batterydata/paper-abstracts huggingface dataset:
Miniaturized portable and wearable electronics have diverse power requirements, ranging from one microwatt to several milliwatts. Fiber-based micro-supercapacitors are promising energy storage devices that can address these manifold power requirements. Here, we demonstrate a hydrothermal assembly method using space confinement fillers to control the formation of nitrogen doped reduced graphene oxide and multi-walled carbon nanotube hybrid fibers. Consequently, the all-carbon hybrid fibers have tunable geometries, while maintaining good electrical conductivity, high ion-accessible surface area and mechanical strength; this allows us to address two important issues in micro-supercapacitor research. First, we found a clear correlation between the geometry of the hybrid fibers and their capacitive energy storage properties. Thinner fibers (30 μm in diameter) have higher specific volumetric capacitance (281 F cm−3), superior rate capability, and better length dependent performance. In contrast, larger-diameter hybrid fibers (236 μm in diameter) can achieve much higher specific length capacitance (42 mF cm−1). Second, we realized the first built-to-order concept for micro-supercapacitors by using all-carbon hybrid fibers with diversified geometry as electrodes. The device energy can cover two orders of magnitude, from <0.1 μW h to nearly 10 μW h, and the device power can be tuned in four orders of magnitude, from 0.2 μW to 2000 μW. Furthermore, multiple mechanically flexible fiber-based micro-supercapacitors can be integrated into complex energy storage units with wider operation voltage windows, demonstrating broad application potentials in flexible devices.
A Li ion polymer battery pack for road vehicles (48V, 20Ah) was tested by charging/discharging tests at different current values, in order to evaluate its performance in comparison with a conventional Pb acid battery pack. The comparative analysis was also performed integrating the two storage systems in a hydrogen fuel cell power train for moped applications. The propulsion system comprised a fuel cell generator based on a 2.5kW polymeric electrolyte membrane (PEM) stack, fuelled with compressed hydrogen, an electric drive of 1.8kW as nominal power, of the same typology of that installed on commercial electric scooters (brushless electric machine and controlled bidirectional inverter). The power train was characterized making use of a test bench able to simulate the vehicle behaviour and road characteristics on driving cycles with different acceleration/deceleration rates and lengths. The power flows between fuel cell system, electric energy storage system and electric drive during the different cycles were analyzed, evidencing the effect of high battery currents on the vehicle driving range. The use of Li batteries in the fuel cell power train, adopting a range extender configuration, determined a hydrogen consumption lower than the correspondent Pb battery/fuel cell hybrid vehicle, with a major flexibility in the power management.
Composites that consisted of Li2MnO3 and LiMn0.5Ni0.5O2 were prepared by a co-precipitation method followed by high-temperature calcination. Several preparation parameters including chemical compositions, calcination temperature, and periods of calcination were systematically investigated to uncover the relationships between structure and electrochemical properties. Increasing the lithium concentration led to an increased content of the layered-type component Li(Mn,Ni)O2, while the cation mixing in the layers decreased. Comparatively, high-temperature calcination increased the content of Li2MnO3 component. Alternatively, periods of calcination had little impacts on the structure of composites, but significantly altered the morphology and particle size. As a consequence of the structural modifications by these preparation parameters, the composites were tailored to have an optimum electrochemical performance as the electrodes for lithium-ion batteries.
LiNi0.5Mn1.5O4−δ cathode materials with two different structures ( F d 3 ¯ m and P4332) were synthesized by ultrasonic spray pyrolysis method. The X-ray diffraction (XRD) data was confirmed that face-centered spinel ( F d 3 ¯ m ) transformed into primitive simple cubic (P4332) structure by annealing process at 700°C. In spite of two electrons operated cut-off voltage range between 2.0 and 5.0V, LiNi0.5Mn1.5O4 with P4332 structure has better electrochemical behaviors than the cathode with simple cubic F d 3 ¯ m structure. Ex situ XRD study of the electrode revealed that LiNi0.5Mn1.5O4 (P4332) has reversible crystal transformation between fully lithiated state (2.0V) and delithiated state (5.0V) whereas LiNi0.5Mn1.5O4−δ ( F d 3 ¯ m ) showed irreversible phase transformed at two voltage region. The LiNi0.5Mn1.5O4−δ ( F d 3 ¯ m ) has voltage drop was occurred after 20th cycled compared without any voltage drop of the P4332 structure.
