Silicon is an important high capacity anode material for the next generation Li-ion batteries.The electrochemical performances of the Si anode are influenced strongly by the properties of the solid electrolyte interph...Silicon is an important high capacity anode material for the next generation Li-ion batteries.The electrochemical performances of the Si anode are influenced strongly by the properties of the solid electrolyte interphase(SEI).It is well known that the addition of flouroethylene carbonate(FEC)in the carbonate electrolyte is helpful to improve the cyclic performance of the Si anode.The possible origin is suggested to relate to the modification of the SEI.However,detailed information is still absent.In this work,the structural and mechanical properties of the SEI on Si thin film anode in the ethylene-carbonate-based(EC-based)and FEC-based electrolytes at different discharging and charging states have been investigated using a scanning atomic force microscopy force spectroscopy(AFMFS)method.Single-layered,double-layered,and multi-layered SEI structures with various Young’s moduli have been visualized three dimensionally at nanoscale based on the hundreds of force curves in certain scanned area.The coverage of the SEI can be obtained quantitatively from the two-dimensional(2D)project plots.The related analysis indicates that more soft SEI layers are covered on the Si anode,and this could explain the benefits of the FEC additive.展开更多
1.Introduction With the superior performance of high energy density,lightweight and long life span,lithium-ion battery(LIB)are perceived as an attractive and reliable power source for modern-used portable electronics,...1.Introduction With the superior performance of high energy density,lightweight and long life span,lithium-ion battery(LIB)are perceived as an attractive and reliable power source for modern-used portable electronics,ecofriendly electric vehicles and power distribution,and thereby a remarkable solution to assuage energy dependence on fossil fuel and environmental concern.Nevertheless,the unexpected Li plating together with the Li dendrites growth on graphite anode surface has been a profound hindrance to the practical application of LIB,of which induces inferior Coulombic efficiency,poor lifespan and safety concern[1].展开更多
The addition of electrolyte additives is an effective strategy for tuning the property of the electrolyte to engineer the electrode/electrolyte interface,and there exist obvious discrepancies regarding the effect of f...The addition of electrolyte additives is an effective strategy for tuning the property of the electrolyte to engineer the electrode/electrolyte interface,and there exist obvious discrepancies regarding the effect of fluoroethylene carbonate(FEC)as an electrolyte additive on the performance of cathodes.Herein FEC is introduced into the electrolyte of the LiMn_(0.8)Fe_(0.2)PO_(4)/Li cell and its effect on the properties of the LiMn_(0.8)Fe_(0.2)PO_(4) is investigated.It is found that the addition of FEC in the electrolyte has a positive effect on the performance of the LiMn_(0.8)Fe_(0.2)PO_(4) cathode,which can be attributed to the reduced products generated by the interfacial side-reactions on the LiMn_(0.8)Fe_(0.2)PO_(4) cathode surface and the decreased metal dissolution in the FEC-containing electrolyte,thanks to the higher oxidation resistance of FEC and the easier and stronger binding of FEC and PF_6^(-).展开更多
Lithium-ion capacitor(LIC),which combines the advantages of lithium-ion battery(LIB)and electrical double layer capacitor(EDLC),has a rapid development during last decade,however,the poor low temperature performance s...Lithium-ion capacitor(LIC),which combines the advantages of lithium-ion battery(LIB)and electrical double layer capacitor(EDLC),has a rapid development during last decade,however,the poor low temperature performance still limits its application.In this paper,three electrolyte additives including vinylene carbonate(VC),fluoroethylene carbonate(FEC)and 1,3,2-dioxathiolane 2,2-dioxide(DTD)have been utilized and their effects on the rate performance of hard carbon(HC)anode of LIC at various temperatures ranging from 25℃ to-40℃ have been well evaluated.The cell containing FEC shows the best rate performance at various temperatures and has the charge and discharge capability even at-40℃.For HC anode,the charge transfer impedance(R_(CT))increases exponentially at low temperature,while the equivalent series resistance(Rs)and the impedance of solid electrolyte interface(SEI)increase relatively few.At low temperatures,the effect of FEC may be mainly reflected in its effect on the charge transfer process.展开更多
Nowadays,lithium-ion capacitors(LICs) have become a type of important electrochemical energy storage devices due to their high power and long cycle life characteristics with fast response time.As one of the essential ...Nowadays,lithium-ion capacitors(LICs) have become a type of important electrochemical energy storage devices due to their high power and long cycle life characteristics with fast response time.As one of the essential components of LICs,the electrolytes not only provide the anions and cations required during charge and discharge processes,but also supply the liquid environment for ions to migrate between anodes and cathodes in LIC cells.It is well accepted that propylene carbonate(PC) cannot be used as a single solvent for Li-ion electrolyte due to the failure to form stable SEI film on graphite surface.In this work,the compatibility of PC-based electrolyte with commercial soft carbon anode and activated carbon cathode has been validated by using the laminated pouch LIC cells.The effects of additives on the electrochemical properties of PC-based LICs have been systematically investigated.Ethylene sulfite(ES) was proved to be an effective additive to promote capacity retention at high C-rate,which is superior to vinylene carbonate and fluoroethylene carbonate.The addition of 5 wt% ES plays an important role in reducing internal resistance,as well as improving electrochemical stability and low-temperature performances.This study is expected to be beneficial to explore robust electrolyte/additive combinations for LICs to reduce the internal resistance and to improve the lowtemperature performances.展开更多
