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A study on the electro-deoxidation of porous titanium dioxide precursors in molten calcium chloride is reported. Experiments were performed with a three-terminal electrochemical cell, comprising a molten salt electrolyte of calcium chloride with additions of calcium oxide, a cathode of compact titanium dioxide with a significant degree of open porosity, as well as a graphite anode and a graphite pseudo-reference electrode. Reductions were carried out under cathodic potential control and at different applied potentials. The results reveal that the formation of titanium metal occurs at electrode potentials significantly more positive than that of calcium deposition, whilst the realisation of very low residual oxygen contents requires potentials around that of calcium deposition. It is demonstrated that oxygen contents in the titanium metal prepared of below 5000ppm by mass may be achieved reproducibly within processing times of 16h and at current efficiencies between 10 and 40%. The kinetic pathway is investigated, by analysing the compositions of samples prepared at different cathode potentials, and compared against the results from foregoing studies. It is found that the presence of calcium oxide in the calcium chloride accelerates the overall rate of electro-deoxidation, and that the temporary occurrence in the cathode of the calcium-containing compounds calcium titanate, CaTiO3, and calcium titanite, CaTi2O4, are inherent features of the reaction path. The overpotential at the anode is shown to be of significant magnitude.
Pyrrole was polymerized onto commercial SFG10 graphite by in situ polymerization technique. Polymerization decreases the initial irreversible capacity loss of the graphite anode. The decrease in the irreversible capacity loss is due to the reduction in the thickness of the solid electrolyte interface (SEI) layer formed. PPy/C (7.8%) gives the optimum performance based on the irreversible capacity loss and the discharge capacity of the composite. The composite material has been studied for specific discharge capacity, coulombic efficiency, rate capability and cycle life using a variety of electrochemical methods. The composite SFG10 graphite possess good reversibility, higher coulombic efficiency, good rate capability and better cycle life than the bare SFG10 graphite.
Reduced graphene oxide nanoribbons (RGONRs) supported platinum catalysts were prepared by microwave-assisted polyol method, in which Pt nanoparticles were uniformly dispersed with a mean particle of 3.5 nm. During the synthesis, Pt ions were first attached to graphene oxide nanoribbons, then the encased metal ions and graphene oxide nanoribbons were simultaneously reduced by ethylene glycol. X-ray photoelectron spectra and X-ray diffraction indicate that the graphene oxide nanoribbons were partially reduced and the Pt nanoparticles were attached to the oxygen-containing groups on the surface of the support. Pt/RGONRs exhibits excellent activity for the oxygen reduction reaction, which is approximately 2 times better than commercial Pt/C with promising durability after 5000 cycles of accelerated durability tests. The enhancement of electrocatalytic activity and better durability may be explicated by the well dispersed Pt NPs on the RGONRs and the attachment of Pt ions with the oxygen-containing groups before the reduction.
LiMn2O4 powders have been directly prepared by flame spray pyrolysis from an aqueous spray solution of the metal salts. The powders prepared at a low fuel gas flow rate (3Lmin−1) comprise particles with a bimodal size distribution, i.e., submicron- and nanometer-sized particles, and have crystal structures of LiMn2O4 and Mn3O4 phases. However, the powders prepared at a high fuel gas flow rate (5Lmin−1) comprise nanometer-sized particles and have pure crystal structure of LiMn2O4 phase. The powders comprising nanosized particles are well crystallized, and the particles have a polyhedral structure. The mean particle size of these powders is 27nm. The powders prepared directly by flame spray pyrolysis comprise nanosized particles and have the pure crystal structure of LiMn2O4, irrespective of the amount of excess lithium in the precursor solution. The initial discharge capacities of these powders increase from 91 to 112mAhg−1 when the amount of excess lithium is increased from 0% to 30% of the stoichiometric amount. The optimum amount of excess lithium required to prepare LiMn2O4 powders with nanosized particles and the maximum possible initial discharge capacity is 10%.
