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In this study, the use of silicon as a capacity-enhancing electrode additive to graphite electrodes was investigated. Based on energy-density estimations, the silicon amount was restricted to less than 20 wt%. The viability of such graphite–Si electrode blends was evaluated with regard to their cycle-life in relation to the silicon content of the electrode, showing how Si content and capacity fade are correlated. The addition of Si gradually alters the electrode morphology as shown by electrode cross-section images, and is partly responsible for the progressive capacity loss. In addition, we also demonstrate how analysis of the voltage hysteresis can provide early indications of cell failure. To complete the picture, one graphite–Si formulation was evaluated in a full-cell setup. The electrochemical study of this 3-electrode setup is complemented by a charge-injection experiment that replenishes the Li inventory and serves to pinpoint the origins of capacity fading more accurately under the cycling conditions chosen.
High-performance energy storage devices are in urgent need due to the fast development of wearable electronics, while the challenge of achieving outstanding flexibility has not been properly addressed yet, let alone the safety, another critical issue determines their practicability. Herein, we report a quasi-solid-state aqueous rechargeable lithium-ion battery (ARLIB) based on carbon cloth substrates and PVA-LiNO3 gel polymer electrolyte (GPE). Thanks to the protective PPy coating layer on LiV3O8 and the use of solid GPE, the as-assembled ARLIB exhibits a good cycling stability of 98.7% and 79.8% capacity retention after 100 and 500 cycles, respectively. It also demonstrates exceptional flexibility to sustain various deformations including bending, squeezing, twisting and folding because of its solid-state design. Moreover, the ARLIB can be tailored into any desired shapes, and even be punched penetrative holes, exhibiting excellent safety. Thus, the creation of numerous tiny through-holes across the whole ARLIB body is testified feasible, and a designed breathability catering to the demand of comfortability in wearable devices is subsequently realized. Obviously, our study offers a promising strategy to construct flexible energy storage device with outstanding stability, flexibility, safety and breathability towards various wearable electronics.
Non-spherical Li(Ni1/3Co1/3Mn1/3)O2 powders have been synthesized using a two-step drying method with 5% excess LiOH at 800°C for 20h. The tap-density of the powder obtained is 2.95gcm−3. This value is remarkably higher than that of the Li(Ni1/3Co1/3Mn1/3)O2 powders obtained by other methods, which range from 1.50gcm−3 to 2.40gcm−3. The precursor and Li(Ni1/3Co1/3Mn1/3)O2 are characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscope (SEM). XPS studies show that the predominant oxidation states of Ni, Co and Mn in the precursor are 2+, 3+ and 4+, respectively. XRD results show that the Li(Ni1/3Co1/3Mn1/3)O2 material obtained by the two-step drying method has a well-layered structure with a small amount of cation mixing. SEM confirms that the Li(Ni1/3Co1/3Mn1/3)O2 particles obtained by this method are uniform. The initial discharge capacity of 167mAhg−1 is obtained between 3V and 4.3V at a current of 0.2C rate. The capacity of 159mAhg−1 is retained at the end of 30 charge–discharge cycle with a capacity retention of 95%.
Alzheimer’s disease (AD) is a genetically complex disorder, and several genes related to cholesterol metabolism have been reported to contribute to AD risk. To identify further AD susceptibility genes, we have screened genes that map to chromosomal regions with high logarithm of the odds scores for AD in full genome scans and are related to cholesterol metabolism. In a European screening sample of 115 sporadic AD patients and 191 healthy control subjects, we analyzed single nucleotide polymorphisms in 28 cholesterol-related genes for association with AD. The genes HMGCS2, FDPS, RAFTLIN, ACAD8, NPC2, and ABCG1 were associated with AD at a significance level of P ≤ 0.05 in this sample. Replication trials in five independent European samples detected associations of variants within HMGCS2, FDPS, NPC2, or ABCG1 with AD in some samples (P = 0.05 to P = 0.005). We did not identify a marker that was significantly associated with AD in the pooled sample (n = 2864). Stratification of this sample revealed an APOE-dependent association of HMGCS2 with AD (P = 0.004). We conclude that genetic variants investigated in this study may be associated with a moderate modification of the risk for AD in some samples.
