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We synthesize Li[Ni1/3Co1/3Mn1/3]O2 (NCM) and Li[Ni1/3Co1/3Mn1/3]FexO2 (NCMF) cathode active materials with various amounts of Fe via hydroxide coprecipitation and calcination processes, which simulate the resynthesis of NCM in leach liquor containing Fe from spent lithium-ion batteries (LIBs). The crystal structure and electrochemical performances of the synthesized NCMF (i.e., NCMF (0.05%), NCMF (0.25%) and NCMF (1.0%)), are investigated and compared with NCM. The structural perfection of NCMF gradually deteriorates with increasing the amount of Fe because of undesirable cation mixing between Ni2+/Fe3+ and Li+ sites. In LIB performances, NCMF (0.05%) and NCMF (0.25%) present relatively reduced overpotential leading to superior rate performance at high C-rates to NCM with NCMF (1.0%) having the poorest. In terms of cycling stability, however, capacity retention improves as the Fe content in NCMF increases. The thermal stability of NCM and NCMF is also measured by differential scanning calorimetry, and the post-mortem analysis of X-ray photoelectron spectroscopy reveals that the ratio of Mn3+ becomes lower after cycling tests as the amount of Fe in NCMF increases. Moreover, the additional post-mortem analysis of energy dispersive spectroscopy on graphite surface after full cell cycling tests further confirms the positive effect of Fe on the improved capacity retention performance of NCMF. Therefore, even if Fe is regarded as an impurity component in the LIB recycling process, a small amount of Fe in the resynthesized NCM cathode material could favor high power and high cycling stability.
The authors regret that incorrect version of Fig. 6, were used in this article. The yellow line (charged to 1.3 V) in this wrong figure was not from the right sample. We are here to replace Fig. 6e with a corrected version. This replacement does not affect the conclusion of the manuscript.Fig. 6(a–c) High resolution XPS of vanadium in the pristine, fully discharged, and charged V2O5 nanopaper; (d) High resolution XPS of zinc in the pristine, fully discharged, and charged V2O5 nanopaper (e) The ex-situ XRD patterns of the V2O5 nanopaper at different states of charge.Fig. 6 The authors would like to apologise for any inconvenience caused.
Hybrid Na-ion capacitors bridge the performance gap between Na-ion batteries and supercapacitors and offer excellent energy and power characteristics. However, designing efficient anode and cathode materials with improved kinetics and long cycle life is essential for practical implementation of this technology. Herein, layered sodium titanium oxide hydroxide, Na2Ti2O4(OH)2, synthesized through hydrothermal technique, is studied as efficient anode material for hybrid Na-ion capacitor. Half-cell electrochemical studies vs. Na/Na+ showed excellent performance for Na2Ti2O4(OH)2 electrode, with ∼57.2% of the total capacity (323.3 C g−1 at 1.0 mV s−1) dominated by capacitive behavior and the remaining due to Na-intercalation. The obtained values are in good agreement with Trasatti plots indicating the potential of this material as efficient anode for hybrid Na-ion capacitor. Further, a full cell Na-ion capacitor is fabricated with Na2Ti2O4(OH)2 as anode and chemically activated Rice Husk Derived Porous Carbon (RHDPC-KOH) as cathode by using organic electrolyte. The hybrid device, operated at a maximum cell voltage of 4 V, exhibits stable electrochemical performance with a maximum energy density of ∼65 Wh kg−1 (at 500 W kg−1, 0.20 A g−1) and with more than ∼ 93% capacitive retention after 3000 cycles.
We combine a detailed battery model with a simple vehicle model to examine the battery size and capacity usage of a Li x C6/Li y+0.16Mn1.84O4 cell (with a normal and artificially flat equilibrium potential) and a Li4+3x Ti5O12/Li y FePO4 cell. The features of cell chemistry we are concerned with are the magnitude and shape of the cell equilibrium potential and internal resistance. Our key findings include that a battery for a hybrid electric vehicle application has a capacity usage from 15 to 25% (for a minimum separator area size), and as one moves from a HEV battery to a plug-in hybrid electric vehicle battery there is a change in the slope of the separator area vs. equivalent-electric range curve due to the shape of the pulse-power capability. We also find that defining the resistance using the HPPC protocol has limitations because in general the pulse resistance depends on the applied current and pulse duration. Our detailed, combined model also shows that the benefits of a flat-potential system may be limited because of the relative positions of a flat and sloped equilibrium potential, and the lack of a driving force for the relaxation of solid-phase concentration gradients throughout the electrode. That latter effect is shown to be more significant for electrodes with a non-uniform current distribution.
