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In this paper, the recent developments and the characteristics of membrane separators for lithium-ion batteries are reviewed. In recent years, there have been intensive efforts to develop advanced battery separators for rechargeable lithium-ion batteries for different applications such as portable electronics, electric vehicles, and energy storage for power grids. The separator is a critical component of lithium-ion batteries since it provides a physical barrier between the positive and negative electrodes in order to prevent electrical short circuits. The separator also serves as the electrolyte reservoir for the transport of ions during the charging and discharging cycles of a battery. The performance of lithium-ion batteries is greatly affected by the materials and structure of the separators. This paper introduces the requirements of battery separators and the structure and properties of five important types of membrane separators which are microporous membranes, modified microporous membranes, non-woven mats, composite membranes and electrolyte membranes. Each separator type has inherent advantages and disadvantages which influence the performance of lithium-ion batteries. The structures, characteristics, manufacturing, modification, and performance of separators are described in this review paper. The outlook and future directions in this research field are also given.
An in-situ scanning vibrating electrode technique is used to investigate the effect of alloyed arsenic on magnesium immersed in chloride containing aqueous solution, both in freely corroding and anodically polarised conditions. Arsenic is shown to strongly suppress cathodic activation of the corroding Mg even under circumstances where breakdown has occurred and subsequent propagation of dark filiform-like tracks is observed. Under galvanostatic anodic polarisation, rates of hydrogen evolution are significantly mitigated compared to pure Mg and no time-dependent evolution of local cathodic sites is detected. The findings support the theory that cathodic activation of the dark corroded Mg surface is associated with accumulated transition metal impurity, which in turn become poisoned towards cathodic hydrogen evolution by the presence of As. In addition, these preliminary studies suggest that alloying with a strong cathodic poison may provide a means of producing a more-charge effective anode material for primary sea-water activated Mg batteries.
The objective of this study was to determine stress levels during hospitalization in patients with Chronic Obstructive Pulmonary Disease (COPD). We wanted to relate stress to previous level of quality of life and patients’ Social Support.
Hierarchically porous one-dimensional (1D) TiO2-carbon tubular composites (TiO2 C-Ts) with interconnected nanoflakes on the porous tube walls, have been successfully created using a simple solvothermal alcoholysis followed by a subsequent calcination process. The as-prepared TiO2 C-Ts demonstrate high electrical conductivity due to the 1D tubular frameworks and the interconnected porous tube walls, offering fast ion/electron transport paths and large space for storing the electrolyte, while buffering the volume change during the Li+ insertion/extraction process. When evaluated as an anode in a lithium-ion battery, the optimized TiO2 C-Ts600 electrode displays a remarkable reversible capacity of 534 mA h g−1 after 100 cycles at 180 mA g−1 and an impressive capacity of 284.9 mA h g−1 (∼80% capacity retention) after 3000 cycles at 3.5 A g−1. Further, the performance of the TiO2 C-Ts600 electrode is also investigated in a full cell using LiFePO4 as the cathode, demonstrating highly reversible discharge capacity (353.8 mA h g−1 after 100 cycles at 100 mA g−1, corresponding to capacity retention of ∼73%) and superior rate capability (254.4 mA h g−1 at 1.0 A g−1), suggesting its great potential application in high-performance energy storage devices.
There is a pressing need to find alternatives to conventional batteries such as Li-ion, which contain toxic metals, present recycling difficulties due to harmful inorganic components, and rely on elements in finite global supply. Thermopower wave (TPW) devices, which convert chemical to electrical energy by means of self-propagating reaction waves guided along nanostructured thermal conduits, have the potential to address this demand. Herein, we demonstrate orders of magnitude higher chemical-to-electrical conversion efficiency of thermopower wave devices, in excess of 1%, with sustainable fuels such as sucrose and NaN3 for the first time, that produce energy densities on par with Li-ion batteries operating at 80% efficiency (0.2 MJ L−1versus 0.8 MJ L−1). We show that efficiency can be increased significantly by selecting fuels such as sodium azide or sucrose with potassium nitrate to offset the inherent penalty in chemical potential imposed by strongly p-doping fuels, a validation of the predictions of Excess Thermopower theory. Such TPW devices can be scaled to lengths greater than 10 cm and durations longer than 10 s, an over 5-fold improvement over the highest reported values, and they are capable of powering a commercial LED device. Lastly, a mathematical model of wave propagation, coupling thermal and electron transport with energy losses, is presented to describe the dynamics of power generation, explaining why both unipolar and bipolar waveforms can be observed. These results represent a significant advancement toward realizing TPW devices as new portable, high power density energy sources that are metal-free.
