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Transition metal oxides are considered promising high-capacity anode materials for lithium ion batteries (LIBs). However, their intrinsic low electric conductivity and large volumetric expansion/contraction during lithiation/delithiation can cause fast capacity degradation. Hence, modification of the electrode materials by appropriate structural design is important to their applications. Here, we present study on design, synthesis and Li-storage performance of a vapor grown carbon fiber (VGCF) enhanced VGCF@ZnMnO3 coaxial-cable nanocomposite anode material for LIBs. This material is synthesized via a novel two-step strategy involving a crucial hydrothermal reaction between ZnO and prefabricated VGCF@δ-MnO2 composite in pure water at 180°C for 12h. This composite material exhibits high specific capacity, good rate performance and excellent cycling performance. The exhibited high performance should be attributed to the improved electric conductance due to the incorporation of VGCFs and the particular architecture of one-dimensional nanocomposite. Additionally, the hydrothermal reaction mechanism is specially focused and preliminarily studied. A dissolution–recrystallization mechanism is proposed for the hydrothermal reaction.
Silicon, a potential anode material for all-solid-state batteries, has the highest theoretical capacity during electrochemical reactions, but is vulnerable to structural expansion and irreversible capacity. Amorphous Si/C composite thin films have received attention as promising materials to address these obstacles. The amorphous Si/C composite thin films were synthesized by radio frequency magnetron co-sputtering, which easily fabricated uniformly dispersed nanocomposites, prevented the agglomeration of silicon particles, and more effectively resisted volume expansion than traditional techniques. Electrochemical evaluation of the Si37C63 specimen showed that it had a high 1st cycle capacity (∼6180 mAh cm−3) and a capacity retention of ∼96% from 100th to 200th cycle. These studies show that the stresses induced by volume expansion during long term cycling tests were reduced by the buffering effects of the carbon content. The homogeneously dispersed amorphous Si/C composite thin films were found to be promising anode materials for all-solid-state batteries.
Solar photovoltaic (PV) rooftops have significant potentials for reducing reliance on conventional energy source and enhancing energy security in response to emergency situations or in remote areas. Widespread adaptation of solar PV rooftops can also help address climate change issue via lower overall emission of Greenhouse Gases. This paper reviewed the latest situation of solar PV rooftop implementation, expansion and execution strategies in Thailand. The review examined factors impacting adoption rate of solar PV rooftops. Supporting factors include optimum solar radiation intensity, active renewable energy development policy and Feed-In Tariff (FIT). Increasing urbanization rate also resulted in an increase in potential space suitable for solar panel installation. Barriers of solar PV rooftop implementation in Thailand were carefully analyzed. Limitation in domestic technology and technical experiences in manufacturing sector is one of the major barriers inhibiting progress in solar rooftop adoption. In addition, government subsidy and support are still needed for solar PV rooftops to be competitive with other forms of energy generation. Increasing public awareness and reforming of energy and related regulations are necessary to promote meaningful implementation of solar energy in Thailand. To enhance rate of solar PV rooftop installation in Thailand, a short-term strategy could be in a form of providing financial supports such as low interest rate loans, tax credits and development of renewable portfolio standards together with the current FIT scheme. In the longer-term, to achieve grid parity, the government and private sectors need to rely less on financial subsidies and focus on establishing R&D centers to develop and strengthen domestic solar energy industry and introduce cost-effective solar PV solutions. With effective policies and credible solutions with a viable market, public demand in solar rooftop implementation in urban areas will naturally increase and create sustainable progress in solar rooftop industry in Thailand.