In order to investigate effect of iron on the performance of lead acid batteries, we systematically study the chemical characteristics, electrochemical characteristics, battery capacity and cycle life using iron-doped lead oxide in this article. Cyclic voltammetry results show that positive discharge current decreases sharply with the increasing content of Fe2O3 from 0.05wt.% to 2wt.%. The release of H2 and O2 are promoted accompanying the increase of Fe2O3 contents. The chemical analysis confirms that the strength of Fe3+, Fe2+ concentration is simultaneously increased with the increase of iron contents after 50 voltammetry cycles. X-ray diffraction phase analysis shows that the amount of PbSO4 increases with the increasing iron content in the positive plates after 50 discharge cycles. Morphologies of positive plates show that many agglomerates from PbSO4 crystals appear. The SEM observations illustrate that there is a lower porosity and specific surface area in the positive active material with iron after 50 discharge cycles. The mechanism of iron decreasing capacity, cycle-life and promoting the release of H2 and O2 has been elucidated in details. We support it is the “redox-diffusion” process of multiple-valence iron and formation of PbSO4 on electrodes that result in above performances.
The difference in capacitive performance between high and low surface area RuO2 electrodes, synthesized with and without a mesoporous silica template, respectively, was investigated in aqueous solutions of sulfuric acid and sulfates by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). RuO2 synthesized with the template was crystalline and the formation of the mesoporous structure with a 6.5nm diameter was confirmed using a transmission electron microscope and the nitrogen adsorption and desorption isotherm. From the CV at the scan rate of 1mVs−1, the specific capacitance of the high surface area electrode in H2SO4(aq) was determined to be 200Fg−1. The high surface area RuO2 has a three times higher BET specific surface area (140m2 g−1) than the low surface area sample (39m2 g−1). Introducing the mesoporous structure was proved effective for increasing the capacitance per mass of the RuO2, though not all the surface functions as a capacitor. Both the CV and EIS suggest that by increasing the charging rate or frequency, the mesoporous structure of the electrode leads to a lower capacitance decrease (higher capacitance retention) than the low surface area electrode. The EIS also indicates that the response time of the capacitor is hardly influenced by the presence of the mesoporous structure.
Both paleobiology and investigations of ‘major evolutionary transitions’ are intimately concerned with the macroevolutionary shape of life. It is surprising, then, how little studies of major transitions are informed by paleontological perspectives and. I argue that this disconnect is partially justified because paleobiological investigation is typically ‘phenomena-led’, while investigations of major transitions (at least as commonly understood) are ‘theory-led’. The distinction turns on evidential relevance: in the former case, evidence is relevant in virtue of its relationship to some phenomena or hypotheses concerning those phenomena; in the latter, evidence is relevant in virtue of providing insights into, or tests of, an abstract body of theory. Because paleobiological data is by-and-large irrelevant to the theory which underwrites the traditional conception of major transitions, it is of limited use to that research program. I suggest that although the traditional conception of major transitions is neither ad-hoc or problematically incomplete, its promise of providing unificatory explanations of the transitions is unlikely to be kept. Further, examining paleobiological investigations of mass extinctions and organogenesis, I further argue that (1) whether or not transitions in paleobiology count as ‘major’ turns on how we conceive of major transitions (that is, the notion is sensitive to investigative context); (2) although major transitions potentially have a unified theoretical basis, recent developments suggest that investigations are becoming increasingly phenomena-led; (3) adopting phenomena-led investigations maximizes the evidence available to paleobiologists.