We have developed a micro-porous gelling polymer layer which is formed on both the sides of support polyolefin separator with wet or dry processing technique. Morphologies of gel-coated layer are dependent on the compositions and process conditions, such as solvent/non-solvent combination and stretching ratios. The micro-porous gelling layer is used for the assembly of the lithium ion polymer battery of LG Chemical Ltd. The structure of battery is given elsewhere and the battery has excellent discharge performance with 94% of 2C discharge performance at room temperature.
This paper provides a review of active materials in the context of applications to manufacturing machining processes. The important concepts and background of active materials are briefly introduced. After which, the applications of these materials are discussed as applied to relevant themes in machining processes. A brief overview of research work on experimental and theoretical studies on various process monitoring and control is considered, and several research papers on these topics are cited. This paper concludes with a discussion of future research areas and a suggests path forward.
By using a multifunctional high-energy biomolecule—adenosine triphosphate (ATP)—we fabricated high-energy quantum dots (HEQDs) with a feature size of less than 10 nm and used them in high-power lithium-ion batteries. We introduced high-energy phosphate bonds into the crystal structure of LiFePO4 nanoparticles and synthesized the mesoporous biocarbon nanowire coated LiFePO4 with HEQDs (MBCNW-LFP-HEQDs) by using ATP as a phosphorus source, a nucleating agent, a structural template and a biocarbon source. HEGDs were homogeneously formed inside the ultra-thin LiFePO4 nanosheet and the mesoporous biocarbon nanowire network structure was coated on the surface of the nanosheet. In LiFePO4 nanoparticles, HEQDs result in more storage sites of Li+ ions and easier transfer kinetics of electrons and lithium ions, where the kinetic transformation path between LiFePO4 and FePO4 is rather different from the path deduced from its equilibrium phase diagram. Compared to the usual LiFePO4 nanoparticle (10–100 nm) cathode, the MBCNW-LFP-HEQD cathode shows the best first discharge capacity of 197 mA h g−1 at the 0.1 C rate, which is higher than the theoretical capacity of LiFePO4 (170 mA h g−1). After 100 cycles at varied current rates: 0.1, 0.5, 1, 5 and 10 C, this cathode still delivered a high discharge capacity of 180 mA h g−1 and an ultra-high coulombic efficiency close to 100%. This is attributed to the quantum tunneling of HEQDs in LiFePO4 nanoparticles and better percolation of mesoporous biocarbon nanowire coating network structures. This work is instructive for fabrication and design of new types of electrochemical energy conversion and storage devices with extraordinary properties and functions.
The objective of the present paper is to conduct an experimental work to measure transient thermal/electrical efficiencies in a combined heat and power (CHP) fuel cell generator. An original-designed fuel cell CHP generator comprising a proton exchange membrane (PEM) fuel cell system, a power conditioning system, and a thermal recovery system is constructed. The thermal recovery system recaptures the thermal energy dissipated by the fuel cell stack, while the power conditioning system distributes the electrical power of the fuel cell system. Performance matrices including stack electrical efficiency, system electrical efficiency, thermal efficiency, and CHP efficiency are presented. Particular attention is placed on the variation of transient system efficiencies as the load is changed drastically. The time-averaged system efficiency is then concluded from the statistics of the transient system efficiency. Results show that the time-averaged efficiencies in electrical, thermal and CHP are about 37%, 24%, and 61%, respectively, under 55% electrical power capacity of the generator. The instantaneous CHP efficiency could reach as high as 85% in the loading period.