This paper presents PM10 fugitive dust emission factors for a range of vehicles types and examines the influence of vehicle and wake characteristics on the strength of emissions from an unpaved road. Vertical profile measurements of mass concentration of the passing plumes were carried out using a series of 3 instrumented towers. PM10 emission fluxes at each tower were calculated from knowledge of the vertical mass concentration profile, the ambient wind speed and direction, and the time the plume took to pass the towers. The emission factors showed a strong linear dependence on speed and vehicle weight. Emission factors (EF=grams of PM10 emitted per vehicle kilometer traveled) ranged from approximately EF=0.8×(kmh−1) for a light (∼1200kg) passenger car to EF=48×(kmh−1) for large military vehicles (∼18000kg). In comparison to emission estimates derived using US EPA AP-42 methods the measured emission factors indicate larger than estimated contributions for speeds generally>10–20kmh−1 and for vehicle weights>3000kg. The size of a wake created by a vehicle was observed to be dependent on the size of the vehicle, increasing roughly linearly with vehicle height. Injection height of the dust plume is least important to long-range transport of PM10 under unstable conditions and most important under stable atmospheric conditions.
In this work we investigate Li4Ti5O12 (LTO) anode material synthesized by conventional solid state reaction method calcined at 850 °C for 16 h. Thermal analysis reveals the temperature dependence of the material properties. The phase composition, micro-morphology and elemental analysis of the compound are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectra (EDS) respectively. The results of XRD pattern possessed cubic spinel structure with space group Fd-3m. The morphological features of the powder sample are in the range of 1.1 μm. The EDS spectra confirm the constituent elemental composition of the sample. Electrical conductivity measurement at different frequencies and temperatures had been carried out; and at room temperature it is found to be 5.96 × 10−7 S/cm. Besides, for the different frequencies applied, the activation energies were calculated and obtained to be in the range of 0.2–0.4 eV.
The hexagon single-crystal Co(OH)2 nanoplates, which obtained by hydrothermal synthesis method, can be transformed to the porous single-crystal Co3O4 nanoplates after the heat treatment above 300 °C in air. Electrochemical tests show that the lithium storage performances of porous Co3O4 nanoplates are influenced more closely to its structural aspects than its morphology and size factors, which can be controlled by changing the heat treatment temperature. When the heat treatment temperature is increased to 500 °C, the robust single-crystal Co3O4 nanoplates with relatively large mesoporous size and low specific surface area can be obtained via the long-range atom diffusion at high temperature, which exhibit low initial irreversible capacity, superior cycling performance and excellent rate capability.
Tin-based intermetallic compounds of different compositions and with micro and nano-sized particles are studied as electrodes for lithium ion batteries. Crystalline microsized particles of CoSn x are obtained at high temperatures, while crystalline nano-sized particles are obtained at low-temperature following a one-pot method which is based on TEG solvent and reduction with NaBH4. The observed capacities of CoSn x compounds in lithium test cells depend on the tin content, electrochemical cycling conditions and crystallite size. The change of the 119Sn Mössbauer isomer shift upon the electrochemical reaction with lithium is more limited for the intermetallic compounds CoSn x than for pure Sn. Nano-sized CoSn x materials show superior specific capacity than microsized CoSn x powders. The maximum observed reversible capacity of nano-Co3Sn2 is equal to 544mAhg−1 in the first cycle, while 413mAhg−1 were observed for nano-CoSn.
Introduction Obstructive sleep apnea patients may develop deficits in the cognitive domains of attention, concentration, executive function, verbal and visuospatial memory, constructional abilities, and psychomotor functioning. As cognitive performance will improve with the treatment, early screening for cognitive dysfunction should be done to prevent further deterioration. Objective We aim to evaluate the cognitive function of obstructive sleep apnea patients by using the ‘Mini Mental State Examination’. Methodology This was a cross sectional study to evaluate the cognitive function of moderate and severe obstructive sleep apnea patients with age ranged from 18 to 60 old who attended our sleep clinic. These patients were confirmed to have moderate and severe obstructive sleep apnea by Type 1 polysomnography (attended full overnight study). The age, gender and ethnicity were noted and other relevant data such as weight, height, body mass index and apnea and hypopnoea index were recorded accordingly. The cognitive function was evaluated using validated Malay version of Mini Mental State Examination which measured 5 areas of cognitive functions comprising orientation, registration, attention and calculation, word recall and language abilities, and visuospatial. Results A total of 38 patients participated in this study. All 19 patients of moderate group and 14 patients of severe group had normal cognitive function while only 5 patients in severe group had mild cognitive function impairment. There was a statistically significant difference between the moderate group and severe group on cognitive performance (p value = 0.042). Conclusions Severe obstructive sleep apnea patients may have impaired cognitive function. Mini Mental State Examination is useful in the screening of cognitive function of obstructive sleep apnea patients but in normal score, more sophisticated test batteries are required as it is unable to identify in ‘very minimal’ or ‘extremely severe’ cognitive dysfunction.