The paper deals with real-time energy management strategies for a hybrid energy storage system including a battery and supercapacitor for an electric vehicle. Besides efficiency concerns, a key issue for real-time applications is ensuring safe operations for the considered system. In such a system it is mandatory to limit the supercapacitor voltage by the energy management strategy to comply with efficiency and safety constraints. An optimisation-based strategy (λ-control) and a rule-based strategy (filtering) are compared in this paper. The active limitation of the supercapacitor voltage is ensured in both strategies. Experimental results show that the two strategies have equivalent performances under real-driving cycles not known in advance. A difference of 2% between the strategies on the battery current root mean square value is shown. By varying the desired supercapacitor voltage range, the results show that the λ-control is better-suited for a high supercapacitor voltage range whereas the filtering gives the best performances for a low supercapacitor voltage range.
This study aims at the investigation of a suitable catalyst for the electrochemical reduction mechanism of metaborate into borohydride with the hope of the construction of rechargeable direct borohydride/peroxide fuel cell. A passive direct borohydride/peroxide fuel cell with Ag anode and Pt/C cathode was constructed. Its maximum power density was calculated as 7mWcm−2 at a cell voltage of 0.5 and a current density of 11mAcm−2. Recycling of the metaborate, the co-product of the borohydride oxidation, to the borohydride is the major issue in order to achieve the rechargeable borohydride fuel cells. Accordingly, the NaBO2 solution was electrolyzed with the use of Ag electrodes for this purpose. The converted borohydride were determined by the cyclic voltammetry using Au and Ag electrodes which are highly selective for this purpose. The cyclic voltammetric curves revealed the peaks which indicated the conversion of NaBO2 into NaBH4. The presence of NaBH4 was also verified iodometrically after the electrolysis. It was observed that there was 10% conversion after 24h of electrolysis which reached up to 17% after 48h. These data are very promising in the quest of the construction of a rechargeable direct borohydride fuel cell.
This paper presents a Proton Exchange Membrane Fuel Cell (PEMFC) system model for locomotives, implemented ad hoc in MATLAB-Simulink environment for a standard drive cycle; the system is hybrid and the energy store system (ESS) is composed of battery and supercapacitor (SC). The PEMFC is the primary energy source of the hybrid locomotive; it supplies the total energy demand. A battery supplies the additional energy demand in acceleration and the SC delivers the power to fill the peaks. Moreover, a regenerative brake recuperates part of the energy lost in deceleration and stores it in the ESS. The hybrid locomotive is controlled by a hybrid strategy, fit for the purpose, composed of Fuzzy Logic Control and Equivalent Consumption Minimization Strategy; the PEMFC power is obtained through an optimization problem and the other variables are calculated by means of IF-THEN rules in order to achieve best results from each energy source, high efficiency and low hydrogen consumption. The simulation results confirm the good response of the hybrid system model: the FC system achieves efficiency of around 50% with a hydrogen consumption of 1.3 kg; the battery State of Charge (SOC) is kept between 60% and 75% and the SC SOC between 30% and 90%.
In order to realize a low-carbon hydrogen economy, a continuous search for materials able to store hydrogen in the solid form has been actively carried out globally. The need to accurately characterize the hydrogen storage properties of a variety of materials, including the thermodynamic and kinetic information, is of paramount importance. However owning to the diversity of potential hydrogen storage materials, it is essential to select a proper technique for characterize hydrogen storage properties to avoid faulty results. This paper serves as a critical review on several techniques commonly employed to characterize hydrogen storage materials. In this context, the working principles, advantages and drawbacks, limitations of six categories of techniques – Sieverts method, gravimetric method, secondary ion mass spectrometry, thermal desorption spectroscopy, neutron scattering and electrochemical techniques – are described and reviewed. It can be seen that Sieverts method is a powerful tool for metal hydride samples under normal testing regime. Gravimetric method can be used to investigate the hydrogen storage of porous samples since it normally suffers less from the sample volume uncertainty, however careful buoyancy correction must be applied to avoid faulty results. Secondary ion mass spectroscopy and thermal desorption spectroscopy can be used to study the surface/subsurface hydrogen profile and thermodynamic/kinetic properties of gas desorption of sample, respectively, providing that these samples are stable under vacuum. Neutron scattering is capable of investigating varies types of information including structural, diffusion and hydrogen dynamics of host material under in-stiu environment, although the neutron resources is not always accessible for most researchers. Electrochemical method can be used to study thermodynamic/kinetic properties for both thin film and bulk samples, but it may not be applicable to samples with low corrosion resistance and high plateau pressure.
