Energy-storage Welding Connection Characteristics of Rapid Solidification AZ91D Mg Alloy Ribbons

Energy-storage welding connection characteristics of rapidly solidified AZ91D Mg alloy ribbons with 40-70 μm thickness are investigated using a microtype energy-storage welding machine. The microstructure and performance of the connection joints are analyzed and studied. The research results indicate that energy-storage welding is able to realize the spot welding connection of AZ9ID Mg alloy ribbons. The welding nugget consists of developed α-Mg equiaxed grains with the sizes of 1.2-2.7 μm and intergranular distributed β-Mg17Al12 compounds. The thickness of bond zone is about 4 μm and the solidification microstructure is characterized by the fine equiaxed grains with the sizes of 0.8-1.2μm and grain boundary has become coarsening. The columnar crystal in HAZ also becomes slightly coarsening and the grain boundary has broadened, however, there is no obvious change in its primitive morphology and crystallographic direction. When welding energy is about 2.0 J, the welding joints with higher shear strength and smaller electrical resistivity are obtained.

Energy-storage configuration for EV fast charging stations considering characteristics of charging load and wind-power fluctuation

Fast charging stations play an important role in the use of electric vehicles(EV)and significantly affect the distribution network owing to the fluctuation of their power.For exploiting the rapid adjustment feature of the energy-storage system(ESS),a configuration method of the ESS for EV fast charging stations is proposed in this paper,which considers the fluctuation of the wind power as well as the characteristics of the charging load.The configuration of the ESS can not only mitigate the effects of fast charging stations on the connected distribution network but also improve its economic efficiency.First,the scenario method is adopted to model the wind power in the distribution network,and according to the characteristics of the EV and the driving probability,the charging demand of each station is calculated.Then,considering factors such as the investment cost,maintenance cost,discharging benefit,and wind curtailment cost,the ESS configuration model of the distribution network is set up,which takes the optimal total costs of the ESS for EV fast charging stations within its lifecycle as an objective.Finally,General Algebraic Modelling System(GAMS)is used to linearize and solve the proposed model.A simulation on an improved IEEE-69 bus system verifies the feasibility and economic efficiency of the proposed model.

Composition and Properties of Thermo-regulated Non-woven Fabrics

A series of non-woven fabrics were fabricated by blending S0- 80wt% of thennoregulated fibres containing n-elcosane, n-nonadecane or n-octadecane with 0 - 40wt% PET fibres and 0- 20wt% PP fibres. The phase change properties, thermal conductivity, thermal resistance, heat flux and inner temperature difference between wool felt and the thermoregulated non-woven fabrics of the non-woven fabrics were measured respectively. The thereto-regulated non-woven fabrics absorb heat at 25- 34℃ and release heat at 10- 25℃. The measured highest enthalpy of the non-woven is approximately 18J/g. During a heating process, heat flux of the non-woven fabrics is composed of three parts, heat absorbed by the cold textile touching the hot plate, heat transmitted from the hot plate to the cold plate, and the heat absorbed by PCM from the hot plate during the phase change process. The measured maximum inner temperature difference in a temperature rising process between the wool felt and the thermo-regulated non-woven fabric is approximately 8℃. The inner temperature difference （Tr-Ts〉0） lasts 16 - 45 min By contrary, the measured maximum inner temperature difference in the temperature decreasing process is approximately - 6. 5℃. The inner temperature difference （Tr-Ts〈0） lasts 16 - 50 min, The temperature regulation properties are obviously observed.

Recent advances in graphene-based phase change composites for thermal energy storage and management

Energy storage and conservation are receiving increased attention due to rising global energy demands.Therefore,the development of energy storage materials is crucial.Thermal energy storage(TES)systems based on phase change materials(PCMs)have increased in prominence over the past two decades,not only because of their outstanding heat storage capacities but also their superior thermal energy regulation capability.However,issues such as leakage and low thermal conductivity limit their applicability in a variety of settings.Carbon-based materials such as graphene and its derivatives can be utilized to surmount these obstacles.This study examines the recent advancements in graphene-based phase change composites(PCCs),where graphene-based nanostructures such as graphene,graphene oxide(GO),functionalized graphene/GO,and graphene aerogel(GA)are incorporated into PCMs to substantially enhance their shape stability and thermal conductivity that could be translated to better storage capacity,durability,and temperature response,thus boosting their attractiveness for TES systems.In addition,the applications of these graphene-based PCCs in various TES disciplines,such as energy conservation in buildings,solar utilization,and battery thermal management,are discussed and summarized.

