Li metal batteries using high-voltage layered oxides cathodes are of particular interest due to their high energy density.However,they suffer from short lifespan and extreme safety concerns,which are attributed to the...Li metal batteries using high-voltage layered oxides cathodes are of particular interest due to their high energy density.However,they suffer from short lifespan and extreme safety concerns,which are attributed to the degradation of layered oxides and the decomposition of electrolyte at high voltage,as well as the high reactivity of metallic Li.The key is the development of stable electrolytes against both highvoltage cathodes and Li with the formation of robust interphase films on the surfaces.Herein,we report a highly fluorinated ether,1,1,1-trifluoro-2-[(2,2,2-trifluoroethoxy)methoxy]ethane(TTME),as a cosolvent,which not only functions as a diluent forming a localized high concentration electrolyte(LHCE),but also participates in the construction of the inner solvation structure.The TTME-based electrolyte is stable itself at high voltage and induces the formation of a unique double-layer solid electrolyte interphase(SEI)film,which is embodied as one layer rich in crystalline structural components for enhanced mechanical strength and another amorphous layer with a higher concentration of organic components for enhanced flexibility.The Li||Cu cells display a noticeably high Coulombic efficiency of 99.28%after 300 cycles and Li symmetric cells maintain stable cycling more than 3200 h at 0.5 mA/cm^(2) and 1.0m Ah/cm^(2).In addition,lithium metal cells using LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) and Li CoO_(2) cathodes(both loadings~3.0 m Ah/cm^(2))realize capacity retentions of>85%over 240 cycles with a charge cut-off voltage of 4.4 V and 90%for 170 cycles with a charge cut-off voltage of 4.5 V,respectively.This study offers a bifunctional ether-based electrolyte solvent beneficial for high-voltage Li metal batteries.展开更多
Silicon monoxide(SiO)is regarded as a potential candidate for anode materials of lithium-ion batteries(LIBs).Unfortunately,the application of SiO is limited by poor initial Coulombic efficiency(ICE)and unsteady solid ...Silicon monoxide(SiO)is regarded as a potential candidate for anode materials of lithium-ion batteries(LIBs).Unfortunately,the application of SiO is limited by poor initial Coulombic efficiency(ICE)and unsteady solid electrolyte interface(SEI),which induce low energy,short cycling life,and poor rate properties.To address these drawbacks of SiO,we achieve in-situ construction of robust and fast-ion conducting F,N-rich SEI layer on prelithiated micro-sized SiO(P-μSiO)via the simple and continuous treatment ofμSiO in mild lithium 4,4′-dimethylbiphenyl solution and nonflammable hexafluorocyclotriphosphazene solution.Chemical prelithiation eliminates irreversible capacity through pre-forming inactive lithium silicates.Meanwhile,the symbiotic F,N-rich SEI with good mechanical stability and fast Li^(+)permeability is conductive to relieve volume expansion ofμSiO and boost the Li+diffusion kinetics.Consequently,the P-μSiO realizes an impressive electrochemical performance with an elevated ICE of 99.57%and a capacity retention of 90.67%after 350 cycles.Additionally,the full cell with P-μSiO anode and commercial LiFePO_(4) cathode displays an ICE of 92.03%and a high reversible capacity of 144.97 mA h g^(-1).This work offers a general construction strategy of robust and ionically conductive SEI for advanced LIBs.展开更多
Aqueous zinc-ion battery systems are attractive for next-generation energy storage devices,however,the unstable electrode electrolyte interphase,especially cathode electrolyte interphase(CEI),has induced rapid capacit...Aqueous zinc-ion battery systems are attractive for next-generation energy storage devices,however,the unstable electrode electrolyte interphase,especially cathode electrolyte interphase(CEI),has induced rapid capacity attenuation,insufficient cycle life,and severe safety issues.Evolving the researching of CEI formation,composition,dynamic structure,and reaction mechanisms would help in understanding the fundamental electrochemistry at CEI such as electron and ion transport processes,further strengthening the specific capacity,rate,and cycle performance of the cathode materials.In this review,we summarized the latest progress in understanding interfacial reaction mechanisms and ion dynamic behavior,emphasizing the impact of surface-specific adsorption and solvation behaviors on the interface's ultimate structure and chemical composition.Subsequently,the significant challenges that persist in CEI formation mechanisms,such as cathodic dissolution,by-product formation,electrostatic interactions,constrained electrochemical windows,oxygen evolution reaction,overpotentials,phase transitions,and additional factors,were discussed.These challenges are explored to identify triggers contributing to the depletion of active materials and alterations in the composition or state of the CEI.Ultimately,with a deep comprehension of interfacial behaviors,the review articulates innovative optimization strategies through a detailed categorization of approaches in electrolyte engineering,cathode engineering,and artificial CEI development.Furthermore,future challenges and development directions of CEI are presented.We hope to offer insights for constructing robust CEI films to achieve high performance aqueous zinc-ion batteries.展开更多
The replacement of Li by Na in an analogue battery to the commercial Li-ion one appears a sustainable strategy to overcome the several concerns triggered by the increased demand for the electrochemical energy storage....The replacement of Li by Na in an analogue battery to the commercial Li-ion one appears a sustainable strategy to overcome the several concerns triggered by the increased demand for the electrochemical energy storage.However,the apparently simple change of the alkali metal represents a challenging step which requires notable and dedicated studies.Therefore,we investigate herein the features of a NaFe_(0.6)Mn_(0.4)PO_(4)(NFMP)cathode with triphylite structure achieved from the conversion of a LiFe0.6Mn0.4PO4(LFMP)olivine for application in Na-ion battery.The work initially characterizes the structure,morphology and performances in sodium cell of NFMP,achieving a maximum capacity exceeding 100 mAh g^(−1)at a temperature of 55℃,adequate rate capability,and suitable retention confirmed by ex-situ measurements.Subsequently,the study compares in parallel key parameters of the NFMP and LFMP such as Na^(+)/Li^(+)ions diffusion,interfacial characteristics,and reaction mechanism in Na/Li cells using various electrochemical techniques.The data reveal that relatively limited modifications of NFMP chemistry,structure and morphology compared to LFMP greatly impact the reaction mechanism,kinetics and electrochemical features.These changes are ascribed to the different physical and chemical features of the two compounds,the slower mobility of Na^(+)with respect to Li^(+),and a more resistive electrode/electrolyte interphase of sodium compared with lithium.Relevantly,the study reveals analogue trends of the charge transfer resistance and the ion diffusion coefficient in NFMP and LFMP during the electrochemical process in half-cell.Hence,the NFMP achieved herein is suggested as a possible candidate for application in a low-cost,efficient,and environmentally friendly Na-ion battery.展开更多
Building a stable solid electrolyte interphase(SEI)has been regarded to be highly effective for mitigating the dendrite growth and parasitic side reactions of Zn anodes.Herein,a robust inorganic composite SEI layer is...Building a stable solid electrolyte interphase(SEI)has been regarded to be highly effective for mitigating the dendrite growth and parasitic side reactions of Zn anodes.Herein,a robust inorganic composite SEI layer is in situ constructed by introducing an organic cysteine additive to achieve long lifetime Zn metal batteries.The chemisorbed cysteine derivatives are electrochemically reduced to trigger a local alkaline environment for generating a gradient layered zinc hydroxide based multicomponent interphase.Such a unique interphase is of significant advantage as a corrosion inhibitor and Zn^(2+)modulator to enable reversible plating/stripping chemistry with a reduced desolvation energy barrier.Accordingly,the cells with a thin glass fiber separator(260μm)deliver a prolonged lifespan beyond 2000 h and enhanced Coulombic efficiency of 99.5%over 450 cycles.This work will rationally elaborate in situ construction of a desirable SEI by implanting reductive additives for dendrite-free Zn anodes.展开更多