Pumping of water requires excessive energy for its operation by consuming a massive amount of diesel, gasoline, electric power etc. The more promising alternative energies to perform the same operation without any energy cost are solar photovoltaic (PV) and wind. These fastest growing renewable energies are more reliable and well suitable for remote villages where there is no possibility of extending transmission lines. Furthermore, these systems are optimal for conditions like only small amount of water needed to be pumped for a particular time. Unlike conventional energy sources of electric power, the renewable energy sources are not dispatchable its power output cannot be controlled. In that case, it involves power conversion stages so that it would necessitate to design an advanced control strategy technique. Those control strategies greatly avoid and protects the system from detrimental operating conditions by monitoring input voltage, water flow, torque, power, pressure, speed and motor vibration etc. Henceforth the use of efficient control strategy not only increase the performance of system it also helps to increase the number of operational hours of solar PV and wind energy systems. In this manuscript, the research work of various control strategies carried out in solar PV and wind energy-based water pumping systems are presented. Additionally, this paper intends to discuss the energy management strategies applied for renewable energy fed water pumping system when the system assisted with third energy system (battery bank, fuel cell, etc). These benefited systems ensure good design, guarantees the control speed required for the motor, regulates the flow of water, assuring accurate operation for all conversion and finally, it maintains precise balance in between the renewable energy generated and power required by the load (pump).
Aqueous zinc (Zn)-ion batteries are gaining considerable attention as grid-scale energy storage systems due to their advantages in rate performance, cost, and safety. Here, we report a layered manganese oxide that contains a high content of crystal water (∼10 wt%) as an aqueous zinc battery cathode. The interlayer crystal water can effectively screen the electrostatic interactions between Zn2+ ions and the host framework to facilitate Zn2+ diffusion while sustaining the host framework for prolonged cycles. By virtue of these ‘water’ effects, this material exhibits a high reversible capacity of 350 mA h g−1 at 100 mA g−1, along with decent cycling and rate performance, in a two-electrode cell configuration. Density functional theory (DFT) calculations and extended X-ray absorption fine structure (EXAFS) analyses jointly reveal that upon Zn2+ ion intercalation, a stable inner-sphere Zn-complex coordinated with water molecules is formed, followed by the formation of a Zn–Mn dumbbell structure, which gives a clue for the observed electrochemical performance. This work unveils the useful function of crystal water in enhancing the key electrochemical performance of emerging divalent battery electrodes.
To increase lifetime, safety, and energy usage battery management systems (BMS) for Li-ion batteries have to be capable of estimating the state of charge (SOC) of the battery cells with a very low estimation error. The accurate SOC estimation and the real time reliability are critical issues for a BMS. In general an increasing complexity of the estimation methods leads to higher accuracy. On the other hand it also leads to a higher computational load and may exceed the BMS limitations or increase its costs. An approach to evaluate and verify estimation algorithms is presented as a requisite prior the release of the battery system. The approach consists of an analysis concerning the SOC estimation accuracy, the code properties, complexity, the computation time, and the memory usage. Furthermore, a study for estimation methods is proposed for their evaluation and validation with respect to convergence behavior, parameter sensitivity, initialization error, and performance. In this work, the introduced analysis is demonstrated with four of the most published model-based estimation algorithms including Luenberger observer, sliding-mode observer, Extended Kalman Filter and Sigma-point Kalman Filter. The experiments under dynamic current conditions are used to verify the real time functionality of the BMS. The results show that a simple estimation method like the sliding-mode observer can compete with the Kalman-based methods presenting less computational time and memory usage. Depending on the battery system’s application the estimation algorithm has to be selected to fulfill the specific requirements of the BMS.
