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Polystyrene foam (PF), commonly used in packaging and insulation purposes, has emerged as a recycling predicament due to its low density and is often found littering the natural environment. Herein, we have reported the utilization of discarded PF as a sacrificial material to synthesize porous carbon nanofibers (CNFs) as a sustainable technique to produce cost-effective, high-performance supercapacitor electrodes while addressing PF disposal. It was found that the solubility difference between PF and polyacrylonitrile (PAN) in N,N-dimethylformamide can be exploited to create micro-mesoporous multi-channel CNFs via electrospinning technique for enhanced ion adsorption leading to higher specific capacitance. CNF-40 (PF:PAN = 40:60) showed the best electrochemical performance with a specific capacitance of 271.6 F g−1 at a current density of 0.5 A g−1. Further, CNF-40 exhibited 100% capacitance retention after 5000 cycles, and the high energy and power densities of 18.8 Wh kg−1 and 8000 W kg−1, respectively. Moreover, in an all-solid-state supercapacitor, it demonstrated a high areal capacitance of 0.32 F cm−2, indicating great potential for application in solid-state devices.
A series of bis(trifluoromethylsulfonyl)amide based “polymeric ionic liquids” (PILs) as high molecular mass analogues of the corresponding imidazolium, ammonium and pyrrolidinium ionic liquids (ILs) was synthesized with high purity and fully characterized including electrochemical properties. The PILs differed by the nature of the cation, the quantity of the ionic centers in each monomer repeating unit, and the alkyl length of the spacer. Two novel ionic liquid like monomers (ILMs), namely 1,3-bis(N,N,N-trimethylammonium)-2-propylmethacrylate bis(trifluoromethylsulfonyl) amide (ILM-2) and N-[(2-methacryloyloxy)-ethyl]-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (ILM-4) were synthesized and characterized. Optimal conditions for the free-radical polymerization of the ILMs were identified for the first time. It was demonstrated that, among the tested organic solvents, 1-methyl-3-ethylimidazolium bis(trifluoromethylsulfonyl)amide IL was the best reaction medium in terms of the achievement of high polymer yields and molecular masses. For the first time, the influence of the residual monomer presence inside the PIL film on the resultant conductivity was clearly shown. The impact of the molecular mass of the PILs on the ionic conductivity was firstly studied as well. Finally, the copolymerization of ILMs with poly(ethylene glycol)dimethacrylate (PEGDM) was carried out yielding tight elastic films with the highest conductivity equal to 3.2×10−6 S/cm at 25 оС.
The aim of the present study was to identify the physical fitness (PF) tests of a multi-component battery more related to the perception of problems in each dimension of the health-related quality of life (HRQoL) assessed by the EuroQol 5 dimensions 3 level questionnaire (EQ-5D-3L) in community-dwelling middle-aged and older adults
Three ZnO-C samples with distinct structures including yolk-shell microspheres, hollow microspheres and solid microspheres are fabricated through a facile chemical solution reaction followed by calcination in argon. When employed as the anode materials for lithium ion batteries, yolk-shell ZnO-C microspheres exhibit the best electrochemical properties than the hollow and solid microspheres. After 150 cycles, yolk-shell ZnO-C microspheres demonstrate a relative high capacity of 520mA h g−1 at a current density of 100mAg−1 with a Coulombic efficiency of about 99.3%. The excellent cycling stability and good rate capability of yolk-shell ZnO-C microspheres stem from the synergistic effect of the unique yolk-shell structures and extra carbon support.