The practical applications of zinc metal batteries are plagued by the dendritic propagation of its metal anodes due to the limited transfer rate of charge and mass at the electrode/electrolyte interphase.To enhance th...The practical applications of zinc metal batteries are plagued by the dendritic propagation of its metal anodes due to the limited transfer rate of charge and mass at the electrode/electrolyte interphase.To enhance the reversibility of Zn metal,a quasi-solid interphase composed by defective metal-organic framework(MOF)nanoparticles(D-UiO-66)and two kinds of zinc salts electrolytes is fabricated on the Zn surface served as a zinc ions reservoir.Particularly,anions in the aqueous electrolytes could be spontaneously anchored onto the Lewis acidic sites in defective MOF channels.With the synergistic effect between the MOF channels and the anchored anions,Zn^(2+)transport is prompted significantly.Simultaneously,such quasi-solid interphase boost charge and mass transfer of Zn^(2+),leading to a high zinc transference number,good ionic conductivity,and high Zn^(2+)concentration near the anode,which mitigates Zn dendrite growth obviously.Encouragingly,unprecedented average coulombic efficiency of 99.8%is achieved in the Zn||Cu cell with the proposed quasi-solid interphase.The cycling performance of D-UiO-66@Zn||MnO_(2)(~92.9%capacity retention after 2000 cycles)and D-UiO-66@Zn||NH_(4)V_(4)O_(10)(~84.0%capacity retention after 800 cycles)prove the feasibility of the quasi-solid interphase.展开更多
The solid electrolyte interphase(SEI)with strong mechanical strength and high ion conductivity is highly desired for Li metal batteries,especially for harsh anode-free batteries.Herein,we report a pragmatic approach t...The solid electrolyte interphase(SEI)with strong mechanical strength and high ion conductivity is highly desired for Li metal batteries,especially for harsh anode-free batteries.Herein,we report a pragmatic approach to the in-situ construction of high-quality SEI by applying synergistic additives of Li NO_(3)and ethylene sulfite(ES)in the electrolyte.The obtained SEI exhibits a high average Young’s modulus(9.02GPa)and exchanging current density(4.59 mA cm^(-2)),which are 3.0 and 1.2 times as large as those using the sole additive of LiNO_(3),respectively.With this improved SEI,Li-dendrite growth and side reactions are effectively suppressed,leading to an ultra-high Coulombic efficiency(CE)of 99.7%for Li plating and stripping.When applying this improved electrolyte in full cells,it achieves a high capacity retention of 89.7%for over 150 cycles in a LiFePO_(4)||Li battery(~12 mg cm^(-2)cathode,50μm Li)and of 44.5%over 100 cycles in a LiFePO_(4)||Cu anode-free battery.展开更多
The resourceful and inexpensive red phosphorus has emerged as a promising anode material of potassium-ion batteries(PIBs) for its large theoretical capacities and low redox potentials in the multielectron alloying/dea...The resourceful and inexpensive red phosphorus has emerged as a promising anode material of potassium-ion batteries(PIBs) for its large theoretical capacities and low redox potentials in the multielectron alloying/dealloying reactions,yet chronically suffering from the huge volume expansion/shrinkage with a sluggish reaction kinetics and an unsatisfactory interfacial stability against volatile electrolytes.Herein,we systematically developed a series of localized high-concentration electrolytes(LHCE) through diluting high-concentration ether electrolytes with a non-solvating fluorinated ether to regulate the formation/evolution of solid electrolyte interphases(SEI) on phosphorus/carbon(P/C) anodes for PIBs.Benefitting from the improved mechanical strength and structural stability of a robust/uniform SEI thin layer derived from a composition-optimized LHCE featured with a unique solvation structure and a superior K+migration capability,the P/C anode with noticeable pseudocapacitive behaviors could achieve a large reversible capacity of 760 mA h g^(-1)at 100 mA g^(-1),a remarkable capacity retention rate of 92.6% over 200 cycles at 800 mA g^(-1),and an exceptional rate capability of 334 mA h g^(-1)at8000 mA g^(-1).Critically,a suppressed reduction of ether solvents with a preferential decomposition of potassium salts in anion-derived interfacial reactions on P/C anode for LHCE could enable a rational construction of an outer organic-rich and inner inorganic-dominant SEI thin film with remarkable mechanical strength/flexibility to buffer huge volume variations and abundant K+diffusion channels to accelerate reaction kinetics.Additionally,the highly reversible/durable full PIBs coupling P/C anodes with annealed organic cathodes further verified an excellent practical applicability of LHCE.This encouraging work on electrolytes regulating SEI formation/evolution would advance the development of P/C anodes for high-performance PIBs.展开更多
Lithium sulfur batteries are regarded as a promising candidate for high-energy-density energy storage devices.However,the lithium metal anode in lithium-sulfur batteries encounters the problem of lithium dendrites and...Lithium sulfur batteries are regarded as a promising candidate for high-energy-density energy storage devices.However,the lithium metal anode in lithium-sulfur batteries encounters the problem of lithium dendrites and lithium metal consumption caused by polysulfide corrosion.Herein we design a dualfunction PMMA/PPC/LiNO3composite as an artificial solid electrolyte interphase(PMCN-SEI)to protect Li metal anode.This SEI offers multiple sites of C=O for polysulfide anchoring to constrain corrosion of Li metal anode.The lithiated polymer group and Li3N in PMCN-SEI can homogenize lithium-ion deposition behavior to achieve a dendrite-free anode.As a result,the PMCN-SEI protected Li metal anode enables the Li||Li symmetric batteries to maintain over 300 cycles(1300 h)at a capacity of 5 m Ah cm^(-2),corresponding to a cumulative capacity of 3.25 Ah cm^(-2).Moreover,Li-S batteries assembled with 20μm of Li metal anode(N/P=1.67)still deliver an initial capacity of 1166 m A h g-1at 0.5C.Hence,introducing polycarbonate polymer/inorganic composite SEI on Li provides a new solution for achieving the high energy density of Li-S batteries.展开更多
The high concentration electrolytes with specific solvation structure could passivate the electrodes to prolong battery cycle life but at the expense of increased cost,which limits the wide application in commercializ...The high concentration electrolytes with specific solvation structure could passivate the electrodes to prolong battery cycle life but at the expense of increased cost,which limits the wide application in commercialization.The regular concentration(1_(M))electrolytes with suitable properties(viscosity,ionic conductivity,etc.)are cost-guaranteed,but undesired reactions would always occur and lead to battery degradation during long cycles.To promote the long-term cycle stability in a cost-effective way,this work constructs bidirectional fluorine-rich electrode/electrolyte interphase(EEI)by redistribution of solvents and electrochemical induction.The fluorinated effect with reasonable zoning planning restricts morphological disintegration,meanwhile,forms spatial confinement on cathode.In particular,the obtained cathode electrolyte interphase(CEI)gets the ample ability of Na^(+)transport,which benefits from the fluorinated organics arranged in the epitaxy and the hemi-carbonate content acting on the thickness.Thus,the electrochemical long cycling performance of F-NVPOFⅡF-CC full cells is significantly enhanced(the decay rate at 1 C per cycle is as low as 0.01%).Such a fluorine-rich EEI engineering is expected to take transitional layers against the degradation of cells and make ultra-long cycle batteries possible.展开更多
Ethers are promising electrolyte solvents for secondary Li metal batteries because of their excellent reduction stability.However,their oxidation stability has been mostly relying on the high concentration approach,an...Ethers are promising electrolyte solvents for secondary Li metal batteries because of their excellent reduction stability.However,their oxidation stability has been mostly relying on the high concentration approach,and limited progress has been made on building effective interphase to protect the cathode from the corrosion of the electrolyte.In this work,we construct a semi-crystalline interfacial layer on the surface of Li(Ni_(0.8)Co_(0.1)Mn_(0.1))O_(2)cathode that can achieve improved electrochemical stability in the highly corrosive chemical environment formed by the decomposition of ether molecules.Different from traditional brittle crystalline interphases,the optimized semi-crystalline layer with low modulus and high ionic conductivity can effectively relieve electrode strain and maintain the integrity of the interface layer.Due to this design,the continuous oxidation decomposition of ether-based electrolytes could be significantly suppressed and the battery shows outstanding cycling stability(84%capacity retention after 300 cycles).This article provides a solution to address the oxidation instability issue of ether-based electrolytes.展开更多
