batterydata/paper-abstracts huggingface dataset:
Highly mesoporous lithium titanate hierarchical microspheres (LTO-HS) consisting of nanosized octahedron-like crystals were innovatively designed as high performance and safe anode materials for lithium ion battery applications. This unique structural control allows us to capitalize on the exemplary surface areas (electrolyte contact) and short Li-ion diffusion path lengths of nanosized particles, while overcoming the challenge of low power tapping density by integrating them into microsized spheres. A thin carbon coating was applied on the surface of LTO-HS (C-LTO-HS) in order to overcome the inherently limited electronic conductivity of these oxide materials. Moreover, this coating technique was found to induce the formation of some anatase TiO2, resulting in uniquely structured anode materials with active multi-component duality. Notably, the C-LTO-HS composite electrode delivers a remarkable capacity of over 230mAhg−1 when discharged at 0.2C, which is much higher than the theoretical capacity of pure Li4Ti5O12 (175mAhg−1) and ascribed to the existence of anatase TiO2 (330mAhg−1) in the C-LTO-HS structure. Furthermore, this electrode yielded excellent cycling and rate capabilities of about 120mAhg−1 (compared to 90mAhg−1 for LTO-HS) at a current density of 10C for up to 100 cycles. These unique mesoporous spheres with deliberately controlled nanostructure arrangements show significant promise as anode materials for lithium ion batteries, fabricated by a simplistic two step hydrothermal procedures, and capable of providing high volumetric energy density and long cycle life.
Several 18650 lithium-ion batteries using LiCoO2, LiMn2O4, and LiFePO4 as cathode materials were assembled separately. Gas species of these batteries under normal cycling and overcharging to 4.5 and 5.0V conditions were examined by means of GC–MS method. Under the normal charge and discharge voltage range, it is found that gas components are independent to the cathode materials. C2H5F gas was detected in all cases. A formation mechanism is proposed. Under overcharging condition, it is found that the gas components are different and there is a correlation between the C2H2 product and the oxidation ability of various delithiated cathode materials.
In the present work, the two-dimensional analytical solution for Li diffusion in grains and grain boundaries of a polycrystalline film electrode is established with consideration of Li-segregation at the grain boundary. The stress field induced by the inhomogeneity of Li concentration, called chemical stress here for brevity, is analyzed via the finite element simulation. The effects of the grain boundary including its size, its diffusion coefficient as well as the segregation phenomenon on the solute concentration and the chemical stress are examined. It shows that grain boundaries can assist fast diffusion and significantly affect the stress profile in the whole film. It proves that tailoring the grain boundary size or other grain boundary-related parameters may provide an alternative strategy for improving the overall diffusivity and mechanical stability of battery electrodes.
Ionic liquids (ILs) and deep eutectic solvents (DESs) have been applied in various fields such as electrolytes for lithium ion batteries, electrodeposition, electropolishing and even in fuel cells. ILs and molten salts have found some applications in redox flow batteries (RFBs) in the past and recently some metal ion based ILs have been proposed and used by Sandia National Laboratories. In addition, only two papers have very recently reported on the application of DESs for the same. This review gives an overview on DESs and discusses the possibility of employing them in RFBs for renewable energy storage and utility-scale load leveling applications. Commencing with a discussion on energy storage technologies and the RFB, this paper goes on to provide an account on ILs and DESs as well as their applications in electrochemistry and energy conversion. A succinct discussion on the results of Sandia National Laboratories on using ILs as electrolytes for RFBs is provided building onto the feasibility of replacing ILs with DESs in the near future (based upon recent publications on the topic).
Lithium-ion cells connected in series are prone to be overdischarged, which may induce internal short circuit (ISC). In this study, the electrical behavior of overdischarge-induced ISC in NMC cells is analyzed. The performance of 11 new cells is tested, and these cells are then overdischarged to different depths. The electrical characteristics of these overdischarged cells are examined to assess the relationship between the ISC and depth of discharge (DOD). The cells are then rested for 100 days to assess the self-repair capability of overdischarged cells. The ISC is characterized by comparing the DOD with the capacity loss, leakage current, and ISC resistance. The degree of the ISC is found to increase nonlinearly with the DOD. A DOD of 120% or more can induce an irreversible ISC, and the electrical characteristics of severely overdischarged cells are similar to linear resistance characteristics. The self-repair behavior occurs in the cells with a DOD of less than 120% after a longtime rest and leads to a decrease in the degree of the ISC. The cyclic test results show that a higher DOD leads to a higher capacity decay rate. The electrical characteristics of the overdischarge-induced ISC are valuable in ISC identification and prediction.
