The cycling performance, impedance variation, and cathode surface evolution of the Li/LiCoO2 cell using Li FSI–KFSI molten salt electrolyte are reported. It is found that this battery shows poor cycling performance, ...The cycling performance, impedance variation, and cathode surface evolution of the Li/LiCoO2 cell using Li FSI–KFSI molten salt electrolyte are reported. It is found that this battery shows poor cycling performance, with capacity retention of only about 67% after 20 cycles. It is essential to understand the origin of the instability. It is noticed that the polarization voltage and the impedance of the cell both increase slowly upon cycling. The structure and the properties of the pristine and the cycled LiCoO2 cathodes are investigated by x-ray diffraction（XRD）, scanning electron microscopy（SEM）, Raman spectroscopy, x-ray photoelectron spectroscopy（XPS）, and transmission electron microscopy（TEM）. It is found that the LiCoO2 particles are corroded by this molten salt electrolyte, and the decomposition by-product covers the surface of the LiCoO2 cathode after 20 cycles. Therefore, the surface side reaction explains the instability of the molten salt electrolyte with LiCoO2.展开更多
Rechargeable lithium metal batteries(RLMBs)have been regarded as promising successors for contemporary lithium-ion batteries,in view of their high gravimetric and volumetric energy densities.Conventional non-aqueous l...Rechargeable lithium metal batteries(RLMBs)have been regarded as promising successors for contemporary lithium-ion batteries,in view of their high gravimetric and volumetric energy densities.Conventional non-aqueous liquid electrolytes containing organic carbonate solvents possess high chemical reactivities with metallic lithium anode and high flammability,which induces considerable safety threats under extreme conditions(e.g.,overcharging and thermal runaway).Herein,we propose the utilization of fluorinated sulfonamide(i.e.,N,N-dimethyl fluorosulfonamide(DMFSA))as solvent,together with lithium(fluorosulfonyl)(n-nonafluorobutanesulfonyl)imide(LiFNFSI)as co-salt and/or electrolyte additive for accessing safer and highperforming RLMBs.Comprehensive physical(e.g.,thermal transition,viscosity,and ionic conductivity)and electrochemical(e.g.,anodic stability on different electrodes)characterizations have been performed,aiming to reveal the inherent characteristics of the sulfonamide-based electrolytes and the particular role of LiFNFSI on the stabilization of LiCoO_(2) cathode.It has been demonstrated that the sulfonamide-based electrolytes exhibit superior flame-retardant abilities and decent ionic conductivities(>1 mS·cm^(-1)at room temperature).The incorporation of LiFNFSI as co-salt and/or electrolyte additive could significantly suppress the side reactions occurring at the cathode compartment,through the preferential decompositions of the FNFSI-anion.This work is anticipated to give an in-depth understanding on the working mechanism of LiFNFSI in the sulfonamide-based electrolytes,and also spurs the development of high-energy and safer RLMBs.展开更多
凝胶聚合物电解质(GPE)是当前最具商业化应用前景之一的准固态电解质,可以缓解甚至解决锂离子电池存在的漏液、挥发、燃烧等潜在安全问题。本文通过高温原位固化技术制备了一种以甲基丙烯酸甲酯为单体、聚乙二醇二甲基丙烯酸酯为交联剂...凝胶聚合物电解质(GPE)是当前最具商业化应用前景之一的准固态电解质,可以缓解甚至解决锂离子电池存在的漏液、挥发、燃烧等潜在安全问题。本文通过高温原位固化技术制备了一种以甲基丙烯酸甲酯为单体、聚乙二醇二甲基丙烯酸酯为交联剂、双(氟磺酰)亚胺锂为导电盐、碳酸乙烯酯/碳酸甲乙酯混合溶剂为增塑剂的GPE。通过热重分析对聚甲基丙烯酸甲酯(PMMA)基GPE的热力学性质进行了表征,采用计时安培法和电子扫描显微镜研究了PMMA基GPE对Al集流体的稳定性。研究结果表明,PMMA基GPE在室温拥有较高的电导率,达到6.61 mS/cm,同时可以将碳酸酯电解液的挥发温度由100.3℃提高至138.1℃。PMMA基GPE在高电位下对Al箔显示出良好的稳定性,4.3 V vs.Li/Li+以下不会发生铝箔腐蚀,而且在商用石墨/LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)软包电池中展现出良好的循环稳定性和容量保持能力,循环1000次后容量保持率为93.4%。展开更多
本工作采用(氟磺酰)(三氟甲基磺酰)亚胺锂{Li[(FSO2)(CF3SO2)N],Li FTFSI}和聚氧乙烯(PEO)分别作为导电锂盐和聚合物主链,通过简单的溶液浇铸法制备了新型固态聚合物电解质(SPEs),并采取示差扫描量热(DSC)、热重(TGA)、线性扫描伏安(LSV...本工作采用(氟磺酰)(三氟甲基磺酰)亚胺锂{Li[(FSO2)(CF3SO2)N],Li FTFSI}和聚氧乙烯(PEO)分别作为导电锂盐和聚合物主链,通过简单的溶液浇铸法制备了新型固态聚合物电解质(SPEs),并采取示差扫描量热(DSC)、热重(TGA)、线性扫描伏安(LSV)、交流阻抗(EIS)和恒电位直流(DC)极化等方法研究了Li FTFSI/PEO(EO/Li^+摩尔比为16)电解质的理化性质和电化学性质。结果表明,Li FTFSI/PEO电解质具有较高的室温离子电导率(σ≈10^(-5) S/cm),较高的氧化电位(4.63 V vs.Li/Li^+),并且耐热温度高达256℃。锂硫电池测试结果表明,该类SPEs展现出相对高的首周放电比容量(881 m A·h/g),有效地抑制了多硫离子的"穿梭效应",表现出良好的电池循环性能。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
基金Project supported by the Beijing S&T Project,China(Grant No.Z13111000340000)the National Basic Research Program of China(Grant No.2012CB932900)the National Natural Science Foundation of China(Grants Nos.51325206 and 51421002)
文摘The cycling performance, impedance variation, and cathode surface evolution of the Li/LiCoO2 cell using Li FSI–KFSI molten salt electrolyte are reported. It is found that this battery shows poor cycling performance, with capacity retention of only about 67% after 20 cycles. It is essential to understand the origin of the instability. It is noticed that the polarization voltage and the impedance of the cell both increase slowly upon cycling. The structure and the properties of the pristine and the cycled LiCoO2 cathodes are investigated by x-ray diffraction（XRD）, scanning electron microscopy（SEM）, Raman spectroscopy, x-ray photoelectron spectroscopy（XPS）, and transmission electron microscopy（TEM）. It is found that the LiCoO2 particles are corroded by this molten salt electrolyte, and the decomposition by-product covers the surface of the LiCoO2 cathode after 20 cycles. Therefore, the surface side reaction explains the instability of the molten salt electrolyte with LiCoO2.