Silicon(Si)is a potential high-capacity anode material for the next-generation lithium-ion battery with high energy density.However,Si anodes suff er from severe interfacial chemistry issues,such as side reactions at ...Silicon(Si)is a potential high-capacity anode material for the next-generation lithium-ion battery with high energy density.However,Si anodes suff er from severe interfacial chemistry issues,such as side reactions at the electrode/electrolyte interface,leading to poor electrochemical cycling stability.Herein,we demonstrate the fabrication of a conformal fl uorine-containing carbon(FC)layer on Si particles(Si-FC)and its in situ electrochemical conversion into a LiF-rich carbon layer above 1.5 V(vs.Li^(+)/Li).The as-formed LiF-rich carbon layer not only isolates the active Si and electrolytes,leading to the suppression of side reactions,but also induces the formation of a robust solid-electrolyte interface(SEI),leading to the stable interfacial chemistry of as-designed Si-FC particles.The Si-FC electrode has a high initial Coulombic effi ciency(CE)of 84.8%and a high reversible capacity of 1450 mAh/g at 0.4 C(1000 mA/g)for 300 cycles.In addition,a hybrid electrode consisting of 85 wt%graphite and 15 wt%Si-FC,and mass 2.3 mg/cm^(2) loading delivers a high areal capacity of 2.0 mAh/cm^(2) and a high-capacity retention of 93.2%after 100 cycles,showing the prospects for practical use.展开更多
Li metal batteries are supposed to reach real application in order to fulfill the high-energy density requirement of energy storage system.Unfortunately,the commonly used carbonate electrolyte react with pristine Li,w...Li metal batteries are supposed to reach real application in order to fulfill the high-energy density requirement of energy storage system.Unfortunately,the commonly used carbonate electrolyte react with pristine Li,which result in short lifetime of lithium metal battery.To alleviate the side reactions of Li metal with liquid electrolyte,here we propose a phosphate rich polymer-inorganic layer as an interphase.Due to the inert properties of lithium phosphate derived from LiPO_(2)F_(2)and poly-ether,the side-reaction of carbonate solvent are prevented.As a result,lithium metal anode sustains for 800 cycles in symmetrical cell test under 1 m A cm^(-2).Even under strict condition(20μm Li,capacity ratio N/P=2.3,electrolyte/active material=3μL mg^(-1)),coin cell test still runs stable for 150 cycles with high Coulombic efficiency.Furthermore,both LiFePO_(4)and LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)pouch cell under 5μL m A^(-1)h^(-1)condition also exhibit good stability at 0.5 C and 2 C rate.With this approach,high-energy and high-power Li metal batteries are approaching to real application in the near future.展开更多
The stability and uniformity of solid electrolyte interphase(SEI)are critical for clarifying the origin of capacity fade and safety issues for lithium metal anodes(LMA).However,understanding the interplay of SEI heter...The stability and uniformity of solid electrolyte interphase(SEI)are critical for clarifying the origin of capacity fade and safety issues for lithium metal anodes(LMA).However,understanding the interplay of SEI heterogeneity and Li electrodeposition is limited by the coupling of complex electrochemistry and mechanics processes.Herein,the correlation between the SEI failure behavior and Li deposition morphology is investigated through a quantitative electrochemical-mechanical model.The local deformation and stress of SEI during Li electrodeposition identify that the heterogeneous interface between different components first fails.Compared with the well-known mechanical strength,component uniformity plays the most important role in the initial SEI failure and uneven Li deposition,and a relative component uniformity(p>0.01)represents a proper balance to ensure the stability of the naturally heterogeneous SEI.Furthermore,the component regulation of SEI via the designed electrolyte experimentally demonstrates that improving component uniformity benefits SEI stability and the uniform Li electrodeposition for LMA,thereby increasing the capacity by~20%after 300 cycles.These fundamental understandings and proposed strategy can be not only used to guide the SEI optimization via the electrolyte regulation,but also extended to the rational designs of artificial SEI for high-performance LMA.展开更多
B-containing electrolyte additives are widely used to enhance the cycle performance at low temperature and the rate capability of lithium-ion batteries by constructing an efficient cathode electrolyte interphase(CEI)t...B-containing electrolyte additives are widely used to enhance the cycle performance at low temperature and the rate capability of lithium-ion batteries by constructing an efficient cathode electrolyte interphase(CEI)to facilitate the rapid Li+migration.Nevertheless,its wide-temperature application has been limited by the instability of B-derived CEI layer at high temperature.Herein,dual electrolyte additives,consisting of lithium tetraborate(Li_(2)TB)and 2,4-difluorobiphenyl(FBP),are proposed to boost the widetemperature performances of LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM)cathode.Theoretical calculation and electrochemical performances analyses indicate that Li_(2)TB and FBP undergo successive decomposition to form a unique dual-layer CEI.FBP acts as a synergistic filming additive to Li_(2)TB,enhancing the hightemperature performance of NCM cathode while preserving the excellent low-temperature cycle stability and the superior rate capability conferred by Li_(2)TB additive.Therefore,the capacity retention of NCM‖Li cells using optimal FBP-Li_(2)TB dual electrolyte additives increases to 100%after 200 cycles at-10℃,99%after 200 cycles at 25℃,and 83%after 100 cycles at 55℃,respectively,much superior to that of base electrolyte(63%/69%/45%).More surprisingly,galvanostatic c ha rge/discharge experiments at different temperatures reveal that NCM‖Li cells using FBP-Li_(2)TB additives can operate at temperatures ranging from-40℃to 60℃.This synergistic interphase modification utilizing dual electrolyte additives to construct a unique dual-layer CEI adaptive to a wide temperature range,provides valuable insights to the practical applications of NCM cathodes for all-climate batteries.展开更多
One of the key challenges for achieving stable lithium(Li) metal anode is the construction of the rational solid electrolyte interphase(SEI),but its realization still faces enormous challenges.In this work,a robust ar...One of the key challenges for achieving stable lithium(Li) metal anode is the construction of the rational solid electrolyte interphase(SEI),but its realization still faces enormous challenges.In this work,a robust artificial fluorinated hybrid interphase consisting of lithium-bismuth(Li3Bi) alloy and lithium-fluoride(LiF) was designed to regulate Li deposition without Li dendrite growth.The obtained hybrid interphase showed the high Li+diffusion rate(3.5 × 10^(-4)S cm^(-1)),high electron resistivity(9.04 × 10^(4)Ω cm),and high mechanical strength(1348 MPa),thus enabling the uniform Li deposition at the Li/SEI interface.Specifically,Li3Bi alloy,as a superionic conductor,accelerated the Li+transport and stabilized the hybrid interphase.Meanwhile,LiF was identified as a superior electron-blocker to inhibit the electron tunneling from the Li anode into the SEI.As a result,the modified Li anode showed the stable Li plating/stripping behaviors over 1000 cycles even at 20 mA cm^(-2).Moreover,it also enabled the Li(50 μm)‖LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(4.4 mA h cm^(-2)) full cell to achieve an average Coulombic efficiency(CE) of 99.6%and a high-capacity retention of 79.2% after 100 cycles,whereas the bare Li anode only exhibited a low-capacity retention of 8.0%.This work sheds light on the internal mechanism of Li+transport within the hybrid interface and provides an effective approach to stabilize the interface of Li metal anode.展开更多