Li-ion Battery Failure Warning Methods for Energy-storage Systems

Energy-storage technologies based on lithium-ion batteries are advancing rapidly.However,the occurrence of thermal runaway in batteries under extreme operating conditions poses serious safety concerns and potentially leads to severe accidents.To address the detection and early warning of battery thermal runaway faults,this study conducted a comprehensive review of recent advances in lithium battery fault monitoring and early warning in energy-storage systems from various physical perspectives.The focus was electrical,thermal,acoustic,and mechanical aspects,which provide effective insights for energy-storage system safety enhancement.

Achieving stable relaxor antiferroelectric P phase in NaNbO_(3)-based lead-free ceramics for energy-storage applications

Compared with antiferroelectric(AFE)orthothombic R phases,AFE orthothombic P phases in Na NbO_(3)(NN)ceramics have been rarely investigated,particularly in the field of energy-storage capadtors.The main bottlenedk is closely related to the contradiction between d fficultly achieved stable relaxor AFE P phase and easily induced P-R phase transition during modifying dhemical compositions.Herein,we reporta novel lead-free AFE ceramic of(1-x)NN-x(Bi_(0.5)K_(0.5))ZrO_(3)((1-x)NN-xBKZ)with a pure AFE P phase str ucture,which exhibits excellent energy-storage characteristics,such as an ultrahigh recoverable energy density(W_(rec))-4.4 J/cm^(3) at x=0.11,a large powder density P_(D)-104 MW/cm^(3) and a fast discharge rate t_(0.9)-45 ns.The analysis of polarization-field response,Raman spectrum and transmission elecron microscopy demonstrates that the giant amplification of W_(rec) by≥177% should be ma inly ascribed to the simultaneously and effectively enhanced AFE P phase stbility and its relaxor dharacteristics,resulting in a diffused reversible electric field-induced AFE P-ferroelectric phase transition with concurrently incre.ased driving electric fields.Different from mast(1-x)NN-xABO_(3) systems,it was found that the reduced polarizability of B-site cations dominates the enhanced AFE P-phase stability in(1-x)NN-xBKZ ceramics,but the almost unchanged tolerance factor tends to ause the AFE R phase to be induced at a relatively high x value.

All Binder-Free Electrodes for High-Performance Wearable Aqueous Rechargeable Sodium-Ion Batteries

Extensive efforts have recently been devoted to the construction of aqueous rechargeable sodium-ion batteries(ARSIBs)for large-scale energy-storage applications due to their desired properties of abundant sodium resources and inherently safer aqueous electrolytes.However,it is still a significant challenge to develop highly flexible ARSIBs ascribing to the lack of flexible electrode materials.In this work,nanocube-like KNiFe(CN)6(KNHCF)and rugby balllike NaTi2(PO4)3(NTP)are grown on carbon nanotube fibers via simple and mild methods as the flexible binder-free cathode(KNHCF@CNTF)and anode(NTP@CNTF),respectively.Taking advantage of their high conductivity,fast charge transport paths,and large accessible surface area,the as-fabricated binder-free electrodes display admirable electrochemical performance.Inspired by the remarkable flexibility of the binder-free electrodes and the synergy of KNHCF@CNTF and NTP@CNTF,a high-performance quasi-solid-state fiber-shaped ARSIB(FARSIB)is successfully assembled for the first time.Significantly,the as-assembled FARSIB possesses a high capacity of 34.21 mAh cm?3 and impressive energy density of 39.32 mWh cm?3.More encouragingly,our FARSIB delivers superior mechanical flexibility with only 5.7%of initial capacity loss after bending at 90°for over 3000 cycles.Thus,this work opens up an avenue to design ultraflexible ARSIBs based on all binder-free electrodes for powering wearable and portable electronics.

Non-aqueous lithium bromine battery of high energy density with carbon coated membrane

Flow batteries with high energy density and long cycle life have been pursued to advance the progress of energy storage and grid application. Non-aqueous batteries with wide voltage windows represent a promising technology without the limitation of water electrolysis, but they suffer from low electrolyte concentration and unsatisfactory battery performance. Here, a non-aqueous lithium bromine rechargeable battery is proposed, which is based on Br;/Br;and Li;/Li as active redox pairs, with fast redox kinetics and good stability. The Li/Br battery combines the advantages of high output voltage（;.1 V）,electrolyte concentration（3.0 mol/L）, maximum power density（29.1 m W/cm;） and practical energy density（232.6 Wh/kg）. Additionally, the battery displays a columbic efficiency（CE） of 90.0%, a voltage efficiency（VE） of 88.0% and an energy efficiency（EE） of 80.0% at 1.0 m A/cm;after continuously running for more than 1000 cycles, which is by far the longest cycle life reported for non-aqueous flow batteries.

