groups. Diagnosis was not a significant predictor of any neurocognitive variable. Discussion Neurocognitive deficits were pronounced in this cross-diagnostic sample of patients with psychotic disorders, and did not differ by diagnosis. Neurocognitive dysfunction may represent a symptom dimension that spans diagnostic categories, and may reflect shared pathogenic processes. As neurocognitive dysfunction is among the strongest predictors of outcome in patients, efforts to treat these deficits, which have shown promise in schizophrenia, should be extended to all patients with psychosis.
Now the lithium ion batteries are widely used in electric vehicles (EV). The battery modeling and state estimation are of great importance. The rigorous physics-based electrochemical model is too complicated for on-line simulation in vehicle. In this work, the simplification of the physics-based model for application on real vehicle is proposed. An improved single particle (SP) model is introduced with high precision and the same level of computations as the original single particle model. A simplified pseudo-two-dimensional (SP2D) model is developed. The distribution of the pore wall flux is analyzed and an approximate method is developed to find the solution. The developed models are compared with rigorous electrochemical model and original SP models. The results demonstrate that the models introduced in this work could simulate the battery efficiently without too much loss of accuracy. A state of charge (SOC) estimation algorithm using the Luenberger observer with the SP2D model is proposed and shows high precision. This SOC estimation method could be used in the BMS in real vehicle.
Ternary metal sulfides are emerging as a new class of electrochemical energy storage materials outperforming their oxide counterparts. We report here a facile and scalable solvothermal synthetic approach for growth of carbon doped MnCo2S4 microcubes (edge length, 10μm) directly on Ni foam. The simple approach of binder-free design, in-situ carbon doping and the use of 3D current collector resulted in an extraordinarily high specific capacity of 1892Cg−1 (525.7mAhg−1) at 5Ag−1 and outstanding rate performance of 516Cg−1 (143.3mAhg−1) at a very high current density of 100Ag−1 when tested as a faradaic electrode in aqueous KOH electrolyte. X-ray photoelectron spectroscopy (XPS) results indicate concurrent intercalation of both H+ and OH− ions from the electrolyte during the electrochemical processes. In two-electrode symmetric MnCo2S4//KOH//MnCo2S4 cells, mimicking the physical configuration of practical cells, specific capacity of 215Cg−1 (59.7mAhg−1) could be achieved at 1Ag−1. Further, the symmetric cell delivers energy densities of 106.5 and 15.2Whkg−1 at power densities of 0.85 and 18kWkg−1 demonstrating great application prospects.
Abstract In this chapter, we discuss the importance of noncovalent interactions in functional nanostructures. From layered materials to porous materials to polymers, we detail the underlying noncovalent interactions that define their behavior and dominate their properties and how theory, modeling and simulation is key to accelerate the process of understanding and design. In particular, we highlight how atomic level details of the underlying physicochemical phenomena can be useful for illuminating the connections between experiments and computational approaches.
Finely dispersed tin alloy/oxide composites were synthesized via the reduction of tin oxide by aluminum under high-energy ball-milling. The morphology and crystal structure of the resulting samples were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The electrochemical measurements reveal that Sn3Co/Al2O3 composite has higher initial efficiency and better cycle performance than Sn/Al2O3. The Sn3Co/Al2O3 composite electrode containing LA132 binder exhibited a reversible capacity about 540mAhg−1 with good capacity retention. On the other hand, it is found that the influence of binder type on the electrode performance is remarkable.
There is a great need to develop efficient and stable anodes suitable for high performance Na ion batteries (NIBs). Here we explore the interaction between Na and silicene in context of NIB anodes with first-principles methods including molecular dynamics simulations. We find that Na ions are adsorbed on silicene mainly via the formation of Na chains based on the agglomeration of Na pairs above and below the silicene sheet around top sites. This chain-on-top model is very different from the usual mechanism of atomic adsorption on a surface, as in Li on graphene. With the increase of Na concentration up to x = 1, a phase transition happens with the formation of a new stable structure Na2Si2. The interaction between Na and silicene is sufficiently strong that there no tendency for formation of Na clusters indicating stability of Na/silicene anodes. Additionally, the interaction is not so strong as to lead to breaking of the silicene lattice. The capacity of Na on silicene may be more than 954 mAh/g, which implies that it has the potential to be an excellent candidate anode material.