Surface modified-LiV3O8 cathode materials with Al2O3 are successfully synthesized via a facile thermolysis process. The 0.5 wt.% Al2O3-coated LiV3O8 exhibits an enhanced cyclic stability at various charge–discharge current densities. At a current density of 100 mA g−1, it delivers an initial specific discharge capacity of 283.1 mAh g−1 between 2.0 and 4.0 V. Moreover, high capacities of 139.4 and 118.5 mAh g−1 are obtained at the 100th cycle at current densities of 2000 and 3000 mA g−1, respectively. The improved electrochemical performance is attributed to the Al2O3 coating, which can hinder the irreversible phase transformation and act as a protective layer to prevent the active material from direct contact with electrolyte. Furthermore, the formation of a Li–V–Al–O solid solution at the LiV3O8/Al2O3 interface provides a fast Li+ diffusion path which is of benefit to the electrochemical behaviors.
The surface layer on a petroleum coke in tetraglyme solutions of LiAsF6 or LiCF3SO3 was analysed with X-ray Photoelectron Spectroscopy, Scanning Electron Microscopy, Gas Chromatography and fluoride selective electrode. Results indicate that solvent reduction is a minor process and salt reduction a major one. Results are consistent with the reduction mechanism of LiAsF6 proposed in the literature. But with LiCF3SO3, we suggest that reduction proceeds via the cleavage of a CF bond instead of a CS bond.
The long-term effects of vagus nerve stimulation (VNS) on seizure frequency were studied in 30 patients with Lennox–Gastaut syndrome. Median observation time was 52 months (17–123). The effect parameters investigated were total number of seizures and different seizure types. The median reduction in number of seizures was 60.6%. The effects of VNS varied considerably between seizure types. Best effects were observed with atonic seizures (80.8% median reduction, number of responders: 8/12), followed closely by tonic seizures (73.3% median reduction, number of responders: 8/13). Least effects were with generalized tonic–clonic seizures (median reduction 57.4%, number of responders: 11/20). Additional positive effects included milder or shorter ictal or postictal phase in 16 patients. Improved alertness was reported in 76.7%. Adverse effects, of which drooling and voice alteration were most frequent, were reported in 20 patients. There was a statistically significant reduction in the median number of antiepileptic drugs used. The discontinuation rate was 16.7%.
The extended Kalman filter (EKF) method for SOC estimation has some problems such as the lack of an accurate model, and model errors due to the variation in the parameters of the model due to the nonlinear behavior of a battery. To solve the aforementioned issues, this paper proposes a reduced order EKF including the measurement noise model and data rejection. In order to do so, the model of a battery in the EKF is simplified into the type of reduced order to decrease the calculation time. Additionally, to compensate the model errors caused by the reduced order model and variation in parameters, a measurement noise model and data rejection are implemented because the model accuracy is critical in the EKF algorithm in order to obtain a good estimation. Finally, the proposed algorithm is verified by short and long term experiments.
The experimental data obtained in stationary field experiments in the conditions of irrigated alluvial meadow-forest soils of the dry subtropics of Azerbaijan (North-Eastern part of the Greater Caucasus) are studied and presented. The use of fertilizer systems (mineral, organic and organic-mineral, i.e. their combined use) had different effects on the accumulation of basic nutrients (NPK) in the aboveground organs (fruits, leaves, stems) of the tomato plant. The efficiency of the influence of different systems of fertilizers under the culture of the tomato is established. Yield and total removal of the potassium effective option the organic - mineral system of organic-mineral system of fertilizers in the norm of the Background—(P90K120) + N60 + manure 12 t/ha; for total removal of phosphorus, organic system of fertilizers in the norm of manure 24 t/ha; and the total removal of nitrogen was efficient Background option—(P90K120) + N120. The overall takeaway was accordingly 272.88 kg/ha potassium; 76.76 kg/ha for phosphorus and 170.56 kg/ha of nitrogen.
