Carbon coated Na7Fe7(PO4)6F3: A novel intercalation cathode for sodium-ion batteries

Electrode materials are being developed to realise sodium-ion batteries that can provide energy storage solutions. Here, we develop amorphous carbon coated Na₇Fe₇(PO₄)₆F₃, prepared by combining hydrothermal and solid state reaction methods, as an insertion electrode for sodium-ion batteries applications. Na₇Fe₇(PO₄)₆F₃ particles are surrounded by a thin layer (∼1.5–2 nm) of amorphous carbon. The Na₇Fe₇(PO₄)₆F₃/C composite cathode undergoes reversible sodium intercalation/de-intercalation with an average operational potential of ∼3.0 V (vs Na⁺/Na). This cathode has a capacity of 65 mA h g⁻¹ at 100 mA g⁻¹ current after 60 cycles and features twice higher capacity than that of an uncoated Na₇Fe₇(PO₄)₆F₃ sample. Therefore, the carbon-coated Na₇Fe₇(PO₄)₆F₃ composite presents feasible sodium intercalation/de-intercalation capacity, offering possibilities for developing a low cost, high performance sodium-ion battery positive electrode.

Effect of zwitterions on electrochemical properties of oligoether-based electrolytes

Solid polymer electrolytes show great potential in electrochemical devices. Poly(ethylene oxide) (PEO) has been studied as a matrix for solid polymer electrolytes because it has relatively high ionic conductivity. In order to investigate the effect of zwitterions on the electrochemical properties of poly(ethylene glycol) dimethyl ether (G5)/lithium bis(fluorosulfonyl) amide (LiFSA) electrolytes, a liquid zwitterion (ImZ2) was added to the G5-based electrolytes. In this study, G5, which is a small oligomer, was used as a model compound for PEO matrices. The thermal properties, ionic conductivity, and electrochemical stability of the electrolytes with ImZ2 were evaluated. The thermal stabilities of all the G5-based electrolytes with ImZ2 were above 150 °C, and the ionic conductivity values were in the range of 0.8–3.0 mS cm−1 at room temperature. When the electrolytes contained less than 5.5 wt% ImZ2, the ionic conductivity values were almost the same as that of the electrolyte without ImZ2. The electrochemical properties were improved with the incorporation of ImZ2. The anodic limit of the electrolyte with 5.5 wt% ImZ2 was 5.3 V vs. Li/Li+, which was over 1 V higher than that of G5/LiFSA.

Robust nonlinear distributed controller design for active and reactive power sharing in islanded microgrids

This paper presents a robust nonlinear distributed controller design for islanded operation of microgrids in order to maintain active and reactive power balance. In this paper, microgrids are considered as inverter-dominated networks integrated with renewable energy sources (RESs) and battery energy storage systems (BESSs), where solar photovoltaic generators act as RESs and plug-in hybrid electric vehicles as BESSs to supply power into the grid. The proposed controller is designed by using partial feedback linearization and the robustness of this control scheme is ensured by considering structured uncertainties within the RESs and BESSs. An approach for modeling the uncertainties through the satisfaction of matching conditions is also provided in this paper. The proposed distributed control scheme requires information from local and neighboring generators to communicate with each other and the communication among RESs, BESSs, and control centers is developed by using the concept of the graph theory. Finally, the performance of the proposed robust controller is demonstrated on a test microgrid and simulation results indicate the superiority of the proposed scheme under different operating conditions as compared to a linear-quadratic-regulator-based controller.

Electrochemical performance of LiFe1-xMnxPO4/C materials prepared by ball milling

LiFe1-xMnxPO4/C composite materials as cathode materials in Li-ion batteries have been synthesised and their electrochemical properties have been investigated. The samples were synthesised by using high energy ball milling of commercially available precursors (Li2C2O4, FeC2O4.2H2O, MnC2O4.2H2O, NH4H2PO4) and then heated at 600°C. The morphology and structure of the heated samples were analysed by means of SEM and X-ray diffraction. The olivine structure of the LiFe1-xMnxPO4/C composite was obtained. A slight shift of the peaks to smaller 2θ angles with the increasing Mn/Fe ratios is observed due to the increase in lattice parameters. The influence of different Mn/Fe ratios on electrical and electrochemical performances were studied by charge-discharge and cyclic voltammetry (CV) testing. The CV curves of the pure LiFePO4 and LiMnPO4 show the expected Fe2+/Fe3+ peak around 3·5 V and Mn2+/Mn3+ peak around 4·1 V, respectively. The addition of manganese increases the discharge voltage from 3·5 to 4·1 V.

A neuropsychological study of prefrontal lobe function in the positive and negative subtypes of schizophrenia.

