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A new zero-strain LiCaFeF6 cathode material for reversible insertion and extraction of lithium ions is presented. LiCaFeF6 is synthesized by a solid-state reaction and processed to a conductive electrode composite via high-energy ball-milling. In the first cycle, a discharge capacity of 112 mAh g−1 is achieved in the voltage range from 2.0 V to 4.5 V. The electrochemically active redox couple is Fe3+/Fe2+ as confirmed by Mössbauer spectroscopy and X-ray absorption spectroscopy. The compound has a trigonal colquiriite-type crystal structure (space group P 3 ¯ 1 c ). By means of in situ and ex situ XRD as well as X-ray absorption fine structure spectroscopy a reversible response to Li uptake/release is found. For an uptake of 0.8 mol Li per formula unit only minimal changes occur in the lattice parameters causing a total change in unit cell volume of less than 0.5%. The spatial distribution of cations in the crystal structure as well as the linkage between their corresponding fluorine octahedra is responsible for this very small structural response. With its zero-strain behaviour this material is expected to exhibit only negligible mechanical degradation. It may be used as a cathode material in future lithium-ion batteries with strongly improved safety and cycle life.
In this paper, tris(trimethylsilyl)borate (TMSB) is evaluated as an electrolyte additive for the self-discharge suppression of 4.9 V LiNi0.5Mn1.5O4 cathode for lithium ion battery. The effect of TMSB on the surface properties of LiNi0.5Mn1.5O4 is investigated via linear sweep voltammetry (LSV), cyclic voltammetry (CV), chronoamperometry (CA), charge–discharge test, electrochemical impedance spectra (EIS), scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma atomic emission spectrometer (ICP-AES) and Fourier transform infrared spectroscopy (FTIR). It is found that the LiNi0.5Mn1.5O4 cathode charged to 4.9 V (vs. Li/Li+) suffers a serious self-discharge in 1 mol L−1 LiPF6–EC/DMC (1:2, in weight), which can be suppressed effectively by adding 1 wt.% TMSB into the electrolyte. After storage for 20 days, the voltage of the charged cathode decreases from 4.7 to 0.5 V (vs. Li/Li+) in the additive-free electrolyte, while that remains almost unchanged in the TMSB-containing electrolyte. The self-discharge suppression of the charged LiNi0.5Mn1.5O4 cathode results from the preferential oxidation of TMSB and the subsequent formation of a protective solid electrolyte interphase film, which prevents electrolyte decomposition and protects LiNi0.5Mn1.5O4 from destruction.
Tungsten carbides materials exhibit highly efficient activity for hydrogen evolution reaction (HER) as promising non-precious electrocatalysts. Herein, a N-doped graphene (NG) supported tungsten carbides composite material (W x C/NG-10, x =1, 2, x is stoichiometric number of W, 10 is the mole quantity of tungsten in the precursors, mmol) was directly synthesized with a simple method by two-step calcining the mixture of sodium tungstate dihydrate (Na2WO4·2H2O), dicyandiamide (DCDA) and glucose anhydrous (GA), which was characterized by HRTEM, FE-SEM, XRD, XPS, EDX, BET and Raman, and estimated the electrocatalytic activity by the LSV, Tafel curves, and electrochemical impedance spectrum (EIS). The investigations indicate that W x C/NG-10, as an electrocatalyst for HER, achieves a lower overpotential of only 77.82mV at the current density of 10mAcm−2 and a Tafel slope of 45.95mVdec−1 in 0.5molL−1 H2SO4 aqueous. Additionally, the W x C/NG-10 has also possessed an electrocatalytic oxygen evolution reaction (OER) activity in 1.0molL−1 KOH aqueous with a lower overpotential of 467.6mV and a Tafel slope of 36.2mVdec−1. And after 10000 cycles the electrocatalytic active of W x C/NG-10 decrease 24.63% and 19.35% for HER and OER, respectively. The modification of W x C has improved the activity of NG materials in electrocatalytic applications.