The initial shape of the secondary arc considerably influences its subsequent shape.To establish the model for the arcing time of the secondary arc and modify the single-phase reclosing sequence,theoretical and experi...The initial shape of the secondary arc considerably influences its subsequent shape.To establish the model for the arcing time of the secondary arc and modify the single-phase reclosing sequence,theoretical and experimental analysis of the evolution process of the short-circuit arc to the secondary arc is critical.In this study,an improved charge simulation method was used to develop the internal-space electric-field model of the short-circuit arc.The intensity of the electric field was used as an independent variable to describe the initial shape of the secondary arc.A secondary arc evolution model was developed based on this model.Moreover,the accuracy of the model was evaluated by comparison with physical experimental results.When the secondary arc current increased,the arcing time and dispersion increased.There is an overall trend of increasing arc length with increasing arcing time.Nevertheless,there is a reduction in arc length during arc ignition due to short circuits between the arc columns.Furthermore,the arcing time decreased in the range of 0°-90°as the angle between the wind direction and the x-axis increased.This work investigated the method by which short-circuit arcs evolve into secondary arcs.The results can be used to develop the secondary arc evolution model and to provide both a technical and theoretical basis for secondary arc suppression.展开更多
In gas metal arc welding(GMAW)process,the short-circuit transition was the most typical transition observed in molten metal droplets.This paper used orthogonal tests to explore the coupling effect law of welding proce...In gas metal arc welding(GMAW)process,the short-circuit transition was the most typical transition observed in molten metal droplets.This paper used orthogonal tests to explore the coupling effect law of welding process parameters on the quality of weld forming under short-circuit transition,the design of 3 factors and 3 levels of a total of 9 groups of orthogonal tests,welding current,welding voltage,welding speed as input parameters:effective area ratio,humps,actual linear power density,aspect ratio,Vickers hardness as output paramet-ers(response targets).Using range analysis and trend charts,we can visually depict the relationship between input parameters and a single output parameter,ultimately determining the optimal process parameters that impact the single output index.Then combined with gray the-ory to transform the three response targets into a single gray relational grade(GRG)for analysis,the optimal combination of the weld mor-phology parameters as follows:welding current 100 A,welding voltage 25 V,welding speed 30 cm/min.Finally,validation experiments were conducted,and the results showed that the error between the gray relational grade and the predicted value was 2.74%.It was observed that the effective area ratio of the response target significantly improved,validating the reliability of the orthogonal gray relational method.展开更多
Aiming at the problemthat the traditional short-circuit current calculationmethod is not applicable to Distributed Generation(DG)accessing the distribution network,the paper proposes a short-circuit current partitioni...Aiming at the problemthat the traditional short-circuit current calculationmethod is not applicable to Distributed Generation(DG)accessing the distribution network,the paper proposes a short-circuit current partitioning calculation method considering the degree of voltage drop at the grid-connected point of DG.Firstly,the output characteristics of DG in the process of low voltage ride through are analyzed,and the equivalent output model of DG in the fault state is obtained.Secondly,by studying the network voltage distribution law after fault in distribution networks under different DG penetration rates,the degree of voltage drop at the grid-connected point of DG is used as a partition index to partition the distribution network.Then,iterative computation is performed within each partition,and data are transferred between partitions through split nodes to realize the fast partition calculation of short-circuit current for high proportion DG access to distribution network,which solves the problems of long iteration time and large calculation error of traditional short-circuit current.Finally,a 62-node real distribution network model containing a high proportion of DG access is constructed onMATLAB/Simulink,and the simulation verifies the effectiveness of the short-circuit current partitioning calculation method proposed in the paper,and its calculation speed is improved by 48.35%compared with the global iteration method.展开更多
In the present paper, based on the two-phase model (Eulerian model), the two dimensional fluid flow liz air-stirred water systems is simulated, and the effect of interphase lift force on the fluid flow is specially d...In the present paper, based on the two-phase model (Eulerian model), the two dimensional fluid flow liz air-stirred water systems is simulated, and the effect of interphase lift force on the fluid flow is specially discussed. In the Eulerian two-phase model, gas and liquid phase are considered to be two different continuous fluids interacting with each other through the finite inter-phase areas. The exchange between the phases is represented by source terms in conversation equations. Turbulence is assumed to be a property of the liquid phase, k - ε model is used to describe the behavior of the liquid phase. The dispersion of phases due to turbulence is represented by introducing a diffusion term in mass consecrvation equation. The contribution of bubble movement to the turbulent energy and its dissipation rate is taken into accounted by adding extra volumetric source terms to the equations of turbulent enemy and its dissipation rate. The comparison between the mathematical simulation and experiment data indicates that the interphase lift force has a big effect on the flow behavior, and considering both drug force and lift force as interphase forces is important to accurately simulate the gas-water two-phase fluid flow in air-stirred systems. The interphase lift force makes bubbles move away from the centerline, the gas concentration is decreased near the centerline, and increased near the wall. The lift force is smaller than drug force at the same place, especially far away from the centerline.展开更多
基金the financial supports from the KeyArea Research and Development Program of Guangdong Province (2020B090919001)the National Natural Science Foundation of China (22078144)the Guangdong Natural Science Foundation for Basic and Applied Basic Research (2021A1515010138 and 2023A1515010686)。
文摘Li metal batteries using high-voltage layered oxides cathodes are of particular interest due to their high energy density.However,they suffer from short lifespan and extreme safety concerns,which are attributed to the degradation of layered oxides and the decomposition of electrolyte at high voltage,as well as the high reactivity of metallic Li.The key is the development of stable electrolytes against both highvoltage cathodes and Li with the formation of robust interphase films on the surfaces.Herein,we report a highly fluorinated ether,1,1,1-trifluoro-2-[(2,2,2-trifluoroethoxy)methoxy]ethane(TTME),as a cosolvent,which not only functions as a diluent forming a localized high concentration electrolyte(LHCE),but also participates in the construction of the inner solvation structure.The TTME-based electrolyte is stable itself at high voltage and induces the formation of a unique double-layer solid electrolyte interphase(SEI)film,which is embodied as one layer rich in crystalline structural components for enhanced mechanical strength and another amorphous layer with a higher concentration of organic components for enhanced flexibility.The Li||Cu cells display a noticeably high Coulombic efficiency of 99.28%after 300 cycles and Li symmetric cells maintain stable cycling more than 3200 h at 0.5 mA/cm^(2) and 1.0m Ah/cm^(2).In addition,lithium metal cells using LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) and Li CoO_(2) cathodes(both loadings~3.0 m Ah/cm^(2))realize capacity retentions of>85%over 240 cycles with a charge cut-off voltage of 4.4 V and 90%for 170 cycles with a charge cut-off voltage of 4.5 V,respectively.This study offers a bifunctional ether-based electrolyte solvent beneficial for high-voltage Li metal batteries.