The symptoms of schizophrenia are frequently divided into positive and negative subtypes. It has been suggested that the negative symptoms are similar to those seen with prefrontal lobe cortical dysfunction. Several neuropsychological investigations of that hypothesis have been carried out, but none have directly compared a negative symptom group with a positive symptom group on the same test battery. In the present study, the Positive and Negative Syndrome Scale (PANSS; Kay, Fiszbein, & Opler, 1987) was used to distinguish two groups of 20 patients with schizophrenia with predominant positive or negative symptoms. A battery of 7 neuropsychological tests considered capable of isolating prefrontal lobe dysfunction was administered. A significant group difference was noted on 6 of the tests; the negative symptom group performed much worse than the positive symptom group. The results of this study support the hypothesis that a relationship exists between the negative symptoms of schizophrenia and prefrontal lobe dysfunction.

Large-scale production of h-In2O3/carbon nanocomposites with enhanced lithium storage properties

h-In2O3/carbon nanocomposites were obtained via a facile ball milling process from a mixture of h-In2O3 nanoparticles and Super P carbon. Compared to pure h-In2O3 nanoparticles, the nanocomposites exhibited an initial discharge capacity of 1360 mAh g-1, a stable reversible capacity of 867 mAh g-1 after 100 cycles as well as a high coulombic efficiency of 99%. The superior lithium-ion battery performance can be attributed to the specific structure of h-In2O3 and the uniform and continuous nano-carbon coating layers. The nano-carbon coating could protect the inner active materials from fragmentation and increase the electronic conductivity. This study not only provides a promising electrode material for high-performance lithium-ion batteries, but also further demonstrates a straightforward, effective and environmental friendly process for synthesizing nanocomposites. © 2014 Elsevier Ltd.

Supplementing cold plasma with heat enables doping and nano-structuring of metal oxides

Nitrogen doped SnO2 polycrystalline nanostructures were produced from commercial SnO powders in a new system that combines a low-temperature plasma with heating. The method has the potential to improve the initial efficiency and the cycling performance of SnO2 anodes in Li-ion batteries. With this system, the temperature of the SnO to SnO2 conversion was lowered from 430 to 320 °C, up to 5 at% of doped nitrogen was detected and a nano-scale polycrystalline structure was observed in the product. Combining heat and low-pressure plasma is a promising approach for the production and treatment of enhanced energy storage materials.

Effect of sintering temperature on electrochemical performance of LiFe0·4Mn0·6PO4/C cathode materials

Carbon coated LiFe0·4Mn0·6PO4 (LiFe0·4Mn0·6PO4/C) was synthesised using high energy ball milling and annealing processes. The starting materials of Li2C2O4, FeC2O4.2H2O, MnC2O4.2H2O, NH4H2PO4 were firstly milled for 40 h, and followed by further milling for 5 h after adding glucose solution. The milled sample was heated at different temperatures (550, 600, 650 and 700°C) for 10 h to produce LiFe0·4Mn0·6PO4/C composites. The structure and morphology of the samples were investigated using X-ray diffraction, field emission scanning electron microscopy, and high resolution electron microscopy. The phase of samples annealed at 550 and 600°C mainly consists of olivine type LiFePO4, but a small amount of Fe2P impurity phase is formed in the samples annealed at 650 and 700°C. Electrochemical analysis results show that LiFe0·4Mn0·6PO4/C synthesised at 600°C exhibits the best performance with the initial discharge capacity of 128 mAh g-1 at 0·1 C, and 109 mAh g-1 at 1 C after 500 cycles. The LiFe0·4Mn0·6PO4/C exhibits excellent electrochemical properties for high energy density lithium ion batteries.

Balancing risk? First year performing arts students’ experience of a community arts event

This study examines participants’ responses to first year students’ street performances as a non-placement work-integrated learning (WIL) activity over a two year period. The purpose of the study was to determine: (1) community perception, (2) continuous improvement, and (3) future needs. Data was collected through surveying participants’ post-viewing of the street performances, students’ reflective notes, and a recorded focus group interview. The findings indicated that audience members require additional assistance to value the students’ street performances. The results revealed that students require more guidance around researching the sites of practice, understanding group work dynamics, relaxation methods, intra- and interpersonal skill development, conflict resolution and how to effectively build community relations with the local government Council. From the findings, specific recommendations for continual improvement are made. These include offering an explanation of the street performances’ historical and aesthetic connections to the building sites for audience members, affording battery operated body-microphones and light rostrum for improved sight lines, delivering group dynamics information and arranging opportunities for students to engage more effectively with the Council. While the recommendations in this study are intended to advance the field of research that evaluates non-placement WIL performing arts curriculum in higher education, the findings are relevant to any group-based performance activity in learning and teaching.

Optimum design and analysis study of stand-alone residential solar PV microgrid

Today’s power system network has become more complex and it has more responsibilities and challenges to provide secure, reliable and quality energysupply to the communities. A small entity of electrical network known as Microgrid (MG) is more popular nowadays to enhance reliablity and secure level of energy supply, in case of any energy crisis in the utility network. The MG can also provide clean energy supply by integrating renewable energy sources effectively. TheMG with small scale solar photovoltaic (PV) power system is more suitable to provide reliable and clean energy supply for remote or urban communities in residential level. This paper presents the basic analysis study of stand-alone solar photovoltaic (PV) MG power system which has been developed with the aid of Matlab - Simulink software, on the basis of residential load profile and solar exposure level in a particular area of Geelong, Victoria State. The simulation result depicts the control behavior of MG power system with optimum sizing of PV (4.385 kW)and battery storage (480Ah/48V) facility, fulfills daily energy needs in residential load level. This study provides a good platform to develop an effective and reliable stand-alone MG power system for the remote communities in the near future.

