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We have been exploring the use of the template method to prepare nanostructured Li-ion battery electrodes. These nanostructured electrodes show improved rate capabilities relative to thin-film control electrodes prepared from the same material. In this paper we discuss nanostructured Sn-based anodes. Li-ion battery anodes derived from oxides of tin have been of considerable recent interest because they can, in principle, store over twice as much Li+ as graphite. However, large volume changes occur when Li+ is inserted and removed from these Sn-based materials, and this causes internal damage to the electrode resulting in loss of capacity and rechargability. We describe here a new nanostructured SnO2-based electrode that has extraordinary rate capabilities, can deliver very high capacities (e.g. >700mAhg−1 at 8°C), and still retain the ability to be discharged and recharged through as many as 800 cycles. These electrodes, prepared via the template method, consist of monodisperse 110nm-diameter SnO2 nanofibers protruding from a current-collector surface like the bristles of a brush. The dramatically-improved rate and cycling performance is related to the small size of the nanofibers that make up the electrode and the small domain size of the Sn grains within the nanofibers.
Reduced graphene oxide (rGO) homogenously wrapped nickel diselenide (NiSe2/rGO) hybrid has been prepared by a facile one-spot hydrothermal method. When investigated as anode material for sodium ion batteries (SIBs), NiSe2/rGO hybrid delivers a high reversible capacity (433 mAh g−1 at 100 mA g−1), superior rate performance (406, 386, 366, 347 and 318 mAh g−1 at 200, 500, 1000, 2000 and 5000 mA g−1, respectively) and excellent cycling stability (a capacity retention of 346 mAh g−1 after 1000 cycles at 1000 mA g−1) within the 0.4–3.0 V voltage range. In situ XRD analysis and ex situ SEM/TEM measurement reveal that the high capacity of NiSe2/rGO is originated from the combined Na+ intercalation and conversion reactions. These results validate the impact of voltage range on electrochemical property, providing a new route to rationalize the limiting factors that affect the performance of NiSe2 anode material. The facile synthesis and superior electrochemical performance of the NiSe2/rGO hybrid render it a promising anode material for SIBs.
Herein, Polypyrrole was used as the conductive wrapping material electro-deposited on the MnO2 nanoflakes covered on C/TiO2 nanowire arrays to form PPy@MnO2@C/TiO2 double shell/core structured arrays electrode for supercapacitor. Their structure and surface morphology were studied by using X-ray diffraction analysis, scanning electron microscopy and transmission electron microscopy. The results suggest that a thin layer of PPy was successfully wrapped on the surface of MnO2, and the shell/core structure of MnO2@C/TiO2 nanowire arrays was not changed after electro-deposition of PPy. The electrochemical tests indicate that the PPy@MnO2@C/TiO2 double shell/core arrays electrode exhibits high specific capacitance of 715Fg−1 at a charge/discharge current density of 1Ag−1 and improved specific capacitance retention to 84.0% after 1000 cycles. These results show that the unique three dimensional (3D) double shell/core structured electrode holds promise for high-performance energy storage devices. The superior capacitive perfomance may due to the unique 3D C/TiO2 nanowires and the unique double shell/core structures. Firstly, the 3D C/TiO2 nanowire arrays, as excellent platform for loading active materials, can facilitate the permeation of electrolyte. Moreover, the thin layer PPy tightly wrapped on the MnO2 nanoflakes can improve the electrical conductivity of MnO2. Therefore, the PPy@MnO2@C/TiO2 electrode is promising candidate for electrochemical energy applications.