基金financially supported by the National Natural Science Foundation of China(Nos.51972198 and 62133007)the Natural Science Foundation of Shandong Province(ZR2020JQ19)the Taishan Scholars Program of Shandong Province(Nos.tsqn201812002 and ts20190908)。
文摘Silicon monoxide(SiO)is regarded as a potential candidate for anode materials of lithium-ion batteries(LIBs).Unfortunately,the application of SiO is limited by poor initial Coulombic efficiency(ICE)and unsteady solid electrolyte interface(SEI),which induce low energy,short cycling life,and poor rate properties.To address these drawbacks of SiO,we achieve in-situ construction of robust and fast-ion conducting F,N-rich SEI layer on prelithiated micro-sized SiO(P-μSiO)via the simple and continuous treatment ofμSiO in mild lithium 4,4′-dimethylbiphenyl solution and nonflammable hexafluorocyclotriphosphazene solution.Chemical prelithiation eliminates irreversible capacity through pre-forming inactive lithium silicates.Meanwhile,the symbiotic F,N-rich SEI with good mechanical stability and fast Li^(+)permeability is conductive to relieve volume expansion ofμSiO and boost the Li+diffusion kinetics.Consequently,the P-μSiO realizes an impressive electrochemical performance with an elevated ICE of 99.57%and a capacity retention of 90.67%after 350 cycles.Additionally,the full cell with P-μSiO anode and commercial LiFePO_(4) cathode displays an ICE of 92.03%and a high reversible capacity of 144.97 mA h g^(-1).This work offers a general construction strategy of robust and ionically conductive SEI for advanced LIBs.
基金supported by the Fundamental Research Funds for the Central Universities,Natural Science Foundation of China(Nos.52202100 and U2004209)China Postdoctoral Science Foundation(No.314500)Postgraduate Research&Practice Innovation Program of Jiangsu Province(Nos.KYCX23_0451).
文摘Aqueous zinc-ion battery systems are attractive for next-generation energy storage devices,however,the unstable electrode electrolyte interphase,especially cathode electrolyte interphase(CEI),has induced rapid capacity attenuation,insufficient cycle life,and severe safety issues.Evolving the researching of CEI formation,composition,dynamic structure,and reaction mechanisms would help in understanding the fundamental electrochemistry at CEI such as electron and ion transport processes,further strengthening the specific capacity,rate,and cycle performance of the cathode materials.In this review,we summarized the latest progress in understanding interfacial reaction mechanisms and ion dynamic behavior,emphasizing the impact of surface-specific adsorption and solvation behaviors on the interface's ultimate structure and chemical composition.Subsequently,the significant challenges that persist in CEI formation mechanisms,such as cathodic dissolution,by-product formation,electrostatic interactions,constrained electrochemical windows,oxygen evolution reaction,overpotentials,phase transitions,and additional factors,were discussed.These challenges are explored to identify triggers contributing to the depletion of active materials and alterations in the composition or state of the CEI.Ultimately,with a deep comprehension of interfacial behaviors,the review articulates innovative optimization strategies through a detailed categorization of approaches in electrolyte engineering,cathode engineering,and artificial CEI development.Furthermore,future challenges and development directions of CEI are presented.We hope to offer insights for constructing robust CEI films to achieve high performance aqueous zinc-ion batteries.
基金The work was performed within the grant“Fondo di Ateneo per la Ricerca Locale(FAR)2022”,University of Ferrara,and the collaboration project“Accordo di Collaborazione Quadro 2015”between University of Ferrara(Department of Chemical and Pharmaceutical Sciences)and Sapienza University of Rome(Department of Chemistry)J.H.and V.M.thank the European Union’s Horizon 2020 research and innovation programme Graphene Flagship,grant agreement No 881603.
文摘The replacement of Li by Na in an analogue battery to the commercial Li-ion one appears a sustainable strategy to overcome the several concerns triggered by the increased demand for the electrochemical energy storage.However,the apparently simple change of the alkali metal represents a challenging step which requires notable and dedicated studies.Therefore,we investigate herein the features of a NaFe_(0.6)Mn_(0.4)PO_(4)(NFMP)cathode with triphylite structure achieved from the conversion of a LiFe0.6Mn0.4PO4(LFMP)olivine for application in Na-ion battery.The work initially characterizes the structure,morphology and performances in sodium cell of NFMP,achieving a maximum capacity exceeding 100 mAh g^(−1)at a temperature of 55℃,adequate rate capability,and suitable retention confirmed by ex-situ measurements.Subsequently,the study compares in parallel key parameters of the NFMP and LFMP such as Na^(+)/Li^(+)ions diffusion,interfacial characteristics,and reaction mechanism in Na/Li cells using various electrochemical techniques.The data reveal that relatively limited modifications of NFMP chemistry,structure and morphology compared to LFMP greatly impact the reaction mechanism,kinetics and electrochemical features.These changes are ascribed to the different physical and chemical features of the two compounds,the slower mobility of Na^(+)with respect to Li^(+),and a more resistive electrode/electrolyte interphase of sodium compared with lithium.Relevantly,the study reveals analogue trends of the charge transfer resistance and the ion diffusion coefficient in NFMP and LFMP during the electrochemical process in half-cell.Hence,the NFMP achieved herein is suggested as a possible candidate for application in a low-cost,efficient,and environmentally friendly Na-ion battery.
基金financially supported by the National Natural Foundation of China(Nos.52272239 and 51821091)the Fundamental Research Funds for the Central Universities(Nos.D5000210894 and 3102019JC005)the testing fund from the Analytical&Testing Center of Northwestern Polytechnical University。
文摘Building a stable solid electrolyte interphase(SEI)has been regarded to be highly effective for mitigating the dendrite growth and parasitic side reactions of Zn anodes.Herein,a robust inorganic composite SEI layer is in situ constructed by introducing an organic cysteine additive to achieve long lifetime Zn metal batteries.The chemisorbed cysteine derivatives are electrochemically reduced to trigger a local alkaline environment for generating a gradient layered zinc hydroxide based multicomponent interphase.Such a unique interphase is of significant advantage as a corrosion inhibitor and Zn^(2+)modulator to enable reversible plating/stripping chemistry with a reduced desolvation energy barrier.Accordingly,the cells with a thin glass fiber separator(260μm)deliver a prolonged lifespan beyond 2000 h and enhanced Coulombic efficiency of 99.5%over 450 cycles.This work will rationally elaborate in situ construction of a desirable SEI by implanting reductive additives for dendrite-free Zn anodes.
