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In this study an electrochemical approach is proposed for the fabrication of nanoporous gold (NPG)-supported manganese oxide nanowires. This method consists in: (i) electrodepositing an Au–Mn alloy, (ii) selectively corroding Mn under electrochemical control, forming simultaneously the NPG support and the functional Mn-oxide decorating the nanopores. The electrodeposition process is carried out from a bath based on eutectic urea/choline chloride ionic liquid. The electrochemical dealloying/oxidation step is performed in an aqueous solution. The oxidation process, performed by cyclic voltammetry (CV) in aqueous solution, has been monitored in situ by visible reflectivity measurements. The crystal structure and the morphology of the electrodeposited Au–Mn alloy have been examined by XRD and SEM, respectively. The 3D morphology of the nanostructure has been characterised by FIB/FEG-SEM. The specific capacity of NPG-supported nanostructured Mn-oxide has been measured by CV and found to be notably better than that of unsupported electrodeposited Mn-oxide nanowires.
The preparation of free-standing electrode materials with high specific capacitance and flexibility is very important for the production of flexible electric double layer capacitors. There is a great incompatibility, however, between the flexibility and the porosity of the electrode material. In this work, by using coaxial electrospinning, we propose an interface miscibility induced approach to the design of double-capillary carbon nanofibers (DCNF) with micropores in the inner capillary and mesopores in the outer capillary. The unique structure achieves synergism between high accessibility to electrolyte, a short diffusion length for ions, high conductivity, and high flexibility. The DCNFs can be directly used as electrodes to assemble flexible supercapacitors, which show a high gravimetric capacitance of 133Fg−1 and excellent high-rate performance in ionic liquid electrolyte. The maximum energy density and power density reach 56.6Whkg−1 and 114kWkg−1, respectively. The combination of scalable coaxial electrospinning technology and supercapacitors with excellent performance may pave the way to wearable and safe electronics.
NASICON is one of the most promising sodium solid electrolytes that can enable the assembly of cheaper and safer sodium all-solid-state batteries. In this study, we perform a combined experimental and computational investigation into the effects of aliovalent doping in NASICON on both bulk and grain boundary (secondary phase) ionic conductivity. Our results show that the dopants with low solid solubility limits in NASICON lead to the formation of a conducting (less insulating) secondary phase, thereby improving the grain boundary conductivity measured by electrochemical impedance spectroscopy (including grain-boundary, secondary-phase, and other microstructural contributions) that is otherwise hindered by the poorly-conducting secondary phases in undoped NASICON. This is accompanied by a change in the Si/P ratio in the primary NASICON bulk phase, thereby transforming monoclinic NASICON to rhombohedral NASICON. Consequently, we have synthesized NASICON chemistries with significantly improved and optimized total ionic conductivity of 2.7 mS/cm. More importantly, this study has achieved an understanding of the underlying mechanisms of improved conductivities via doping (differing from the common wisdom) and further suggests a new general direction to improve the ionic conductivity of solid electrolytes via simultaneously optimizing the primary bulk phase and the microstructure (including grain boundary segregation and secondary phases).
In this paper series of novel NaFeyCo1-yO2 (y = 0.1–1) cathode materials were synthesized and studied in terms of their structural properties, electrical conductivity and electrochemical performance in Na/Na+/NaxFeyCo1-yO2 cells. The materials were fabricated by a high-temperature solid-state reaction. XRD measurements with Rietveld analysis confirmed the presence of an O3-type phase with R-3m symmetry for all compositions with the existence of the monophase region within 0.3 ≤ y ≤ 0.7 Fe substitution range. The linear variation of the unit cell parameters of the R-3m structure was found for the broad Fe concentration. The combined studies of thermogravimetric analysis, XPS and Mössbauer spectroscopy pointed at the formation of the oxygen vacancies along with spontaneous magnetization at low temperatures. The electrical conductivity of the NaFeyCo1-yO2 exhibits thermally activated character with low activation energies and decreases with the increasing of iron content. Electrochemical investigation of Na/Na+/NaxFeyCo1-yO2 revealed changes in the character of discharge curve as a function of iron content and enabled us to select the NaFe0.3Co0.7O2 as a material exhibiting optimal chemical composition assuring high, stable discharge capacity (180 mAh g−1) along with high operational potential. The EIS and GITT studies were performed in order to investigate the kinetics of the electrode processes. The relation between sodium diffusion coefficients and chemical composition confirmed enhanced performance in case of the NaFe0.3Co0.7O2 material.