The discharge characteristics of silver vanadium oxide (SVO) as a cathode in lithium–silver vanadium oxide (Li–SVO) primary battery was studied under various operating conditions. The cathode yielded a capacity of 260 mAh g−1 at a current density of 0.08 mA cm−2, although the theoretical capacity of this material is 315 mAh g−1. The pulse discharge characteristics were studied under conditions that simulate battery operation inside an implantable cardio-verter defibrillator (ICD). The variation of the ohmic resistance of the system was studied as a function of depth of discharge. Rate capability and impedance studies indicated high diffusion limitations for this system especially at high depth of discharge. Morphological changes during discharge were also discussed using scanning electron microscopic studies.
With electricity consumption increasing within the United States, new paradigms of delivering electricity are required in order to meet demand. One promising option is the increased use of distributed power generation. Already a growing percentage of electricity generation, distributed generation locates the power plant physically close to the consumer, avoiding transmission and distribution losses as well as providing the possibility of combined heat and power. Despite the efficiency gains possible, regulators and utilities have been reluctant to implement distributed generation, creating numerous technical, regulatory, and business barriers. Certain governments, most notable California, are making concerted efforts to overcome these barriers in order to ensure distributed generation plays a part as the country meets demand while shifting to cleaner sources of energy.
The present study investigated the relation between reaction to negative stimuli and memory for stimuli. The relation was further investigated using as a framework individuals’ affective temperaments (AFTs). Eighty adolescents participated in the study. The AFTs are based on selfreported affect and categorizes individuals in four temperaments: self-actualizing, high affective, low affective and self-destructive. Reaction to negative stimuli was measured by interpretation of specific words in a short story. Two days later, participants were presented with a list of words and asked which of them were present in the short story. Individuals’ AFTs were expected to predict the promotion of pleasure or the prevention of displeasure. On a general level, reaction to negative stimuli predicted memory for negative, positive and neutral words. At an individual level, self-actualizers and high affectives’ negative reaction predicted the memory of positive words (i.e., promotion). In contrast, low affectives’ negative and positive reaction predicted the memory of neutral words (i.e., prevention).
Designing a molecule with pH, temperature and ion concentration sensitive luminescence properties is always fascinating. Tin disulfide (SnS2), a member of layered metal dichalcogenides (LMDs) family, is explored much for their commendable applications, however, its fluorescence property is still less explored. Present study reports a facile and eco-friendly bottom up synthesis route for tin disulfide quantum dots (SnS2-QDs). Transmission electron microscopic (TEM), and Atomic force microscopic (AFM) analysis revealed an average particle size of ∼3.6 nm. Our reported synthesis method provide the in-situ functionalization of quantum dots (QDs) making it highly sensitive to its environment. SnS2-QDs are found to be pH sensitive and hence a detailed pH dependent luminescence study has been performed. Interestingly it was found that SnS2-QDs possess ∼16 fold enhanced luminescence intensity in acidic condition (pH ∼ 1, QY = 5.32%) rather its basic condition (pH ∼ 12, QY = 1.17%). To explain this pH dependent behavior of SnS2-QDs, a mechanism has been proposed where this luminescence switching is mainly supposed due to protonation and deprotonation between –NH2 and –COOH groups. We believe present study may provide an insight for the development of pH sensor using SnS2-QDs for practical applications.
New Zealand faces significant ecological problems caused by the introduction of a variety of invasive small mammal species. Many of these species originate from temperate to subarctic climates and occur across wide elevations in their native range, and so arrived predisposed to adapt to a variety of habitats and bioclimatic zones in their new environs, including the alpine zone. Almost all of New Zealand’s invasive small mammal species have been recorded in the country’s alpine zones, yet neither the altitudinal distribution nor the extent to which such species use high elevation areas has been clearly defined. We conducted extensive camera trap surveys in summer to autumn periods of 2019 and 2020 across an elevation range of 500–2250 m above sea level, and used detection rates and occupancy modelling to reveal the altitudinal distributions and habitat associations of all 10 invasive small mammals that occur in the dryland zone of the central South Island. We found altitudinal distributions varied greatly across species, and that while most exhibited decreasing detection rates and site occupancy probabilities with increasing elevation, some used the subalpine and alpine zones to a greater degree than adjacent lower elevations. There were clear habitat associations, as well as interspecific associations that helped to explain the altitudinal distribution of some species. Understanding how such factors influence the distribution of invasive small mammals has both broad implications for invasive species management, and direct applications in evaluating threats to native taxa, advancing management strategies, and benchmarking distributions in a changing climate.