Solid waste management (SWM) has been an integral part of every human society. The approaches for SWM should be compatible with the nature of a given society, and, in this regard, Asian countries are no exception. In keeping with global trends, the systems are being oriented to concentrate on sustainability issues; mainly through the incorporation of 3R (reduce, reuse and recycle) technologies. However, degree and nature of improvements toward sustainability are varying and depend on the economic status of a country. High-income countries like Japan and South Korea can afford to spend more to incorporate 3R technologies. Most of the latest efforts focus on “Zero Waste” and/or “Zero Landfilling” which is certainly expensive for weaker economies such as those of India or Indonesia. There is a need to pragmatically assess the expectations of SWM systems in Asian countries. Hence, in this paper, we analyze the situation in different Asian countries, and explore future trends. We conceptually evaluate issues surrounding the sustainability of SWM. We propose a multi-pronged integrated approach for improvement that achieves sustainable SWM in the context of national policy and legal frameworks, institutional arrangement, appropriate technology, operational and financial management, and public awareness and participation. In keeping with this approach, a generic action plan has been proposed that could be tailored to suit a situation in a particular country. Our proposed concept and action plan framework would be useful across a variety of country-specific scenarios.
The structure and electrochemical properties of epitaxial thin film LiNi0.5Mn1.5O4 electrodes are investigated for lithium ion secondary batteries applications. The orientation and thickness of the LiNi0.5Mn1.5O4 films are controlled by changing the substrate orientation and the pulse laser deposition time, respectively. The lattice parameters of the films increase with film thickness and the manganese valence decreases without any change in the nickel valence. Regardless of their orientation, all the films exhibit reversible capacities of 80–130 mAh g−1. The dependence of the discharge capacity on film thickness indicates a nanosize effect. The electrochemical properties of the high voltage spinel system are significantly dependent on their electronic properties, lattice orientations, and film thicknesses of the electrodes.
A comprehensive working memory battery and tests of mathematical skills were administered to 90 children—41 in Year 1 (5–6years of age) and 49 in Year 3 (7–8years of age). Working memory could explain statistically significant variance in number writing, magnitude judgment, and single-digit arithmetic, but the different components of working memory had different relationships with the different skills. Visual–spatial sketchpad (VSSP) functioning predicted unique variance in magnitude judgments and number writing. Central executive functioning explained unique variance in the addition accuracy of Year 1 children. The unique variance explained in Year 3 multiplication explained by phonological loop functioning just missed conventional levels of significance (p =.06). The results are consistent with the VSSP having a role in the development of number writing and magnitude judgments but a lesser role in early arithmetic.
Flexible lithium-ion batteries (FLIBs) potentially offer lithium-ion battery energy density required for the production of flexible electronics. The design of FLIBs depends not only on the electrode materials but also on the entire weight of the battery device. However, low capacity contribution from the flexible substrate and poor interactions between the flexible substrate and active electrode materials lead to low capacity, representing low energy density. Herein, we concentrated on designing a flexible substrate (carbon cloth, CC), improving its conductivity and surface area to deliver high capacity, and further coating porous NiCo2O4 nanowires on it to achieve a monolithic anode for high-gravimetric energy density FLIBs. Theoretical and in situ analyses were used to investigate Li-ion pathways and capacity contribution of the flexible substrate, respectively. In this regard, a 39.0 cm2 all-flexible lithium-ion battery (with an entire weight of 281 mg) with high gravimetric energy density (314 W h kg−1), excellent flexibility, and good storage performance is attained, and it exhibits potential application for future flexible energy storage devices.
This Review discusses key aspects of experimental design to evaluate intergenerational and transgenerational epigenetic inheritance. It describes advantages of patrilineal and matrilineal design, and it offers advice for selecting animals for breeding and for determining the weaning scheme and group size.
The structures of modified carbons from bean dregs were regulated via graphitization treatment and chemical activation. The microstructure and electrochemical performance were studied using X-ray diffraction, Raman spectrometer, SEM and TEM techniques. The electrochemical performance was investigated using electrochemical methods. After heat-treatment at 2800°C, the obtained BDC-2800 possessed a high degree of graphitization and showed an outstanding cycling performance, delivering capacity decay from 423 to 396mAhg−1 at 0.1C after 100 cycles. The chemical-treated carbons also demonstrated enhanced electrochemical performance, especially for the KOH-treated sample. The BDC-K displayed superior specific charge capacity of 801mAhg−1 at 0.1C, and showed an impressive rate capability of 643mAhg−1 at 1C. In addition, this sample delivered capacity retention of 94% after 500 cycles at 1C. This good electrochemical performance was mainly due to its high surface area and abundant mesoporous structure.