Average discharge voltage of the P-type-layered oxides cathode materials is one of the key factors that determine the sodium-ion batteries (SIBs) performance, especially for the high energy density performance. Inspired by the strategy of lithium and magnesium doping in the transition metal layer to promote the anionic oxygen redox and the synergistic effect of composite materials for SIBs, we develop a layered P2/P3-Na0.75Li0.2Mg0.05Al0.05Mn0.7O2 composite cathode material enabled by the anionic oxygen redox. The synthesized composite delivers a reversible capacity of 180 mAh g−1 between 2.0 and 4.5 V at 0.2 C and keep ≈ 3.1 V stable average voltage above 2.5 V the discharge cutoff voltage. With a combination of the electrochemical performance, hard and soft X-ray absorption spectroscopy, we demonstrate that the irreversible anionic oxygen activity in the high-voltage region results in the capacity fading and the irreversible cationic manganese activity in the low-voltage region is responsible for the voltage decay. These findings provide a simple and effective method for designing low-voltage decay and high-energy density Na-deficient layered oxide composite.
The composition of the plate in lead acid battery plays a vital role on battery performance. Therefore, controlling and monitoring of plate composition is utmost important in order to attain required battery performance. While monitoring negative plate, it has to be ensured that they are not exposed to air, which would otherwise result in Pb oxidation; thereby affecting the accuracy of the test data. Nevertheless, published information is scarce on the “pretreatment and preservation of the negative plates”. The objective of this study is to develop a suitable procedure to “preserve and pretreat the negative plate” prior to chemical composition analysis. A host of experimental parameters like immersion time in water, effect of drying reagent and air drying time were studied. Two drying solvents; namely, methanol and acetone were studied to evaluate their suitability.
A high molecular weight poly(2,2′-dithiodianiline) (PDTDA) was chemically synthesized by simple solution polymerization method. The weight average molecular weight ( M ̄ w ) was observed to be 420,000 by GPC analysis. The chemical structures of the undoped and the doped PDTDA were characterized by UV-Vis spectroscopy. It was confirmed that the SS bonds within repeating units could be conserved well after polymerization and doping process by FTIR spectroscopic analysis. The PDTDA powders were found to have granular structure and the average particle size was 1μm. The charge–discharge behavior of the Li/liquid electrolyte (1M LiPF6 in EC–PC)/PDTDA cell was also investigated with cycles.
In this paper a new electrocatalytic hydrogenation process is reported based on the use of LaNi5 electrodes. The charge/discharge of hydrogen within the intermetallic compound through cyclic voltammetry experiments was observed using a powder microelectrode in classical aqueous KOH medium, as well as in other buffered aqueous or hydro-organic media. Most voltammograms are modified in the presence of unsaturated compounds, which indicates that a hydrogenation reaction occurs. Electrocatalytic hydrogenation on a preparative scale was carried out with three unsaturated compounds taken as models (methyl vinyl ketone, 1-decene, 5-hexen-2-one) and it was found that only the CC bond is hydrogenated with Faradaic efficiencies up to 100%.
A sophisticated BMS often requires an accurate yet simple battery model. Simplified models such as the single particle model (SPM), however, provide limited insight because lithium concentration variations over the cell thickness dimension are often neglected. In this study, we propose a simplified electrochemical model that, by reviving the lithium concentration variation across the cell thickness, provides significantly improved prediction power over the SPM. The lithium concentration profiles are first derived according to the electrochemistry-based pseudo-two dimensions (P2D) model under the steady-state assumption, they are then relaxed into a dynamic model. By employing steady-state concentration profiles coupled with averaged dynamics, the proposed model predicts electrolyte and solid surface concentrations (c e and c ss , respectively) and potential variations across the cell during both transients and stead-state conditions. The proposed model is validated by comparing the cell voltage, c e , and c ss concentration RMS errors with respect to the P2D model under pulse and constant current inputs. The simulation shows that the proposed model achieves at least 74%, 77%, and 65% RMS error reductions for cell voltage, c ss and c e , respectively, when compared to SPM in constant current simulation. Finally, the presented model is used to predict and detect local lithium plating, which the SPM is not capable of doing; our method yields predictions similar to those of the original P2D model at computational loads comparable to SPM.