Phosphate-based compounds with the high working voltage, such as Li3V2(PO4)3, LiVPO4F and LiMnPO4, have been proposed as a new class of cathode materials for lithium-ion batteries. To improve the operating voltage of LiFePO4, we introduce LiVPO4F to prepare xLiFePO4·(1 − x)LiVPO4F (LFP–LVPF) composites through an aqueous precipitation and carbothermal reduction method. A series of LFP-LVPF composites have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and total organic carbon (TOC) analysis. The discharge capacity of LFP–LVPF composites for x:(1 − x) = 1:0, 0.99:0.01, 0.75:0.25, 0.5:0.5, 0.25:0.75 and 0:1 at a 0.2 C-rate is 153, 160, 132, 106, 92 and 78 mAh g−1, respectively. The discharge capacity decreases with increasing mole fraction of LVPF. Moreover, the operating voltage of LFP-LVPF composites for x:(1 − x) = 0.75:0.25, 0.5:0.5 or 0.25:0.75 is higher than that of LFP, and the charge/discharge plateaus around 4.35/4.15 V for LFP-LVPF composites become longer as the value of x decreases.
The BEACH study is a continuous national study of general practice activity. Each year approximately 1000 randomly sampled GPs provide data about 100 000 encounters. It contains data about pathology ordered at these encounters. In 2009-2010, GPs ordered 45.0 pathology tests/batteries per 100 encounters or 29.3 per 100 problems. At least one pathology test order was recorded at 17.7% of encounters (for 13.2% of problems managed), chemistry tests accounting for more than half of all pathology tests. Since 2000, rises in the number of tested problems and the number of problems managed at GP encounters contributed to overall increases in the proportion of encounters involving a pathology test, and the number of tests ordered by GPs. BEACH pathology data have been used to investigate: • the problems responsible for the highest volume and growth of testing in primary care and how GPs’ testing behaviour in the management of these problems has changed; • the extent to which GP-ordered pathology for type 2 diabetes, hypertension, lipid disorders, weakness/tiredness, ‘health checks’ and overweight/obesity aligned with testing recommended in inter/national guidance; • expected volume of GP-ordered testing in 2020 using patient age-sex-specific test rates, extrapolated using GP-attendance rates and national population projections.
This paper demonstrates a new modified precipitated silica (SiO2) and PAN/TMS – poly(acrylonitrile)/sulfolane – polymeric matrix as a composite gel polymer electrolyte for a lithium-ion battery. Synthetic inorganic material was obtained by the emulsion method with cyclohexane as the organic phase and sodium silicate solution as a precipitating agent. The characterisation included determination of dispersion and morphology of the systems (particle size distribution, scanning electron microscope images), as well as impedance analysis, cyclic voltammetry and charging/discharging. It was found that the silica fillers were homogeneously dispersed in the polymeric matrix, while conductivity and electrochemical stability of porous polymer electrolytes were enhanced. Applicability of the prepared gel electrolytes for the Li-ion technology was estimated on the basis of specific conductivity measurements. Basic electrochemical properties of the composite gel polymer electrolyte was also presented based on PVdF-HFP/TMS/LiPF6/SiO2. A significantly poorer capacity and conductivity were observed. The Li|GPE|LiMn2O4 cell using modified SiO2 in the composite gel polymer electrolyte PAN/TMS shows a high discharge capacity.
In the charged condition, batteries are in a state of high energy relative to that of the system in the discharged state. Hence, there is a ‘driving force’, corresponding to the free energy of discharge, which tends to spontaneously diminish the charge if some mechanisms for self-discharge exist. We determined the self-discharge of Li/LiCoO2 cells from the decline of their open-circuit voltage and the rate of loss of the discharge capacity. In addition, we studied ac impedance of Li/LiCoO2 cells. Prevention of self-discharge is especially important for munitions that have remained in a state of disuse. In the case of nanocrystalline LiCoO2, cycle performance is superior to coarse-grained LiCoO2. However, self-discharge performance is inferior to coarse-grained LiCoO2. A better cycle performance of up to 200 cycles might be due to a well-formed SEI layer and smaller particle size in nanocrystalline LiCoO2.