Switching and energy-storage characteristics in PLZT 2/95/5 antiferroelectric ceramic system

Switching mechanisms and energy-storage properties have been investigated in(Pb_(0.98)La_(0.02)T(Zr_(0.95)Ti_(0.05)T_(0.995O_(3)) antiferroelectric ceramics.The electric field dependence of polarization(P–E hysteresis loops)indicates that both the ferroelectric(FE)and antiferroelectric(AFE)phases coexist,being the AFE more stable above 100℃.It has been observed that the temperature has an important influence on the switching parameters.On the other hand,the energy-storage density,which has been calculated from the P–E hysteresis loops,shows values higher than 1 J/cm^(3) for temperatures above 100℃ with around 73%of efficiency as average.These properties indicate that the studied ceramic system reveals as a promising AFE material for energy-storage devices application.

Comparison of the topologies for a hybrid energy-storage system of electric vehicles via a novel optimization method

The combination of batteries and ultracapacitors has become an effective solution to satisfy the requirements of high power density and high energy density for the energy-storage system of electric vehicles.Three aspects of such combination efforts were considered for evaluating the four types of hybrid energy-storage system(HESS)topologies.First,a novel optimization framework was proposed and implemented to optimize the voltage level of a battery pack and an ultracapacitor pack for the four types of HESS topologies.During the optimization process,the dynamic programming(DP)algorithm was iteratively applied to determine the optimal control actions.The simulation results with DP were used to evaluate the energy efficiency of different HESS topologies at different voltage levels.Second,the optimized voltage level of the battery and ultracapacitor in each topology indicates that a higher voltage level usually results in a better system performance.The simulation results also illustrate that the optimized rated voltage level of the battery pack is approximately 499.5 V,while for the ultracapacitor pack,the optimized voltage level is at its maximum allowed value.Note that the constraint of the battery voltage is initialized at200–600 V.Third,the control rules for different HESS topologies were obtained through the systematic analysis of the simulation results.In addition,advantages and disadvantages of the four topologies were summarized through evaluation of the efficiency and operating currents of the batteries and the ultracapacitor.

Reduced graphene oxide modified melamine sponges filling with paraffin for efficient solar-thermal conversion and heat management

A novel type of reduced graphene oxide(rGO)modified melamine sponges(rGS)filling with paraffin(rGS-pf)is developed for efficient solar-thermal conversion and heat management.The microstructures,filling and holding capacity of paraffin in porous rGS,solar-thermal energy conversion and energy harvesting efficiency of the prepared rGS-pf have been investigated systematically.The content of rGO nanosheets coated on the skeletons of rGS-pf is only 0.11%,while the loading content of paraffin in the rGS-pf is as high as 97.53%.Based on the solar-thermal conversion property of rGO nanosheets in the rGS-pf and the heat storage ability of paraffin in the rGS-pf,the proposed rGS-pf provides excellent performance for heat management.The efficiency of solar-thermal conversion could reach up to 92.5%.The thermo-regulation provided by the proposed rGS-pf is real-time,repeatable and long-term stable.The results in this study provide valuable guidance for developing functional materials for efficient solarthermal conversion and heat management.

Degradation of Aqueous 2,6-Dibromophenol Solution by In-Liquid Dielectric Barrier Microplasma

Degradation of 2,6-dibromophenol (2,6-DBP) in the aqueous solution was studied using dielectric barrier discharge in micro-bubbles. Experimental comparison of working gas Ar, N2, O2, and air showed that oxygen and air plasma efficiently decomposed 2,6-DBP to bromide ion, and inorganic carbon. The molecular orbital model was applied in the analysis of the degradation in electrophilic, nucleophilic, and radical reactions.

