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In this study we report a series of nickel-rich layered cathodes LiNi1−2 x Co x Mn x O2 (x = 0.075, 0.05, 0.025) prepared from chlorides solution via ultrasonic spray pyrolysis. SEM images illustrate that the samples are submicron-sized particles and the particle sizes increase with the increase of Ni content. LiNi0.85Co0.075Mn0.075O2 delivers a discharge capacity of 174.9 mAh g−1 with holding 93% reversible capacity at 1 C after 80 cycles, and can maintain a discharge capacity of 175.3 mAh g−1 at 5 C rate. With increasing Ni content, the initial specific capacity increases while the cycling and rate performance degrades in some extent. These satisfying results demonstrate that spray pyrolysis is a powerful and efficient synthesis technology for producing Ni-rich layered cathode (Ni content > 80%).
LiNi x Co1−x O2 solid solutions are synthesised and their electrochemical performance as cathodes is examined in lithium cells. Through DTA/TG analysis and self-discharge tests, it is found that both the thermal stability at high temperature and the electrochemical stability in the fully-charged state for LiNi x Co1−x O2 increases with increasing content of cobalt in the compound. The average operating potentials for the solid solutions are lower than those for pure LiCoO2. This indicates that both cobalt and nickel take part in the redox reactions during lithium insertion and extraction. The substitution of Ni3+ for Co3+ in LiNi x Co1−x O2 can improve the specific capacity, but with a small sacrifice in cycleability.
MoO2–graphene composite was synthesized via a two-step of hydrothermal-calcination method. The morphology and structure of the products were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray power diffraction (XRD), and Raman spectroscopy. The content of the graphene in MoO2–graphene composite was examined by thermogravimetric (TG)–differential scanning calorimetry (DSC) analysis. The electrochemical performances of the products were examined by Galvanostatical charge–discharge method, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). When used as anode material for lithium ion batteries, the MoO2–graphene composite shows an enhanced cyclic performance and lithium storage property. The first discharge capacity of the composite can reach 674.4mAhg−1 with a reversible capacity of 429.9mAhg−1. Significantly, the composite can also deliver a reversible capacity of as high as1009.9mAhg−1 after 60 charge/discharge cycles.
Lithium dendrite growth in Li/poly(ethylene oxide) (PEO)–Li(CF3SO2)2N (LiTFSI)–nano-SiO2/Li was examined using direct in situ observation under galvanostatic conditions at 60°C. Both the onset time of dendrite formation and the short-circuit time of the cells were extended by the addition of nano-SiO2 filler into the polymer electrolyte, of which an acid-modified nano-SiO2 filler was the most effective. The onset time was dependent on the current density in the range from 0.1 to 1.0mAcm−2. Li dendrite growth in Li/PEO18LiTFSI/Li at 60°C for current densities of 0.1 and 0.5mAcm−2 started at 125 and 15h, respectively. PEO18 LiTFSI with addition of 10wt% acid-modified 50nm SiO2 showed extended dendrite formation onset times of 250h at 0.1mAcm−2 and 32h at 0.5mAcm−2. The suppression of dendrite formation at the Li/PEO18 LiTFSI interface could be explained by enhancement of the conductivity and suppression of the interface resistance between lithium and the polymer electrolyte by addition of the nano-SiO2 filler. The electrical conductivity of 4.1×10−4 Scm−1 and interface resistance of 405Ωcm2 for PEO18 LiTFSI at 60°C were respectively increased to 7.2×10−4 Scm−1 and decreased to 77Ωcm2 by the addition of 10wt% acid-modified nano-SiO2.
Substances may enter the economy and the environment through both intentional and non-intentional flows. These non-intentional flows, including the occurrence of substances as pollutants in mixed primary resources (metal ores, phosphate ores and fossil fuels) and their presence in re-used waste streams from intentional use may have environmental and economic consequences in terms of pollution and resource availability. On the one hand, these non-intentional flows may cause pollution problems. On the other hand, these flows have the potential to be a secondary source of substances. This article aims to quantify and model the non-intentional flows of lead, to evaluate their long-term environmental consequences, and compare these consequences to those of the intentional flows of lead. To meet this goal, the model combines all the sources of non-intentional flows of lead within one model, which also includes the intentional flows. Application of the model shows that the non-intentional flows of lead related to waste streams associated with intentional use are decreasing over time, due to the increased attention given to waste management. However, as contaminants in mixed primary resources application, lead flows are increasing as demand for these applications is increasing.