The high growth (HG) mouse mutation is a 460 Kb deletion of chromosome 10 which causes a 30–50% increase in growth in the homozygous animal. We have shotgun sequenced six bacterial artificial chromosomes which span the length of the deletion to an average depth of 13.2× to generate a 649,868 bp sequence. Sequence analysis revealed the presence of three genes, suppressor of cytokine signaling-2 (Socs-2), caspase and RIP adaptor with death domain (Raidd/Cradd), and viral encoded semaphorin receptor (Plexin C1, viral encoded semaphorin receptor). The two deletion breakpoints lie in within the second introns of both Socs-2 and Plexin C1, resulting in the formation of a novel expressed fusion transcript between Socs-2 and Plexin C1 in HG mice. Expression of the fusion transcript, the presence of four splice variants of Raidd/Cradd and the exon structure of Socs-2 were illustrated using polymerase chain reaction. Genomic comparisons of the mouse and human sequence were used to verify the sequence assembly.
A methyl-substituted p-phenylenediamine (PD), N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD), is examined as a positive redox couple with high energy density for non-aqueous Li-flow batteries. Methyl substitution affects the solubility of the redox couple, as the solubility is increased by a factor of ten, to a maximum solubility of 5.0 M in 1.0 M lithium tetrafluoroborate-propylene carbonate supporting electrolyte due to elimination of the hydrogen bonding between the solute molecules. The methyl substitution also enhances the chemical stability of the cation radical and di-cation being generated from PD, as the redox center is shielded by the methyl groups. Furthermore, this organic redox couple demonstrate two-electron redox reactions at 3.2 and 3.8 V (vs. Li/Li+); therefore, the volumetric capacity is twice higher compared to conventional one-electron involved redox couples. In a non-flowing Li/TMPD coin-cell, this organic redox couple demonstrates very stable cycleability as a positive redox couple for non-aqueous flow batteries.
The ambient energy as an available and harvestable energy source which has a high potential to generate electricity for powering electronics devices. Piezoelectric materials, as one of the well-known energy harvesting mechanisms, play a significant role in converting ambient energy into electrical energy, particularly in small electronic devices such as measuring devices in remote or hostile environments where batteries are not an acceptable option. For this reason, piezoelectric energy harvester (PEH) can help to optimize the weight of structures. In addition, PEH can produce an output voltage in response to the inputs such as thermal, electrical, mechanical and electromagnetic energies. This paper provides a holistic review of the energy harvesting techniques from fluid flow using piezoelectric materials. To this end, the recently conducted research studies in the context of energy harvesting based on the fluid flow motion have been reviewed, considering various modeling and methods for improving the PEH efficiency. Various types of energy harvesting mechanisms, based on vibration by using piezoelectric, have been investigated to identify their opportunities and challenges.
The structural changes of pristine and ZrO2-coated LiMn0.5Ni0.5O2 cathode materials were investigated by using in situ X-ray diffraction (XRD) during charging process. An obviously solid solution phase transition from a hexagonal structure (H1) to another hexagonal structure (H2) was observed during the charging process at a constant current of 0.3mA in the potential range of 2.5–5.7V. The second hexagonal structure has a shorter a-axis and a longer c-axis before the crystal collapse. Before the structure collapses the c-axis length increases to maximum and then significantly decreases to 14.1Å. The c-axis length of the pristine and ZrO2-coated LiMn0.5Ni0.5O2 increases to the maximum at the charge capacity of 119.2 and 180.9mAhg−1, respectively. It can be concluded that the ZrO2 coating can strongly stabilize the crystal structure of the LiMn0.5Ni0.5O2 compound from the comparison of the lattice parameter variations between the pristine and the ZrO2-coated LiMn0.5Ni0.5O2 compounds upon charge. The potential fluctuation resulting from the decomposition of electrolytes starts at the charge capacity of around 200 and 260mAhg−1 for the pristine and ZrO2-coated LiMn0.5Ni0.5O2, respectively. It suggests that the ZrO2 coating layer can impede the reaction between the cathode material and electrolyte.
