batterydata/paper-abstracts huggingface dataset:
To evaluate the potential of Na-ion batteries, we contrast in this work the difference between Na-ion and Li-ion based intercalation chemistries in terms of three key battery properties—voltage, phase stability and diffusion barriers. The compounds investigated comprise the layered AMO2 and AMS2 structures, the olivine and maricite AMPO4 structures, and the NASICON A3V2(PO4)3 structures. The calculated Na voltages for the compounds investigated are 0.18–0.57 V lower than that of the corresponding Li voltages, in agreement with previous experimental data. We believe the observed lower voltages for Na compounds are predominantly a cathodic effect related to the much smaller energy gain from inserting Na into the host structure compared to inserting Li. We also found a relatively strong dependence of battery properties on structural features. In general, the difference between the Na and Li voltage of the same structure, ΔVNa–Li, is less negative for the maricite structures preferred by Na, and more negative for the olivine structures preferred by Li. The layered compounds have the most negative ΔVNa–Li. In terms of phase stability, we found that open structures, such as the layered and NASICON structures, that are better able to accommodate the larger Na+ ion generally have both Na and Li versions of the same compound. For the close-packed AMPO4 structures, our results show that Na generally prefers the maricite structure, while Li prefers the olivine structure, in agreement with previous experimental work. We also found surprising evidence that the barriers for Na+ migration can potentially be lower than that for Li+ migration in the layered structures. Overall, our findings indicate that Na-ion systems can be competitive with Li-ion systems.
Access to electric power supply has always had a significant role in promoting improvements in all the society sectors, nevertheless nowadays 1.3 billion of people still do not have electricity access. Moreover, most of them live in rural areas of developing countries which are often isolated, scattered populated and characterized by poor infrastructure and services. In this situation, the growing consideration towards the target of universal access to energy has emphasized the role of rural electrification, and off-grid small-scale generation represents one of the most appropriate options. As a consequence, the scientific literature has devoted attention to this topic with a large number of papers. In this frame, the present analysis focuses on off-grid systems for rural electrification and provides a general framework to this topic and an analytical review of the literature. The work is based on the review of more than 350 papers mainly published from 2000 to 2014 within selected journals, and it is organized in two sections. In the first one we describe the role of small-scale generation systems throughout the process of electrification, the main features of rural areas and their typical energy uses, and we propose a new comprehensive taxonomy for off-grid systems for rural electrification. In the second one we develop an extensive review of the selected literature according to the proposed classification and to five main research areas: Technology: layout and components; Models and methods for simulation and sizing; Techno-economic feasibility analyses and sustainability analyses; Case studies analyses; Policy analyses. The work results in a comprehensive review which organizes and capitalizes the main fundamentals of the addressed topic and provides elements to get acquainted with the literature.
Co3O4 has shown acceptable electrochemical properties as the anode material of Li secondary batteries. In detail, its capacity reached about 700mAh/g, twice as high as graphite, and 93.4% of initial capacity was retained after 100 cycles. EIS (electrochemical impedance spectroscopy) analyses revealed that after the 1st cycle, the insertion or extraction of Li ions in Co3O4 can occur homogeneously and reversibly (randless-like behavior, homogeneous mixture: Co+Li2O (in the state of Li insertion), Co3O4 (in the state of Li extraction)). In fact, the coulombic efficiency of Co3O4 was almost 100% except for the 1st cycle. According to P. Poizot's research on several kinds of transition metal oxides, such as Co3O4, CoO, NiO, etc., a small Li2O particle size and catalytic activity of the transition metal are expected to decrease the binding energy of Li2O tremendously. As a result, Li2O should be easy to decompose, and transition metal oxides should be able to charge or discharge reversibly by formation or decomposition of Li2O. However, this assumption has never been confirmed by experimental results. In our results, the CV (cyclic voltammogram) of a Li2O–Co mixture shows much larger oxidation and reduction peaks than that of Li2O. Based on XRD analyses, oxidation and reduction in the CV of Li2O correspond, respectively, to the decomposition and formation of Li2O. So, it can be asserted that Co addition to Li2O facilitates decomposition and formation processes in Li2O and that the catalytic effect of the transition metal must be one of the main causes that make Li2O form or decompose repeatedly.