Commonly displayed functional asymmetries such as hand dominance and hemispheric speech lateralisation are well researched in adults. However there is debate about when such functions become lateralised in the typically developing brain. This study examined whether patterns of speech laterality and hand dominance were related and whether they varied with age in typically developing children. 148 children aged 3–10 years performed an electronic pegboard task to determine hand dominance; a subset of 38 of these children also underwent functional Transcranial Doppler (fTCD) imaging to derive a lateralisation index (LI) for hemispheric activation during speech production using an animation description paradigm. There was no main effect of age in the speech laterality scores, however, younger children showed a greater difference in performance between their hands on the motor task. Furthermore, this between-hand performance difference significantly interacted with direction of speech laterality, with a smaller between-hand difference relating to increased left hemisphere activation. This data shows that both handedness and speech lateralisation appear relatively determined by age 3, but that atypical cerebral lateralisation is linked to greater performance differences in hand skill, irrespective of age. Results are discussed in terms of the common neural systems underpinning handedness and speech lateralisation.
Spherically shaped vanadium pentoxide (V2O5) cathode powders with porous or dense morphologies are prepared directly via spray pyrolysis by varying the preparation temperatures between 600 and 1000°C. The powders prepared at 600°C consist of nanometer-sized rod-shaped crystals with porous structures. The V2O5 powders prepared at 1000°C have spherical shapes, clean surfaces, and dense structures, because of complete melting of the powders that occurs inside the hot-wall reactor. The Brunauer–Emmett–Teller (BET) surface areas of the V2O5 powders decrease from 24.7 to 3.2m2 g−1 when the preparation temperature increases from 600 to 1000°C. The V2O5 powders prepared at 1000°C have better cycle properties than those prepared at 600 and 800°C. The discharge capacity of the V2O5 powders prepared at 1000°C decreases from 432mAhg−1 to 263mAhg−1 after 20 cycles, in which the capacity retention is 61%.
A nanoarchitecture of sulfur encapsulated inside the N-doped hollow carbon sphere and 3D graphene framework (S@NHC-GFW) is designed via a self-conversion template and self-assembly strategy. Herein, ZnS nanospheres serve as scaffold and sulfur source for the formation of 3D graphene frameworks and their subsequent conversion into sulfur through a facile oxidation reaction. Our self-template conversion route for in situ encapsulation of sulfur inside a carbon shell can prevent the aggregation of sulfur and effectively control uniformity. Hollow carbon nanostructure offers an internal void space, which can accommodate the volumetric change in sulfur upon lithiation. N-doped carbon shell serves as a physical barrier and offers active sites for the chemical adsorption of polysulfides, thereby effectively alleviating the loss of polysulfides. In addition, graphene introduction in the construction of a 3D conductive network interconnected with different S@NHC spheres under plane-to-point mode is beneficial to the continuous transfer of electrons in different dimensions. Consequently, the conductivity of the whole electrode increases. Given these advantages, S@NHC-GFW can serve as a cathode with a good rate capability and an excellent long-term cycling stability.
Resource optimization is a major factor in the assessment of the effectiveness of renewable energy systems. Various methods have been utilized by different researchers in planning and sizing the grid-connected PV systems. This paper analyzes the optimal photovoltaic (PV) array and inverter sizes for a grid-connected PV system. Unmet load, excess electricity, fraction of renewable electricity, net present cost (NPC) and carbon dioxide (CO2) emissions percentage are considered in order to obtain optimal sizing of the grid-connected PV system. An optimum result, with unmet load and excess electricity of 0%, for serving electricity in Makkah, Saudi Arabia is achieved with the PV inverter size ratio of R = 1 with minimized CO2 emissions. However, inverter size can be downsized to 68% of the PV nominal power to reduce the inverter cost, and hence decrease the total NPC of the system.