In this article we describe efforts to improve performance and cycle life of cells containing Li1.2Ni0.15Mn0.55Co0.1O2-based positive and graphite-based negative electrodes. Initial work to identify high-performing materials, compositions, fabrication variables, and cycling conditions is conducted in coin cells. The resulting information is then used for the preparation of double-sided electrodes, assembly of pouch cells, and electrochemical testing. We report the cycling performance of cells with electrodes prepared under various conditions. Our data indicate that cells with positive electrodes containing 92 wt.% Li1.2Ni0.15Mn0.55Co0.1O2, 4 wt.% carbons (no graphite), and 4 wt.% PVdF (92–4–4) show ∼20% capacity fade after 1000 cycles in the 2.5–4.4 V range, significantly better than our baseline cells that show the same fade after only 450 cycles. Our analyses indicate that the major contributors to cell energy fade are capacity loss and impedance rise. Therefore incorporating approaches that minimize capacity fade and impedance rise, such as electrode coatings and electrolyte additives, can significantly enhance calendar and cycle life of this promising cell chemistry.
A 2-V lithium-ion battery consisting of Li[Li1/3Ti5/3]O4 (zero-strain insertion material) and LiCo1/2Ni1/2O2 was constructed, and accelerated cycle tests were performed for 50,000 cycles in order to examine whether or not high-rate charge and discharge were possible for the lithium-ion battery. Mode of accelerated cycle tests consisted of quick charge at 2.5V and discharge at 1.7V, respectively, for 25.6s, which corresponded to about 10% change in capacity determined for the fresh cell. Maximum charge and discharge currents were, respectively, 3.4 and 4.2Ag−1 based on LiCo1/2Ni1/2O2 weight. Capacity failure was not observed even after 50,000 cycles; specifically 90% of initial capacity was observed when the cell was cycled at 0.17mAcm−2 in voltages of 1.0–2.7V. However, power fade was observed during the accelerated cycle tests for both input and output. Impedance spectra as a function of depth-of-discharge (DOD) were measured before and after the cycle tests. After the 50,000 cycle tests, internal resistance observed at 0.1Hz increased twice, while that at 1kHz increased about 10% for 50% of DOD. From these results, an application of impedance measurements to basic researches on lithium insertion materials for high-power and long-life lithium-ion batteries was discussed.
This study assesses whether sterile surgical helmet systems (SSHS) provide surgeons with additional protection from aerosol pathogens alongside their traditional role protecting against splash. There has been debate on whether to use such systems in reopening elective orthopaedic surgery during the current COVID-19 pandemic environment.
A fuel cell (FC) using liquid fuel and oxidizer is under investigation. H2O2 is used in this FC directly at the cathode. Either of two types of reactant, namely a gas-phase hydrogen or an aqueous NaBH4 solution, are utilized as fuel at the anode. Experiments demonstrate that the direct utilization of H2O2 and NaBH4 at the electrodes results in >30% higher voltage output compared to the ordinary H2/O2 FC. Further, the use of this combination of all liquid fuels, provides numerous advantages (ease of storage, reduced pumping requirements, simplified heat removal, etc.) from an operational point of view. This design is inherently compact compared to other cells that use gas phase reactants. Further, regeneration is possible using an electrical input, e.g. from power lines or a solar panel. While the peroxide-based FC is ideally suited for applications such as space power where air is not available and a high energy density fuel is essential, other distributed and mobile power uses are of interest.