A methodology for designing semi-physical fuzzy models is proposed. Prior physical knowledge about the dynamics of the system is modeled with continuous time differential equations. Fuzzy knowledge bases are embedded in these equations as nonlinear constructive blocks. Rules comprising the knowledge bases are fitted to interval-valued data with metaheuristics. A possibilistic filter is proposed that is able to gradually evolve an initial estimation of the latent variables of the model on the basis of successive prediction errors. This methodology has been applied to the prediction of voltage and state of charge of LiFePO4 batteries. An empirical study has been carried over data gathered in experiments at the Battery Laboratory at Oviedo University. Fitting between the proposed model and actual measurements is studied for four different manufacturers and different charge–discharge patterns. Predictions of the evolution of the voltage during charge, discharge and inactivity compare favorably to different models in the literature. The possibilistic filter allows to estimate the state of charge of batteries after an arbitrary path that may include partial charges and discharges. It is shown that the accuracy of the open loop model improves that of other approaches in the literature, and at the same time the observer-based online model is able to approximate the effective remnant charge of the battery after a reasonably short time.
The reduction of oxygen on boron-doped diamond (BDD) and glassy carbon (GC) electrodes was studied in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C2mim][NTf2]. O2 reduction at both electrodes was found to involve the 1e− reduction of oxygen to superoxide. The formation of superoxide was verified by repeating the oxygen reduction on BDD in the presence of benzoic acid, resulting in a shift from the 1e− reduction observed in the absence of benzoic acid to a 2e− reduction yielding the hydroperoxyl anion. The reduction of O2 was found to be quasi-reversible on GC and irreversible on BDD. The significantly slower kinetics observed on the BDD electrode are likely due to the lower electronic density of states in BDD.
We have developed a new binder-free hybrid anode material for lithium-ion batteries, by directly coating spinel Li4Ti5O12 particles using in-situ polymerization of styrenesulfonate (SS) to form a core-shell structure. The resulting hybrid anode has significantly improved electrochemical performance, with higher reversible capacity, rate-capability, and capacity value compared with pure Li4Ti5O12. Of the initial discharge capacity of 239.2 mAh g−1, 95.6% was retained after 100 cycles at 0.1 C-rate. The high cycle performance with increased discharge capacity is attributed to the coated poly (styrenesulfonate) (PSS) shell, which takes part in lithium ion storage and prevents the growth of a solid electrolyte interface (SEI) layer. The fast electron transfer in PSS also allows high rate-capability. Moreover, we clarify the contribution of carbon conductor in the range of 0.01 V–1.0 V.
Many people with schizophrenia (50–80 %) demonstrate impaired insight, something which has been associated with a poorer outcome. Two types of empathy can be distinguished: affective empathy via shared emotions and cognitive empathy, also referred to as Theory of Mind (ToM). ToM can be subdivided into cognitive ToM (knowledge about beliefs of other people via perspective taking) and affective ToM (knowledge about other people’s emotions via perspective taking). Recent studies show a relationship between Theory of Mind (ToM) and insight. However, the relationship between affective empathy and insight in schizophrenia was not examined previously. This was the aim of the present study. We expected that affective empathy would show a stronger relationship with insight than both cognitive and affective ToM. We assessed forty-six patients with a diagnosis of schizophrenia, and fifty-three healthy controls were assessed with a test battery consisting of tests of social cognition (a self-rating scale for affective empathy, a ToM task assessing both cognitive and affective ToM, and two tests of emotion perception), verbal memory, executive functioning, psychomotor speed, and intelligence. Insight was assessed with item G12 of the PANSS-interview. A regression equation showed that affective empathy made the strongest unique contribution to insight, followed closely by affective ToM. Together, they explained 45 % of the variance in insight. None of the other independent variables made a unique contribution to the prediction of insight. Both affective ToM and affective empathy are associated with insight in schizophrenia. Being able to take empathize with other peoples feeling at both the affective and cognitive level may enhance insight in schizophrenia.