Ni, Co-double hydroxide wire structures with controllable voids for electrodes of energy-storage devices

We re port the facile synthesis of Ni,Co-double hydroxide wire(NCHW)-based electrodes directly grown on a conductive substrate via a hydrothermal process.Various NCHW nanostructures were grown on Ni foam,and the growth was controlled using different compositions of solvents(ethanol and water).With increasing volume ratio of ethanol to water,the density of the wires decreased,and the spatial voids between the wires increased.The formation of large empty spaces improved the electrochemical performance because the exposure of a large surface area of the structure to the electrolyte resulted in a large number of active sites and facile electrolyte penetration into the structure.The different NCHW structures were ascribed to the pivotal role of the solvent in the urea hydrolysis;the solvent triggered the formation of hydroxides during the hydrothermal synthesis.The electrochemical performance of the NCHW electrodes was investigated via galvanostatic charge/discha rge tests,cyclic voltammetry,and electrochemical impedance spectroscopy.The highest specific capacitance was 1694.7 m F/cm^2 at 2 mA/cm^2,with excellent capacitance retention of 81.5% after 5000 cycles.The superior electrochemical performance of the NCHW electrodes is attributed to the large number of active sites and facile electrolyte diffusion into the structure,due to the well-organized structure with an optimized density of nanowires and large voids between the wires.

Ordered Macroporous MoS_(2)-Carbon Composite with Fast and Robust Sodium Storage Properties to Solve the Issue of Kinetics Mismatch of Sodium-Ion Capacitors

Metal-ion capacitors(including Li^(+),Na^(+),and K^(+))effectively combine a battery negative electrode capable of reversibly intercalating metal cations,together with an electrical double-layer positive electrode.However,such novel cell design has a birth defect,namely kinetics mismatch between sluggish negative electrode and fast positive electrode,thus limiting the energy-power performance.Herein,we design a MoS_(2)-carbon composite anode with the ordered macroporous architecture and interlayer-expanded feature,exhibiting the fast and reversible Na^(+)redox processes.This kinetically favored anode is coupled with a homemade activated carbon cathode that allows for the excellent electrochemical performance of sodiumion capacitor with respect to large specific capacity,high-rate capability,and robust cycling.Through quantification of the potential swings of anode and cathode via a three-electrode Swagelok cell,we for the first time observe the abnormal variation law of potential swings and thus directly providing the evidence that the kinetics gap has been filled up by this kinetically favored anode.Our results represent a crucial step toward understanding the key issues of kinetics mismatch for hybrid cell,thus propelling the development of design of kinetically favored anode materials for high-performance metalion capacitors.

Achieving high dielectric energy-storage properties through a phase coexistence design and viscous polymer process in BNT-based ceramics

In the last few decades,dielectric capacitors have gotten a lot of attention because they can store more power and charge and discharge very quickly.But it has a low energy-storage density(Wrec),efficiency(h),and temperature stability.By adding Pb(Mg1/3Nb2/3)O3(PMN)and(Bi0$1Sr0.85)TiO3(BST)to a nonstoichiometric(Bi0$51Na0.5)TiO3(BNT)matrix,the goal is to change the phase transition properties and make the material more relaxor ferroelectric(RFE)by lowering the remnant polarization Pr and keeping the maximum polarization Pmax.A viscous polymer process(VPP)is used to improve the electric breakdown strength,which is also a key part of being able to store energy.By working together,ceramics with the formula 0.79[0.85BNT-0.15PMN]-0.21BST(BP-0.21BST)are made.The phase structure has been changed from a rhombohedral phase to a rhombohedral-tetragonal coexisted phase.This is beneficial for RFE properties and gives a Wrec of 6.45 J/cm^(3) and a h of 90%at 400 kV/cm.Also,the energy-storage property is very temperature stable between 30 and 150C.These results show that process optimization and composition design can be used to improve the energy storage properties,and that the dielectric ceramic materials made can be used in high-powder pulse dielectric capacitors.

Techno-economic analysis of the Li-ion batteries and reversible fuel cells as energy-storage systems used in green and energy-efficient buildings

Green buildings have become broadly adopted in commercial and residential sectors with the objective of minimizing environmental impacts through reductions in energy usage and water usage and,to a lesser extent,minimizing environmental disturbances from the building site.In this paper,we develop and discuss a techno-economic model for a green commercial building that is 100%powered by a photovoltaic(PV)system in stand-alone configuration.A medium-sized office building in El Paso,TX was modelled to rely on a photovoltaic system to supply all of its electricity needs either directly from the PV system or through an energy-storage system(ESS)using Li-ion batteries(LIBs)or reversible fuel cells(RFCs).Cost results show that a 400-kW PV system can generate electricity at a cost of 2.21 cents/kWh in El Paso,TX and the average levelized cost of energy storage(LCOS)using 450-kW RFC is~31.3 cents/kWh,while this could reach as low as 25.5 cents/kWh using a small LIB ESS.While the RFC provides the flexibility required to meet building-energy demand,LIBs may not be able to meet building needs unless the storage size is increased substantially,which in turn incurs more energy-storage cost,making LIBs less favourable from an economic perspective.Sensitivity analysis revealed that capital cost,discount rate and expected system lifetime play key roles in shaping the LCOS in both systems.

