batterydata/paper-abstracts huggingface dataset:
Diatomite, a natural clay mineral, is mainly composed of silica and contains a large number of fine microscopic pores. In the present work, a series of porous Si/C composites are successfully synthesized by employing diatomite as a raw material, followed by low temperature magnesiothermic reduction, impregnation and carbonization of phenolic resin. The obtained Si/C composites are consisted of porous Si coated with a 15 nm thick amorphous layer of carbon. Porous Si/C composites with different ratios of Si and C are investigated as anode materials for Li-ion batteries. The porous Si/C composite containing 33% carbon exhibits the highest reversible capacity of about 1628 mAh g−1 at the first cycle with excellent capacity retention in the following cycles. Moreover, the porous Si/C composites display the excellent rate performance at high current densities such as 1 and 2 A g−1. The optimum electrochemical performance could also be tuned by varying the proportions of porous Si and carbon precursors during the preparation process. The results indicate that the natural pore structures of Si and C are conducive to the electrochemical performance and clay mineral diatomite could be considered as a promising raw material for Si/C composites for lithium-ion batteries.
A low-cost electrochemical sensor for lead detection was designed and developed in the present study, using an organo-clay obtained by the intercalation of 1,10-phenanthroline (OP) within montmorillonite (MMT). Intercalates of 1,10-phenanthroline in montmorillonite were prepared from a 1/1 water–ethanol aqueous solutions at pHs 3, 5 and 8. Their structural characterisation was done by a variety of spectroscopic and analytical techniques: XRD, FTIR, 13C and 23Na NMR, ICP and thermal analysis. Under acidic conditions, OP was protonated and a cation exchange took place with the interlayer sodium ions, leading to a two-dimensional arrangement of protonated OP molecules laying parallel to the clay mineral interlayer surfaces. Under basic conditions, neutral OP was intercalated in the presence of hydrated Na+ ions forming two OP layers plausibly H-bonded to the water molecules coordinating the sodium ions. This latter OP-MMT intercalate was used as Pb(II) sensor via a carbon paste electrode (CPE) by adsorptive stripping voltammetry because it should lead to the exchange of hydrated sodium ions by Pb(II). The amount of accumulated Pb(II) increased with an increase of the accumulation time and remained constant after saturation. The optimal pH of the accumulation medium was 6 and the best electrolysis time and potential were 60s and −0.8V respectively. The results obtained in the case of Pb(II) led to a limit of detection in the sub-nanomolar range (4×10−10 M), two orders of magnitude lower than in the case of Cu(II) (4.0×10−8 M). There were no interferences with Cu(II) when it was at concentrations 0.1×[Pb(II)]. For equimolar concentrations, the Pb(II) signal was reduced by 50%. The interferences were minimal in the case of Ag(I). In contrast, the Pb(II) signal was reduced by 70% in the presence of Hg(II) at concentrations 0.1×[Pb(II)], showing a strong Hg(II) interference.
The interfacial resistance between the composite electrode and PEO-based solid polymer electrolyte was examined using two different symmetrical cells and AC impedance measurements in the temperature range of 30–60°C. Of the four major resistance components identified in our previous study, three components due to the resistances of the polymer electrolyte and the charge transfer resistance between LiFePO4-C and the electrolyte were assigned; however, one resistance component, in the medium frequency range has not yet been assigned. In this report, the medium frequency range resistance component was investigated using a symmetrical cell with composite electrodes composed of active and inactive materials (LiCoO2, LiMn2O4 and SiO2), solid polymer electrolyte, and carbon fiber as an electron conductor. The resistance was not affected by the carbon coating in LiFePO4-C and the conductive carbon additive (VGCF). An electron blocking cell was also prepared and the resistance was measured in the temperature range of 30–60°C to confirm the effect of the electrode thickness and the electrode composition. The resistance was not affected by the thickness, and decreased with decreasing PEO-LiTFSI electrolyte content in the composite electrode. However, no significant change in the activation energy was evident with the change in the electrode composition.