Si-based anode materials have been widely accepted as one of the most potential candidates for lithium ion batteries due to their abundance and high theoretical specific capacity. However, their practical application is seriously restricted by huge volume change and low intrinsic electric conductivity. Herein, a sandwich structured mesocarbon microbeads/nano-Si/amorphous carbon (MSC) composite was successfully fabricated through simple solution process and magnesiothermic reduction. The MCMB core acts as perfect materials support for nano-Si and conductive network for high electrochemical lithiation stability. Nano-Si provides high lithium storage capacity for enhanced energy density, and the amorphous carbon layer can effectively buffer the volume change from the nano-Si. As a result, the obtained MSC composite with optimal design displays high reversible capacity of 648 mA h g−1 at a current density of 100 mA g−1, along with a satisfactory capacity retention ratio of 90.3% after 100 cycles. To sum up, we develop a simple approach for large-scale preparation of silicon-based composites with high capacity and long-term cycle stability, which shows great potential for applications in the next-generation lithium ion batteries.
As members of the redox-flow battery (RFB) family, nonaqueous RFBs can offer a wide range of working temperature, high cell voltage, and potentially high energy density. These key features make nonaqueous RFBs an important complement of aqueous RFBs, broadening the spectrum of RFB applications. The development of nonaqueous RFBs is still at its early research stage and great challenges remain to be addressed before their successful use for practical applications. As such, it is essential to understand the major components in order to advance the nonaqueous RFB technology. In this perspective, three key major components of nonaqueous RFBs: organic solvents, supporting electrolytes, and redox pairs are selectively focused and discussed, with emphasis on providing an overview of those components and on highlighting the relationship between structure and properties. Urgent challenges are also discussed. To advance nonaqueous RFBs, the understanding of both components and systems is critically needed and it calls for inter-disciplinary collaborations across expertise including electrochemistry, organic chemistry, physical chemistry, cell design, and system engineering. In order to demonstrate the key features of nonaqueous RFBs, herein we also present an example of designing a 4.5 V ultrahigh-voltage nonaqueous RFB by combining a BP/BP˙− redox pair and an OFN˙+/OFN redox pair.
The influence of BrCl on the impedance response of both the lithium anode and the carbon cathode in Li/SOCl2 cells was studied. The impedance of the lithium anode increases with storage time while the addition of BrCl to Li/SOCl2 cells decreases the impedance. However, the porous carbon cathode shows a small film resistance before discharge. The addition of BrCl to Li/SOCl2 cells also decreases the impedance, especially for that part of the interface reaction resistance R2. As a rule, the film resistance of the lithium anode decreases sharply during the early period of discharge, while that of the porous carbon cathode rises rapidly. It follows that the porous carbon cathode is the rate controlling electrode during discharge.
Multiple sclerosis (MS) is a demyelinating disease of the central nervous system that mainly affects young adults and that is one of the leading causes of disability in this age group, with cognitive impairment occurring early in the course of the disease. This article summarizes the current knowledge about cognitive dysfunction in the early phase of MS, including biomarkers, MRI correlates, and its value as a prognostic marker.
The SiOC ceramic was prepared with vinyltriethoxysilane as the sol−gel precursor, and followed by etching with KOH. The effect of KOH etching on the morphology, structure and electrochemical properties of SiOC anodes was investigated. The amorphous SiOC ceramics with different free carbon content is obtained by KOH etching. The reaction of oxygen-enriched units with KOH and the activation of free carbon resulted in the formation of micro and mesopores. The galvanostatic charging/discharging and rate capability suggest that the electrochemical performance of SiOC ceramics is improved by KOH etching. As compared with SiOC sample, KOH-SiOC-5 (KOH/SiOC weight ratio of 5:1) with a high BET surface area of 249.2m2 g−1 deliveres a discharge capacity of 607mAhg−1 at the current density of 36mAg−1. Nano-sized pores, mixed SiOxC4-x structures and the free carbon phase both work together for the excellent electrochemical performance. The contribution of carbon to reversible capacity is higher than that of SiOxC4-x phases and surface area. However, the specific surface area, pore volume and free carbon content are decreased by excessive etching with KOH, which resulted in the decrease of electrochemical properties.