This paper analyzes a new fuel cell Hybrid Power Source (HPS) topology having the feature to mitigate the current ripple of the fuel cell inverter system. In the operation of the inverter system that is grid connected or supplies AC motors in vehicle application, the current ripple normally appears at the DC port of the fuel cell HPS. Consequently, if mitigation measures are not applied, this ripple is back propagated to the fuel cell stack. Other features of the proposed fuel cell HPS are the Maximum Power Point (MPP) tracking, high reliability in operation under sharp power pulses and improved energy efficiency in high power applications. This topology uses an inverter system directly powered from the appropriate fuel cell stack and a controlled buck current source as low power source used for ripple mitigation. The low frequency ripple mitigation is based on active control. The anti-ripple current is injected in HPS output node and this has the LF power spectrum almost the same with the inverter ripple. Consequently, the fuel cell current ripple is mitigated by the designed active control. The ripple mitigation performances are evaluated by indicators that are defined to measure the mitigation ratio of the low frequency harmonics. In this paper it is shown that good performances are obtained by using the hysteretic current control, but better if a dedicated nonlinear controller is used. Two ways to design the nonlinear control law are proposed. First is based on simulation trials that help to draw the characteristic of ripple mitigation ratio vs. fuel cell current ripple. The second is based on Fuzzy Logic Controller (FLC). The ripple factor is up to 1% in both cases.
Recently, dual-ion cells based on the anion intercalation into a graphite positive electrode have been proposed as electrochemical energy storage devices. For this technology, in particular electrolytes which display a high stability vs. oxidation are required due to the very high operation potentials of the cathode, which may exceed 5 V vs. Li/Li+. In this work, we present highly promising results for the use of graphite as both the anode and cathode material in a so-called “dual-graphite” or “dual-carbon” cell. A major goal for this system is to find suitable electrolyte mixtures which exhibit not only a high oxidative stability at the cathode but also form a stable solid electrolyte interphase (SEI) at the graphite anode. As an electrolyte system, the ionic liquid-based electrolyte mixture Pyr14TFSI-LiTFSI is used in combination with the SEI-forming additive ethylene sulfite (ES) which allows stable and highly reversible Li+ ion and TFSI− anion intercalation/de-intercalation into/from the graphite anode and cathode, respectively. By addition of ES, also the discharge capacity for the anion intercalation can be remarkably increased from 50 mA h g−1 to 97 mA h g−1. X-ray diffraction studies of the anion intercalation into graphite are conducted in order to understand the influence of the electrolyte additive on the graphite structure and on the cell performance.
There is an increasing demand for improvement of the capacity, rate performance, and life cycle of lithium-ion batteries to meet the requirements of low-emission vehicles, such as hybrid electric and plug-in hybrid electric vehicles. In this article, we report the application of graphdiyne (GDY) as high efficiency lithium storage materials and elucidate the method of lithium storage in multilayer GDY. GDY is a novel carbon allotrope comprising sp- and sp2-hybridized carbon atoms. Lithium-ion batteries featuring GDY-based electrode exhibit excellent electrochemical performance, including high specific capacities, outstanding rate performances, and a long cycle lives. We obtained reversible capacities of up to 520mAh/g after 400 cycles at a current density of 500mA/g. At an even higher current density of 2A/g, cells incorporating GDY-based electrodes retained a high specific capacity of 420mAh/g after 1000 cycles.
A binder-free LiFePO4 cathode is prepared by simple in situ gelatin carbonation at 600°C under pure N2. In this process, gelatin which is used as a binder in the traditional electrodes, is converted into carbon materials evenly and coated on LiFePO4 with acetylene black particles. The obtained binder-free cathode possesses uniform distribution of LiFePO4 and acetylene black, gelatin-based carbon coating and the porous structure. The gelatin-based carbon coating can enhance the effective electronic conductivity among LiFePO4, acetylene black particles and current collector. And the porous structure formed by decomposition and shrinkage during carbonation of gelatin can facilitate penetration of the liquid electrolyte into the pores, serving as a fast ionic pathway. The electrochemical results show the rate capability is greatly improved and the discharge capacity still reaches 108mAh/g at 5C. There is almost no capacity fading at the same C-rate cycles.