The performance of the positive electrode composed of a mixture of nickel hydroxide (Ni(OH)2) and a small amount of manganese dioxide (MnO2) was investigated for the positive electrode of Fuel Cell/Battery (FCB) system. It was found that the positive electrode can function not only as an active material of secondary batteries when it is charged but also as a catalyst of fuel cells when oxygen is supplied, which was confirmed by the following characterization: electrochemical characterization was performed with cyclic voltammetry (CV) and galvanostatic discharge curve in oxygen and oxygen-free atmosphere. CV of Ni(OH)2/MnO2 positive electrode exhibited the redox reaction of Ni(OH)2 as well as oxygen reduction reaction. It was observed that the discharge curves of positive electrode had two working potentials in half cell test when the electrode was charged and oxygen was supplied: one from the reactions of nickel oxyhydroxide (NiOOH); the other from the fuel cell reactions of manganese dioxide (MnO2). It was also observed that the discharge curves had two working voltages in full cell test when the cell was fully charged and oxygen was supplied: one at 1.2V from the battery reactions of NiOOH; the other at 0.8V from the fuel cell reactions of MnO2. In particular, the discharge capacity of overcharged cell was improved approximately 2 times compared with a battery of the same electrode quantity due to the additional function of this system as a fuel cell by using oxygen generated by water electrolysis. XRD analysis showed that there was no crystal structure change before and after (over)charge–discharge cycles. In summary, these experimental results showed that the novel bi-functional FCB system could provide an improved overall energy density per weight compared with conventional secondary batteries.
Energy plays a pivotal role in socio-economic development by raising standard of living. It is becoming gradually accepted that current energy systems, networks encompassing every thing from primary energy sources to final energy services, are becoming unsustainable. Development of conventional forms of energy for meeting the growing energy needs of society at a reasonable cost is the responsibility of the Governments. In recent years, public and political sensitivities to environmental issues and energy security have led to the promotion of renewable energy resources. Diversification of fuel sources is imperative to address these issues; and limited fossil resources and environmental problems associated with them have emphasized the need for new sustainable energy supply options that use renewable energies. Development and promotion of new non-conventional, alternate and renewable sources of energy such as solar, wind and bio-energy, etc. are now getting sustained attention. Solar power is one of the hottest areas in energy investment right now, but there is much debate about the future of solar technology and solar energy markets. This investigates the progress and challenges for solar power in Pakistan according to the overall concept of sustainable development, and identifies the region wise potential of solar power in Pakistan and its current status. Barriers are examined over the whole solar energy spectrum and policy issues and institutional roles and responsibilities are discussed.
This study describes the case of a global alexic patient with a severe reading deficit affecting words, letters and Arabic numbers, following a left posterior lesion. The patient (VA) could not match spoken letters to their graphic form. A preserved ability to recognize shape and canonical orientation of letters indicates intact access to the representation of letters and numbers as visual objects. A relatively preserved ability to match lowercase to uppercase letters suggests partially spared access to abstract letter identities independently of their visual forms. The patient was also unable to match spoken letters and numbers to their visual form, indicating that she could not access the graphemic representations of letters from their phonological representations. This pattern of performance suggests that the link between graphemic and phonological representations is disrupted in this patient. We hypothesize that VA’ residual reading abilities are supported by the right hemisphere.
Multiple 24-h average outdoor, indoor and personal respirable particulate matter (RPM) measurements were made in different urban residential colonies to determine major routes of personal exposure. The study area was Bhilai-Durg, District Durg, Chhattisgarh, India. About 100 residentials from each of two selected colonies have been surveyed for consent to participate in the study and for preparation of time–activity diary. On the basis of their time–activity diary, residentials have been categorized into three types: type-A, purely residential; type-B, residents who go out, and type-C, residence who go into work, specially in industrial area. A total of 28 adult participants (14 males and 14 females; mean age 40±15, range 21–61 years) were selected and monitored longitudinally during the summer (15 March–15 June) of 2004. Participants’ residential indoor RPM level and also local ambient outdoor RPM levels were measured,and these are done simultaneous with personal monitoring. Residential indoor and ambient outdoors RPM monitoring sessions were throughout the year to obtain infiltration factor more precisely. To compare RPM levels with Indian National Ambient Air Quality Standards (NAAQS) of PM10, simultaneous measurements of PM10 were also done with the course of ambient outdoor RPM monitoring. RPM levels in indoors were higher compared to ambient outdoors. The annual average ratio RPM/PM10 was found to vary significantly among residential sites due to variation in surroundings. Source contribution estimates (SCE) of personal exposure to RPM in selected 12 residences (six from each colony) have been investigated using chemical mass balance model CMB8. Ambient outdoors, residential indoors, soils and road-traffic borne RPM were identified as main routes and principal sources of personal RPM. Results of model output have shown that residential indoors and soil-borne RPM are the major routes of personal exposure.