In this work, ultrathin-shell graphene hollow spheres have been designed and synthesized from the graphene oxide nanosheets by a simple template assisted method without surfactant. It is found that the obtained graphene hollow spheres have a high surface area (248.3 m2 g−1), ultrathin porous shells (5nm) and an interconnected structure. More strikingly, the as-prepared graphene hollow spheres exhibit outstanding electrochemical performance as an anode material for lithium-ion batteries. Even at a high current density of 5000mAg−1, a high reversible specific capacity of 249.3 mAh g−1 can be achieved. Furthermore, after 100 cycles, about 97.1% of the specific capacity is maintained at a high current density of 1000mAg−1. The excellent electrochemical properties could be attributed to the attractive structure advantages of the graphene hollow spheres including the high surface area, ultrathin porous shells and an interconnected structure.
Advocates of eating locally offer a wide range of arguments in favor of the practice, but their ethical import is not always clear. Some locavore statements and arguments seem to imply a strong form of moral obligation; that eating locally is not merely instrumental to some other good, but has intrinsic value in its own right. This article examines standard arguments on behalf of eating locally, including arguments linked to the value of small farms and agrarianism, the environment, taste and health, trust, and relational markets. Most arguments put forward on behalf of eating locally value it instrumentally, the main exception being arguments based on relational markets. Although these arguments provide important motives for eating locally, the strength of obligation varies widely, and even the strongest arguments possess significant qualifications. While eating locally can play a role in reducing environmental impacts, this is not necessarily so, and once removed from instrumental considerations, eating locally is more likely at best an imperfect duty.
LiFePO4/gel/natural graphite (NG) cells have been prepared and cycled under a fixed protocol for cycle and calendar life determination. Cell compression of 68kPa was found to represent an optimal balance between cell impedance and the first cycle losses on the individual electrodes with the gel electrolyte. Cells with a Li anode showed capacities of 160 and 78mAh/g LiFePO4 for C/25 and 2C discharge rates, respectively. Rapid capacity and power fade were observed in the LiFePO4/gel/NG cells during cycling and calendar life studies. Diagnostic evaluations point to the consumption of cycleable Li though a side reaction as the reason for performance fade with minimal degradation of the individual electrodes.
Aim The World Health Organization Disability Assessment Schedule II (WHODAS II) was developed for assessing disability. This study provides data on the validity and utility of the Spanish version of the WHODAS II in a large sample of patients with schizophrenia. Methods The sample included 352 patients with a schizophrenia spectrum disorder. They completed a comprehensive assessment battery including measures of psychopathology, functionality and quality-of-life. A sub-sample of 36 patients was retested after six months to assess its temporal stability. Results Participation in society (6.3%) and Life activities (4.0%) were the domains with the highest percentage of missing data. The internal consistency (Cronbach's alpha) of the total scale was 0.94, and the test–retest stability reached an intraclass correlation coefficient of 0.92. It became apparent that the six primary factor models represent a better fit with reality than other competing models. Relationships between the WHODAS and measures of symptomatology, social and work-related functionality, and quality-of-life were in the expected direction and the scale was ultimately found to be able to differentiate among patients with different degrees of disease severity and different work status. Conclusions Assessment of disability using appropriate tools is a crucial aspect in the context of mental health and, in this regard, the Spanish version of the WHODAS II shows ample evidence of validity in patients with schizophrenia. The most important contribution of this study is that it is the first analyzing the Spanish version of the WHODAS II (36-item version) in a large sample of patients with schizophrenia.
A body sensor network is a network of small sensor devices (biosensors) that sense health parameters of an individual, allowing 24/7 monitoring, providing biofeedback services. These networks have typically two layers: the sensor array and a sink node. The sink node manages the network, gathering sensor data continuously. However, raw sensor data is not enough to achieve biofeedback. One of the challenges body sensor networks present is the processing of raw biosensor data, in order to achieve a proper medical visualization of monitored parameters. This paper surveys some of the current approaches, proposes an interface classification based on features, and presents a solution based on a mobile device. The mobile application can run on a Java and Bluetooth enabled phone, allowing data retrieval, storage, and analysis in a single solution. The mobile application proposes a three-layer approach to BSN operation, adding the mobile device to the solution. The final system provides the user with a completely functional health-monitoring platform, which is easy to use and setup, validated through a complete series of tests on different mobile devices.