In the present study,the effects of relative humidity on filtrating coal-fired fly ash with hydrophobic poly tetra fluoroethylene(PTFE) membranes were investigated.The intergranular force of particulate matter at diff...In the present study,the effects of relative humidity on filtrating coal-fired fly ash with hydrophobic poly tetra fluoroethylene(PTFE) membranes were investigated.The intergranular force of particulate matter at different RH conditions was measured by analyzing the critical angle between particles.Effects of humidity(from 30% to 70%) on filtration pressure drop and membrane fouling conditions were characterized.It was found the membrane showed optimal filtration resistance of 530 Pa at RH of 60% and the gas permeance can be maintained at 1440 m^(3)·m^(-2)·h^(-1)·kPa^(-1).Moreover,to optimize the operation parameters for this filtration system,effects of fly ash concentration,diameter,membrane pore size,and gas velocities were systematically investigated.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
With increasing application demands of electronics and electric vehicles,the energy density of lithiumion batteries(LIBs)is expected to be higher and higher.The silicon-based anode materials have triggered global rese...With increasing application demands of electronics and electric vehicles,the energy density of lithiumion batteries(LIBs)is expected to be higher and higher.The silicon-based anode materials have triggered global research interest due to low operating voltage and high specific capacity.However,for the Sibased anode,the large volume change during cycling causes cracking and pulverization of Si particles,leading to the sluggish kinetics and poor cycle life.In this work,fluoroethylene carbonate(FEC)and lithium bis(fluorosulfonyl)imide(LiFSI)are used as synergistic functional additives to enhance the performance of siliconecarbon(SieC)composite anode in pouch cell.The properties of solid electrolyte interphase(SEI)formed on the surface of SieC composite anode have been systematically investigated.The images of different electrolytes infiltration and gas production after formation are analyzed with ultrasonic transmission scanning technique.DFT calculations are used to illustrate the mechanism.All date collection is at pouch cell level,which is more persuasive.展开更多
Organic cathode materials present a promising alternative for the inorganic counterparts in conventional lithiumion batteries(LIBs)due to lower cost,reduced environmental impact,renewability,and enhanced energy densit...Organic cathode materials present a promising alternative for the inorganic counterparts in conventional lithiumion batteries(LIBs)due to lower cost,reduced environmental impact,renewability,and enhanced energy density.However,their practical application is hindered by dissolution in electrolytes,structural degradation,and sluggish lithium-ion transport.In this study,we introduce fluoroethylene carbonate(FEC)as an electrolyte additive to engineer a protective cathode–electrolyte interphase(CEI)layer,effectively mitigating cathode pulverization and enhancing battery stability of the organic cathode material,dilithium salt of 2,5-dihydroxy-1,4-benzoquinone(Li_(2)DHBQ).Electrochemical,morphological,and compositional analyses,including cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and X-ray photoelectron spectroscopy(XPS),confirm that an optimal 1%FEC concentration forms a uniform CEI layer,significantly improving structural integrity and reducing interfacial resistance.Consequently,the battery with 1%FEC retains 185 mAh·g^(−1) after 200 cycles at 500 mA·g^(−1),with a capacity decay rate of just 0.049%per cycle,compared to 81 mAh·g^(−1) and 0.302%per cycle for the FEC-free battery.Additionally,the 1%FEC battery exhibits a capacitive charge storage contribution of up to 93.7%,resulting in excellent rate performance.These findings underscore the crucial role of CEI engineering in stabilizing organic cathodes,offering a practical approach to achieving high-rate and long-cycle LIBs.展开更多
基金Project supported by the State Grid Technology Project,China(Grant No.DG71-17-010)。
文摘Silicon is an important high capacity anode material for the next generation Li-ion batteries.The electrochemical performances of the Si anode are influenced strongly by the properties of the solid electrolyte interphase(SEI).It is well known that the addition of flouroethylene carbonate(FEC)in the carbonate electrolyte is helpful to improve the cyclic performance of the Si anode.The possible origin is suggested to relate to the modification of the SEI.However,detailed information is still absent.In this work,the structural and mechanical properties of the SEI on Si thin film anode in the ethylene-carbonate-based(EC-based)and FEC-based electrolytes at different discharging and charging states have been investigated using a scanning atomic force microscopy force spectroscopy(AFMFS)method.Single-layered,double-layered,and multi-layered SEI structures with various Young’s moduli have been visualized three dimensionally at nanoscale based on the hundreds of force curves in certain scanned area.The coverage of the SEI can be obtained quantitatively from the two-dimensional(2D)project plots.The related analysis indicates that more soft SEI layers are covered on the Si anode,and this could explain the benefits of the FEC additive.