基金supported by Zhejiang University K.P.Chao’s High Technology Development Foundation.
文摘The practical applications of zinc metal batteries are plagued by the dendritic propagation of its metal anodes due to the limited transfer rate of charge and mass at the electrode/electrolyte interphase.To enhance the reversibility of Zn metal,a quasi-solid interphase composed by defective metal-organic framework(MOF)nanoparticles(D-UiO-66)and two kinds of zinc salts electrolytes is fabricated on the Zn surface served as a zinc ions reservoir.Particularly,anions in the aqueous electrolytes could be spontaneously anchored onto the Lewis acidic sites in defective MOF channels.With the synergistic effect between the MOF channels and the anchored anions,Zn^(2+)transport is prompted significantly.Simultaneously,such quasi-solid interphase boost charge and mass transfer of Zn^(2+),leading to a high zinc transference number,good ionic conductivity,and high Zn^(2+)concentration near the anode,which mitigates Zn dendrite growth obviously.Encouragingly,unprecedented average coulombic efficiency of 99.8%is achieved in the Zn||Cu cell with the proposed quasi-solid interphase.The cycling performance of D-UiO-66@Zn||MnO_(2)(~92.9%capacity retention after 2000 cycles)and D-UiO-66@Zn||NH_(4)V_(4)O_(10)(~84.0%capacity retention after 800 cycles)prove the feasibility of the quasi-solid interphase.
基金supported by the National Natural Science Foundation of China(21975207,52202303)the Westlake Education Foundation,and the Zhejiang Provincial Natural Science Foundation of China(LQ21B030006)。
文摘The solid electrolyte interphase(SEI)with strong mechanical strength and high ion conductivity is highly desired for Li metal batteries,especially for harsh anode-free batteries.Herein,we report a pragmatic approach to the in-situ construction of high-quality SEI by applying synergistic additives of Li NO_(3)and ethylene sulfite(ES)in the electrolyte.The obtained SEI exhibits a high average Young’s modulus(9.02GPa)and exchanging current density(4.59 mA cm^(-2)),which are 3.0 and 1.2 times as large as those using the sole additive of LiNO_(3),respectively.With this improved SEI,Li-dendrite growth and side reactions are effectively suppressed,leading to an ultra-high Coulombic efficiency(CE)of 99.7%for Li plating and stripping.When applying this improved electrolyte in full cells,it achieves a high capacity retention of 89.7%for over 150 cycles in a LiFePO_(4)||Li battery(~12 mg cm^(-2)cathode,50μm Li)and of 44.5%over 100 cycles in a LiFePO_(4)||Cu anode-free battery.
基金supported by the National Key Research and Development Program of China(2021YFB2400200)the National Natural Science Foundation of China(52104313,22172117,52072298)the Scientific Research Program of Shaanxi Provincial Education Department(21JK0808)。
文摘The resourceful and inexpensive red phosphorus has emerged as a promising anode material of potassium-ion batteries(PIBs) for its large theoretical capacities and low redox potentials in the multielectron alloying/dealloying reactions,yet chronically suffering from the huge volume expansion/shrinkage with a sluggish reaction kinetics and an unsatisfactory interfacial stability against volatile electrolytes.Herein,we systematically developed a series of localized high-concentration electrolytes(LHCE) through diluting high-concentration ether electrolytes with a non-solvating fluorinated ether to regulate the formation/evolution of solid electrolyte interphases(SEI) on phosphorus/carbon(P/C) anodes for PIBs.Benefitting from the improved mechanical strength and structural stability of a robust/uniform SEI thin layer derived from a composition-optimized LHCE featured with a unique solvation structure and a superior K+migration capability,the P/C anode with noticeable pseudocapacitive behaviors could achieve a large reversible capacity of 760 mA h g^(-1)at 100 mA g^(-1),a remarkable capacity retention rate of 92.6% over 200 cycles at 800 mA g^(-1),and an exceptional rate capability of 334 mA h g^(-1)at8000 mA g^(-1).Critically,a suppressed reduction of ether solvents with a preferential decomposition of potassium salts in anion-derived interfacial reactions on P/C anode for LHCE could enable a rational construction of an outer organic-rich and inner inorganic-dominant SEI thin film with remarkable mechanical strength/flexibility to buffer huge volume variations and abundant K+diffusion channels to accelerate reaction kinetics.Additionally,the highly reversible/durable full PIBs coupling P/C anodes with annealed organic cathodes further verified an excellent practical applicability of LHCE.This encouraging work on electrolytes regulating SEI formation/evolution would advance the development of P/C anodes for high-performance PIBs.
基金supported by the Jilin Province Science and Technology Department Program(YDZJ202201ZYTS304)the Science and Technology Project of Jilin Provincial Education Department(JJKH20220428KJ)+3 种基金the Jilin Province Science and Technology Department Program(YDZJ202101ZYTS047)the National Natural Science Foundation of China(21905110,21905041,22279045,22102020)the Special foundation of Jilin Province Industrial Technology Research and Development(2019C042)the Fundamental Research Funds for the Central Universities(2412020FZ008)。
文摘Lithium sulfur batteries are regarded as a promising candidate for high-energy-density energy storage devices.However,the lithium metal anode in lithium-sulfur batteries encounters the problem of lithium dendrites and lithium metal consumption caused by polysulfide corrosion.Herein we design a dualfunction PMMA/PPC/LiNO3composite as an artificial solid electrolyte interphase(PMCN-SEI)to protect Li metal anode.This SEI offers multiple sites of C=O for polysulfide anchoring to constrain corrosion of Li metal anode.The lithiated polymer group and Li3N in PMCN-SEI can homogenize lithium-ion deposition behavior to achieve a dendrite-free anode.As a result,the PMCN-SEI protected Li metal anode enables the Li||Li symmetric batteries to maintain over 300 cycles(1300 h)at a capacity of 5 m Ah cm^(-2),corresponding to a cumulative capacity of 3.25 Ah cm^(-2).Moreover,Li-S batteries assembled with 20μm of Li metal anode(N/P=1.67)still deliver an initial capacity of 1166 m A h g-1at 0.5C.Hence,introducing polycarbonate polymer/inorganic composite SEI on Li provides a new solution for achieving the high energy density of Li-S batteries.
基金supported by the National Natural Science Foundation of China(No.91963118 and 52102213)Science Technology Program of Jilin Province(No.20200201066JC)the 111 Project(No.B13013).