Energy-harvesting textiles based on triboelectric nanogenerators (TENGs) have attracted intense attention, due to their broad potential applications in wearable electronics. However, the bottlenecks of limited and alternating current electrical output have greatly hindered the development of textile TENGs. Here, by simply and easily coating two electrodes on the top side (breakdown electrode) and bottom side (friction electrode) of a polyester–cotton fabric, a light-weight, highly flexible and wearable fabric-based direct current TENG (FDC-TENG) with high power output is developed. Various structural parameters and environmental factors are thoroughly and systematically explored for comprehensive understanding of the FDC-TENG. The surface charges induced by triboelectrification can be unidirectionally and efficiently harvested through the conductive plasma channel caused by air breakdown, which endows the finger-sized FDC-TENG with the abilities to light up 99 bulbs and 1053 LEDs and drive watches and calculators easily and directly without rectifying or capacitor charging. This work may provide a paradigm shift for high output direct-current power fabrics and expand their scope for application in wearable electronics.
In this paper, five types of waste tea-leaves, which come from five of the most typical tea in China, are first used to prepare activated carbons (ACs) by high-temperature carbonization and activation with KOH. The resulting ACs show typical amorphous character, and display porous structures with high specific surface areas ranging from 2245m2 g−1 to 2841m2 g−1. As the electro-active electrode materials, the as-made five ACs exhibit ideal capacitive behaviors in aqueous KOH electrolyte, and the maximal specific capacitance is as high as 330Fg−1 at the current density of 1Ag−1. Furthermore, they all show excellent electrochemical cycle stability with ∼92% initial capacitance being retained after 2000 cycles. The desirable capacitive performances enable the waste tea-leaves to act as a new biomass source of carbonaceous materials for high performance supercapacitors and low-cost energy storage devices.
The assembly of two different materials into a composite with binary superlattices can provide a most efficient and inexpensive path to the synthesis of electrode materials with high energy density. Here, Li9Fe3P8O29/Na2HPO4 binary superlattice ceramic membrane-coated mesoporous soft carbon/hard carbon microspheres (BSLCM-MSC/HCMs) are synthesized via a hydrothermal carbonization method using acyl nucleoside triphosphate disodium salt (Na2ATP) as a multifunctional template. Here Na2ATP is not only a phosphorus source, a sodium source and a nucleating agent for the rapid synthesis of BSLCM, but also is a carbon source which is easily transformed into MSC/HCMs after being heat-treated in a N2 atmosphere. This special structure design brings a remarkable synergic effect for both Li+/Na+ mixed-ion storage and transfer kinetics. As a new nanocomposite cathode for mixed-ion batteries (MIBs), the BSLCM-MSC/HCMs display a self-enhancement of discharge capacity via electrolyte penetration in the core-shell mesoporous microspheres. Importantly, the discharge specific energy of a MIB assembled with the BSLCM-MSC/HCMs-2 cathode is up to 400 W h kg−1 at a high current rate of 10C, which outperforms all lithium-ion batteries and sodium-ion batteries reported so far. The findings in this study may benefit to the development of high energy mixed-ion batteries.
LiCo0.9M0.1PO4 (M=Co2+, Mg2+, Ca2+) compounds are synthesized by Pechini-assisted sol–gel process and after annealing at 300°C for 5min in air, then at 730°C for 12h in nitrogen (2-steps annealing process). The XRD-patterns reveal the presence of LiCoPO4 as major crystalline phase and of CoP2O7 (M=Co), of Co2P (M=Mg), of Co2P, Li3PO4, (Ca,Co)3(PO4)2 (M=Ca) as impurities. The morphological investigation shows a homogenous spongy-like structure for M=Co, and a more compact structure with spherical particles separated on the surface in Mg- and Ca-containing systems. In the voltammetric curves, a very good reversibility with mean peak maxima in the cathodic region of 4.4V for M=Co, 4.5V for M=Ca and 4.6V for M=Mg respectively are observed. The discharge specific capacities, at a discharge rate of C/10 and room temperature, were 60mAhg−1 for M=Co, 36mAhg−1 for M=Mg and 68mAhg−1 for M=Ca respectively. The electrochemical impedance spectroscopy data reveal a decrease of the electrical resistance and the improvement of the Li-ion conductivity after the addition of Ca and Mg-ions into the LiCoPO4 system.