In this paper, we present a simple method for scalable synthesis of uniform carbon nanoshell coated monodispersed iron oxide nanocrystals and report on the electrochemical performances of such nanocomposites. The structure and morphology of the resulting nanocomposites are investigated with X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). Cyclic voltammetry (CV) and cyclic test of the nanocomposites as an anode material for lithium ion batteries are also studied. The magnetite-C nanostructured material have a very high specific capacity of 859 mAh g−1 in the initial cycle and high capacity retention out to 50 cycles at a constant current density of 100mA/g, showing its potential as an anode material in lithium-ion batteries. The superior electrochemical characteristics are a result of the uniform distribution of magnetite nanoparticles, proper nanostructure, and good conductivity as well as the prevention of aggregation by the carbon nanoshell during cycling.
The process of Li+ reduction from room temperature ionic liquids consisting of N-methyl-N-propylpyrrolidinium cation (MPPyr+) and bis(fluorosulfonyl) imide (FSI−) or bis(trifluoromethanesulfonyl) imide (TFSI−) anions was studied with the use of impedance spectroscopy. Reduction was carried out on both metallic lithium (Li) and graphite (G) electrodes. It has been found that the FSI anion in high amounts is able to form a protective film on both graphite and metallic lithium. The Li+/Li couple should rather be represented by a Li+/SEI/Li system. The SEI structure depends on the manner of its formation (chemical or electrochemical) and is not stable with time. The rate constant for the Li+ +e− →Li process at the Li/SEI/Li+ (in MPPyrFSI) interface is k o =4.2×10−5 cm/s. In the case of carbon electrodes (G/SEI/Li+ interface), lithium diffusion in solid graphite is the rate determining step, reducing current by ca. two orders of magnitude, from ca. 10−4 A/cm2, characteristic of the Li/SEI/Li+ electrode, to ca. 10−6 A/cm2.
Silicon is a promising photocathode material for solar hydrogen evolution because of its small band gap, negative conduction band position, and ideal theoretical current density. In this study, p-type Si microwire (p-Si MW) arrays were prepared as photocathodes because of the large surface area and high light-harvesting capability. However, Si MWs suffered from low photocatalytic activity because of slow photo-induced carriers during driving of water-splitting reaction. Therefore, molybdenum sulfide (MoS2) with appropriate band alignment with p-Si material was employed for surface modification to function as a co-catalyst for collecting photo-generated minority carriers and reducing recombination possibility. The onset potential and current density at 0V versus reversible hydrogen electrode (RHE) of Si@MoS2 MWs were +0.122V and −8.41mAcm−2. Heterometal atoms were employed to dope MoS2 co-catalyst and expose more sulfur-terminated active sites to further boost photoelectrochemical performance. Optimal activity of Si@MMoSx (M = Fe, Co, Ni) was achieved by doping Co heteroatoms, and its turn-on voltage and photocurrent density at 0V (vs. RHE) were respectively increased to +0.192V and −17.2mAcm−2. X-ray absorption spectroscopy was applied to demonstrate that Fe ions of FeMoSx were dichalcogenide materials, forming a composite with MoS2 and contributing better photoelectrolytic efficiency. By contrast, two-valent heteroatoms of CoMoSx and NiMoSx substituted the Mo4+ ions in MoS2. For charge compensation, more defects and edges were revealed as active sites of solar hydrogen production by adding Co or Ni dopants in MoS2 co-catalyst, which led to lower overpotential.
In spite of its excellent discharge capacity, low conductivity and poor cycling stability prevent to commercialize silicon negative electrodes for the Lithium ion batteries (LIBs). Since graphene has large surface area, high electrical conductivity and discharge capacity, silicon/graphene nanocomposite anodes in proper architectures alleviate difficulties to improve electrochemical performances of the LIBs. This article demonstrates the nanocomposite synthesizing with 10wt.%, 30wt.% and 50wt.% graphene oxide (GO) dispersion in the silicon matrix following reduction of GO (rGO) result in remarkable improvements in the discharge capacity, cycle stability and rate capability. Mechanical milling after GO reduction provides decoration of silicon nanoparticles between the rGO sheets and improves interfacial bonding between silicon and rGO which alleviates huge volume increase during cycling. Among the nanocomposite negative electrodes, 50wt.% rGO exhibits highest reversible capacity of about 2000mAhg−1 after 100 cycles and good coulombic efficiency approximately 99%. This study proves that dispersion of silicon with rGO and the increase content of rGO lead to improve ionic conductivity, cycling stability, reversibility and rate capability of the Lithium ion cell. Because of the easy scaling-up possibility of the method Si/rGO hybrid nanocomposites can be new electrodes for electrochemical energy storage. .