基金supported by the National Natural Science Foundation of China (U2033204)the China Postdoctoral Science Foundation (2021M703053)+1 种基金supported by the China National Postdoctoral Program for Innovative Talents(BX20220286)supported by Youth Innovative Promotion Association CAS (Y201768)
文摘1.Introduction With the superior performance of high energy density,lightweight and long life span,lithium-ion battery(LIB)are perceived as an attractive and reliable power source for modern-used portable electronics,ecofriendly electric vehicles and power distribution,and thereby a remarkable solution to assuage energy dependence on fossil fuel and environmental concern.Nevertheless,the unexpected Li plating together with the Li dendrites growth on graphite anode surface has been a profound hindrance to the practical application of LIB,of which induces inferior Coulombic efficiency,poor lifespan and safety concern[1].
基金supported by National Natural Science Foundation of China(Nos.51874155 and 52177214)the Fujian Provincial STS program supporting project of Chinese Academy of sciences(No.2022T3001)。
文摘The addition of electrolyte additives is an effective strategy for tuning the property of the electrolyte to engineer the electrode/electrolyte interface,and there exist obvious discrepancies regarding the effect of fluoroethylene carbonate(FEC)as an electrolyte additive on the performance of cathodes.Herein FEC is introduced into the electrolyte of the LiMn_(0.8)Fe_(0.2)PO_(4)/Li cell and its effect on the properties of the LiMn_(0.8)Fe_(0.2)PO_(4) is investigated.It is found that the addition of FEC in the electrolyte has a positive effect on the performance of the LiMn_(0.8)Fe_(0.2)PO_(4) cathode,which can be attributed to the reduced products generated by the interfacial side-reactions on the LiMn_(0.8)Fe_(0.2)PO_(4) cathode surface and the decreased metal dissolution in the FEC-containing electrolyte,thanks to the higher oxidation resistance of FEC and the easier and stronger binding of FEC and PF_6^(-).
基金supported by the National Natural Science Foundation of China(No.51777140)the Fundamental Research Funds for the Central Universities at Tongji University(No.22120210173)。
文摘Lithium-ion capacitor(LIC),which combines the advantages of lithium-ion battery(LIB)and electrical double layer capacitor(EDLC),has a rapid development during last decade,however,the poor low temperature performance still limits its application.In this paper,three electrolyte additives including vinylene carbonate(VC),fluoroethylene carbonate(FEC)and 1,3,2-dioxathiolane 2,2-dioxide(DTD)have been utilized and their effects on the rate performance of hard carbon(HC)anode of LIC at various temperatures ranging from 25℃ to-40℃ have been well evaluated.The cell containing FEC shows the best rate performance at various temperatures and has the charge and discharge capability even at-40℃.For HC anode,the charge transfer impedance(R_(CT))increases exponentially at low temperature,while the equivalent series resistance(Rs)and the impedance of solid electrolyte interface(SEI)increase relatively few.At low temperatures,the effect of FEC may be mainly reflected in its effect on the charge transfer process.