After many years of successful and disappointing results, the field of Li–O2 research seems to have reached an equilibrium state. The extensive knowledge that has accrued through advanced analytical studies enables us to delineate the weaknesses of the Li–O2 battery. It is now clear that the instability of the cell components toward extreme conditions existing during cell operation leads to early cell failure as well. One serious challenge is the high oxidation potential applied during the charge process. Redox-mediators may reduce the over-potential and, therefore, improve the efficiency and cyclability of Li–O2 cells. Their use in Li–O2 cells is mandatory. We have previously shown that LiI can indeed behave in such a manner; however, it also promotes the formation of side products during cell operation. We have, therefore, embarked on a comprehensive study of lithium halide salts as electrolytes for use in Li–O2 cells. We examine herein the effect of other components in the cell, such as solvents and contaminants, on the lithium halide salt activity. Based on the electrochemical behavior and the identity of the final cell products under various conditions, we can glean substantial information regarding the detailed operation mechanisms for each specific case. We have concluded that low concentration of LiBr in diglyme solution can improve the cell performance with fewer side effects than LiI. With LiBr, only the desired Li2O2 is formed during discharge. During charge, the bromine redox couple (Br−/Br3−) can reduce the oxidation potential to only 3.5 V. Higher efficiency and better cyclability of cells containing LiBr demonstrate that the electrolyte solution is the key to a successful Li–O2 battery.
Introducing lattice mismatch-induced tensile strain at hetero-interfaces may be an efficient approach to enhance ionic conductivity at moderate temperatures. Extensive theoretical and experimental research has focused on strain-versus-ionic conductivity correlations. However, the correlation between strain and ionic conductivity still lacks a systematic and quantitative investigation. In this report, we derive an analytical expression to evaluate quantitatively the strain-induced enhancement in ionic conductivity. We demonstrate that simulation and experimental data in the literature, are well explained in the framework of our derived expressions. Our studies provide a powerful platform for quantitatively designing and engineering heterostructure interfaces for a number of applications, including fuel cells/batteries and optical/magnetic devices.
The roles of conductivity and structure in the reversibility, rate capability, capacity and capacity retention of nickel oxide anodes for lithium-ion batteries were investigated. Conductivity was controlled by the systematic addition of non-intercalating carbon. The NiO nanostructure was controlled through four different preparation procedures. Overall, the top-performing electrodes were made from tetrahedral-shaped particles with a broad particle size distribution that were derived from a simple direct calcination of nickel nitrate salt. Capacity values >700 mA h/g after 100 cycles at 1C were observed, and a rate capability >400 mA h/g at 5C was achieved for electrodes with 40% carbon added. The addition of carbon universally improved anode performance by influencing the charge transferability, as evidenced by SEI peak shifts and reduced resistances seen via EIS. Reversibility was greatly enhanced as the conductivity was improved through carbon addition, which enabled otherwise inactive anode particles to maintain activity after many cycles. This work suggests that improved conductivity, as opposed to the conventional opinion regarding nanostructure, is the key to creating high performance anodes for next generation lithium-ion batteries.