The effects of both intravenous administration of recombinant human erythropoietin (rhEPO) and blood withdrawal, either individually or in combination, on the frequency of micronucleated immature erythrocytes (MIE) in the bone marrow were investigated in 10-week old male Han Wistar rats. Clear increases in MIE frequency and evidence of erythroid hyperplasia were seen in the bone marrow after 1350 IU kg−1 rhEPO but only marginal increases in MIE were seen at the lower dose of 135 IU kg−1. At the lower dose, blood levels of rhEPO were found to be approximately 120 pg mL−1 within one hour of dosing. Withdrawal of 5 blood samples of 0.45 mL on each occasion during 24 hours, the maximum allowed by the Home Office licence, did not increase MIE frequency but did result in levels of endogenous EPO of 15–19 pg mL−1 24 to 72 hours after the start of treatment, with some evidence of increased erythropoiesis. Although the increased plasma amounts of EPO, resulting from blood withdrawal, were lower than the blood levels achieved by the administration of exogenous rhEPO that were required to give increases in micronucleus frequency, the possibility that blood withdrawal might influence the MIE response to genotoxins cannot be totally excluded without further investigation.
Li[Li1/6Ni1/6Co1/6Mn1/2]O2-xFx (x = 0.00 to 0.07) materials were synthesized with low temperature heat treatment (700 °C) and their electrochemical performances were evaluated. With the addition of fluorine, the reversible capacity significantly increased as the irreversibility was suppressed during the first cycle. The reduction of irreversibility was mainly attributed to the enhanced first cycle efficiency of Li2MnO3-like component after the fluorine addition. By combining results of the X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), In-situ X-ray absorption spectroscopy (XAS) analyses, and first principle calculations, it was proposed that the presence of fluorine facilitated the reduction of cobalt and manganese ions in Li-rich layered oxide, and that the reduced transition metal (TM) ions suppressed structural changes.
In many researches on load balancing in multi-sink WSN, sensors usually choose the nearest sink as destination for sending data. However, in WSN, events often occur in specific area. If all sensors in this area all follow the nearest-sink strategy, sensors around nearest sink called hotspot will exhaust energy early. It means that this sink is isolated from network early and numbers of routing paths are broken. In this paper, we propose an adaptive learning scheme for load balancing scheme in multi-sink WSN. The agent in a centralized mobile anchor with directional antenna is introduced to adaptively partition the network into several zones according to the residual energy of hotspots around sink nodes. In addition, machine learning is applied to the mobile anchor to make it adaptable to any traffic pattern. Through interactions with the environment, the agent can discovery a near-optimal control policy for movement of mobile anchor. The policy can achieve minimization of residual energy’s variance among sinks, which prevent the early isolation of sink and prolong the network lifetime.
A high temperature polymer electrolyte membrane water electrolyser (PEMWE) was investigated at temperatures between 80 and 130°C and pressures between 0.5 and 4bar. Nanometer size Ru0.7Ir0.3O2 and Pt/C were employed as anode and cathode catalysts respectively. The catalyst coated on membrane (CCM) method was used to fabricate the membrane electrode assemblies. The membrane, oxygen evolution catalysts and MEAs were characterized with SEM, XRD and TEM. The influence of high temperature and pressure was investigated using in situ electrochemical measurements. Increasing temperature and pressure produced higher current densities for oxygen evolution, and smaller terminal voltages. The high temperature PEMWE achieved a voltage of 1.51V at a current density of 1Acm−2, at 130°C and 4bar pressure.