Here we report a Li-metal-free full battery, using interlayer-expanded V6O13 ultra-thin nanosheets and prelithiated graphite for cathodes and anodes, respectively. This full Li-ion battery exhibits a superior specific capacity of 233mAhg−1 at a current density of 100mAg−1 and 91% capacity retention after 500 cycles. Our first-principle calculations reveal that the interlayer-expansion is induced by the interaction between V6O13 and water which breaks interlayer V-O bonds and forms hydroxyls. The unique structure provides short lithium-ion diffusion path, excellent charge transport, abundant binding sites and volume flexibility for Li+ intercalation/deintercalation, thus leading to high capability (280mAhg−1) and cycling performance (capacity retain 96.1% at 2.4Ag−1 for 1000 cycles). Using novel prelithiation process, the Li-metal-free full cells with high controllability and performance is expected to contribute significantly to the development of safe, green, and powerful energy storage devices.
Though anodes with high Li gravimetric capacities, beyond commercial graphite, have been intensively studied, gravimetric capacity does not precisely reflect the performance of a packed cell. Li anodes with high mass loadings, which can achieve high areal capacities, are required for many commercial applications. Herein, anodes with high mass loadings were fabricated using two-dimensional transition metal carbides (MXenes). Powders of the latter were cold pressed, without binders, at a pressure of 1GPa, to create ∼300μm thick, free-standing discs. When Ti3C2 was used as the anode for lithium, the initial reversible areal capacity was ∼15mAh/cm2, which decreased to 5.9mAh/cm2 after 50 cycles, but the decrease after the first ∼20 cycles was very gradual. The latter is one of the highest values ever reported to date. When Nb2C was used as the anode instead, the initial reversible capacity was ∼16mAh/cm2; this value decreased to 6.7mAh/cm2 after 50 cycles, which is about a 14% increase compared to Ti3C2. As the research on MXenes for lithium ion batteries has just begun, there is certainly room for further improving their electrochemical performance.
Study objective The impact of the broad spectrum of SDB severity on cognition in childhood has not been well studied. This study investigated cognitive function in children with varying severities of SDB and control children with no history of SDB. Methods One hundred thirty-seven children (75M) aged 7–12 were studied. Overnight polysomnography (PSG) classified children into four groups: primary snoring (PS) (n =59), mild obstructive sleep apnea syndrome (OSAS) (n =24), moderate/severe OSAS (n =19), and controls (n =35). Cognition was measured with a short battery of psychological tests including the Wechsler Abbreviated Scale of Intelligence (WASI), the Wide Range Achievement Test-3rd Edition (WRAT-3), the Rey Complex Figure Test (RCFT) and the Controlled Oral Word Association Test (COWAT). Results There was lower general intellectual ability in all children with SDB regardless of severity. Higher rates of impairment were also noted on measures of executive and academic functioning in children with SDB. Conclusions Our findings suggest that neurocognitive deficits are common in children with SDB regardless of disease severity, highlighting that such difficulties may be present in children in the community who snore but are otherwise healthy; thus our results have important implications for the treatment of pediatric SDB.
The structural transformations of silicon nanowires when cycled against lithium were evaluated using electrochemical potential spectroscopy and galvanostatic cycling. During the charge, the nanowires alloy with lithium to form an amorphous Li x Si compound. At potentials <50mV, a structural transformation occurs. In studies on micron-sized particles previously reported in the literature, this transformation is a crystallization to a metastable Li15Si4 phase. X-ray diffraction measurements on the Si nanowires, however, show that they are amorphous, suggesting that a different amorphous phase (Li y Si) is formed. Lithium is removed from this phase in the discharge to form amorphous silicon. We have found that limiting the voltage in the charge to 70mV results in improved efficiency and cyclability compared to charging to 10mV. This improvement is due to the suppression of the transformation at low potentials, which alloys for reversible cycling of amorphous silicon nanowires.