Acute chest pain is a common diagnostic and management problem that places a considerable burden on emergency departments (EDs). Amongst a large group of patients with a good prognosis exists a small number of individuals harbouring a high risk of potentially fatal recurrent ischaemic events in the short to medium term. Rapid identification of these high risk patients with acute coronary syndrome (ACS) remains a challenge. The detection of a raised cardiac troponin (cTn) is an integral part of the diagnosis of acute myocardial infarction (AMI). However there are numerous causes for a raised troponin in patients presenting to the ED. The diagnosis of AMI requires evidence of a rise and/or fall of cTn in association with clinical evidence of myocardial ischaemia. Few studies have addressed the implications of the use of delta troponin in the ED, where the focus of both rapid identification of patients with an AMI and exclusion of serious pathology is required in a heterogenous population. The presentation will focus on the evidence of use of delta troponin in the ED for the diagnosis of AMI and other conditions. Results from ED-based research will be presented.
Patient acceptance is one of the major barriers toward widespread use of mHealth systems. The aim of this study was to assess system operability and whole trial feasibility, including patients’ experience with their use of COMMODITY12 mHealth system under. Secondary study aims included assessment of several metabolic parameters as well as patient adherence to the treatment. This was a prospective parallel-arm randomized controlled trial in outpatients diagnosed with DM2, being treated in the primary care settings in Lodz region, Poland, with 6 weeks period of follow-up. Patients opinions were collected with 7-item questionnaire, assessing different aspects of system use, as well as EuroQol-5D-5 L questionnaire, assessing health-related quality of life. Sixty patients (female, 24, male, 36, mean age +/− SD 59.5 +/− 6.8) completed study. All four layers of the COMMODITY12 system proved to work smooth under real-life conditions, without major problems. All dimensions of experience with system use were assessed well, with maximum values for clearness of instructions, and ease of use (4.80, and 4.63, respectively). Health related quality of life, as assessed with cumulative utility measure, improved significantly in COMMODITY12 system users (P < 0.05). mHealth system modestly improved glycaemic and blood pressure control, assuring high level of patient adherence with overall adherence reaching 92.9 %. Study proved that the COMODITY12 system is well accepted by type 2 diabetes patients taking part in clinical trial, leading to several clinical benefits, and improved quality of life. Nevertheless, before future commercialisation of the system, several minor problems identified during the study need to be addressed.
Alloy anode with good reversibility of lithium plating/stripping and long cycling stability is considered as promising anode materials. Here, Cu–Sn alloy is used as the substrate for Li deposition to induce the most densely packed arrangement of Li atoms, thus presenting high lithiophilicity and improving Li plating behaviors. The LiFePO4-based full cell with the as-prepared dendrite-free Li metal anode retained at 85 mAh g−1 with a high coulombic efficiency of 99.5% after 300 cycles, presenting a capacity retention of 79.4%. This strategy provides a new perspective to structure dendrite-free Li anode for the next-generation high-energy density batteries.
Thin layers of Pd–Pt–Au alloys were prepared by metal codeposition at constant potential from chloride solutions. The process of hydrogen electrosorption into Pd–Pt–Au alloys was investigated in acidic solution (0.5M H2SO4) using cyclic voltammetry and chronoamperometry, also coupled with the electrochemical quartz crystal microbalance. It was found that Pd alloying with both Pt and Au decreases the maximum hydrogen solubility, but improves the kinetics of absorbed hydrogen oxidation, which is mirrored in a negative shift of the potential of hydrogen desorption peak and shorter hydrogen desorption time. In Pd–Pt–Au alloys the effect of absorption/desorption hysteresis and the stresses connected with hydrogen absorption are reduced in comparison with pure Pd. After prior hydrogen absorption in Pd–Pt–Au alloys, surface oxides are formed and reduced at potentials even by 200mV lower than before hydrogen treatment.
Non-flammable rechargeable aqueous sodium-ion batteries (RASB) made from natural abundant resources offer promising opportunities in large-scale energy storage, yet the low energy density as well as low voltage output and the limited cycle life hinder their practical applications. Here, we develop a high-voltage RASB based on rhombohedral zinc hexacyanoferrate as cathode materials, carbon-coated NaTi2(PO4)3 as anode materials and ternary NaClO4-H2O-polyethylene glycol (Na-H2O-PEG) as electrolyte to overcome these drawbacks. Such an RASB can deliver a high voltage output of 1.6 V with a specific energy density of 59 Wh kg−1 based on the total mass of active electrode materials. In addition, it possesses an excellent rate capability as an ultra-capacitor (2.7 kW kg−1). The capacity retention more than 91% is obtained after 100 cycles. Finally, a reversible phase transformation between rhombohedral Zn3[Fe(CN)6]2 and rhombohedral Na2Zn3[Fe(CN)6]2 that are accompanied by the insertion/extraction of sodium ion in zinc hexacyanoferrate is unveiled.