Composite polymer electrolyte based on a new class of filler added to a PEGDME/LiClO4 model system has been investigated. “Ceramic super acids” used consist of grafted SO4 2− groups on Al2O3 particles surface obtained by calcinations route. Conductivity, DSC and FT-IR measurements performed on such composite electrolytes, when compared to the model PEGDME/LiClO4 electrolyte, showed only slight improvement of their inner characteristics. In contrary, Li/Li symmetric cells study, by means of impedance spectroscopy, has presented a spectacular decrease of the interfacial resistance compare to the model electrolyte. This result opens a new pathway of investigation to master the lithium metal/polymer electrolyte interface.
The potential of conducting polymer coatings for corrosion protection is a topic of current controversy. In general, the efficacy of conducting polymers very much depends on how they are applied and on the conditions of the corrosion experiment, i.e. depending on the exact conditions a conducting polymer may have excellent protection capability or may lead to a disastrously enhanced corrosive attack. A number of possible protection mechanisms are proposed. The most interesting corrosion protection mechanism that is currently discussed for conducting polymer-based coatings is the intelligent release of inhibitor anions. However, in many cases this does not work in the presence of larger defects. Based on scanning Kelvin probe studies of artificial defect initiated reduction and delamination of polypyrrole films in nitrogen (reduction) or air (reduction and delamination) atmospheres it will be shown in this paper that this is due to a switching from mixed anion release and cation incorporation during reduction of the conducting polymer to an exclusive cation incorporation for reduction over extended length scales. Although only results for polypyrrole are discussed here, for fundamental reasons this is postulated to be of general validity for all conducting redox polymers such as polypyrrole, polyaniline, and polythiophene. Hence, all coatings based on pure conducting polymer layers or pigments with macroscopic percolation networks will fail in the presence of larger defects, even though they may show excellent corrosion protection for smaller ones.
This study highlights the effects of a biomass-derived carbon coating on the properties of flexible lithium iron phosphate polymer batteries. Pure LiFePO4 (LFP) and carbon-coated LiFePO4 (C-LFP) cathode materials are synthesized by a modified mechanical activation process. LiFePO4 was uniformly coated with biomass-derived carbon by the addition of orange peel during the synthesis. C-LFP with a particle size of approximately 90 nm, having a homogeneous particle size distribution with particles smaller than that of pure LFP (140 nm), is obtained with 6.0 wt% carbon content. The electrochemical properties are evaluated at room temperature by cyclic voltammetry and charge-discharge performance analysis using porous carbon current collector with a lithium metal anode and gel polymer electrolyte that is prepared by the phase inversion method. C-LFP exhibits a high discharge capacity of 147.3 mAh g−1 (corresponding to 87% of the theoretical capacity) at 0.5 C-rate and 139.8 mAh g−1 at 1 C-rate. Good rate capability and stable cycle performance were realized for flexible lithium polymer cells employing the biomass derived-carbon coated LiFePO4.
Silicon has been considered as one of the most promising anode materials for the next generation lithium-ion battery due to its high theoretical capacity, but large volume changes during the electrochemical cycling limit its commercial application. In this study, we report the synthesis of silicon carbide @ silicon core–shell nanowires on carbon paper and their application in lithium-ion batteries. The hybrid nano-structures are fabricated via a two-step chemical vapor deposition method and directly used as the working electrode without any additional binder, exhibiting high specific capacity, high coulombic efficiency and good cycling stability. After 50 cycles, the discharge capacities still remain 2837 and 1809 mAh g−1 at the rates of 0.1C and 0.5C, respectively. Furthermore, we also study the influence of the growth time of SiC NWs and the thickness of Si film on the lithium-ion batteries' performance, and propose the possible method to further improve the battery performance.