The conversion of H2 and CO2 to liquid fuels via Power-to-Liquid (PtL) processes is gaining attention. With their higher energy densities compared to gases, the use of synthetic liquid fuels is particularly interesting in hard-to-abate sectors for which decarbonisation is difficult. However, PtL poses new challenges for the synthesis: away from syngas-based, continuously run, large-scale plants towards more flexible, small-scale concepts with direct CO2-utilisation. This review provides an overview of state of the art synthesis technologies as well as current developments and pilot plants for the most prominent PtL routes for methanol, DME and Fischer–Tropsch-fuels. It should serve as a benchmark for future concepts, guide researchers in their process development and allow a technological evaluation of alternative reactor designs. In the case of power-to-methanol and power-to-FT-fuels, several pilot plants have been realised and the first commercial scale plants are planned or already in operation. In comparison power-to-DME is much less investigated and in an earlier stage of development. For methanol the direct CO2 hydrogenation offers advantages through less by-product formation and lower heat development. However, increased water formation and lower equilibrium conversion necessitate new catalysts and reactor designs. While DME synthesis offers benefits with regards to energy efficiency, operational experience from laboratory tests and pilot plants is still missing. Furthermore, four major process routes for power-to-DME are possible, requiring additional research to determine the optimal concept. In the case of Fischer–Tropsch synthesis, catalysts for direct CO2 utilisation are still in an early stage. Consequently, today's Fischer–Tropsch-based PtL requires a shift to syngas, benefiting from advances in co-electrolysis and reverse water-gas shift reactor design.
LiNi0.5Mn0.3Co0.2O2 cathode materials synthesized via conventional one-step and two-step calcination strategies suffer from high contents of surface impurities and structural defects (i.e., Ni2+/Li+ cation mixing and oxygen vacancy), resulting in suboptimal electrochemical performance. In the present study, the formation of Li2O during calcination is found to be detrimental and responsible for the low quality of LiNi0.5Mn0.3Co0.2O2. Thus, a three-step calcination strategy is devised to significantly reduce surface impurities and structural defects through strategically suppressing Li2O formation. The calcination strategy involves first melting of Li precursor, then reaction and conversion of Li precursor with Ni0.5Mn0.3Co0.2(OH)2 to form LiNi0.5Mn0.3Co0.2O2 without Li2O generation, and finally formation of a layered structure. The as-prepared LiNi0.5Mn0.3Co0.2O2 possesses smooth morphology, much reduced surface impurities, Ni2+/Li+ cation mixing, and oxygen vacancy. The corresponding Ni2+ occupancy at Li sites and oxygen vacancy are only 2.2% and 1.7%, respectively. The as-prepared LiNi0.5Mn0.3Co0.2O2 also exhibits high capacity (178.8 mAh g−1 at 0.1 C), good cycle performance (83.4% capacity retention at 100th cycle), and excellent rate capability (97.4 mAh g−1 at 5 C). This calcination strategy is applicable to LiOH·H2O, LiNO3 and Li2CO3 as Li precursors. The underlying mechanism of this three-step calcination strategy is elucidated.
Electrochemical impedance spectroscopy (EIS) is an effective technique for diagnosing the behaviour of electrochemical devices such as batteries and fuel cells, usually by fitting data to an equivalent circuit model (ECM). The common approach in the laboratory is to measure the impedance spectrum of a cell in the frequency domain using a single sine sweep signal, then fit the ECM parameters in the frequency domain. This paper focuses instead on estimation of the ECM parameters directly from time-domain data. This may be advantageous for parameter estimation in practical applications such as automotive systems including battery-powered vehicles, where the data may be heavily corrupted by noise. The proposed methodology is based on the simplified refined instrumental variable for continuous-time fractional systems method (‘srivcf’), provided by the Crone toolbox [1,2], combined with gradient-based optimisation to estimate the order of the fractional term in the ECM. The approach was tested first on synthetic data and then on real data measured from a 26650 lithium-ion iron phosphate cell with low-cost equipment. The resulting Nyquist plots from the time-domain fitted models match the impedance spectrum closely (much more accurately than when a Randles model is assumed), and the fitted parameters as separately determined through a laboratory potentiostat with frequency domain fitting match to within 13%.
Nanometer copper–tin alloy anode materials with amorphous structure were prepared by a reverse microemulsion technique for lithium-ion batteries. It was found that the electrochemical performance of alloy was influenced by its particle size, which was controlled by appropriate surfactant content. The nanometer copper–tin alloy with particle size of 50–60nm presented the best performance, showing a reversible specific capacity of 300mAh/g over the full voltage range 0.0–1.2V and capacity retention of 93.3% at 50 cycles. A great irreversible capacity was caused by the formation of a SEI layer on the surface of nanometer alloy. The contact resistance between nanometer particles resulted in the poor electric conductivity and the match of particle size and conductive agent content had a great impact on the electrochemical performance of the nanometer copper–tin alloy anode.