文摘The high concentration electrolytes with specific solvation structure could passivate the electrodes to prolong battery cycle life but at the expense of increased cost,which limits the wide application in commercialization.The regular concentration(1_(M))electrolytes with suitable properties(viscosity,ionic conductivity,etc.)are cost-guaranteed,but undesired reactions would always occur and lead to battery degradation during long cycles.To promote the long-term cycle stability in a cost-effective way,this work constructs bidirectional fluorine-rich electrode/electrolyte interphase(EEI)by redistribution of solvents and electrochemical induction.The fluorinated effect with reasonable zoning planning restricts morphological disintegration,meanwhile,forms spatial confinement on cathode.In particular,the obtained cathode electrolyte interphase(CEI)gets the ample ability of Na^(+)transport,which benefits from the fluorinated organics arranged in the epitaxy and the hemi-carbonate content acting on the thickness.Thus,the electrochemical long cycling performance of F-NVPOFⅡF-CC full cells is significantly enhanced(the decay rate at 1 C per cycle is as low as 0.01%).Such a fluorine-rich EEI engineering is expected to take transitional layers against the degradation of cells and make ultra-long cycle batteries possible.
基金supported by the National Natural Science Foundation of China(22179124,21905265)the Fundamental Research Funds for the Central Universities(WK3430000007)。
文摘Ethers are promising electrolyte solvents for secondary Li metal batteries because of their excellent reduction stability.However,their oxidation stability has been mostly relying on the high concentration approach,and limited progress has been made on building effective interphase to protect the cathode from the corrosion of the electrolyte.In this work,we construct a semi-crystalline interfacial layer on the surface of Li(Ni_(0.8)Co_(0.1)Mn_(0.1))O_(2)cathode that can achieve improved electrochemical stability in the highly corrosive chemical environment formed by the decomposition of ether molecules.Different from traditional brittle crystalline interphases,the optimized semi-crystalline layer with low modulus and high ionic conductivity can effectively relieve electrode strain and maintain the integrity of the interface layer.Due to this design,the continuous oxidation decomposition of ether-based electrolytes could be significantly suppressed and the battery shows outstanding cycling stability(84%capacity retention after 300 cycles).This article provides a solution to address the oxidation instability issue of ether-based electrolytes.
基金supported by the Innovation Fund of Wuhan National Laboratory for Optoelectronics of Huazhong University of Science and Technology.
文摘Silicon(Si)is a potential high-capacity anode material for the next-generation lithium-ion battery with high energy density.However,Si anodes suff er from severe interfacial chemistry issues,such as side reactions at the electrode/electrolyte interface,leading to poor electrochemical cycling stability.Herein,we demonstrate the fabrication of a conformal fl uorine-containing carbon(FC)layer on Si particles(Si-FC)and its in situ electrochemical conversion into a LiF-rich carbon layer above 1.5 V(vs.Li^(+)/Li).The as-formed LiF-rich carbon layer not only isolates the active Si and electrolytes,leading to the suppression of side reactions,but also induces the formation of a robust solid-electrolyte interface(SEI),leading to the stable interfacial chemistry of as-designed Si-FC particles.The Si-FC electrode has a high initial Coulombic effi ciency(CE)of 84.8%and a high reversible capacity of 1450 mAh/g at 0.4 C(1000 mA/g)for 300 cycles.In addition,a hybrid electrode consisting of 85 wt%graphite and 15 wt%Si-FC,and mass 2.3 mg/cm^(2) loading delivers a high areal capacity of 2.0 mAh/cm^(2) and a high-capacity retention of 93.2%after 100 cycles,showing the prospects for practical use.
基金supported by the Jilin Province Science and Technology Department Program(Nos.YDZJ202201ZYTS304)the Science and Technology Project of Jilin Provincial Education Department(JJKH20220428KJ)+3 种基金the R&D Program of Power Batteries with Low Temperature and High Energy,Science and Technology Bureau of Changchun(19SS013)the Key Subject Construction of Physical Chemistry of Northeast Normal Universitythe Fundamental Research Funds for the Central Universities(2412020FZ007,2412020FZ008)the National Natural Science Foundation of China(22102020)。
文摘Li metal batteries are supposed to reach real application in order to fulfill the high-energy density requirement of energy storage system.Unfortunately,the commonly used carbonate electrolyte react with pristine Li,which result in short lifetime of lithium metal battery.To alleviate the side reactions of Li metal with liquid electrolyte,here we propose a phosphate rich polymer-inorganic layer as an interphase.Due to the inert properties of lithium phosphate derived from LiPO_(2)F_(2)and poly-ether,the side-reaction of carbonate solvent are prevented.As a result,lithium metal anode sustains for 800 cycles in symmetrical cell test under 1 m A cm^(-2).Even under strict condition(20μm Li,capacity ratio N/P=2.3,electrolyte/active material=3μL mg^(-1)),coin cell test still runs stable for 150 cycles with high Coulombic efficiency.Furthermore,both LiFePO_(4)and LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)pouch cell under 5μL m A^(-1)h^(-1)condition also exhibit good stability at 0.5 C and 2 C rate.With this approach,high-energy and high-power Li metal batteries are approaching to real application in the near future.
基金supported by the National Natural Science Foundation of China(52175317,U22B2069)the Fundamental Research Funds for the Central Universities(YCJJ202202004)+3 种基金the National Natural Science Foundation of China(52105325)the NSFC Projects of International Cooperation and Exchanges(52020105012)the Guangzhou Science and Technology Program(202201010405)the Key-Area Research and Development Program of Huizhou City(2022BQ010001)。
文摘The stability and uniformity of solid electrolyte interphase(SEI)are critical for clarifying the origin of capacity fade and safety issues for lithium metal anodes(LMA).However,understanding the interplay of SEI heterogeneity and Li electrodeposition is limited by the coupling of complex electrochemistry and mechanics processes.Herein,the correlation between the SEI failure behavior and Li deposition morphology is investigated through a quantitative electrochemical-mechanical model.The local deformation and stress of SEI during Li electrodeposition identify that the heterogeneous interface between different components first fails.Compared with the well-known mechanical strength,component uniformity plays the most important role in the initial SEI failure and uneven Li deposition,and a relative component uniformity(p>0.01)represents a proper balance to ensure the stability of the naturally heterogeneous SEI.Furthermore,the component regulation of SEI via the designed electrolyte experimentally demonstrates that improving component uniformity benefits SEI stability and the uniform Li electrodeposition for LMA,thereby increasing the capacity by~20%after 300 cycles.These fundamental understandings and proposed strategy can be not only used to guide the SEI optimization via the electrolyte regulation,but also extended to the rational designs of artificial SEI for high-performance LMA.
基金supported by the National Natural Science Foundation of China(No.21972049)。
文摘B-containing electrolyte additives are widely used to enhance the cycle performance at low temperature and the rate capability of lithium-ion batteries by constructing an efficient cathode electrolyte interphase(CEI)to facilitate the rapid Li+migration.Nevertheless,its wide-temperature application has been limited by the instability of B-derived CEI layer at high temperature.Herein,dual electrolyte additives,consisting of lithium tetraborate(Li_(2)TB)and 2,4-difluorobiphenyl(FBP),are proposed to boost the widetemperature performances of LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM)cathode.Theoretical calculation and electrochemical performances analyses indicate that Li_(2)TB and FBP undergo successive decomposition to form a unique dual-layer CEI.FBP acts as a synergistic filming additive to Li_(2)TB,enhancing the hightemperature performance of NCM cathode while preserving the excellent low-temperature cycle stability and the superior rate capability conferred by Li_(2)TB additive.Therefore,the capacity retention of NCM‖Li cells using optimal FBP-Li_(2)TB dual electrolyte additives increases to 100%after 200 cycles at-10℃,99%after 200 cycles at 25℃,and 83%after 100 cycles at 55℃,respectively,much superior to that of base electrolyte(63%/69%/45%).More surprisingly,galvanostatic c ha rge/discharge experiments at different temperatures reveal that NCM‖Li cells using FBP-Li_(2)TB additives can operate at temperatures ranging from-40℃to 60℃.This synergistic interphase modification utilizing dual electrolyte additives to construct a unique dual-layer CEI adaptive to a wide temperature range,provides valuable insights to the practical applications of NCM cathodes for all-climate batteries.