Modeling and Controlling of an Active Power Filter Using Photovoltaic System with Reduced Energy Storage Capacitor

A novel three-phase active power filter （APF） circuit with photovoltaic （PV） system to improve the quality of service and to reduce the capacity of energy storage capacitor is presented. The energy balance concept and sampling technique were used to simplify the calculation algorithm for the required utility source current and to control the voltage of the energy storage capacitor. The feasibility was verified by using the Pspice simulations and experiments. When the APF mode was used during non-operational period, not only the utilization rate, power factor and power quality could be improved, but also the capacity of energy storage capacitor could sparing. As the results, the advantages of the APF circuit are simplicity of control circuits, low cost, and good transient response.

An Overview of Bidirectional DC-DC Converter Topologies and Control Strategies for Interfacing Energy Storage Systems in Microgrids

A microgrid is defined as a local electric power distribution system with diverse DG （distributed generation） units, energy storage systems, and loads, which can operate as a part of the distribution system or when needed can operate in an islanded mode. Energy storage systems play a key role in improving security, stability, and power quality of the microgrid. During grid-connected mode, these storage units are charged from various DG sources as well as the main grid. During islanded mode, DG sources along with the storage units need to supply the load. Power electronic interfaces between the microgrid buses and the storage units should be able to detect the mode of operation, allow seamless transition between the modes, and allow power flow in both directions, while maintaining stability and power quality. An overview of bidirectional converter topologies relevant to microgrid energy storage application and their control strategies will be presented in this paper.

Two-electron redox chemistry enables potassium-free copper hexacyanoferrate as high-capacity cathode for aqueous Mg-ion battery

Prussian blue analogs(PBAs)are potential contestants for aqueous Mg-ion batteries(AMIBs)on account of their high discharge voltage and threedimensional open frameworks.However,the low capacity arising from single reaction site severely restricts PBAs'practical applications in highenergy-density AMIBs.Here,an organic acid co-coordination combined with etching method is reported to fabricate defect-rich potassium-free copper hexacyanoferrate with structural water on carbon nanotube fiber(DCuHCF@CNTF).Benefiting from the high-valence-state reactive sites,arrayed structure and defect effect,the well-designed D-CuHCF@CNTF exhibits an extraordinary reversible capacity of 146.6 mAh g
1 with two-electron reaction,nearly close to its theoretical capacity.It is interesting to unlock the reaction mechanism of the Fe2+/Fe3+and Cu+/Cu2+redox couples via x-ray photoelectron spectroscopy.Furthermore,density functional theory calculations reveal that Fe and Cu in potassium-free D-CuHCF participate in charge transfer during the Mg2+insertion/extraction process.As a proof-of-concept demonstration,a rocking-chair fiber-shaped AMIBs was constructed via coupling with the NaTi2(PO4)3/CNTF anode,achieving high energy density and impressive mechanical flexibility.This work provides new possibilities to develop potassium-free PBAs with dual-active sites as high-capacity cathodes for wearable AMIBs.

Solar-absorbing metamaterial microencapsulation of phase change materials for thermo-regulating textiles

This paper presents a novel concept for designing solar-absorbing metamaterial microcapsules of phase change materials(PCMs)integrated with thermo-regulating smart textiles intended for coats or garments,especially for wear in space or cold weather on earth.The metamaterial is a periodically nanostructured metal-dielectric-metal thin film and can acquire surface plasmons to trap or absorb solar energy at subwavelength scales.This kind of metamaterial microencapsulation is not only able to take advantage of latent heat that can be stored or released from the PCMs over a tunable temperature range,but also has other advantages over conventional polymer microencapsulation of PCMs,such as enhanced thermal conductivity,improved flame-retardant capabilities,and usage as an extra solar power resource.The thermal analysis for this kind of microencapsulation has been done and can be used as a guideline for designing integrated thermo-regulating smart textiles in the future.These metamaterial microcapsules may open up new routes to enhancing thermo-regulating textiles with novel properties and added value.