This paper describes studies on the reduction of birnessite thin layers electrodeposited onto a cheap transparent semiconductor substrate, tin dioxide (SnO2), in neutral sulphate solutions. A coupled approach based on electrochemical measurements (cyclic voltammetry and chronoamperometry) and X-ray diffraction (XRD) characterisation allowed us to give information about reduction mechanism of birnessite in presence or absence of Mn(II) in solution. In absence of Mn(II), birnessite is reduced only at low potential (E =−0.6V) into β-MnOOH (feitkneichtite), if Q reduction is lower than Q synthesis, and in amorphous Mn(II) compound, if Q reduction is equal to Q synthesis. In presence of Mn(II) in solution, hausmannite (Mn3O4) was detected, and even at high potentials (E =0.15V). These results signify that a complex between Mn(III), coming from the reduction of Mn(IV) species, and Mn(II) present in solution, can be formed near the surface and leads to the formation of Mn3O4, a very resistive compound. These results are important for studies devoted to environmental applications, chemical sensors and also for energy storage.
A novel graphene-containing Li2FeSiO4 composite (Li2FeSiO4/C/G) has been synthesized successfully which shows superior performance when used as the cathode material for lithium ion batteries. The Li2FeSiO4/C precursor was synthesized via a modified sol-gel method and mixed with graphene oxide nanosheets which were then reduced by annealing to obtain electron conductive graphene. The structure characterizations by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) show that phase-pure Li2FeSiO4/C nanoparticles are mixed homogeneously with graphene nanosheets. When used as the cathode materials for rechargeable lithium ion batteries, the composite Li2FeSiO4/C/G shows superior large capacities and long-time cyclabilities. Specific discharge capacities of 310 mAh g−1, corresponding to 1.86 Li+ ions exchange per Li2FeSiO4 molecule, can be reached at the charging/discharging rate of 0.1C (1C=166mAg−1). At the high rate of 30C and 50C, the composite still shows ∼110 and ∼50 mAh g−1 discharge capacities after 1000 charging-discharging cyclings. These superior–the best up to now–performances of the composite are believed to be the cooperative result of the 3D conducting network, formed by the flexible and planar graphene nanosheets, and the nanoscale sizes of the carbon-coated Li2FeSiO4 particles.
As the use of plug-in electric vehicles (PEVs) further increases in the coming decades, a growing stream of batteries will reach the end of their service lives. Here we study the potential of those batteries to be used in second-life applications to enable the expansion of intermittent renewable electricity supply in California through the year 2050. We develop and apply a parametric life-cycle system model integrating battery supply, degradation, logistics, and second-life use. We calculate and compare several metrics of second-life system performance, including cumulative electricity delivered, energy balance, greenhouse gas (GHG) balance, and energy stored on invested. We find that second-life use of retired PEV batteries may play a modest, though not insignificant, role in California's future energy system. The electricity delivered by second-life batteries in 2050 under base-case modeling conditions is 15 TWh per year, about 5% of total current and projected electricity use in California. If used instead of natural gas-fired electricity generation, this electricity would reduce GHG emissions by about 7 million metric tons of CO2e per year in 2050.
The year 2008 saw the emergence of the first generation of commercial ocean energy devices, with the first units being installed in the UK and Portugal. This means that there are currently four ways of obtaining energy from sea areas, namely from wind, tides, waves and thermal differences between deep and shallow sea water. This paper focuses on current developments in offshore wind and ocean energy, highlighting the efforts currently underway in a variety of countries, principally some of the projects typically less talked about such as those in the Asian-Pacific countries. Finally, the growth potential of these industries will be assessed, using as a basis the historical trends in the offshore wind industry and extrapolating it to compute future growth potentials. Using this as a basis, the percentage of the world’s electricity that could be produced from ocean based devices is estimated to be around 7% by 2050, and this would employ a significant amount of people by this time, possibly around 1 million, mostly in the maintenance of existing installations. The paper will also evaluate the likely cost of production per kW of ocean energy technologies using a variety of learning factors.