Commercial Li-ion batteries are typically cycled between 3.0 and 4.2 V. These voltages limits are chosen based on the characteristics of the cathode (e.g. lithium cobalt oxide) and anode (e.g. graphite). When alternative anode/cathode chemistries are studied the same cut-off voltages are often, mistakenly, used. Silicon (Si) based anodes are widely studied as a high capacity alternative to graphite for Lithium-ion batteries. When silicon-based anodes are paired with high capacity cathodes (e.g. Lithium Nickel Cobalt Aluminium Oxide; NCA) the cell typically suffers from rapid capacity fade. The purpose of this communication is to understand how the choice of upper cut-off voltage affects cell performance in Si/NCA cells. A careful study of three-electrode cell data will show that capacity fade in Si/NCA cells is due to an ever-evolving silicon voltage profile that pushes the upper voltage at the cathode to >4.4 V (vs. Li/Li+). This behaviour initially improves cycle efficiency, due to liberation of new lithium, but ultimately reduces cycling efficiency, resulting in rapid capacity fade.
Lineage-based mechanisms are widely used to generate cell type diversity in both vertebrates and invertebrates. For the past few decades, the nematode Caenorhabditis elegans has served as a primary model system to study this process because of its fixed and well-characterized cell lineage. Recent studies conducted at the level of single cells and individual cis-regulatory elements suggest a general model by which cellular diversity is generated in this organism. During its developmental history a cell passes through multiple transient regulatory states characterized by the expression of specific sets of transcription factors. The transition from one state to another is driven by a general binary decision mechanism acting at each successive division in a reiterative manner and ending up with the activation of the terminal differentiation program upon terminal division. A similar cell fate specification system seems to play a role in generating cellular diversity in the nervous system of more complex organisms such as Drosophila and vertebrates.
A characteristic of magnesium (Mg) dissolution is that dissolution is accompanied by a concomitant increase in the hydrogen evolution reaction (HER), a phenomenon known as cathodic activation. When magnesium undergoes free corrosion or forced dissolution in response to anodic polarisation, cathodic activation is manifest, which allows magnesium dissolution to readily proceed. However, recent work revealed that alloying magnesium with micro additions of arsenic, As (a group 15 element) was capable of retarding cathodic activation, resulting in a significant reduction in the corrosion rate of Mg-As alloys. As such, in the pursuit of elements with similar chemical and electrochemical properties to arsenic, but with less toxicity, a number of group 14 and 15 elements were alloyed with magnesium and reported herein. Based on the binary alloying additions studied herein, it was revealed that Bi, Ge, Pb, Sb and Sn, demonstrated suppression of cathodic activation of Mg following anodic polarisation (about one order of magnitude lower based on the cyclic galvanostatic-potentiostatic testing), in addition to lower free corrosion rates (about one order of magnitude based on the mass loss and hydrogen evolution testing). Employing a number of corrosion rate assessments, including online atomic emission spectroelectrochemistry, it was shown that reduction in Mg corrosion rates – historically considered difficult to achieve – can be robustly demonstrated. The present work has implications for the development of more corrosion resistant Mg alloys, Mg anodes for cathodic protection, or for the use of Mg as a primary battery electrode.
Co-location of energy storage with demand provides several benefits over other locations, while still being able to provide balancing services to the grid. One of these additional benefits is deferral of distribution infrastructure reinforcement, allowing increased load growth. This paper considers the potential of electricity storage for peak shaving on distribution networks, focusing on residential areas. A demand model is used to synthesise high resolution domestic load profiles, and these are used within Monte Carlo analysis to determine how much peak shaving could be achieved with storage. An efficient method of finding the potential peak shaving using electricity storage is developed for this purpose. It is shown that moderate levels of storage capacity can deliver significant demand reductions, if suitably coordinated and incentivised. With 2 kWh of battery storage per household, the peak demand at low voltage substations could potentially be halved. The effects of PV capacity, household size and C rates are considered. With 3 kW PV per house, 4.5 kWh of batteries could keep peak flows at the same level as before the addition of PV. It is also shown that 3 kWh of battery storage per household could allow provision of all heating from heat pumps without increasing the peak demand.