Nanocomposites comprising silicon (Si), graphite (C) and single-walled carbon nanotubes (SWNTs), denoted as Si/C/SWNTs, have been synthesized by dispersing SWNTs via high power ultrasonication into a pre-milled Si/C composite mixture, followed by subsequent thermal treatment. The Si/C composite powder was prepared by high-energy mechanical milling (HEMM) of elemental Si and graphite using polymethacrylonitrile (PMAN) as a diffusion barrier suppressing the possible mechanochemical reaction between silicon and graphite to form SiC, and further prevent the amorphization of graphite during extended milling. A nanocomposite with nominal composition of Si-35wt.% SWNTs-37wt.% exhibits a reversible discharge capacity of ∼900mAhg−1 with an excellent capacity retention of capacity loss of 0.3% per cycle up to 30 cycles. Functionalization of the SWNTs with LiOH significantly improves the cyclability of the nanocomposite containing Si-45wt.% SWNTs-28wt.% exhibiting a reversible capacity of 1066mAhg−1 and displaying almost no fade in capacity up to 30 cycles. The improved electrochemical performance is hypothesized to be attributed to the formation of a nanoscale conductive network by the dispersed SWNTs which leads to successful maintenance of good electrical contact between the electrochemically active particles during cycling.
LiFe y Mn2−y O4 (0≤y<1) is prepared and examined by electrochemical, X-ray diffractional (XRD), and Mössbauer-spectral methods. Li[Fe y Mn2−y ]O4(Fd 3 ̄ m) having a normal spinel-framework structure can be prepared with 0≤y<0.6 and an intermediate between a normal and inverse spinel for 0.6<y. Li[Fe y Mn2−y ]O4 shows discrete operating voltages at 3, 4, and 5 V versus Li. When the iron concentration y is increased from 0 to 0.5, the capacity at 5 V increases while the capacity at 4 V decreases. The operating voltage at 3 V is not affected so much by the iron concentration. The XRD examinations for the oxidation and reduction of Li[Fe0.5Mn1.5]O4 show that the reaction proceeds in a topotactic manner over an entire range, i.e. the cubic phase at voltages above 3 V, the cubic/tetragonal phases in the range 2–3 V, and the tetragonal phase below 2 V. Reversible capacity observed below 2 V is not explained in terms of a topotactic reaction from □[Fe0.5Mn1.5]O4(cubic) to Li2[Fe0.5Mn1.5]O4(tetragonal) via Li[Fe0.5Mn1.5]O4(cubic). Mössbauer spectra indicate that Fe4+ is formed above 4.5 V and Fe3+ (high spin state) below 4.5 V. From these results the reaction mechanism is discussed in terms of the solid-state redox reaction.
Fracture and wrinkling are two main failure modes in deep drawing of a coated metal sheet. With the development of damage mechanics and finite element modeling, it is possible to exactly predict the failure mode of a material during deep drawing. In this paper, a coated metal sheet during deep drawing is studied by finite element simulation and dimensional analysis. Based on a few dimensionless process parameters, a failure map is established, which can be divided into three regions including fracture, wrinkling, and success.
Lithium-ion cells based on Graphite/LiFePO4 (Cgr/LFP), Li4Ti5O12/LiFePO4 (LTO/LFP) and Li4Ti5O12/LiNi1/3Mn1/3Co1/3O2 (LTO/NMC), using [C1CnIm][NTf2]- and [C1C1CnIm][NTf2] (n = 4 and 6)-based electrolytes with different lithium salts such as Li[N(SO2CF3)2] (LiNTf2), Li[N(SO2F)2] (LiFSI) and LiPF6 were tested at 333 K and compared to a commercial carbonate-based electrolyte [EC:DEC][LiPF6]. The impact of different factors such as length of side-alkyl chain on imidazolium ring or its C2-H substitution with CH3 group was studied, and the influence of the presence of organic additives as well as the value of the nominal voltage of the systems, was also reported. Finally, common trends for all these IL-based electrolyte systems were discussed.