This review discusses major findings from the Women's Health Initiative Memory Study (WHIMS). WHIMS reported hormone therapy (HT) – conjugated equine estrogen (CEE) with or without medroxyprogesterone acetate (MPA) – increased the risk for dementia (HR 1.76 [95% CI, 1.19–2.60]; P =0.005) and global cognitive decline, with a mean decrement relative to placebo of 0.21 points on the Modified Mini Mental State Examination (3MS) (P =0.006) in women age 65 and older. A subset of WHIMS participants joined the ancillary WHI Study of Cognitive Aging (WHISCA) trials, in which domain-specific cognitive tests and mood were measured annually. Compared with placebo, CEE+MPA had a negative impact on verbal memory over time (P =0.01); and CEE-Alone was associated with lower spatial rotational ability (P ≤0.01) at the initial assessment, but the difference diminished over time. The ancillary WHIMS-MRI study measured subclinical cerebrovascular disease to possibly explain the negative cognitive findings reported by WHIMS and the increased clinical stroke in older women reported by the WHI. WHIMS-MRI reported that while CEE+MPA and CEE-Alone were not associated with increased ischemic brain lesion volume relative to placebo; both CEE+MPA and CEE-Alone were associated with lower mean brain volumes in the hippocampus (P =0.05); frontal lobe (P =0.004); and total brain (P =0.07). HT-associated reductions in hippocampal volumes were greatest in women with baseline 3MS scores ≤90.
In recent work the ionic transportation properties of organic electrolyte in Li-ion batteries has been described in detail by the present authors, taking into account ionic diffusion and migration processes. Advanced battery electrolytes may, however, be composed of various salts. Therefore the ionic transport properties of such complex electrolytes have been investigated from a theoretical point of view. Detailed information about transient and steady-state behavior of the electrolyte has been simulated, including potential gradients and the diffusion and migration fluxes for all ions. It was found that supportive electrolytes are an effective way to reduce the electric field and, consequently, the migration overpotential. Simultaneously, the diffusion overpotential, in general, increases. Nethertheless, supportive salts reduce the total overpotential across the electrolyte, especially when high currents are applied for short periods of time.
The electrochemical synthesis of poly(o -phenylenediamine) (PoPD) from an aqueous medium was suitably modified by controlling the switching potential to enhance the growth of the polymer. The charge–discharge data for the cell Zn/1 M ZnSO4 (pH 4)/PoPD are presented. The polymer was modified by incorporating Pt microparticles into its matrix during electropolymerization. The PoPD-Pt composite electrode was also characterized as a cathode active material in aqueous cells.
In this study, single crystal V3O7·H2O nanobelts were successfully synthesized using a simple hydrothermal route, in which templates or catalysts were absent. The synthesized V3O7·H2O nanobelts are highly crystalline and have lengths up to several tens of micrometers. The width and thickness of the nanobelts are found to be about 30–50 and 30nm, respectively. A lithium battery using V3O7·H2O nanobelts as the positive electrode exhibits a high initial discharge capacity of 409mAhg−1, corresponding to the formation of Li x V3O7·H2O (x =4.32). Such a high degree of electrochemical performance is attributed to the intrinsic properties of the single-crystalline V3O7·H2O nanobelts.
The relationship between cannabis and cognitive performance is controversial. While both acute administration and long-term cannabis use impair cognitive performance in healthy subjects, several studies have shown improved cognitive outcomes in patients with schizophrenia spectrum disorders who use cannabis. The aim of this study was to determine the relationship between lifetime cannabis use, as assessed longitudinally over 10 years of follow-up in a sample of 42 patients and 35 of their unaffected siblings, and current cognitive performance. Forty-two healthy control subjects were assessed at follow-up with the same instruments. Stepwise linear regression revealed a negative effect of longitudinal cannabis use on performance in a social cognition task in the patient group. In the sibling group, lifetime cannabis use had a negative effect on processing speed and declarative memory performance. In the control group, cannabis use per se did not predict cognitive performance; however, when adding lifetime tobacco use to the model, we found a negative association between lifetime cannabis and tobacco use and processing speed and social cognition performance. Moreover, a lower IQ associated with current cannabis use predicted worse attentional performance in the control group. The differential pattern of associations between cannabis use and cognitive performance in patients compared with siblings and controls can be explained by the negative impact of illness on cognition.