This paper is based on my award acceptance talk on the occasion of receiving the Grove Medal for Fuel Cell Science and Technology, at the 2006 Grove meeting in Torino, Italy. I chose to name the talk: “Fuel Cell Techno-Personal Milestones 1984–2006”, trying to reflect on important milestones in the history of the science and technology of hydrogen/air and methanol/air polymer electrolyte fuel cells, in which I was fortunate to be involved for over 20 years.
This chapter summarizes the types of reviews that will generally be required for typical process industry applications both for initial project design and initial process facility evaluations. Specific safety and security review lists are provided for petroleum/chemical industry facilities as an example. Finally, the application of such reviews during facility changes is examined.
Diagnosis of vascular malformations is essentially clinical, based on the evolution and morphology of lesions. A biopsy is rarely needed to evaluate the nature of the vessels. Imaging examinations are necessary to assess the extension of malformations as well as the osteomuscular and visceral compromise. New techniques such as 3D angio-CT scan and angio-MRI improve the diagnosis of some vascular malformations, especially the large combined ones such as Klippel-Trénaunay syndrome, thus limiting the need for invasive procedures. On the other hand, the advances in laser technology, particularly pulsed dye laser for port-wine stains and Nd:YAG laser for superficial venous malformations constitute new alternatives for the management of these patients. Other emergent treatments include microfoam sclerotherapy for venous and combined, slow-flow malformations, and new embolizing materials associated to surgery for arteriovenous malformations. The second part of this review is focused on the complementary diagnosis (imaging exams, pathology and accessory tests) and multidisciplinary and specific treatment based on the different groups.
Although ZnMn2O4 is widely studied as Li-ion battery anodes, it remains a challenge to tailor suitable microstructures of the oxide for supercapacitor applications. Carbon-coated ZnMn2O4 (C@ZMO) nanocrystallites showing high-performance pseudocapacitor behaviours in neutral aqueous electrolyte are for the first time successfully synthesised via a novel solution combustion process using polyethylene glycol as a multifunctional microstructure-directing agent. Controlling the molecular weight and amount of the polymer in the combustion solution enables the formation of highly-crystalline C@ZMO having substantially higher, by more than 5 folds, specific surface areas with mesoporous structures and conformal carbon coating via the one-pot synthesis process. The resulting C@ZMO supercapacitor electrodes in Na2SO4(aq) electrolyte exhibit ideal capacitive behaviours with specific capacitances up to 150 F g−1 and cycle stability showing no capacitance fade after 10,000 cycles at 60% of full capacity and >99% Coulombic efficiency. This study not only illustrates a new powerful synthesis route capable of producing conductive mesoporous crystalline oxide-based nanomaterials for energy storage applications but also reveals a new class of high-performance pseudocapacitive materials for neutral aqueous electrolytes.
Depression and anxiety are well documented in patients with end-stage heart failure and correlate with a higher risk of suicide. We report a 69-year-old depressed patient who committed suicide by disconnecting the driveline of his left ventricular assist device almost 3 years after implantation. We provide the medical, psychologic, and psychiatric background of this unique case. This report highlights the importance of pre-implant psychologic screening, the need for regular and long-term psychologic support for this vulnerable patient population, and the need for more qualitative research on patients' views on living with a left ventricular assist device, together with research exploring risk profiles for depression and suicide.
Silicon (Si)-based materials have the highest capacity among the investigated anode materials and have been recognized as one of the most promising materials for lithium-ion batteries. However, it is still a significant challenge to obtain good performance for practical applications due to the huge volume change during the electrochemical process. To date, the most successful strategy is to introduce other components into Si to form composite or alloy materials. In this review, the recent progress in Si-based materials utilized in lithium-ion batteries is reviewed in terms of composite systems, nano-structure designs, material synthesis methods, and electrochemical performances. The merits and disadvantages of different Si-based materials, the understanding of the mechanisms behind the performance enhancement as well as the challenges faced in Si anodes are also discussed. We are trying to present a full scope of the Si-based materials, and help understand and design future structures of Si anodes in lithium-ion batteries.