This paper discusses a regenerative braking system for the electric motorcycle that performs regenerative energy recovery based on neural network control with a boost converter. A constant regenerative current control scheme is proposed, thereby providing improved performance and high energy recovery efficiency at minimum cost. The neural network controller is used to simulate the regenerative system in Matlab/Simulink and neural network toolbox. We can sieve out the suitable training samples to obtain good performance of the controllers, and the neural network with genetic algorithms is used to design the controller. Simulation results of neural network controller show a more steady quality and extended time of charging. The proposed scheme not only increases the traveling distance of the vehicle but also improves the performance and life-cycle of batteries, and the energy recovery of batteries becomes more stable. Therefore, the market of the electric vehicle will become more competitively.
Crystalline CuF2 thin films were prepared by pulsed laser deposition under room temperature. The physical and electrochemical properties of the as-deposited thin films have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), galvanostatic cycling and cyclic voltammetry (CV). Reversible capacity of 544mAhg−1 was achieved in the potential range of 1.0–4.0V. A reversible couple of redox peaks at 3.0V and 3.7V was firstly observed. By using ex situ XRD and TEM techniques, an insertion process followed by a fully conversion reaction to Cu and LiF was revealed in the lithium electrochemical reaction of CuF2 thin film electrode. The reversible insertion reaction above 2.8V could provide a capacity of about 125mAhg−1, which makes CuF2 a potential cathode material for rechargeable lithium batteries.
A new approach to define of the thermal parameters, such as heat capacity and through-plane thermal conductivity, of pouch-type cells is introduced. Application of local heat flux measurement with a gradient heat flux sensor (GHFS) allows determination of the cell thermal parameters in different surface points of the cell. The suggested method is not cell destructive as it does not require deep discharge of the cell or application of any charge/discharge cycles during the measurements of the thermal parameters of the cell. The complete procedure is demonstrated on a high-power lithium-ion (Li-ion) pouch cell, and it is verified on a sample with well-known thermal parameters. A comparison of the experimental results with conventional thermal characterization methods shows an acceptably low error. The dependence of the cell thermal parameters on the state of charge (SoC) and measurement points on the surface was studied by the proposed measurement approach.
In this paper, we report an investigation of three tin-based composite materials as negative electrodes for lithium-ion batteries. Theses composites were synthesized by solid state reaction from dispersion of micrometric tin into BPO4, Li-doped BPO4 (LiBPO) and Na-substituted BPO4 (NaBPO) matrix, respectively. We have investigated more particularly the influence of the two alkaline ions (Li+, Na+) introduced into the matrix on electrochemical performances. The morphology of powders was observed by SEM and the composition studied by EDX analysis. The conductivity measurements showed that the modified BPO4 matrixes (Li or Na) exhibit improved conductivity (σ RT =2×10−11 Scm−1 for NaBPO). A focus of our interest was to relate the nature and structural composition of the composite interface between active tin and inactive matrix to the irreversible capacity in this type of composite materials. The electrochemical analysis shows a decrease of the irreversible capacity for the composite based on modified matrixes (around 150 and 190mAhg−1 for SnNaBPO and SnLiBPO, respectively) with respect to the reference composite SnBPO (245mAhg−1).