In this work, the electrochemical performance of LiNi1/3Co1/3Mn1/3O2 cathode is investigated under high voltage with fluoroethylene carbonate (FEC) as co-solvent for lithium ion battery. Charge/discharge tests show that the cycling and rate performances of LiNi1/3Co1/3Mn1/3O2 are dramatically improved at high voltage operation when ethylene carbonate (EC) is replaced by FEC in electrolyte solution. After 100 cycles between 3.0 and 4.6V (vs. Li/Li+) at 0.2C rate, the capacity retention of LiNi1/3Co1/3Mn1/3O2 with FEC/dimethyl carbonate (DMC) (1/4, vol.%) solution is 82.7%, while the EC-containing electrolyte is only 41.3%. The effects of FEC on the high-voltage performance and the surface properties of the LiNi1/3Co1/3Mn1/3O2 cathode are characterized by electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). It is found that FEC as co-solvent participates in the formation of protective surface films on the LiNi1/3Co1/3Mn1/3O2 cathode, which efficiently suppresses the decomposition of the electrolyte, prevents the severe structure destruction and improves the cycling stability and rate capability of LiNi1/3Co1/3Mn1/3O2 electrode under high voltage.
Poly(vinyl chloride)/poly(ethyl methacrylate)-based polymer blend electrolytes comprising propylene carbonate as a plasticizer and a lithium salt LiX (X=BF4 −, ClO4 −, CF3SO3 −) are prepared by a solvent casting technique. The electrolytes are subjected to characterization by ionic conductivity, X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetic/differential thermal analysis. The electrolytes that contain LiBF4 exhibit maximum conductivity and are thermally stable up to 254°C.
We report a supramolecular strategy to fabricate high-doping-leveled (10.5 at.%) porous nitrogen-doped reduced graphene oxide (P-NrGO) with outstanding electrochemical properties as electrode material for supercapacitors. The introduced supramolecular polymers melamine cyanurate (MC) acts a barrier to prevent the graphene sheets from restacking, and meanwhile functions as a soft template to create porous structure as well as nitrogen source for in-situ N-doping. The transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images show that the P-NrGO exhibits wrinkled and loose-packed thin layer structure with a large number of pores. X-ray photoelectron spectrometer (XPS) spectra demonstrate that pyridine and pyrrole-N was the main nitrogen bonding states, which were favorable for the improvements of supercapacitive performance. Attributed to the synergistic effects of the porous structure and the N-doping, the P-NrGO1 exhibits an increase of 56.5% in the specific capacitance (335 F g−1) when compared with the rGO (214 F g−1). In addition, the capacitance retention ratio reaches 94.3% after 10000 cycles, indicating the excellent electrochemical stability. The present work benefits the large-scale production of N-doped graphene oxide for high-performance supercapacitors.
Interpenetrating networks (IPNs) of titania, having high cycling stability and rate capability, and carbon, having high electrical conductivity and capacity, ultrafine fibers were fabricated by a co-electrospinning technique in opposite directions. The IPN structure promoted a contact between titania and carbon fibers, minimized strain during ion de-insertion, and prevented agglomeration that shortened the cycling stability. Images from scanning electron microscopy with backscattering electron detector and X-ray diffraction spectra confirm the existence of the IPN structure of both types of fibers. Thermogravimetric analysis and Raman spectroscopy of the composite fibers reveal their 37wt% of titania content and 1.2 ratio between disorder and graphitic carbon (ID/IG). A galvanostatic curve displays stable reversible capacities of 202 and 247mA h g−1 for charge and discharge after the fifth cycle at a current density of 25mAg−1. The material had a superior discharge capacity of 151 and 123mA h g−1 at 125 and 250mAg−1, respectively. Moreover, the discharge capacity could be maintained at 134mA h g−1 after 100 cycles at 125mAg−1 with a Coulombic efficiency of more than 98%, presenting a long life cycle of batteries. Therefore, the prepared IPN composite fibers can be an efficient anode for sodium-ion batteries.