Vanadium redox flow battery performance is actually hindered by increased overpotentials at high current, due to poor electrochemical activity of the most commonly used carbon electrodes and to electrolyte distribution, implying local mass transport limiting conditions. Moreover, vanadium cross-contamination leads to coulombic efficiency reduction and uncontrolled electrolytes imbalance. This work presents the application of through-plate reference electrodes at inlet and outlet of both positive and negative electrodes. The utility of the electrodes potential measurement is firstly demonstrated in the identification of a relation between electrolytes potential and the corresponding state of charge. Subsequently, local overpotentials and impedance spectra at both electrodes are evaluated, evidencing that the negative electrode is kinetically dominated and presents high overpotential even at low current, while the positive exhibits mass transport effects at high current, especially at cell outlet. Finally, during cycling operation with fixed capacity reference electrode measurements permit to monitor electrolytes imbalance induced by cross-contamination, that mainly affects negative electrolyte. Moreover, additional insights into electrodes potential loss during cycling are provided.
Sn–Co alloy films are deposited electrochemically directly onto nickel foam in an aqueous solution. The influence of electrochemical current density and heat treatment on the structure and morphology of the electrodeposited films is studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical properties of the Sn–Co alloy films are further investigated by galvanostatic charge–discharge tests. As anodes for lithium ion batteries, the Sn–Co alloy-film anodes, after further heat treatment at 200°C for 30min, delivers a specific capacity of 663mAhg−1 after 60 cycles. This high capacity retention is attributed to the unique electrode configuration with an enhanced interface strength between the active material and the current collector formed in the heat-treatment process.
The dynamics of a rotating tool, commonly employed in deep hole honing, is considered. A mathematical model of the process including a dynamic representation of tool, workpiece surface and honing stones interaction is suggested and analyzed. It is shown that interaction forces are non-conservative. The honing tool is modeled as a rotating continuous slender beam with a mandrel attached at an intermediate cross-section. The transverse oscillations of tool shaft cause variation in expansion pressure and change the interaction forces on the surface of the workpiece. The interaction forces are nonlinear and non-conservative in the general case including delayed functions. The expansion pressure of stones turns out to be a critical parameter in a honing process. Since the removal of stock increases linearly with pressure, the productivity can be improved by increasing expansion pressure, but in certain conditions may cause dynamic instability of the tool shaft. On the other hand, the lower expansion pressure and feed rates increase accuracy. Another source of shaft instability is due to the asymmetry of the tool that leads to discrepancy of the system stiffness in the transverse directions. As a result, under certain conditions unstable parametric vibrations may occur. Needless to say, the dynamic behavior of the tool can considerably influence the machined surface formation. In this study a model of honing surface formation is introduced and integrated into the model of process simulation. The system response is studied for different parameters in a non-dimensional form. Thus it is possible to analyze a set of real processes by applying the similarity conditions. The variation in the machined surface having various initial discrepancies from ideal cylinder is also analyzed.
Methods of accurate modeling and power capability predicting for ultracapacitors are of great significance in management and application of lithium-ion battery/ultracapacitor hybrid energy storage system. To overcome the simulation error coming from constant capacitance model, an improved ultracapacitor model based on variable capacitance is proposed, where the main capacitance varies with voltage according to a piecewise linear function. A novel state-of-charge calculation approach is developed accordingly. After that, a multi-constraint power capability prediction is developed for ultracapacitor, in which a Kalman-filter-based state observer is designed for tracking ultracapacitor's real-time behavior. Finally, experimental results verify the proposed methods. The accuracy of the proposed model is verified by terminal voltage simulating results under different temperatures, and the effectiveness of the designed observer is proved by various test conditions. Additionally, the power capability prediction results of different time scales and temperatures are compared, to study their effects on ultracapacitor's power capability.