Objective To assess the nature of learning and verbal memory deficits in adolescents with schizophrenia-spectrum disorders (SzS) (i.e., schizophrenia, schizoaffective disorder, and schizophreniform disorder). Method Sixty patients with SzS (mean age=16.1 years, S.D.=2.2) and 60 age- and gender-matched diagnosis-free healthy volunteers were assessed using the California Verbal Learning Test (CVLT). Planned analyses were conducted to assess the following aspects of memory: span of apprehension, verbal learning, short-term and long-term memory, rate of forgetting, interference, and organizational strategies. Adolescents with schizophrenia (Sz) were compared to those with schizoaffective disorder (SzA). Second, patients' test profiles were compared to those of controls. Relationships between initial learning and overall verbal learning with organizational strategy were explored. Results Neurocognitive profiles did not significantly differ between Sz and SzA participants. Patients performed significantly worse than healthy comparison subjects on measures of span of apprehension, verbal learning, short- and long-term memory, and organizational strategies after adjusting for differences in premorbid intelligence. No group differences were found in rate of forgetting or susceptibility to proactive or retroactive interference. Conclusions Adolescents with SzS are characterized by significant verbal memory dysfunction similar to what has been observed in adults with first-episode schizophrenia. Deficits in consistency of learning over several trials, as well as a strong relationship between semantic organizational strategies and reduced learning capacity, implicate dysfunction of the dorsolateral prefrontal cortex as a contributor to verbal memory deficits in adolescents with SzS.
Numerous biocorrosion studies have stated that biofilms formed in aerobic seawater induce an efficient catalysis of the oxygen reduction on stainless steels. This property was implemented here for the first time in a marine microbial fuel cell (MFC). A prototype was designed with a stainless steel anode embedded in marine sediments coupled to a stainless steel cathode in the overlying seawater. Recording current/potential curves during the progress of the experiment confirmed that the cathode progressively acquired effective catalytic properties. The maximal power density produced of 4mWm−2 was lower than those reported previously with marine MFC using graphite electrodes. Decoupling anode and cathode showed that the cathode suffered practical problems related to implementation in the sea, which may found easy technical solutions. A laboratory fuel cell based on the same principle demonstrated that the biofilm-covered stainless steel cathode was able to supply current density up to 140mAm−2 at +0.05V versus Ag/AgCl. The power density of 23mWm−2 was in this case limited by the anode. These first tests presented the biofilm-covered stainless steel cathodes as very promising candidates to be implemented in marine MFC. The suitability of stainless steel as anode has to be further investigated.
Bifunctional catalysts for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are highly desirable for rechargeable metal–air batteries and regenerative fuel cells. However, the commercial oxygen electrocatalysts (mainly noble metal based) can only exhibit either ORR or OER activity and also suffer from inherent cost and stability issues. It remains challenging to achieve efficient ORR and OER bifunctionality on a single catalyst. Metal-free structures offer relatively large scope for this bifunctionality to be engineered within one catalyst, together with improved cost-effectiveness and durability. Herein, by closely coupled computational design and experimental development, highly effective bifunctionality was achieved in a phosphorus and nitrogen co-doped graphene framework (PNGF) – with both ORR and OER activities reaching the theoretical limits of metal-free catalysts, superior to their noble metal counterparts in both (bi)functionality and durability. In particular, with the identification of active P–N sites for OER and N-doped sites for ORR, we successfully intensified these sites by one-pot synthesis to tailor the PNGF. The resulting catalyst achieved an ORR potential of 0.845 V vs. RHE at 3 mA cm−2 and an OER potential of 1.55 V vs. RHE at 10 mA cm−2. Its combined ORR and OER overpotential of 705 mV is much lower than those previously reported for metal-free bifunctional catalysts.
Past work shows that even young children know that occupations are differentially linked to men and women in our society. In our research, we studied whether 6- and 11-year-old children's (a) beliefs about job status and (b) job interests would be affected by the gendered nature of jobs. When asked about familiar occupations, children gave higher status ratings to masculine jobs and expressed greater interest in jobs culturally associated with their own sex. To circumvent the extant confounds between job gender and job status in our culture, we also developed a new methodology in which novel jobs were portrayed with either male or female workers. Older children rated novel jobs portrayed with male workers as having higher status than the identical jobs portrayed with female workers. Portrayal sex had no effect on children's own interests in these novel jobs at either age. Methodological, theoretical, and educational issues are discussed in relation to sex-role development and vocational aspirations.