基金the National Natural Science Foundation of China(Nos.52077207,51822706,51777200 and 51772127)Beijing Natural Science Foundation(No.JQ19012)Dalian National Laboratory for Clean Energy Cooperation Fund,the CAS(No.DNL201912)。
文摘Nowadays,lithium-ion capacitors(LICs) have become a type of important electrochemical energy storage devices due to their high power and long cycle life characteristics with fast response time.As one of the essential components of LICs,the electrolytes not only provide the anions and cations required during charge and discharge processes,but also supply the liquid environment for ions to migrate between anodes and cathodes in LIC cells.It is well accepted that propylene carbonate(PC) cannot be used as a single solvent for Li-ion electrolyte due to the failure to form stable SEI film on graphite surface.In this work,the compatibility of PC-based electrolyte with commercial soft carbon anode and activated carbon cathode has been validated by using the laminated pouch LIC cells.The effects of additives on the electrochemical properties of PC-based LICs have been systematically investigated.Ethylene sulfite(ES) was proved to be an effective additive to promote capacity retention at high C-rate,which is superior to vinylene carbonate and fluoroethylene carbonate.The addition of 5 wt% ES plays an important role in reducing internal resistance,as well as improving electrochemical stability and low-temperature performances.This study is expected to be beneficial to explore robust electrolyte/additive combinations for LICs to reduce the internal resistance and to improve the lowtemperature performances.
基金supported by the National Key Research and Development Project of China (2018YFE0203500)the High-end Research and Training Project for Specialty Leading Person of Jiangsu Higher Vocational Colleges (2020GRGDYX039)the Qing Lan Project of Jiangsu Colleges。
文摘In the present study,the effects of relative humidity on filtrating coal-fired fly ash with hydrophobic poly tetra fluoroethylene(PTFE) membranes were investigated.The intergranular force of particulate matter at different RH conditions was measured by analyzing the critical angle between particles.Effects of humidity(from 30% to 70%) on filtration pressure drop and membrane fouling conditions were characterized.It was found the membrane showed optimal filtration resistance of 530 Pa at RH of 60% and the gas permeance can be maintained at 1440 m^(3)·m^(-2)·h^(-1)·kPa^(-1).Moreover,to optimize the operation parameters for this filtration system,effects of fly ash concentration,diameter,membrane pore size,and gas velocities were systematically investigated.
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(Grant Nos.52027816,52231009).
文摘With increasing application demands of electronics and electric vehicles,the energy density of lithiumion batteries(LIBs)is expected to be higher and higher.The silicon-based anode materials have triggered global research interest due to low operating voltage and high specific capacity.However,for the Sibased anode,the large volume change during cycling causes cracking and pulverization of Si particles,leading to the sluggish kinetics and poor cycle life.In this work,fluoroethylene carbonate(FEC)and lithium bis(fluorosulfonyl)imide(LiFSI)are used as synergistic functional additives to enhance the performance of siliconecarbon(SieC)composite anode in pouch cell.The properties of solid electrolyte interphase(SEI)formed on the surface of SieC composite anode have been systematically investigated.The images of different electrolytes infiltration and gas production after formation are analyzed with ultrasonic transmission scanning technique.DFT calculations are used to illustrate the mechanism.All date collection is at pouch cell level,which is more persuasive.
基金supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)through the Discovery Grants(No.RGPIN-2022-03835)Alliance Grants(No.ALLRP 581429-23)the Mitacs Accelerate Fellowship(No.IT35432).
文摘Organic cathode materials present a promising alternative for the inorganic counterparts in conventional lithiumion batteries(LIBs)due to lower cost,reduced environmental impact,renewability,and enhanced energy density.However,their practical application is hindered by dissolution in electrolytes,structural degradation,and sluggish lithium-ion transport.In this study,we introduce fluoroethylene carbonate(FEC)as an electrolyte additive to engineer a protective cathode–electrolyte interphase(CEI)layer,effectively mitigating cathode pulverization and enhancing battery stability of the organic cathode material,dilithium salt of 2,5-dihydroxy-1,4-benzoquinone(Li_(2)DHBQ).Electrochemical,morphological,and compositional analyses,including cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and X-ray photoelectron spectroscopy(XPS),confirm that an optimal 1%FEC concentration forms a uniform CEI layer,significantly improving structural integrity and reducing interfacial resistance.Consequently,the battery with 1%FEC retains 185 mAh·g^(−1) after 200 cycles at 500 mA·g^(−1),with a capacity decay rate of just 0.049%per cycle,compared to 81 mAh·g^(−1) and 0.302%per cycle for the FEC-free battery.Additionally,the 1%FEC battery exhibits a capacitive charge storage contribution of up to 93.7%,resulting in excellent rate performance.These findings underscore the crucial role of CEI engineering in stabilizing organic cathodes,offering a practical approach to achieving high-rate and long-cycle LIBs.