The objective of this paper is to close the scientific gap that there is a lack of comprehensive matching analysis for the increasingly complicated on-site hybrid energy systems with a continuously decreased annual primary energy consumption/equivalent CO2 emission. Thus, a thorough matching analysis is conducted for the on-site hybrid systems of two office buildings under distinct climate conditions. Both of the studied buildings are equipped with PV and solar thermal assisted ground source heat pumps (GSHP), which can be controlled by six excess renewable electrical (REe) and one excess renewable thermal (REth) treatments with respect to certain thermal storage recharging and grid exporting strategies. The assessment criteria are six recently defined indices. With the aid of these indices, the key methodology is to conduct parametric analyses from the aspect of matching for solar thermal collector area and connection type, PV panel area, and electrical battery size regarding certain excess REe or REth treatments. The outcomes of matching analyses show the advantages of solar thermal collectors connected in a parallel fashion in meeting office heating demands, the consistency between electrical generation and demand in the daytime in office buildings, the enhancement of on-site heating and cooling by GSHP and free ground cooling, and the battery effect in technically improving electrical matching. Furthermore, the fluctuations of indices in the instantaneous matching analysis clearly reflect the matching situations of on-site renewable energy resources and demand conditions at each time-step, which will be helpful for the detailed investigation of specific system operations and user behaviours. It has been shown that the methodology used in the study can be helpful for aiding the design of increasingly complicated on-site hybrid energy systems.
Co–Al–CO3 layered double hydroxide (LDH) with the different Co/Al molar ration is synthesized by hydrothermal method and investigated as an additive for positive material of the Ni–MH cells. The Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM) and X-ray diffraction (XRD) show the Co–Al-LDH with Co/Al = 4:1 (molar ration) is well-crystallized and hexagon structure. The electrochemical performances of the nickel electrode added with different Co/Al molar ration Co–Al-LDH, the pure nickel electrode and the nickel electrode added with CoO are investigated by the cyclic voltammograms (CV), galvanostatic charge–discharge measurements, and AC electrochemical impedance spectroscopy (EIS). Compared with the pure nickel electrode and the nickel electrode added with CoO, the nickel electrode added with Co/Al = 4:1 (molar ration) Co–Al-LDH has higher discharge capacity and more stable cycling performances. This cell can undergo at least 400 charge–discharge cycles at constant current of 1 C. The discharge capacity of this cell remains about 287 mAh g−1 after the 400th cycle. Meanwhile, compared with the pure electrode, the nickel electrode added with Co/Al = 4:1 (molar ration) Co–Al-LDH possess a higher rate capability to meet the needs of high-storage applications.
Anxiety is one of the most fundamental emotions required to survive or to cope with potential threatening stimuli. Under certain circumstances, it can change to excessive or maladaptive response and might manifest in anxious personality or even anxiety disorders. Genetic studies provide a number of promising candidate genes that, however, account for only a few percent of the phenotypic variance. Social and material environmental effects such as stressful life events, drugs or chemicals and particular behavioural influences such as parental care are suggested to interact with gene effects presumably involving epigenetic processes. Such interaction probably modifies an individual’s predisposition, personality and susceptibility to develop normal or low anxiety or even maladaptive or excessive anxiety. Since human anxiety involves complex emotions as well as cognitions, unique experiences and an individual genetic make-up, studies trying to clarify the complex and functionally interwoven pathogenesis of anxious personality or anxiety disorders often adopt a reductionistic, simplifying approach. Therein, mice constitute an invaluable tool for modelling human anxiety in its various forms as they display remarkable similarities on anatomical, physiological, biochemical, molecular and behavioural levels. This review aims to fit observations and results obtained from men and mice on behavioural, genetic and environmental levels in response to different threatening stimuli elucidating different genetic and epigenetic effects.
A Si-based alloy as the anode material in Li-ion batteries has advantages of safety and excellent performances, but poor electronic conductivity and excessive volume expansion limit the long cycle life required for practical application. In this work, in order to solve these problems, a core-shell nanocomposite has been developed, which is composed of a Si core and NiSi2/Ni shell with a carbon layer coating as the outer surface, which is referred to as a Si@NiSi2/Ni/C nanocomposite. Results show a reversible charge capacity of 1194mAhg−1 and 98% retention after 105 cycles, which are superior to its Si/C and NiSi2/Si counterparts. Furthermore, the fabrication method used has advantages of low cost and easy operation, which make it feasible to commercialize the Si@NiSi2/Ni/C nanocomposite as the anode in a lithium-ion battery.