Electrochemical and physicochemical properties of small phosphonium cation ionic liquid electrolytes with high lithium salt content

Electrolytes of a room temperature ionic liquid (RTIL), trimethyl(isobutyl)phosphonium (P111i4) bis(fluorosulfonyl)imide (FSI) with a wide range of lithium bis(fluorosulfonyl)imide (LiFSI) salt concentrations (up to 3.8 mol kg−1 of salt in the RTIL) were characterised using a combination of techniques including viscosity, conductivity, differential scanning calorimetry (DSC), electrochemical impedance spectroscopy (EIS), nuclear magnetic resonance (NMR) and cyclic voltammetry (CV). We show that the FSI-based electrolyte containing a high salt concentration (e.g. 1:1 salt to IL molar ratio, equivalent to 3.2 mol kg−1 of LiFSI) displays unusual transport behavior with respect to lithium ion mobility and promising electrochemical behavior, despite an increase in viscosity. These electrolytes could compete with the more traditionally studied nitrogen-based ionic liquids (ILs) in lithium battery applications.

Deficient cognitive control fuels children's exuberant false allegations.

In eyewitness studies as in actual investigations, a minority of children generate numerous false (and sometimes incredulous) allegations. To explore the characteristics of these children, we reinterviewed and administered a battery of tasks to 61 children (ages 4-9 years) who had previously participated in an eyewitness study where a man broke a "germ rule" twice when he tried to touch them. Performance on utilization, response conflict (Luria tapping), and theory of mind tasks predicted the number of false reports of touching (with age and time since the event controlled) and correctly classified 90.16% of the children as typical witnesses or exuberant (more than 3) false reporters. Results of a factor analysis pointed to a common process underlying performance on these tasks that accounted for 49% of the variability in false reports. Relations between task performance and testimony confirmed that the mechanisms underlying occasional intrusions are different from those that drive persistent confabulation and that deficient cognitive control fuels young children's exuberant false reports.

Biocompatible ionic liquid-biopolymer electrolyte-enabled thin and compact magnesium-air batteries.

With the surge of interest in miniaturized implanted medical devices (IMDs), implantable power sources with small dimensions and biocompatibility are in high demand. Implanted battery/supercapacitor devices are commonly packaged within a case that occupies a large volume, making miniaturization difficult. In this study, we demonstrate a polymer electrolyte-enabled biocompatible magnesium-air battery device with a total thickness of approximately 300 μm. It consists of a biocompatible polypyrrole-para(toluene sulfonic acid) cathode and a bioresorbable magnesium alloy anode. The biocompatible electrolyte used is made of choline nitrate (ionic liquid) embedded in a biopolymer, chitosan. This polymer electrolyte is mechanically robust and offers a high ionic conductivity of 8.9 × 10(-3) S cm(-1). The assembled battery delivers a maximum volumetric power density of 3.9 W L(-1), which is sufficient to drive some types of IMDs, such as cardiac pacemakers or biomonitoring systems. This miniaturized, biocompatible magnesium-air battery may pave the way to a future generation of implantable power sources.

Acute mood but not cognitive improvements following administration of a single multivitamin and mineral supplement in healthy women aged 50 and above : a randomised controlled trial

A number of randomised controlled trials have indicated that multivitamin/mineral supplementation for a period of 4 weeks or greater can enhance mood and cognition. To date, no studies have investigated whether a single multivitamin dose can benefit mental function in older adults. This study investigated the acute effects of a single multivitamin and mineral and herbal (MVMH) supplement versus placebo on self ratings of mood and the performance of an effortful computerised cognitive battery in a sample of 76 healthy women aged 50-75 years. Mood was assessed using the depression anxiety stress scale (DASS), state trait anxiety inventory-state anxiety scale and visual analogue scales (VAS). Mood was rated at 1 h post supplementation and again after the competition of the cognitive assessments at 2 h post supplementation. It was demonstrated that the MVMH supplement improved overall DASS mood ratings; however, the most prominent effects appeared to be a reduction in ratings of perceived mental stress. These findings were confirmed using visual analogue scales, with these measures also demonstrating MVMH-related increased ratings of calmness. There were no benefits of the MVMH to mood ratings of depression and performance was not enhanced on the cognitive battery. Supplementation with a single multivitamin, mineral and herbal supplement reduces stress several hours after intake in healthy older people.

Rectenna circuits for RF energy harvesting in miniature DBS devices.

 Development of an optimum rectenna for radio frequency energy harvesting in miniature head-mountable deep brain stimulation (DBS) devices. The designed miniature rectenna can operate a DBS device without battery for murine preclinical research. The battery-less operation of the device eliminates battery related difficulties.