Young drivers are over-represented in road injury statistics, partly because they engage in more risky driving than older people. Although it is assumed that younger people have greater risk-propensity, defined as a positive attitude to risk, relevant theory is imprecise and relevant research is clouded by inappropriate measures. 89 participants aged 16–25 and 110 participants aged over 35 were recruited outside motor registries. Participants completed a battery of questionnaires including Rohrmann’s [Rohrmann, B. 2004. Risk attitude scales: concepts and questionnaires. Project report. Available at http://www.rohrmannresearch.net/pdfs/rohrmann-racreport.pdf (last accessed 12th February 2008)] measures of risk-aversion, risk-propensity, and risk-related motives for risky driving, as well as measures of risk-perception and risky driving. Compared to older drivers, younger drivers demonstrated lower risk-aversion, and higher propensity for taking accident risks, as well as stronger motives for risky driving in relation to experience-seeking, excitement, sensation-seeking, social influence, prestige-seeking, confidence/familiarity, underestimation of risk, irrelevance of risk, “letting off steam”, and “getting there quicker”. Further, these variables were associated with risky driving. Some evidence was observed for the possibility that risk propensity moderates the relationship between perceived risk and risky behaviour. These results suggest approaches to targeting the “young driver problem”.
In this study, the effect of the anodic current density in the regime of reversing current (RC) on the quantity of evolved hydrogen and morphology of copper deposits was considered. The quantity of evolved hydrogen was quantified by the determination of the average current efficiency for hydrogen evolution reaction, while morphology and internal structures of electrodeposited copper were analyzed using scanning electron (SEM) and optical microscopy techniques, respectively. In all RC experiments, the cathodic current density of 440mA/cm2, cathodic pulse of 10ms and anodic pulse of 5ms were applied, while the analyzed anodic current densities were: 40, 240, 440 and 640mA/cm2. The number, size and shape of holes formed of detached hydrogen bubbles strongly depended on the selected parameters of square waves RC. Due to the decrease of the quantity of evolved hydrogen with the increasing anodic current density, the change of morphology of copper deposits formed around holes from cauliflower-like agglomerates of copper grains to dendrites was observed. Honeycomb-like structures were formed with the anodic current density values up to 440mA/cm2. The compactness of the honeycomb-like structures increased with the increase of the anodic current density. The improvement of structural characteristics of the honeycomb-like electrodes was achieved by the application of the RC regime in comparison with both the pulsating current (PC) and constant galvanostatic regimes. It was found that the regime of reversing current is superior in the production of the honeycomb-like electrodes in relation to other current regimes of electrolysis.
Development of a fast and accurate tool for simulation of batteries is greatly interested in the applications which require real-time estimation of the battery operating status, e.g., battery monitoring, online prognostics, and control. This study proposes three lumped model for the real-time simulation of Lead-acid batteries. The first one, named ordinary lumped model, replaces the elliptic terms in the governing equations with engineering approximations. The second and third models are structure-based lumped models which are developed based on dominant structures (modes) of the acid concentration field. Proper orthogonal decomposition and cluster analysis are utilized as reduced-order models to extract the dominant structures. All models are capable of predicting the transient behavior of lead-acid batteries during charge and discharge processes in terms of acid concentration, state of charge, cell voltage, and electrodes’ porosity and active-area. The proposed models provide good consistency with previous experimental and numerical studies. Moreover, they produce results in a fraction of a second and simulate the battery orders of magnitude (∼103) faster than the finite-volume method. Furthermore, the results show that structure-based lumped models improve the accuracy of ordinary lumped model significantly.
This paper reviews the compositions, design and methods of fabrication of air cathodes for alkali zinc–air fuel cells (ZAFCs), one of the few successfully commercialized fuel cells. The more promising compositions for air cathodes are based on individual oxides, or mixtures of such, with a spinel, perovskite, or pyrochlore structure: MnO2, Ag, Co3O4, La2O3, LaNiO3, NiCo2O4, LaMnO3, LaNiO3, etc. These compositions provide the optimal balance of ORR activity and chemical stability in an alkali electrolyte. The sol–gel and reverse micelle methods supply the most uniform distribution of the catalyst on carbon and the highest catalyst BET surface area. It is shown that the design of the air cathode, including types of carbon black, binding agents, current collectors, Teflon membranes, thermal treatment of the GDL, and catalyst layers, has a strong effect on performance.