For an operating flow battery system, how the battery’s performance varies with ambient temperatures is of practical interest. To gain an understanding of the general thermal behavior of vanadium redox flow batteries (VRFBs), we devised and tested a laboratory-scale single VRFB by varying the operating temperature. The voltage efficiency of the VRFB is found to increase from 86.5% to 90.5% at 40mA/cm2 when the operating temperature is increased from 15°C to 55°C. The peak discharge power density is also observed to increase from 259.5mW/cm2 to 349.8mW/cm2 at the same temperature increment. The temperature increase, however, leads to a slight decrease in the coulombic efficiency from 96.2% to 93.7% at the same temperature increments. In addition, the capacity degradation rate is found to be higher at higher temperatures.
Electrochemically-reduced graphene oxide (Er-GO) and cobalt oxides (CoOx) were co-electrodeposited by cyclic voltammetry, from an electrolyte containing graphene oxide and cobalt nitrate, directly onto a stainless steel substrate to produce composite electrodes presenting high charge storage capacity. The electrochemical response of the composite films was optimized by studying the parameters applied during the electrodeposition process, namely the number of cycles, scan rate and ratio between GO/Co(NO3)2 concentrations in the electrolyte. It is shown that, if the appropriate conditions are selected, it is possible to produced binder-free composite electrodes with improved electrochemical properties using a low-cost, facile and scalable technique. The optimized Er-GO/CoOx developed in this work exhibits a specific capacitance of 608Fg−1 at a current density of 1Ag−1 and increased reversibility when compared to single CoOx.
We report three-dimensional bicontinuous nanoporous Au/polyaniline (PANI) composite films made by one-step electrochemical polymerization of PANI shell onto dealloyed nanoporous gold (NPG) skeletons for the applications in electrochemical supercapacitors. The NPG/PANI based supercapacitors exhibit ultrahigh volumetric capacitance (∼1500Fcm−3) and energy density (∼0.078Whcm−3), which are seven and four orders of magnitude higher than these of electrolytic capacitors, with the same power density up to ∼190Wcm−3. The outstanding capacitive performances result from a novel nanoarchitecture in which pseudocapacitive PANI shells are incorporated into pore channels of highly conductive NPG, making them promising candidates as electrode materials in supercapacitor devices combing high-energy storage densities with high-power delivery.
The nucleus-encoded 17β-hydroxysteroid dehydrogenase type 10 (17β-HSD10) regulates cyclophilin D (cypD) in the mitochondrial matrix. CypD regulates opening of mitochondrial permeability transition pores. Both mechanisms may be affected by amyloid β peptides accumulated in mitochondria in Alzheimer's disease (AD). In order to clarify changes occurring in brain mitochondria, we evaluated interactions of both mitochondrial proteins in vitro (by surface plasmon resonance biosensor) and detected levels of various complexes of 17β-HSD10 formed in vivo (by sandwich ELISA) in brain mitochondria isolated from the transgenic animal model of AD (homozygous McGill-R-Thy1-APP rats) and in cerebrospinal fluid samples of AD patients. By surface plasmon resonance biosensor, we observed the interaction of 17β-HSD10 and cypD in a direct real-time manner and determined, for the first time, the kinetic parameters of the interaction (ka 2.0 × 105 M1s−1, kd 5.8 × 104 s−1, and KD 3.5 × 10–10 M). In McGill-R-Thy1-APP rats compared to controls, levels of 17β-HSD10–cypD complexes were decreased and those of total amyloid β increased. Moreover, the levels of 17β-HSD10–cypD complexes were decreased in cerebrospinal fluid of individuals with AD (in mild cognitive impairment as well as dementia stages) or with Frontotemporal lobar degeneration (FTLD) compared to cognitively normal controls (the sensitivity of the complexes to AD dementia was 92.9%, that to FTLD 73.8%, the specificity to AD dementia equaled 91.7% in a comparison with the controls but only 26.2% with FTLD). Our results demonstrate the weakened ability of 17β-HSD10 to regulate cypD in the mitochondrial matrix probably via direct effects of amyloid β. Levels of 17β-HSD10–cypD complexes in cerebrospinal fluid seem to be the very sensitive indicator of mitochondrial dysfunction observed in neurodegeneration but unfortunately not specific to AD pathology. We do not recommend it as the new biomarker of AD.