Chain-like and rod-like Co-B nanomaterials are prepared by chemical reduction method in cetyltrimethylammonium bromide (CTAB) and polyvinylpyrrolidone (PVP) aqueous solution, respectively. XRD patterns demonstrate that the two materials both have amorphous structures. SEM and TEM images show that the chain-like Co-B constructs of one-by-one tactic ball-like particles with nanoflakes on the surface, whereas the rod-like Co-B alloy possesses a porous nanostructure. The results of electrochemical measurements indicate that, as negative electrode materials of Ni-MH batteries, their electrochemical properties are both better than those of regular Co-B alloy. At the discharge current density 25mAg−1, the discharge capacities of the chain-like and the rod-like Co-B alloys are 314mAhg−1 and 292mAhg−1 after 50 cycles, respectively, which are both higher than that of regular Co-B alloy. XRD patterns of the electrodes on different charge–discharge states illustrate that the discharge capacity is attributed to hydrogenation of Co-B alloy.
A novel glass-ceramic electrolyte of (100-x)(70Li2S-30P2S5)-xLi2ZrO3 (x = 0, 1, 2, 5) is successfully prepared by a vibratory ball-milling method and followed by a heat-treatment process. Composition of the ternary sulfide electrolyte and the heat-treatment process are optimized by physical characterizations and electrochemical measurements. The testing results show that the optimal substitution quantity of Li2ZrO3 into the Li2S-P2S5 electrolyte substrate is 1 mol %. An appropriate heat-treatment temperature of 99(70Li2S-30P2S5)-1Li2ZrO3 glass-ceramic electrolyte is 285 °C. Among the as-prepared ternary electrolyte samples, 99(70Li2S-30P2S5)-1Li2ZrO3 glass-ceramic electrolyte may exhibit the highest conductivity of 2.85 × 10−3 S cm−1 at room temperature, which is much higher than that of the 70Li2S-30P2S5 glass-ceramic electrolyte. Compared to that of the all-solid-state lithium-ion battery of LiCoO2/70Li2S-30P2S5/In-Li, discharge capacities of all-solid-state lithium-ion battery of LiCoO2/99(70Li2S-30P2S5)-1Li2ZrO3/In-Li may increase 41.0% at the 10th charge-discharge cycle and 21.9% at the 50th charge-discharge cycle, respectively. Furthermore, electrochemical impedance spectroscopy (EIS) analyses of all-solid-state lithium-ion batteries reveal that addition of Li2ZrO3 into the Li2S-P2S5 electrolyte substrate may decrease the interfacial resistance between the electrodes and solid electrolyte. The improvement of electrochemical performances of 99(70Li2S-30P2S5)-1Li2ZrO3 glass-ceramic electrolyte is ascribed to both the stable crystal structure and a high lithium-ion diffusion coefficient of Li2ZrO3.
The cycling performance of LiNi0.8Co0.1Mn0.1O2 has been effectively enhanced by Li2TiO3 thin film coating. The Li2TiO3 coating layer with an average thickness of 1nm has been proved by XRD, HRTEM, FFT and XPS. Compared with the 80.5% capacity retention of bare materials, the modified LiNi0.8Co0.1Mn0.1O2 materials Exhibit 98% capacity retention after 170 cycles at 1C rate. The reason for the improved cycling performance of LiNi0.8Co0.1Mn0.1O2 is due to the surface layer of Li2TiO3, which suppresses the direct contact between the active materials and the electrolytes, enhances the lithium ion diffusion between the electrode/electrolyte interface, and prevents the pulverization of the active materials during repeated charging/discharging.
High-voltage aqueous electrolyte based supercapacitors (U > 1.23 V) attract significant attention for next-generation high power, low cost and environmentally friendly energy storage applications. Cell ageing is however markedly pronounced at elevated voltages and results in accelerated overall performance fade and increased safety concerns. Online electrochemical mass spectrometry, combined with cell pressure analysis, is for the first time shown to provide a powerful means for in situ investigation of degradation mechanisms in aqueous electrolyte/carbon based supercapacitors. The activated carbon electrodes possess high specific surface area and oxygen-based surface functionalities (mainly phenol, lactone and anhydride groups), which are oxidized already at a cell voltage of 0.6 V to provoke the evolution of minor amounts of CO and CO2. Noticeable water decomposition starts at a high voltage of 1.6 V with the evolution of H2 on the negative electrode and carbon corrosion on the positive electrode with the generation of predominantly CO. In this paper we also report that short-term cycling leads to partly reversible gas evolution/consumption side-reactions giving negligible capacitance. On the other hand, long-term cycling causes irreversible side-reactions, deteriorates the electrochemical performance, and increases the internal pressure of the cell. Repeated cycling (U < 2 V) is confirmed as a more harmful technique for the electrode integrity compared to the voltage holding in a floating test. In situ gas analysis is shown to provide valuable insights into the electrochemical cell ageing aspects, such as the nature and potential onsets of side-reactions, hence paving the way for fundamental understanding and mitigating the performance and safety loss of high-energy aqueous supercapacitors.