基金supported by the Natural Science Foundation of Henan Province (202300410163)the Innovative Research Team(in Science and Technology) in University of Henan Province(20IRTSTHN016)+1 种基金the Outstanding Talent Introduction Project of University of Electronic Science and Technology of China(08JC00303)the Innovative Research Team of Sichuan Fuhua New Energy High-Tech Co.,Ltd (621006)。
文摘One of the key challenges for achieving stable lithium(Li) metal anode is the construction of the rational solid electrolyte interphase(SEI),but its realization still faces enormous challenges.In this work,a robust artificial fluorinated hybrid interphase consisting of lithium-bismuth(Li3Bi) alloy and lithium-fluoride(LiF) was designed to regulate Li deposition without Li dendrite growth.The obtained hybrid interphase showed the high Li+diffusion rate(3.5 × 10^(-4)S cm^(-1)),high electron resistivity(9.04 × 10^(4)Ω cm),and high mechanical strength(1348 MPa),thus enabling the uniform Li deposition at the Li/SEI interface.Specifically,Li3Bi alloy,as a superionic conductor,accelerated the Li+transport and stabilized the hybrid interphase.Meanwhile,LiF was identified as a superior electron-blocker to inhibit the electron tunneling from the Li anode into the SEI.As a result,the modified Li anode showed the stable Li plating/stripping behaviors over 1000 cycles even at 20 mA cm^(-2).Moreover,it also enabled the Li(50 μm)‖LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(4.4 mA h cm^(-2)) full cell to achieve an average Coulombic efficiency(CE) of 99.6%and a high-capacity retention of 79.2% after 100 cycles,whereas the bare Li anode only exhibited a low-capacity retention of 8.0%.This work sheds light on the internal mechanism of Li+transport within the hybrid interface and provides an effective approach to stabilize the interface of Li metal anode.
基金supported by National Natural Science Foundation of China(Nos.92066108 and 51277061)。
文摘The initial shape of the secondary arc considerably influences its subsequent shape.To establish the model for the arcing time of the secondary arc and modify the single-phase reclosing sequence,theoretical and experimental analysis of the evolution process of the short-circuit arc to the secondary arc is critical.In this study,an improved charge simulation method was used to develop the internal-space electric-field model of the short-circuit arc.The intensity of the electric field was used as an independent variable to describe the initial shape of the secondary arc.A secondary arc evolution model was developed based on this model.Moreover,the accuracy of the model was evaluated by comparison with physical experimental results.When the secondary arc current increased,the arcing time and dispersion increased.There is an overall trend of increasing arc length with increasing arcing time.Nevertheless,there is a reduction in arc length during arc ignition due to short circuits between the arc columns.Furthermore,the arcing time decreased in the range of 0°-90°as the angle between the wind direction and the x-axis increased.This work investigated the method by which short-circuit arcs evolve into secondary arcs.The results can be used to develop the secondary arc evolution model and to provide both a technical and theoretical basis for secondary arc suppression.
基金supported by Major Special Projects of Science and Technology in Fujian Province,(Grant No.2020HZ03018)Natural Science Foundation of Fujian Province(Grant No.2020J01873).
文摘In gas metal arc welding(GMAW)process,the short-circuit transition was the most typical transition observed in molten metal droplets.This paper used orthogonal tests to explore the coupling effect law of welding process parameters on the quality of weld forming under short-circuit transition,the design of 3 factors and 3 levels of a total of 9 groups of orthogonal tests,welding current,welding voltage,welding speed as input parameters:effective area ratio,humps,actual linear power density,aspect ratio,Vickers hardness as output paramet-ers(response targets).Using range analysis and trend charts,we can visually depict the relationship between input parameters and a single output parameter,ultimately determining the optimal process parameters that impact the single output index.Then combined with gray the-ory to transform the three response targets into a single gray relational grade(GRG)for analysis,the optimal combination of the weld mor-phology parameters as follows:welding current 100 A,welding voltage 25 V,welding speed 30 cm/min.Finally,validation experiments were conducted,and the results showed that the error between the gray relational grade and the predicted value was 2.74%.It was observed that the effective area ratio of the response target significantly improved,validating the reliability of the orthogonal gray relational method.
基金funded by the National Natural Science Foundation of China(52077004)Anhui Electric Power Company of the State Grid(52120021N00L).
文摘Aiming at the problemthat the traditional short-circuit current calculationmethod is not applicable to Distributed Generation(DG)accessing the distribution network,the paper proposes a short-circuit current partitioning calculation method considering the degree of voltage drop at the grid-connected point of DG.Firstly,the output characteristics of DG in the process of low voltage ride through are analyzed,and the equivalent output model of DG in the fault state is obtained.Secondly,by studying the network voltage distribution law after fault in distribution networks under different DG penetration rates,the degree of voltage drop at the grid-connected point of DG is used as a partition index to partition the distribution network.Then,iterative computation is performed within each partition,and data are transferred between partitions through split nodes to realize the fast partition calculation of short-circuit current for high proportion DG access to distribution network,which solves the problems of long iteration time and large calculation error of traditional short-circuit current.Finally,a 62-node real distribution network model containing a high proportion of DG access is constructed onMATLAB/Simulink,and the simulation verifies the effectiveness of the short-circuit current partitioning calculation method proposed in the paper,and its calculation speed is improved by 48.35%compared with the global iteration method.
文摘In the present paper, based on the two-phase model (Eulerian model), the two dimensional fluid flow liz air-stirred water systems is simulated, and the effect of interphase lift force on the fluid flow is specially discussed. In the Eulerian two-phase model, gas and liquid phase are considered to be two different continuous fluids interacting with each other through the finite inter-phase areas. The exchange between the phases is represented by source terms in conversation equations. Turbulence is assumed to be a property of the liquid phase, k - ε model is used to describe the behavior of the liquid phase. The dispersion of phases due to turbulence is represented by introducing a diffusion term in mass consecrvation equation. The contribution of bubble movement to the turbulent energy and its dissipation rate is taken into accounted by adding extra volumetric source terms to the equations of turbulent enemy and its dissipation rate. The comparison between the mathematical simulation and experiment data indicates that the interphase lift force has a big effect on the flow behavior, and considering both drug force and lift force as interphase forces is important to accurately simulate the gas-water two-phase fluid flow in air-stirred systems. The interphase lift force makes bubbles move away from the centerline, the gas concentration is decreased near the centerline, and increased near the wall. The lift force is smaller than drug force at the same place, especially far away from the centerline.