A perovskite-type oxide LaNi0.8Co0.2O3 is prepared as a direct borohydride fuel cell (DBFC) cathode catalyst. Its electrochemical properties are studied by cyclic voltammetry. The results demonstrate that LaNi0.8Co0.2O3 exhibits excellent electrochemical activity with respect to the oxygen reduction reaction (ORR) and good tolerance of BH4 − ions. Maximum power densities of 114.5mWcm−2 at 30°C and 151.3mWcm−2 at 62°C are obtained, and good stability (300-h stable performance at 20mAcm−2) is also exhibited, which shows that such perovskite-type oxides as LaNi0.8Co0.2O3 can be excellent catalysts for DBFCs.
Herein, we have presented a supercapacitor based on carbide derived carbon (CDC) electrode with natural graphite (NG) addition. The capacitor was analyzed at 22 °C by cyclic voltammetry, galvanostatic charge-discharge and impedance techniques using a 0.5 mol/L of magnesium (II) bis (trifluoro methanesulfonyl) imide (MgTFSI) in ethylene carbonate-propylene carbonate (EC: PC = 1: 1, v/v) as electrolyte. The results conclude that the CDC cell enhancements have been proven by the composite electrode (5%–30% NG to CDC) especially on the cell efficiency and voltage i.e., the CDC cell around 2.5 V limit was improved. An obtainable specific capacitance, real power and energy density are 15 F·g−1, 1.2 kW·kg−1 and 15 Wh·kg−1, respectively.
It is very important to explore novel anode materials alternative to graphite considering its poor safety and rate performance working at low temperature in lithium ion batteries. Li4Ti5O12, as a promising anode material with high safety, has poor electronic conductivity and low specific capacity, thus limiting its electrochemical performance at low temperature. Herein, we report the preparation of W-doped hierarchical porous Li4Ti5O12/brookite nanocomposites to enhance the specific capacity and rate perfornance. The as-prepared nanocomposites as anode in lithium ion batteries are studied at −20 °C and room temperature. With the introduction of brookite phase and W doping, the W-doped LTO/brookite nanocomposites show a large specific reversible capacity (~ 195 mAhg−1 at 0.1 Ag−1), very good cycling stability (~ 95 % within 1000 cycles) and high rate performance (158 mAhg−1 at 2 Ag−1) at −20 °C, displaying excellent electrochemical performance at low temperature. Furthermore, the as-prepared nanocomposites also show excellent electrochemical performance at room temperature, exhibiting great adaptation capability in a wide temperature range.
Currently, over a billion people including children (or about 15% of the world's population) are estimated to be living with disability. The lack of support services can make handicapped people overly dependent on their families, which prevents them from being economically active and socially included. The Internet of Things can offer people with disabilities the assistance and support they need to achieve a good quality of life and allows them to participate in the social and economic life. In this paper, an overview of the Internet of Things for people with disabilities is provided. For this purpose, the proposed architecture of the Internet of Things is introduced. Different application scenarios are considered in order to illustrate the interaction of the components of the Internet of Things. Critical challenges have been identified and addressed.