It is highly desirable to develop high-performance and cost-effective cathode materials for lithium-ion batteries (LIBs). In this work, functionalized graphene nanosheets (FGNS) were facilely synthesized utilizing ethylene glycol as both reducing agent and solvent. When employed as cathode materials for LIBs, FGNS were demonstrated to exhibit superior electrochemical performance when compared with traditional metal oxide-based cathodes. For instance, FGNS deliver outstanding cycle stability and high specific discharge capacity of 280mAhg−1 at 0.05Ag−1 without obvious capacity fading after 300 cycles. Furthermore, FGNS reveal high rate capacity of 152mAhg−1 at a high current density of 0.4Ag−1. The excellent electrochemical performance is attributed to the oxygen-containing functional groups and specific poriferous structure of FGNS. The proposed FGNS are expected to be a simple, low-cost, efficient, and large-scale production of cathode materials for LIBs.
The sine wave that we dissected in the previous chapter is an example of a periodic function, or a function that repeats. When current alternates periodically between positive and negative values it is known as alternating current, or AC. AC electricity has some very unique properties that we will soon learn about.
All-solid state supercapacitors (SCs) using Ionic Liquid based Polymer Electrolyte (IL-b-PE) and activated carbon were assembled and characterized electrochemically. IL-b-PE consisted of a binary blend of a polymeric ionic liquid (PIL), poly(diallyldimethylammonium) bis(trifluoromethanesulfonyl)imide (pDADMATFSI), and their corresponding ionic liquid (IL), N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR14TFSI) in a ratio of 40:60,w/w respectively. Assembling of supercapacitors simply consists of facing two impregnated electrodes without the need of additional separator. Several all-solid state SCs with impregnation ratios (IL-b-PE mass/active material mass) ranging from 5 to 18 were characterized. An all-solid state SC with impregnation ratio of 7 showed the best performance with specific capacitance (Cam) and real energy (Ereal) of 100 F g−1 and 32 Wh kg−1, respectively. After increasing temperatures to 60 °C, the performance of SCs further improved exhibiting Ereal values of 42 Wh kg−1 at 1 mA cm−2. These figures of merit are only slightly lower than those obtained for convectional SCs using pure PYR14TFS and much higher as compared with other solid SCs based on conventional polymer electrolytes. This is mainly due to the high electrochemical stability of this IL-b-PE that allows these solid SCs to operate at maximum voltages as high as 3.5 V for the first time.
This paper discusses the interrelated phenomena of solid electrolyte interphase (SEI) formation and the irreversible charge consumption which occurs during the first cycle of a graphite electrode, as well as their relevance to the cycling stability of lithium-ion batteries. Thus, results from relevant characterization methods, namely, in situ mass spectrometry, in situ infrared spectroscopy, in situ Raman and video microscopy, in situ scanning probe microscopy, in situ quartz crystal microbalance, and differential scanning calorimetry were combined for a more thorough understanding of observations made in cycling experiments. From electrochemical cycling tests, we have learned that a high specific charge (∼360Ah/kg of carbon), satisfactory cycle life of the graphite electrodes (1000 deep cycles), and an irreversible charge of <7% during SEI formation can only be obtained when water contamination of the cell is avoided. Under such conditions, a good-quality SEI film is formed on the carbon surface. We conclude that during SEI film formation, at first the carbonate solvent(s) are reduced, forming ethylene gas, organic radicals, oligomers, and polymers. Then a SEI film is precipitated on the surface via a nucleation and growth mechanism. The irreversible charge consumption due to SEI formation is proportional to the BET specific surface area of the graphite and rapidly increases with increasing water content in the cell.