Si with x =0.000, 0.015, 0.030, and 0.050 is successfully doped into layered LiNi0.5Mn0.5-xSixO2 using a sol − gel method. Si doping results in a decrease in lattice constant, Li/Ni mixing, stress, and size of primary particles. Si is distributed at the Mn site probably nonuniformly to cause two different states of Si4+. Si doping exerts no influence on the 2p bands of Ni2+, and however gives rise to a slight splitting of 2p3/2 band of Mn4+, and tends to increase the diffusion activation energy of Li+. The optimum performance is achieved for LiNi0.5Mn0.5-xSixO2 with x =0.015 which has the highest BET surface area. Detailed analysis of structural modifications allows one to conclude that the remarkable alleviation of agglomeration of primary particles other than the optimization of structure related parameters such as the lattice constant, metal − oxygen bond length, ordering, cation mixing, size, and stress is responsible predominantly for the performance improvement. This study suggests that silicon is not an effective dopant for performance improvement of layered LiMO2 simply from the perspective of structural modifications and optimization.
Publisher Summary This chapter presents a discussion on physical network layer. The chapter describes physical design issues for networks on chips (NoCs). A major design problem in NoCs is the interconnect realization that requires modeling and performance metrics—such as the signal integrity and noise immunity. High-speed signaling—such as current-mode signaling and wave-pipelining—and low-power interconnection designs—such as low-swing signaling and transition-reducing coding—are widely used within the NoC physical layer. The chapter analyzes the clock and data synchronizing methods as well as the physical design issues of NoC building blocks such as switches, buffeting memories, and SERDES. Although a new design approach such as NoC is required to get a more process independent interconnection architecture, still more emphasis is put on the physical design of interconnection and more detail understanding of the physics in the interconnect of deep submicron (DSM) technology is required than before. Four factors are referred to cause new challenges in DSM: (1) increase of the operation frequency so that the inductance characteristics are more conspicuous than before, (2) signal reflection and transmission because of impedance mismatch, (3) increase of fringe capacitance because of increased aspect ratio of the interconnection wire, and (4) increase of resistance with sheet resistance because of skin effect of high frequency and contact resistance.
A NiFe2O4–graphene heteroarchitecture with differing graphene content is prepared by a straightforward hydrothermal strategy. The NiFe2O4–graphene (with 20 wt% graphene) nanocomposite as the anode material for lithium-ion batteries shows a high specific reversible capacity up to 960mAhg−1 with good cycling stability and rate capability. The superior electrochemical performance of the NiFe2O4–graphene nanocomposite can be attributed to its unique heteroarchitecture, which enables high utilization of active material, good structural stability and fast charge transport.
Mild cognitive impairment (MCI), often considered as an early stage of dementia, is heterogeneous, and not all subjects with MCI progress into clinically diagnosed dementia. Low body weight (and body mass index, BMI) as well as losing weight while in MCI stadium have been proposed as possible risk factors of MCI-to-dementia conversion.
Nano-Fe3O4-loaded tubular carbon nanofibers (nano-Fe3O4/TCNFs) were synthesized by adding TCNFs into the high-temperature solution-phase reactions of iron(III) acetylacetonate with 1,2-hexadecanediol in the presence of oleic acid and oleylamine. The morphology and structure of this material were investigated by transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurements. TEM observation clarified that nano-sized Fe3O4 particles with a uniform diameter of several nanometers were distributed and loaded tightly on the TCNF surfaces (inside and outside). After being annealed at 500°C in Ar gas flow, nano-Fe3O4/TCNFs were used as the active material of negative electrodes for Fe/air batteries. Using an alkaline aqueous electrolyte with K2S additive, a high specific capacity of 786mAhg−1 and cycling efficiency of 76% at the 30th cycle were obtained. The downsizing of the conductive Fe3O4 nano-particles was considered to have contributed to the good electrochemical properties of the material.