Parent TiO2 nanotubes were synthesized through an anodizing process and Cu coating was applied on these nanotubes by electroplating to take advantage of their improved Li ion intercalation properties. The field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) results demonstrated that the products consisted of impurity-free, anatase-phase TiO2 nanotubes uniformly coated with a Cu layer. The charge-transfer resistance of the Cu-coated TiO2 nanotubes decreased by more than 39% compared to that of the parent TiO2 nanotubes. The first reversible capacity of the Cu-coated TiO2 nanotubes was 226.5mAhg−1 at a high current density of 200mAg−1. After the 300th cycle, the discharge capacity of the Cu-coated TiO2 nanotubes decreased by 18.1%, compared to the initial discharge capacity, to 185.6mAhg−1. These results represent 23.6% and 35.3% improvements, respectively, over the parent TiO2 nanotubes. The enhanced electrical performances of the Cu-coated TiO2 nanotubes, ascribed to the increase in electrical conductivity, led to improvements in the reversible capacity and cycle stability of the anode materials. It is speculated that Cu-coated TiO2 nanotubes are a promising anode material for Li ion batteries.
Polymer electrolytes based on poly(ethylene glycol) dimethyl ether (PEGdME) and the ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6) have been prepared and characterized by different techniques. Coordination of the IL by the polymer occurs mainly in the amorphous phase. This finding was correlated with previous theoretical investigations of a similar model for polymer electrolytes based on poly(ethylene oxide), PEO, and IL. It has been obtained ionic conductivity σ ∼10−3 Scm−1 for the polymer electrolyte with 35wt% of IL at 100°C. The same order of magnitude for σ was obtained by molecular dynamics simulation of PEO/IL. This work demonstrates consistency between experimental and theoretical results for polymer electrolytes containing ionic liquids.
Sodium-ion batteries (SIBs) are attracting considerable attention with expectation of replacing lithium-ion batteries (LIBs) in large-scale energy storage systems (ESSs). To explore high performance anode materials for SIBs is highly desired subject to the current anode research mainly limited to carbonaceous materials. In this study, a series of transition metal oxides (TMOs) is successfully demonstrated as anodes for SIBs for the first time. The sodium uptake/extract is confirmed in the way of reversible conversion reaction. The pseudocapacitance-type behavior is also observed in the contribution of sodium capacity. For Fe2O3 anode, a reversible capacity of 386mAhg−1at 100mAg−1 is achieved over 200 cycles; as high as 233mAhg−1is sustained even cycling at a large current–density of 5Ag−1.
Due to flexible property and light weight, the lithiated Nafion membrane swollen with PC (PC-Li-Nafion) has been employed as both solid-state electrolyte and separator to fabricate solid-state Li-S cells. The electrochemical measurements of PC-Li-Nafion membrane show that its Li-ion transference number is 0.928, ionic conductivity of 2.1 × 10−4 S cm−1 can be achieved at 70 °C and its electrochemical window is 0 ∼ +4.1 V vs. Li+/Li. It is observed that the Li dendrites are suppressed by using PC-Li-Nafion membrane due to its single-ion conducting property. The amounts of Li-Nafion resin binder and conductive carbon in the cathode are optimized as 40% and 10% respectively to make a balance of ionic and electronic conductivities. A thin-layer Li-Nafion resin with a thickness of around 2 μm is fabricated between the cathode and PC-Li-Nafion membrane to improve the interfacial contact and further enhance the specific capacity of the cell. When measured at 70 °C, the Li-S cell delivers a reversible specific capacity of 1072.8 mAh g−1 (S) at 0.05 C and 895 mAh g−1 (S) at 1 C. The capacity retention at 1 C is 89% after 100 cycles. These results suggest that high-performance solid-state Li-S cells can be fabricated with the Li-Nafion polymer electrolyte.