New powertrain technologies, such as Hybrid Electric Vehicles, have a price premium which can often be offset by lower running costs. Total Cost of Ownership combines these purchase and operating expenses to identify the most economical choice of vehicle. This is a valuable assessment for private and fleet purchasers alike. Studies to date have not compared Total Cost of Ownership across more than two vehicle markets or analysed historic costs. To address this gap, this research provides a more extensive Total Cost of Ownership assessment of conventional, Hybrid, Plug-in Hybrid and Battery Electric Vehicles in three industrialized countries – the UK, USA (using California and Texas as case studies) and Japan – for the time period 1997–2015. Finally, the link between Hybrid Electric Vehicle Total Cost of Ownership and market share is analysed with a panel regression model. In all regions the incremental Total Cost of Ownership of hybrid and electric vehicles compared to conventional vehicles has reduced from the year of introduction and 2015. Year on year Hybrid Electric Vehicles Total Cost of Ownership was found to vary least in the UK due to the absence of subsidies. Market share was found to be strongly linked to Hybrid Electric Vehicle Total Cost of Ownership through a panel regression analysis. Financial subsidies have enabled Battery Electric Vehicles to reach cost parity in the UK, California and Texas, but this is not the case for Plug-in Hybrid Electric Vehicles which haven’t received as much financial backing. This research has implications for fleet purchasers and private owners who are considering switching to a low-emission vehicle. The findings are also of interest to policymakers that are keen to develop effective measures to stimulate decarbonisation of the fleet and improve air quality.
Existing methods for electromotive force (EMF) characterization that make use of readily available data, such as terminal voltage and applied current, require a significant time commitment and a constant temperature environment. Both linear interpolation and extrapolation rely on state-of-charge (SOC) calculation by Coulomb-counting which only serves to reduce the accuracy of the resulting EMF-SOC curve(s). A battery management system requires accurate EMF-SOC data for periodic recalibration otherwise it cannot apply proper charge control. This paper presents an alternative concentration-based method for EMF characterization and the key lies in the fact that molality is not influenced by temperature. A modified version of the Nernst equation and temperature-compensated open-circuit voltage measurements are used to estimate the molality when the cell is at rest. During operation, the energy into or out of the cell is mapped to changes in the estimated molality to calculate the EMF as the cell charges or discharges. The concentration-based method is verified using experimental data from valve-regulated lead-acid cells and its EMF curves are compared to those of linear interpolation and extrapolation. The proposed method has less stringent practical requirements and validation results indicate a significant improvement in accuracy and applicability over the existing methods.
Fragile X syndrome is a neurodevelopmental disorder that is caused by the silencing of a single gene on the X chromosome, the fragile X mental retardation 1 (FMR1) gene. Affected individuals display a unique neurocognitive phenotype that includes significant impairment in inhibitory control, selective attention, working memory, and visual–spatial cognition. In contrast, little is known about the trajectory and specificity of any cognitive impairment associated with the fragile X premutation (i.e., “carrier status”) or its relationship with the recently identified neurodegenerative disorder, fragile X-associated tremor/ataxia syndrome (FXTAS). In the present study, we evaluated a broad sample of 40 premutation males (PM) aged 18–69 years matched on age and IQ to 67 unaffected comparison males (NC). Performance was compared across a range of cognitive domains known to be impaired in fragile X syndrome (i.e., “full mutation”). Tremor was also assessed using a self-report neurological questionnaire. PM displayed statistically significant deficits in their ability to inhibit prepotent responses, differentiating them from NC from age 30 onwards. With increasing age, the two groups follow different trajectories, with PM developing progressively more severe problems in inhibitory control. This deficit also has a strong co-occurrence in males displaying FXTAS-related symptomatology (p <.001). Selective attention was also impaired in PM but did not show any disproportionate aging effect. No other cognitive deficits were observed. We conclude that an inhibitory deficit and its impact across the lifespan are specifically associated with the fragile X premutation status, and may be a precursor for development of a more severe form of cognitive impairment or dementia, which has been reported in patients with the diagnosis of FXTAS.