Advanced charged membranes with highly symmetric spongy structures were specially designed for vanadium flow batteries (VFBs). These membranes are formed with a unique stack of closed cells consisting of positively charged ultrathin walls and combine excellent V ion rejection with high proton conductivity. They achieve impressive VFB performance in a wide operation current density range, further promoting the development of much needed energy storage.
Literature on categorization often invokes historical legacies to explain why states adhere to statistical categories that inadequately capture their population, and especially minority groups. The failure of the 2011 German census to produce reliable numbers on the country’s largest religious minority, Muslims, could be viewed as a case in point. However, this ignores the fact that in the late 1980s officials successfully counted Muslims. This article traces how officials changed their approach to Muslim enumeration over the course of designing the 2011 census. Drawing on internal ministerial documents and interviews, I show that the reversal of statistical visibility was the result of a recoupling process. Through this process, old state-religion laws that officials had previously ignored now became rigorously applied to the census. An extra-statistical debate on religious education triggered this recoupling by reviving narrow, legal categories of religion and alerting church representatives and legal experts to imprecise census terms. Using the German case and other empirical examples, I describe a more uneven influence of historical legacies than commonly suggested by research on categorization. Rather than viewing legacies as having a stable, or even growing, influence on categorization, I argue that they only take effect when they become politicized and enforced by powerful actors. I call for a more nuanced analysis of the role historical factors play in determining trajectories of census categorization, especially those that are invoked to explain the reluctance of European states to collect ethno-cultural data.
Islands are highly diverse in their climatic, physical, social, and economic characteristics. Thus, each island’s energy system needs to be designed according to its specific features. However, similarities among islands exist which can enable the fast transfer of concepts and experiences with energy systems. In the Philippines, only few off-grid islands are incorporating smart energy systems through hybrid electricity systems. While most off-grid islands still do not have access to electricity, the majority of off-grid Philippine islands having access to electricity are powered primarily by diesel-fired generators. In this work, a cluster analysis is performed for 502 off-grid islands in the Philippine archipelago, classifying the islands according to their similarities in socio-economic and physical characteristics, and indigenous energy resource potential. The results show that most of the islands belong to five clusters of very small and small islands for which photovoltaic-battery systems would be the favourable backbone of a future energy system based on renewable energies. These islands show a varying level of feasibility for harnessing wind energy. In medium and big islands, opportunities of linking electricity systems to water supply and thermal energy loads as well as to the transport sector, are identified and their relevance in the clusters is discussed. The results are consistent with the validation of the individual characteristics of chosen off-grid islands. The cluster analysis results support policy makers and private investors in deciding which smart energy system projects are suitable for which particular islands.
The LiFePO4/C composite with 3D-grape-bunch structure is successfully synthesized through a novel hydrothermal method. Sucrose is used as in-situ coating carbon source, and the hydroxylated MWCNTs are used as connecting carbon wires which can be embedded into the carbon coating via self-assembling of the hydrophilic groups to form 3D-grape-bunch structure. The influences of the 3D-grape-bunch structure on the morphology, structure and electrochemical performance of the LiFePO4/C composites are investigated by XRD, SEM, TEM, BET, galvanostatic charge/discharge tests, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) tests. Especially, four kinds of the equivalent circuit models usually employed to analysis the EISs of LiFePO4 as cathode material for Li-ion battery are discussed, and the suitable equivalent circuit for fitting EIS of LiFePO4/C composite with 3D-grape-bunch structure is selected. The optimal LiFePO4/C composite with 3D-grape-bunch structure owing to its good conductive network and high graphitic degree (low I D /I G value) of residual carbon exhibits a stable and high reversible capacity of 160.5 mAh g−1 at 0.1C and 108.4 mAh g−1 even at 10.0C, and the cycling capacity retention rate reaches 99.9% over 60 cycles. Moreover, it also exhibits high conductivity, good reversibility and excellent stability in EIS and CV tests.