Iron diselenide (FeSe2) has been of recent interest as a potentially useful electrode material. Here we demonstrate, for the first time, the synergistic effect between multi-walled carbon nanotubes (MWCNT) and FeSe2 in a form of MWCNT/FeSe2 composite, for the heterogeneous electron transfer (HET) reaction with the [Ru(NH3)6]3+/2+ redox probe and the electrochemical hydrogen evolution reaction (HER) in acidic media. Plain FeSe2 and the MWCNT/FeSe2 composite were synthesized using a one-pot hydrothermal method. Although all electrode materials (pristine MWCNT, FeSe2, and MWCNT/FeSe2) show a quasi-reversible electrode behavior, MWCNT/FeSe2 has a smaller peak separation potential and exhibits an enhanced HET rate constant, k 0 = 5.4 × 10−3 cm/s, which is 3.2 and 1.6 times higher than that of FeSe2 and MWCNT, respectively. Similarly, the HER performance of the composite demonstrates a smaller Tafel slope of 70 mV/dec and a reduced overpotential. We anticipate that such promising outcome can be further improved by employing different morphologies of FeSe2 and engineered interaction with other conductive supports suitable for their applications in electrochemical sensing and energy conversion.
ABSTRACT An empirical model for commercial lithium-ion batteries is developed based on electrochemical impedance spectroscopy (EIS) tests. An equivalent circuit is established according to EIS test observations at various battery states of charge and temperatures. A Laplace transfer time based model is developed based on the circuit which can predict the battery operating output potential difference in battery electric and plug-in hybrid vehicles at various operating conditions. This model demonstrates up to 6% improvement compared to simple resistance and Thevenin models and is suitable for modeling and on-board controller purposes. Results also show that this model can be used to predict the battery internal resistance obtained from hybrid pulse power characterization (HPPC) tests to within 20 percent, making it suitable for low to medium fidelity powertrain design purposes. In total, this simple battery model can be employed as a real-time model in electrified vehicle battery management systems.
Oppositely charged poly(allylamine hydrochloride) (PAH) and 5nm-sized TiO2 nanoparticles were assembled into {PAH/TiO2} n layer-by-layer (LBL) films on electrodes. The cyclic voltammetric (CV) response of K3Fe(CN)6 at {PAH/TiO2} n film electrodes was very sensitive to the solution pH. At pH 4.0, the probe showed a nearly reversible CV peak pair with large peak currents; at pH 9.0, however, the CV response was significantly suppressed. This reversible pH-dependent on–off property could be used to switch the bioelectrocatalysis of H2O2 by horseradish peroxidase (HRP) with Fe ( CN ) 6 3 - as the mediator by changing the surrounding pH. The mechanism of the pH-dependent permeability of the films toward the probe was explored and discussed by comparative experiments.
Graphite, as a typical carbon allotrope, is demonstrated as an available intercalation-type anode material for potassium-ion batteries (PIBs). The main challenges associated with graphite anodes are structural pulverization and instability of the solid electrolyte interphase (SEI) resulting from the repeated volume change during charge/discharge. In this work, a layer of interweaved carbon nanotubes (CNTs) are grown on the surface of micro-size graphite flakes through controllable in-situ catalytic chemical vapor deposition method (CCVD), and the CNTs content can be easily adjusted by varying the deposition time. The CNTs-interweaved layer can not only stabilize the graphite structure but also enhance the diffusion kinetics of K+ during cycling. Furthermore, CNTs also provide a certain amount of capacity. The composite material of in situ growing carbon nanotubes and modified graphite flakes (CNTs-MG) exhibit a reversible capacity of 234 mAh g−1 at 2 A g−1 after 1500 cycles, which is obviously better than that of counterpart graphite flakes. Besides, the K storage mechanism and the effect of the contents of CNTs are also investigated systemically by in-situ Raman spectra and electrochemical characterizations.
A multi-objective parameter identification method for modeling of Li-ion battery performance is presented. Terminal voltage and surface temperature curves at 15 °C and 30 °C are used as four identification objectives. The Pareto fronts of two types of Li-ion battery are obtained using the modified multi-objective genetic algorithm NSGA-II and the final identification results are selected using the multiple criteria decision making method TOPSIS. The simulated data using the final identification results are in good agreement with experimental data under a range of operating conditions. The validation results demonstrate that the modified NSGA-II and TOPSIS algorithms can be used as robust and reliable tools for identifying parameters of multi-physics models for many types of Li-ion batteries.