The dual influences of the resource supply and protection in ecological environments will pose a significant challenge to China’s sustainable development. Solid waste management offers opportunities to improve profits by conserving resources and improving environmental performance. This paper examines municipal solid waste (MSW) management in urban Chongqing, the nation’s fourth largest municipality after Beijing, Shanghai and Tianjin. In this paper, we will provide information on the quantity and composition of MSW, as well as give an overview of different methods for collection, transport, treatment and disposal of MSW. At present the daily amount of MSW generated per person is about 1.08kg; food waste accounts for about 59% of total MSW. MSW in Chongqing has a higher moisture content (64.1%) and a lower LHV (3728kJ/kg) than other cities in Asia, which is an obstruction for incineration. Landfills are the main method of disposal in Chongqing, but pollution caused by simple landfills and lack of backup MSW disposal capacity are becoming major problems in the main districts of Chongqing. In this paper, the challenges being faced and opportunities to MSW in Chongqing are analyzed and some suggestions are given for improving the MSW system in the future.
Two large-scale resources for studying microRNA function are presented: one is a library of fluorescent sensors with a corresponding assay for global profiling of microRNA activity in different cell types; the other is a decoy library for suppressing microRNA activity individually or in pooled loss-of-function screens.
Definition, evaluation and management of concussion are contentious issues in sports medicine, and evidence-based guidelines on these issues are urgently needed. An updated practice parameter on sport-related concussion from the AAN is, therefore, timely. However, these new guidelines fail to meet the needs of clinicians in this field.
Facile and scalable fabrication of high-performing sulfur cathodes is challenging in the commercialization of Li–S batteries. The authors report a strategy of simply burning Li foils in a CS2 vapour for the cathode design, which shows promising battery performance.
Genetic factors may partly account for between-person differences in brain integrity in old age. Evidence from human and animal studies suggests that the dopaminergic system is implicated in the modulation of white-matter integrity. We investigated whether a genetic variation in the Catechol-O-Methyltransferase (COMT) Val158Met polymorphism, which influences dopamine availability in prefrontal cortex, contributes to interindividual differences in white-matter microstructure, as measured with diffusion-tensor imaging. In a sample of older adults from a population-based study (60–87 years; n = 238), we found that the COMT polymorphism affects white-matter microstructure, indexed by fractional anisotropy and mean diffusivity, of several white-matter tracts in the oldest age group (81–87 years), although there were no reliable associations between COMT and white-matter microstructure in the two younger age groups (60–66 and 72–78 years). These findings extend previous observations of magnified genetic effects on cognition in old age to white-matter integrity.
Doping with Sn and Ca is seen to improve the reversibility and charging efficiency of lead anodes used in lead acid batteries. However, one drawback of these materials is their increased corrosion rate as compared to pure lead anodes. In the present investigation, the dissolution of Pb–Sn and Pb–Sn–Ca alloys has been evaluated under different float charge conditions for extended periods of time. The float potential has been optimized based on minimum anode dissolution and oxygen evolution. Extended cycling studies show that doping with Sn maintains the reversibility of the anode. In order to minimize the weight of the anode, a small amount of Sn was coated on Pb by electrodeposition. The coated electrode reveals similar reversibility and dissolution characteristics as the Sn doped anode. Electrodeposition is seen to offer an inexpensive route for increasing the charging efficiency of Pb anodes in lead acid cells without increasing the weight of the battery.
The electrochemical behavior of mixed Ru–Sn oxides fabricated by a modified sol–gel process and a co-annealing method are systematically compared (using cyclic voltammetric and electrochemical impedance spectroscopic analyses), for the application of supercapacitors. Influences of annealing temperature and time on the specific capacitance and textural properties of oxides are also studied. Based on the quasi-linear dependence of voltammetric current density on the scan rate of CV (from 25 to 500mVs−1), the lowest proton diffusion resistance, and the high-frequency (∼426Hz) capacitive responses of the co-annealed composite (RTOCco) as well as its ease in composition control, co-annealing of hydrous RuO2 and SnO2 at 200°C for 2h is recommended as a promising and practical method for preparing mixed oxides in the supercapacitor application.