Electrochemical characteristics for several redox systems at diamond films with highly ordered nanometer-scale cylindrical pores (‘nano-honeycombs’) were examined with cyclic voltammetry (CV) and electrochemical impedance measurements. The cyclic voltammetric anodic–cathodic peak separations for these nano-honeycomb electrodes were in the same range as those for polished polycrystalline diamond films, indicating that the involvement of the oxygen-terminated surface of the nano-pore walls, which should give rise to large peak separations for certain redox couples was only slight. Moreover, the peak currents in the CV were not enhanced to the extent expected on the basis of the roughness factors of the nano-honeycomb films. Ac impedance plots results indicated the existence of a concentration gradient of the reactant in the nano-pores, which is in agreement with theoretical predictions for charge transfer reactions in porous electrodes. The average concentration of the reactant (Fe2+/3+) inside the nano-pores was a factor of ca. 80 lower than that in the bulk electrolyte. The results of the impedance analysis also indicated an increase in the reaction resistances with decreasing pore diameters.
Dense ceramics with La0.80Sr0.20Ga0.85Mg0.15O2.825 and La0.80Sr0.15Ga0.85Mg0.20O2.825 compositions have been prepared by sintering of mechanosynthesized precursors. The perovskite is synthesized after 85h of milling in a planetary mill. Single phases have been obtained at conditions that are not possible if traditional solid-state reaction (SSR) method is used. The influence of milling time and composition in the reactivity of the precursors is studied. Highest purity is obtained in Sr=0.15 and Mg=0.20 composition, with relative density higher than 97%. The total elimination of typical secondary phases for these compositions, as SrLaGaO4 and SrLaGa3O7, allows the total conductivity of the ceramics to be improved. The influence of the grain size and the nature of the grain boundaries on the electrical characteristic of the ceramics are also discussed.
Plasma-fluorination of natural graphite samples with average particle sizes of 5μm, 10μm and 15μm (NG5μm, NG10μm and NG15μm) was performed using CF4 and charge/discharge characteristics of surface-fluorinated samples were investigated in 1moldm−3 LiClO4–ethylene carbonate (EC)/diethyl carbonate (DEC)/propylene carbonate (PC) (1:1:1, v/v/v). Fluorine contents obtained by elemental analysis were in the range of 0.3–0.6at.% and surface fluorine concentrations determined by X-ray photoelectron microscopy (XPS) were 14.8–17.3at.%. Plasma-fluorination increased surface disorder of natural graphite samples though reduced surface areas due to its surface etching effect. Electrochemical decomposition of PC was highly reduced on surface-fluorinated NG10μm and NG15μm with high disorder. First coulombic efficiencies of plasma-fluorinated NG10μm and NG15μm increased by 9.7 and 19.3% at 150mAg−1, respectively.
The direct three-dimensional reconstruction of a polymer electrolyte fuel cell cathode catalyst layer from focused ion beam/scanning electron microscope (FIB/SEM) images is presented. The carbon and pore distribution is shown and quantitatively analysed. A new catalyst layer sample (Fumapem-F950/HiSpec13100) is sliced with FIB and a series of SEM images is taken. The images are registered, segmented and a three-dimensional stack is reconstructed. The three-dimensional carbon and pore distribution is shown. Based on the reconstruction the pore size distribution is evaluated. The total porosity and the unconnected pores space is analysed. The fully segmented 2D images are provided as supplemental material to this paper for future analysis and modeling work.
Li2FeSiO4 is a promising cathode active material for lithium-ion batteries due to its high theoretical capacity. Spray-freezing/freeze-drying, a practical process reported for the synthesis of various ceramic powders, is applied to the synthesis of Li2FeSiO4/C composite powders and high-performance Li2FeSiO4/C composite powders are successfully synthesized by using starting solutions containing both Indian ink and glucose as carbon sources followed by heating. The synthesized composite powders have a unique structure, composed of Li2FeSiO4 nanoparticles coated with a thin carbon layer formed by the carbonization of glucose and carbon nanoparticles from Indian ink. The carbon layer enhances the electrochemical reactivity of the Li2FeSiO4, and the carbon nanoparticles play a role in the formation of electron-conducting paths in the cathode. The composite powders deliver an initial discharge capacity of 195 and 137 mAh g−1 at 0.1 C and 1 C, respectively, without further addition of conductive additive. The discharge capacity at 1 C is 72 mAh g−1 after the 100th cycle, corresponding to approximately 75% of the capacity at the 2nd cycle.