Fractal dimension of a LiMn2O4 electrode prepared by sol–gel method was determined using electrochemical techniques based on the phenomenon of “diffusion towards electrode surface”. A simple discussion was made on the methodology to understand what is really estimated as the fractal dimension. It was demonstrated that the value of fractal dimension determined based on electrochemical methods is strongly dependent on the electrochemical system situation. This is generally true for all real electrodes involving insertion/extraction processes. This comes from the fact that surface morphology of the electrode is subject of significant changes during the electrochemical experiment.
Si–O–C composite materials with various compositions are prepared from a phenyl-substituted polysiloxane. The pyrolyzing temperature and atmosphere is varied to determine the effect that these parameters have on the final composition. The compositional effect of using a divinylbenzene (DVB) as an alternative carbon source is also investigated. Materials prepared at either 800 or 1000°C under a hydrogen atmosphere have a significantly larger reversible capacity than those prepared at the same temperature under an argon atmosphere. Utilizing DVB as the carbon source further increases the reversible capacity of the Si–O–C material. The specific capacity increases with an increase of the C/Si ratio and with a decrease of O/Si ratio of the source materials when the O/Si ratio is in the range of 1.0–2.0. A model based on the nanostructure of the Si–O–C material is employed to express the relationship between the specific reversible capacity and the structure of the Si–O–C phase. According to the utilized model, the reversible capacity of lithium in the Si–O–C phase is much greater than that in carbon, and the capacity increases with the increase of the p value in SiO2(1−p)C p . The “free carbon” in the synthesized materials was found to store twice as many lithium ions as the same amount of graphite.
The dynamic electrochemical impedance spectroscopy (DEIS) of a three-electrode pouch type lithium-ion battery is measured using a series of sine wave perturbations super-imposed on pulse charge and discharge. The DEIS reveals noticeable differences between charge and discharge at frequencies corresponding to the charge transfer reaction. The charge transfer resistance during intercalation is generally found to be larger than that during deintercalation for the battery chemistry in this study. This result is mainly attributed to the decreased Li ion concentration in the electrolyte during intercalation. At low frequencies, an abnormal inductive behavior is also observed. Such abnormality is found to result from the violation of stationary condition, i.e. the state of the battery under pulse charge or discharge deviates significantly from its initial condition for the perturbation of low frequencies. To analytically define the stationary condition, we develop electrochemical models of a single active particle in both time and frequency domain, which describes the transport of lithium ions in both active particle and electrolyte phase and the interfacial charge transfer reactions at their interface. The lower frequency limit is a key parameter to ensure a quasistationary state during the DEIS measurement. An explicit formulation of the stationary condition predicts a positive correlation between the lower frequency limit and the DC pulse current.
Plug-in electric vehicles (PEVs) have several capabilities to help the power system; for instance, one of them is participation in the energy market via vehicle to grid (V2G) technology. Due to some uncertain parameters such as battery state of charge (SOC), PEV availability, etc, they have stochastic behavior and it can affect the settlement of energy market. Accordingly, this paper proposes a framework for the stochastic clearing of electricity energy market in the presence of the PEVs while the uncertainties of PEVs and the synchronous generators are considered. The proposed stochastic energy market is cleared in two steps: at the first step, the random scenarios are generated using Monte-Carlo Simulation (MCS); then, at the second step, the stochastic market-clearing procedure is implemented as a series of deterministic optimization problems (scenarios) including non-contingent scenario and different post-contingency states. The network Total Cost (TC) is defined as an objective function and it is minimized for each scenario. In other words, the stochastic energy market is cleared based on the selection of the cheaper and proper energy providers, PEVs and synchronous generators, while the constraints are satisfied. The proposed optimization formulation is in the form of mixed integer nonlinear programming. Consequently, a heuristic based particle swarm optimization method has been adopted for the solution strategy. The effectiveness of the proposed method is examined based on a real case low voltage distribution system with 134 nodes.