A strategy for portable high-power applications with a controlled thermal environment has been developed and has demonstrated the advantage of using the novel phase change material (PCM) thermal management systems over conventional active cooling systems. A passive thermal management system using PCM for Li-ion batteries is tested for extreme conditions, such as ambient temperature of 45°C and discharge rate of 2.08C-rate (10A). Contrary to Li-ion packs without thermal management system, high-energy packs with PCM are discharged safely at high currents and degrading rate of capacity of the Li-ion packs lowered by half. Moreover, the compactness of the packs not only decreases the volume occupied by the packs and its associated complex cooling system, but also decreases the total weight for large power application.
Surface-modified graphite for application as an anode material in lithium ion batteries was obtained by etching with KOH under mild conditions without high-temperature annealing. The surface of the etched graphite is covered with many nano-sized pores that act as entrances for lithium ions during the charging process. As compared with pristine graphite and other references such as pitch-coated or etched graphite samples with annealing, our non-annealed etched graphite exhibits excellent electrochemical properties, particularly at fast charging rates of over 2.5 C. While avoidance of the trade-off between increase of irreversible capacity and good rate capability has previously been a main concern in highly porous carbonaceous materials, we show that the slightly larger surface area created by the etching does not induce a significant increase of irreversible capacity. This study shows that it is important to limit the size of pores to the nanometer scale for excellent battery performance, which is possible by etching under relatively mild conditions.
Composite electrodes for supercapacitors were prepared by electropolymerization of polyaniline (PANI) on the surface of activated-porous carbons. The surface morphology and the chemical composition of composite electrodes were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of electrodes and the capacitive behavior of the resulting capacitors were systematically studied using cyclic voltammetry (CV), ac impedance and constant current charge–discharge tests. The specific capacitance of PANI-carbon composite electrode was exhibited as high as 160F/g, in comparison with a value of 95F/g for the bare-carbon (BC) electrode. An increase in capacitance more than 60% has been achieved, that identifies the significant contribution of pseudocapacitance from PANI on the overall capacitance.
We synthesized an electrospun SnO2 hollow nanofibers (SnO2 hNFs) coated with carbon and wrapped with graphene oxide layer by simple hydrothermal and electrostatic force method, respectively. Thin carbon layer as electrolyte blocking layer was formed on the SnO2 hNFs by using glucose as a carbon source (SnO2@C hNFs). Also, layers of graphene oxide are wrapped on SnO2@C hNFs by the electrostatic interaction force (SnO2@C@G hNFs). At high C rate, the average capacity of the SnO2@C@G hNFs still kept high capacity comparing with the SnO2 hNFs and SnO2@C hNFs and then increased above 250% at 3C. It also exhibits a greatly enhanced synergic effect with an extremely high lithium storage capability up to 1,600mAhg−1 and kept 900mAhg−1 after 50 cycles benefiting from the advanced structural features.
Spinel lithium manganese oxides (LiMn2O4) modified with and without bismuth by sol–gel method were investigated by theoretical calculation and experimental techniques, including galvanostatic charge/discharge test (GC), cyclic voltammetry (CV), chronopotentiometry (CP), electrochemical impedance spectroscopy (EIS), inductively coupled plasma (ICP), powder X-ray diffraction (XRD), BET measurement, and infrared spectroscopy (IR). It is found that the performance of LiMn2O4 can be improved by the bismuth modification. The modified and the unmodified samples have almost the same initial discharge capacity, 118 and 120mAhg−1, respectively. However, the modified sample has better cyclic stability than the unmodified sample. After 100 cycles, the capacity remains 100 and 89mAhg−1 for the modified and the unmodified samples, respectively. Moreover, the results from EIS show that the modified sample has a quicker kinetic process for Li ion intercalation/de-intercalation than the unmodified one; the charge-transfer resistance of the former is less than one-sixth of that of the latter. After immersion in electrolyte (DMC:EC:EMC=1:1:1, 1molL−1 LiPF6) for 10h at room temperature, the modified sample has less change in open circuit potential, crystal volume, and vibration absorption of Mn–O bond, and has less dissolution of manganese into solution than the unmodified sample.