The Sodium-ion-battery, using the layered oxide material as cathodes coupled with carbon anodes, has been proposed for utilization in practice long time ago. However, the prevailing layered oxides is still hindered by serious phase transition and volume strain upon sodium release. Herein, we show a novel copper doped layered P_1 manganese-based oxide material (NCM) with unique bulk and nanoscale Na-free surface structures as a sodium host to overcome the above limitation. Our research disclosed this P_1 NCM material has a wide phase-transition-free zone between 2 V and 4.5 V with a tiny lattice volume change upon cycling. Besides, it delivers an excellent chemical stability during humid air exposure. In contrast to most environmentally sensitive layered materials, after aging for 60 days in humid air, P_1 NCM still exhibits the superior cycling performance (95.8% capacity retention after 1000 cycles) and excellent rate capability as well as an outstanding sodium storage performance in full cells.
Li4Ti5O12 particles are synthesized coated with very thin graphene-like sheets in situ using liquid-polyacrylonitrile (LPAN) as the carbon source and added utilized conductivity additives to improve the conductivity of the electrode materials. The crystalline structures of Li4Ti5O12 with 20% LPAN and different conductivity additives composites were examined by XRD. The structure and electrochemical performance of the graphene-like sheets coated Li4Ti5O12, with conductivity additives added, was systematically investigated. The electrochemical performance also revealed that the graphene-like sheets significantly improved the discharge capacity and cycling stability of Li4Ti5O12. In particular, the coated Li4Ti5O12 with 20wt% LPAN and 1% acetylene black (CB) reached 166.2mAhg−1 at 10C. The performance improvement is a result of the graphene-like nanosheet conformal coating, which creates an electrically conductive network for the electrode.
In an effort to reduce the cost of manufacturing lithium ion batteries, a novel approach is being developed to build a one piece integrated cell via layer by layer coating deposition rather than manufacturing separate pieces followed by electrode stacking and assembly. This new process would hold several advantages by providing excellent contact and thinner deposits, which will conserve space for energy storing materials while reducing production costs. Anode and cathode half stacks are made using a new process and the electrodes have been investigated in coin cells. Each half stack consists of a current collector, electrode, and separator combined into a single component. The stack cells successfully cycle as graphite stack/lithium and LiNi1/3Mn1/3Co1/3O2/lithium cells and together in graphite stack/LiNi1/3Mn1/3Co1/3O2 stack cell arrangements. Cross sectional SEM images show very little change in the anode and cathode materials indicating that the material is stable under typical cycling conditions and at moderately elevated temperature (55 °C). While the electrode stacks investigated are not optimized, the results support good cycling performance for a stacked cell design.
Modern economic growth started in the West in the early nineteenth century. This survey discusses the precise connection between the Industrial Revolution and the beginnings of growth, and connects it to the intellectual and economic factors underlying the growth of useful knowledge. The connections between science, technology and human capital are re-examined, and the role of the eighteenth century Enlightenment in bringing about modern growth is highlighted. Specifically, the paper argues that the Enlightenment changed the agenda of scientific research and deepened the connections between theory and practice.
The effects of gel polymer with chelating groups on polymer matrix were been characterized by differential scanning calorimeter (DSC) and Fourier transform infrared spectroscopy (FT-IR). The mechanical properties were elucidated using an Instron instrument. The gel polymer, poly(AN-co-GMA-IDA), was made by the copolymerizing acrylonitrile (AN) and (2-methylacrylic acid 3-(bis-carboxymethylamino-2-hydroxy-propyl ester) (GMA-IDA), mixing the product with a plasticizer—propylene carbonate (PC). In a study on gel-type polymer electrolytes, lithium perchloride was doped into the gel polymer. FT-IR and 7Li solid-state NMR spectra elucidate the interactions between lithium ions and the unpaired electrons on the groups based on the gel polymer. Additionally, the 7Li solid-state NMR reveals that lithium ions are preferentially coordinated with the GMA-IDA segments. The glassy transition temperature (T g) of the gel-type polymer electrolyte increases with the doping of LiClO4, indicating interactions among lithium ions, the plasticizer (PC) and the copolymer. The Arrhenius-like behavior of the conductivity reveals that the charge carries move in a liquid-like environment. The maximum conductivity in this investigation is 2.17×10−3 Scm−1. The GMA-IDA unit in the gel-type polymer electrolytes improves the dissociation of the lithium salt and the mechanical strength and conductivity of the electrolytes.