Executive function and intelligence are negatively associated with aggression, yet the role of executive function has rarely been examined in the context of school bullying. We studied whether different domains of executive function and non-verbal intelligence are associated with bullying involvement in early elementary school. The association was examined in a population-based sample of 1,377 children. At age 4 years we assessed problems in inhibition, shifting, emotional control, working memory and planning/organization, using a validated parental questionnaire (the BRIEF-P). Additionally, we determined child non-verbal IQ at age 6 years. Bullying involvement as a bully, victim or a bully-victim in grades 1–2 of elementary school (mean age 7.7 years) was measured using a peer-nomination procedure. Individual bullying scores were based on the ratings by multiple peers (on average 20 classmates). Analyses were adjusted for various child and maternal socio-demographic and psychosocial covariates. Child score for inhibition problems was associated with the risk of being a bully (OR per SD = 1.35, 95%CI: 1.09–1.66), victim (OR per SD = 1.21, 95%CI: 1.00–1.45) and a bully-victim (OR per SD = 1.55, 95%CI: 1.10–2.17). Children with higher non-verbal IQ were less likely to be victims (OR = 0.99, 95%CI: 0.98–1.00) and bully-victims (OR = 95%CI: 0.93–0.98, respectively). In conclusion, our study showed that peer interactions may be to some extent influenced by children’s executive function and non-verbal intelligence. Future studies should examine whether training executive function skills can reduce bullying involvement and improve the quality of peer relationships.
Recently, Wireless Sensor Networks (WSNs) have attracted lot of attention due to their pervasive nature and their wide deployment in Internet of Things, Cyber Physical Systems, and other emerging areas. The limited energy associated with WSNs is a major bottleneck of WSN technologies. To overcome this major limitation, the design and development of efficient and high performance energy harvesting systems for WSN environments are being explored. We present a comprehensive taxonomy of the various energy harvesting sources that can be used by WSNs. We also discuss various recently proposed energy prediction models that have the potential to maximize the energy harvested in WSNs. Finally, we identify some of the challenges that still need to be addressed to develop cost-effective, efficient, and reliable energy harvesting systems for the WSN environment.
Deep brain stimulation (DBS) has been increasingly used for primary and secondary movement disorders in children and young people. Reports of hardware related complications have been sparse for this population and from small cohorts of patients. We report DBS complications from a single large DBS centre with 10 year experience. Data was collected as a prospective audit and additionally from a questionnaire on recharging of the stimulators. 129 patients with a minimum 6 months follow up were identified, mean age10.8 y (range 3.0–18.75), mean follow up 3.3y (range 0.5–10.3), weight 10.4–94.2 kg, 126 new implants (92 Activa RC) and 69 revisions for reasons other than infection. 26 patients were 7y or younger. Surgical site infections (SSI) rates were 10.3% for new implants and revisions, lower 8.6% for new Activa RC and even lower, 4.7%, for new Activa RC in patients under 7y (1/21). SSI occurred within first 6 months and necessitated total system removal in 86% of those infected. Electrode/extension problems were recorded in 18.4% of patients, fracture in 4.6% malfunction in 7.7%, short extension 3.8% and electrode migration in 2.3%. Other complications involved clinically silent intracranial bleed in 1 patient, skin erosions (2.3%), unexpected switching off in 18.7% of Soletra/Kinetra and 3.4% of Activa RC, transient seroma at IPG site in postoperative period (8%). Of the 48 returned recharging questionnaires, 38% of families required recharger replacement and 23% experienced frequent problems maintaining connection during recharging. However, 83% of responders considered recharging not at all or only a little care burden. We identified lower than previously reported DBS infection rates particularly for patients under 7 years, but relatively high incidence of technical problems with electrodes, extensions and in particular recharging. This has to be considered when offering DBS for children with movement disorders.