The regulation of catalytic activity in the oxygen reduction reaction (ORR) is significant to the development of metal–air batteries and other oxygen involving energy conversion devices. Herein, we propose an atomic interface strategy to construct a single atom copper catalyst (denoted as Cu-SA/SNC) which exhibits enhanced ORR activity with a half-wave potential of 0.893 V vs. RHE in alkaline media. Moreover, synchrotron-radiation-based X-ray absorption fine structure (XAFS) investigations together with density functional theory (DFT) calculations reveal that the isolated bond-shrinking low-valence Cu (+1)–N4–C8S2 atomic interface moiety serves as an active site during the ORR process, and the synergistic mechanism between the Cu species and the carbon matrix at the atomic interface plays a critical role in boosting the ORR efficiency, by adjusting the reaction free energy of intermediate adsorption. This atomic interface concept may provide an alternative methodology for the rational design of advanced oxygen electrode materials and new probability to improve their catalytic performance.
Pseudocubic α-Fe2O3/C nanocomposites with sizes of 30–35nm were synthesized via in situ carbonization of surfactants under Ar atmosphere using oleic acid-capped α-Fe2O3 nanoparticles as precursors. The transformation from oleic groups to carbon was evidenced in detail by Fourier transform infrared spectroscopy, elemental analysis and thermogravimetric analysis. The high resolution transmission electron microscope further confirmed that a thin carbon layer of 1–2nm in thickness tightly coated α-Fe2O3 nanocrystals. Compared with bare α-Fe2O3 nanoparticles, α-Fe2O3/C composites exhibited excellent cycling performance (a reversible capacity of 688mAh/g after 50 cycles at 0.2C rate) and rate capability (370mAh/g after 20 cycles at 2C) as anode materials for lithium-ion batteries. The remarkably improved electrochemical performance of α-Fe2O3/C nanocomposites was attributed to in situ carbon coating, which prevented nanoparticle aggregation, increased electronic conductivity and stabilized solid electrolyte interface (SEI) films.
Mesoporous hollow TiO2 microspheres with controlled size and hierarchical nanostructures are designed from a process employing in suit template-assisted and hydrothermal methods. The results show that the hollow microspheres composed of mesoporous nanospheres possess very stable reversible capacity of 184mAhg−1 at 0.25C and exhibit extremely high power of 122mAhg−1 at the high rate of 10C. The superior high-rate and high-capacity performance of the sample is attributed to the efficient hierarchical nanostructures. The hollow structure could shorten the diffusion length for lithium ion in the microspheres. The large mesoporous channels between the mesoporous nanospheres provide an easily-accessed system which facilitates electrolyte transportation and lithium ion diffusion within the electrode materials. The electrolyte, flooding the mesoporous channels, can also lead to a high electrolyte/electrode contact area, facilitating transport of lithium ions across the electrolyte/electrode interface. The small mesopores in the meosporous nanospheres can make the electrolyte and lithium ion further diffuse into the interior of electrode materials and increase electrolyte/electrode contact area. The small nanoparticles can also ensure high reversible capacity.
Sodium-ion full cell with hard carbon as anode and a layered oxide cathode based on earth abundant elements i.e., Na0.67[Fe0.5Mn0.5]O2 is reported. The irreversible capacity of the negative electrode in the full cell configuration is compensated by the addition of a sacrificial salt such as NaN3 to the P2-Na0.67[Fe0.5Mn0.5]O2 cathode material. 60% increase in the reversible capacity is achieved with the addition of 10% of sodium azide in the composite cathode without compromise on the cycle life. Though, there is a limit in its use because of the capacity fade which can be observed with the further increase in NaN3 content. The quantification of sodium ions at the end of discharge (at 1 V) after 40 cycles by ex-situ X-ray diffraction and solid state nuclear magnetic resonance supports the electrochemical data. Scanning electron microscopy shows the effect of NaN3 on the electrode microstructure in terms of the porosity created by NaN3 decomposition.
40%-titanium substituted Li2MnO3 (Li1+x (Ti0.4Mn0.6)1−x O2, 0 < x < 1/3) before and after carbothermal reduction was characterized by annular dark field scanning transmission electron microscopy (ADF-STEM) and electron energy-loss spectroscopy (EELS) to investigate the effects of the pre-reduction treatment. EELS spectra with high energy resolution using monochromator clearly reveal the appearance of reduced Mn ions after the reduction process. The spatial distribution of the reduced phase was visualized by multi-linear least-squares (MLLS) fitting method using Mn L-edge energy-loss near-edge structure (ELNES). The morphology change of a primary particle was observed around the Mn reduction phase.