Two types of polymer electrolyte membranes were prepared using poly(ethylene oxide) (PEO) and poly(vinylidene difluoride-co-hexafluoropropylene) (PVdF-HFP), with different amounts of the ionic liquid N-methyl-N-propylpiperidinium bis(trifluoromethane-sulfonyl)imide ([PP13][TFSI]) added. The results from differential scanning calorimetry and conductivity measurements show that in the case of PVdF-HFP membranes the glass transition temperature Tg decreases and the room temperature ionic conductivity increases with increasing content of the ionic liquid (up to 60 wt.%). However, in the case of PEO based membranes Tg is less significantly affected and the room temperature ionic conductivity increases only up to 30 wt.% of ionic liquid, beyond which a steady value of about 5⋅10−5 S/cm is reached. The results from Raman spectroscopy show that the characteristic vibrational mode of the TFSI anion at ∼742 cm−1 is weakly affected in the membranes prepared from PVdF-HFP, whereas for those based on PEO it has a clearer composition dependence. These results suggest ion-ion and ion-polymer interactions of different nature, which together with the different nanomorphologies adopted by PEO and PVdF-HFP, as revealed by X-ray scattering, give rise to different composition dependences of the macroscopically measured ionic conductivity.
In China, a significant amount of activity is focused on electric vehicles (EV) in recent years. Propelled by the national government, electric buses powered by installed lithium-ion batteries are operating on some metropolitan streets of China. With the drawbacks of short range and long recharge time, the technical features and operating characteristics of battery electric buses and conventional diesel vehicles are different. These differences lead to great changes of the vehicle scheduling method. It is necessary to learn more about the specific scheduling method of electric buses to update traditional bus operation, management rules and scheduling methods. This paper proposes a study to establish a single depot vehicle scheduling model (SDVS) with specific constraints concerning the operation features of electric buses to solve the electric vehicle scheduling problem. Two independent objective functions of minimizing the capital investment for the electric fleet and the total charging demand in stations are involved in the model. To solve the problem, a modified multi-objective optimization method adopting the basic idea of Non-dominated Sorting Genetic Algorithm (NSGA- II) is established. This analysis is performed by solving the scheduling problem for the electric bus demonstration project to be undertaken in Shanghai. Results are reported and verify the practicability of the method proposed in this paper. These findings were valuable to assist the electric bus operation and EV applications.
Nano-SnO2/carbon composite materials were synthesized in situ using the polyol method by oxidizing SnCl2·2H2O in the presence of a carbon matrix. All the as-synthesized composites consisted of SnO2 nanoparticles (5–10nm) uniformly embedded into the carbon matrix as evidenced by TEM. XRD confirmed the presence of nano-sized SnO2 particles that are crystallized in a rutile structure and XPS revealed a tin oxidation state of +4. Cyclic voltammetry of the composites showed an irreversible peak at 1.4V in the first cycle and a typical alloying/de-alloying process at 0.1–0.5V. The best composite (“composite I”, 15wt% SnO2) showed an improved lithium storage capacity of 370mAhg−1 at 200mAg−1 (∼C/2) which correspond to 32% improvement and lower capacity fade compared to commercial SnO2 (50nm). We have also investigated the effect of the heating method and we found that the use of a microwave was beneficial in not only shortening reaction time but also in producing smaller SnO2 particles that are also better dispersed within the carbon matrix which also resulted in higher lithium storage capacity.