Lesotho's energy profile is characterized by a predominance of traditional biomass energy to meet the energy needs of the rural households and a heavy dependence on imported petroleum for the modern economic sector needs. As a result, the country faces challenges related to unsustainable use of traditional forms of biomass and exposure to high and unstable oil import prices. There are relatively abundant renewable energy resources in the form of hydro, solar and wind. The average daily solar radiation in Lesotho varies between 4.5 and 6.5kWh/m2, with some areas in the South West averaging over 7kWh/m2/day. Under the UNDP/GEF-supported Lesotho Renewable Energy-Based Rural Electrification (LREBRE) Project, a total of 5000 solar home systems (SHS) will be installed by 2012. Since the start of the project, a total of 1537 SHS with a capacity of 65W have been installed, and an estimated 500 SHS have also been independently installed as a result of the project's influence. This paper examines the role of PV technologies in the sustainable development process, with particular reference to UNDP/GEF-LREBRE Lesotho PV project, and the extent to which this project is impacting on the PV industry. The paper also analyses national grid electrification and energy provision in rural areas and shows that the problem of rural electrification could be tackled by conventional and non-conventional means.
Ultrafine Li4Ti5O12/C composite is synthesized by microemulsion with oleic acid as carbon precursor and particle size controller. The as-prepared sample is characterized with X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), thermogravimetry analysis (TGA) and nitrogen absorption–desorption isotherms, and its performance as anode of lithium ion battery is determined with charge–discharge test and electrochemical impedance spectroscopy (EIS). The characterizations show that the as-prepared sample is composed of ultrafine Li4Ti5O12 particles with average size of 25 nm, which are uniformly dispersed in carbon matrix with a carbon content as low as 2.69 wt%. Charge–discharge test indicates that the as-prepared sample exhibits excellent rate performance and cycling stability. At 10C, the highest discharge capacity reaches 136.3 mAh g−1 and the capacity retention is 96.4% after 100 cycles. The improved performance of the Li4Ti5O12/C composite is attributed to the ultrafine particle size and the uniform composite of Li4Ti5O12 with carbon.
Surface modified electrodes are used in electro-analysis, electro-catalysis, sensors, biomedical applications, etc. and could also be used in batteries. The properties of modified electrodes are determined by the surface functionality. Therefore, the steps involved in the surface modification of the electrodes to obtain specific functionality are of prime importance. We illustrate here bridging of two routes of surface modifications namely electrochemical grafting, and chemical or electrochemical reduction. First, by electrochemical grafting an organic moiety is covalently immobilized on the surface. Then, either by chemical or by electrochemical route the terminal functional group of the grafted moiety is transformed. Using the former route we prepared lithium alkyl carbonate (–O(CH2)3OCO2Li) modified carbon with potential applications in batteries, and employing the latter we prepared phenyl hydroxyl amine (–C6H4NHOH) modified carbon which may find application in biosensors. Benzyl alcohol (–C6H4CH2OH) modified carbon was prepared by both chemical as well as electrochemical route. We report combinations of conjugating the two steps of surface modifications and show how the optimal route of terminal functional group modification depends on the chemical nature of the moiety attached to the surface in the electrochemical grafting step.
Chemically prepared polyaniline is tested for its supercapacitive behaviour in an aqueous electrolyte of 1.0M H2SO4. In order to improve the cycleability of the polyaniline electrode, it is made into a composite with Nafion. This composite electrode shows improved cycleability and higher specific capacitance compared with a pure polyaniline electrode. It is therefore used as a matrix for the electrochemical deposition of hydrous RuO2. The resulting ternary composite electrode has a high specific capacitance of 475Fg−1 at 100mVs−1 and 375Fg−1 at 1000mVs−1 in the voltage range of −0.2 to 0.8V versus Ag/AgCl. All three types of electrode are characterized by cyclic voltammetry and impedance anaylsis.
A self-assembly approach is used to fabricate a hierarchical nanostructure using functionalized carbon spheres as nano-spacers to separate graphene nanosheets. The nanostructure significantly enhances capacitance of a graphene supercapacitor by more than 70%, while providing a universal method to self-assembling various carbons into hierarchical structures for energy conversion/storage systems.