The decay and lifetime of the graphite electrodes in lithium ion batteries are determined by coupling of deformation and lithium concentration. In this paper, lithium concentration and strain in graphite electrodes are investigated in-situ during an electrochemical process. We propose an experimental method to simultaneously measure the electrode concentration field and strain field in real time. A visual electrochemical simulation cell is developed, and a dual optical experimental system for in-situ image acquisition during electrochemical cycling is designed and built. On the basis of the relationship between the lithium concentration and color, we combine a color imaging technique to measure the concentration distribution. We also apply an improved digital image correlation technology to measure the strain field, and realize real time simultaneous measurements of the lithium concentration and strain distribution of graphite electrodes during the electrochemical lithiation process. It is founded that lithium concentration and strain in the graphite electrode show a nonlinear distribution along the direction of diffusion, and higher concentrations are associated with greater strain. This paper proposes a new experimental method to quantify the coupling relationship between the lithium concentration and strain, which provides an important experimental means for analyzing mechano-electrochemical coupling mechanisms.
Enhancing the energy stored and power delivered by layered materials relies strongly on improved understanding of the intricate interplay of electrolyte ions, solvents, and electrode interactions as well as the role of confinement. Here we report a highly integrated study with multiscale theory/modelling and experiments to track the intercalation of aqueous Li+, Na+, K+, Cs+, and Mg2+ ions into Ti3C2 MXene. The integrated analysis of experiments assisted by theory/modelling allows for a deep understanding of energy storage processes highlighting the importance of the dynamics of cations, their positionings between MXene sheets, their effects on mechanical properties and capacitive energy storage. Computational simulations and operando calorimetry measurements prove the processes involving cation dehydration and H+ rehydration, showing a good correlation for heat variations between experiments and theory. Operando liquid AFM mapped energy dissipation of ions appears non-uniformly across the MXene surface, indicating heterogeneities of ions inside the MXene and confirming partially the ion behaviour obtained in theory. We directly demonstrate that the average distance between the cation and MXene surface follows a modified two-sided Helmholtz model when plotted versus the open circuit potential capacitance, revealing a different electrical double layer mechanism in confinement. This new fundamental understanding lays the foundation for improved functional devices utilizing electrodes and membranes made of two-dimensional materials.
The poor activation of the Zr-based AB2 Laves phase alloy hydride electrode is one of the problems retarding their commercialization. A surface treatment technique was carried out here to improve the poor activation of the alloys Zr(V0.1 Mn0.3Ni0.6)2, Zr(V0.1Mn0.3Ni0.6Co0.05)2, ZrTi0.1(V0.1Mn0.3Ni0.6Co0.05)2 and ZrTi0.1(V0.1Mn0.3Ni0.6Co0.05Cr0.05)2. We pre-treated the alloy powders by immersing and stirring them in solution of NH4F/NiCl2 to make the alloy surface clean and form a layer of nickel-rich, which has been regarded as an indispensable factor for the electrochemical activity of the alloy. It was found that the activation of the alloy electrode has been greatly improved by this method. The discharge capacity of the electrodes made from the treated alloy powder is over 345mAhg−1 at the discharge current density of 100mAg−1. Especially, the alloy electrode of the treated ZrTi0.1(V0.1Mn0.3Ni0.6Co0.05Cr0.05)2 gives a discharge capacity of 390mAhg−1 at the first cycle, however, the discharge capacity of the untreated alloy electrode is only 42mAhg−1 at the first cycle. The analysis of X-ray diffraction (XRD) shows that the alloy of crystal structure is a cubic AB2 Laves phase. The different activation property of the alloy electrode was analyzed on the basis of surface examination by scanning electron microscope (SEM), specific surface area (SSA) and X-ray photoelectron spectroscopy (XPS).