Lithium-sulfur (Li–S) batteries have the potential to outperform state-of-the-art lithium-ion batteries. One of the bottle necks is the limited power density which most conversion based systems have in common. One of the reasons is the formation of solid, insulating charge and discharge products which passivate active surfaces during operation of the cell. In depth knowledge of the formation and dissolution is needed in order to develop counter-measures overcoming the current limitations. In this article we present a continuum model of Li–S batteries including a detailed description of the formation and dissolution of solid particles based on the classical theory of nucleation and growth. By evolving a particle size distribution of the Li2S and S8 phase we are able to provide a qualitative description of the resulting particle morphology as well as their effect on active surface areas and transport processes. Results of the simulations are in agreement with experimental data published in the literature. We perform intensive parameter studies which provide guidelines for the development of surface modifications enabling a spatial control of solid discharge product precipitation resulting in improved battery performance.
A novel porous nanoarchitecture composed of 2D graphene–SnS2 (G–SnS2) units is developed via a two-step approach in this work. The special structure endows the high-rate transportation of electrolyte ions and electrons throughout the electrode matrix, resulting in remarkable electrochemical performance when it was used as anode in lithium ion batteries.
The phenotype of calcium channel subunit (CACN) α2δ3 knockout (KO) mice includes sensory cross-activation and deficient pain perception. Sensory cross-activation defines the activation of a sensory cortical region by input from another modality due to reorganization in the brain such as after sensory loss. To obtain mechanistic insight into both phenomena, we employed a comprehensive battery of neuroanatomical techniques. While CACNα2δ3 was ubiquitously expressed in wild-type mice, it was absent in α2δ3 KO animals. Immunostaining of α1A, α1B, and α1E revealed upregulation of N-type and R-type, but not P/Q-type Cav2 channels in cortical neurons of CACNα2δ3 KO mice. Compared to wild-type mice, axonal processes in somatosensory cortex were enhanced, and dendritic processes reduced, in CACNα2δ3 KO mice. Immunohistochemical and MRI analyses, investigating morphology, thalamocortical and intra-/intercortical trajectories, revealed a disparity between projection and commissural fibers with reduction of the number of spatial specificity of thalamocortical projections. L1cam staining revealed wide-ranging projections of thalamocortical fibers reaching both somatosensory/motor and visual cortical areas. Activation (c-fos+) of excitatory and inhibitory neurons suggested that deficient pain perception in α2δ3 KO mice is unlikely to result from cortical disinhibition. Collectively, our data demonstrate that knock out of CACN α2δ3 results in some structural abnormalities whose functional implications converge to dedifferentiation of sensory activation.
A Co3O4@Ni(OH)2 core/shell nanowire arrays (NAs) material is synthesized and successfully applied to the energy storage device. Combining the performance advantages of Co3O4 nanowires and Ni(OH)2 nanosheets, Co3O4@Ni(OH)2 NAs exhibit a remarkable specific capacity (SC) of 912Cg−1 at the current density of 1Ag−1, good rate capability and cycling stability. A asymmetric supercapacitor based on Co3O4@Ni(OH)2 NAs positive electrode and active carbon (AC) negative electrode shows a broad operation voltage of 1.6V and a good specific capacitance of 140Fg−1 at 1Ag−1. All of the electrolyte used in this work is 6M KOH aqoeous solution. Furthermore, the Co3O4@Ni(OH)2//AC asymmetric supercapacitor represents prominent specific energy (49.8Whkg−1 at 801Wkg−1) and specific power (16.1kWkg−1 at 28.1Whkg−1). So, those excellent properties of Co3O4@Ni(OH)2 NAs focus more interest on similar core/shell materials.