Due to their high theoretical capacity compared to that of state-of-the-art graphite-based electrodes, silicon electrodes have gained much research focus for use in the development of next generation lithium-ion batteries. However, a major drawback of silicon as an electrode material is that it suffers from particle fracturing due to huge volume expansion during electrochemical cycling, thus limiting commercialization of such electrodes. Understanding the role of material microstructure in electrode degradation will be instrumental in the design of stable silicon electrodes. Here, we demonstrate the application of synchrotron-based X-ray tomographic microscopy to capture and track microstructural evolution, phase transformation and fracturing within a silicon-based electrode during electrochemical lithiation.
Lithium vanadium fluorophosphate, LiVPO4F, a cathode material for lithium ion batteries, was synthesized by a sol–gel method followed by low temperature calcinations. V2O5·nH2O hydro-gel, NH4H2PO4, LiF and carbon were used as starting materials to prepare a precursor, and LiVPO4F was finally obtained by sintering the precursor at 550°C for 2h. X-ray diffraction results show that the LiVPO4F sample is triclinic structure. TEM image indicates that the LiVPO4F particles are about 70nm in diameter embedded in carbon network. The LiVPO4F system showed the discharge capacity of about 130mAhg−1 in the range of 3.0–4.6V at the first cycle, and the discharge capacity remained about 124mAhg−1 after 30 cycles. The sol–gel method is suitable for the preparation of LiVPO4F cathode materials with good electrochemical Li intercalation performances.
We discuss the theoretical approaches for various electrochemical capacitor systems via performance-potential estimation in regard to specific energy and power densities. Typical energy storage systems, such as symmetric capacitor system and asymmetric capacitor system, are classified with the symmetry of the electrodes (symmetric/asymmetric), and the types of electrolytes (aqueous/organic). Energy and power densities of each system are theoretically calculated using various factors and coefficients for performance comparison. Then, theoretical modeling for the BatCap system is conducted to indicate the electrochemical performance of this new concept device followed by consideration of ideal structure of the BatCap electrode material. Conclusively, this study successively indicates the performance of each energy storage system depending on the specified conditions of the electrodes and electrolyte which consist of the energy storage systems.
Three-dimensionally ordered macroporous (3DOM) carbons having walls composed of mesosized spherical pores were prepared by a colloidal crystal templating method. A composite electrode consisting of bimodal porous carbon and polypyrrole (PPy) was prepared by electropolymerization of pyrrole within the macropores of the bimodal porous carbon. The porous structure of the composite electrode was analyzed using a scanning electron microscope and by nitrogen adsorption–desorption measurement. It was found that the deposition of PPy decreased the porosity and specific surface area of the electrode. The electrochemical properties of the composite electrode were characterized in a mixed solution of ethylene carbonate and diethyl carbonate containing 1moldm−3 LiPF6. The discharge capacity of the carbon–PPy composite electrode was 78mAhgcarbon–PPy −1 in the potential range of 2.0–4.0V vs. Li/Li+, which corresponded to a volumetric discharge capacity of 53mAhcm−3. Both the double-layer capacity (31mAhg−1) and the redox capacity of PPy (47mAhg−1) contributed to the discharge capacity of the composite electrode. This indicates that the incorporation of PPy into the macropores of bimodal porous carbon is effective in increasing the volumetric discharge capacity of the composite electrode. The composite of carbon and PPy showed good rate capability, and its discharge capacity at a high current density of 4.0Ag−1 was as high as 49mAhg−1.
We elicit distributional fairness ideals of impartial spectators using an incentivized experiment in a large and heterogeneous sample of the German population. We document several empirical facts: (i) egalitarianism is more popular than efficiency- and maxi-min ideals; (ii) females are more egalitarian than men; (iii) men are relatively more efficiency minded; (iv) left-leaning voters are more likely to be egalitarians, whereas right-leaning voters are more likely to be efficiency-minded; and (v) young and high-educated participants hold different fairness ideals than the rest of the population. Moreover, we show that fairness ideals predict preferences for redistribution and intervention by the government, as well as actual charitable giving, even after controlling for a range of covariates. This paper thus contributes to our understanding of the underpinnings of voting behavior and ideological preferences and to the literature that links laboratory measures and field behavior.