基金This work is financially supported by the Fundamental Research Funds for Central Universities,HUST(No.2020kfyXJJS095)the National Natural Science Foundation of China(Nos.52203223 and 22279037).
文摘Rechargeable lithium metal batteries(RLMBs)have been regarded as promising successors for contemporary lithium-ion batteries,in view of their high gravimetric and volumetric energy densities.Conventional non-aqueous liquid electrolytes containing organic carbonate solvents possess high chemical reactivities with metallic lithium anode and high flammability,which induces considerable safety threats under extreme conditions(e.g.,overcharging and thermal runaway).Herein,we propose the utilization of fluorinated sulfonamide(i.e.,N,N-dimethyl fluorosulfonamide(DMFSA))as solvent,together with lithium(fluorosulfonyl)(n-nonafluorobutanesulfonyl)imide(LiFNFSI)as co-salt and/or electrolyte additive for accessing safer and highperforming RLMBs.Comprehensive physical(e.g.,thermal transition,viscosity,and ionic conductivity)and electrochemical(e.g.,anodic stability on different electrodes)characterizations have been performed,aiming to reveal the inherent characteristics of the sulfonamide-based electrolytes and the particular role of LiFNFSI on the stabilization of LiCoO_(2) cathode.It has been demonstrated that the sulfonamide-based electrolytes exhibit superior flame-retardant abilities and decent ionic conductivities(>1 mS·cm^(-1)at room temperature).The incorporation of LiFNFSI as co-salt and/or electrolyte additive could significantly suppress the side reactions occurring at the cathode compartment,through the preferential decompositions of the FNFSI-anion.This work is anticipated to give an in-depth understanding on the working mechanism of LiFNFSI in the sulfonamide-based electrolytes,and also spurs the development of high-energy and safer RLMBs.
文摘凝胶聚合物电解质(GPE)是当前最具商业化应用前景之一的准固态电解质,可以缓解甚至解决锂离子电池存在的漏液、挥发、燃烧等潜在安全问题。本文通过高温原位固化技术制备了一种以甲基丙烯酸甲酯为单体、聚乙二醇二甲基丙烯酸酯为交联剂、双(氟磺酰)亚胺锂为导电盐、碳酸乙烯酯/碳酸甲乙酯混合溶剂为增塑剂的GPE。通过热重分析对聚甲基丙烯酸甲酯(PMMA)基GPE的热力学性质进行了表征,采用计时安培法和电子扫描显微镜研究了PMMA基GPE对Al集流体的稳定性。研究结果表明,PMMA基GPE在室温拥有较高的电导率,达到6.61 mS/cm,同时可以将碳酸酯电解液的挥发温度由100.3℃提高至138.1℃。PMMA基GPE在高电位下对Al箔显示出良好的稳定性,4.3 V vs.Li/Li+以下不会发生铝箔腐蚀,而且在商用石墨/LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)软包电池中展现出良好的循环稳定性和容量保持能力,循环1000次后容量保持率为93.4%。
文摘本工作采用(氟磺酰)(三氟甲基磺酰)亚胺锂{Li[(FSO2)(CF3SO2)N],Li FTFSI}和聚氧乙烯(PEO)分别作为导电锂盐和聚合物主链,通过简单的溶液浇铸法制备了新型固态聚合物电解质(SPEs),并采取示差扫描量热(DSC)、热重(TGA)、线性扫描伏安(LSV)、交流阻抗(EIS)和恒电位直流(DC)极化等方法研究了Li FTFSI/PEO(EO/Li^+摩尔比为16)电解质的理化性质和电化学性质。结果表明,Li FTFSI/PEO电解质具有较高的室温离子电导率(σ≈10^(-5) S/cm),较高的氧化电位(4.63 V vs.Li/Li^+),并且耐热温度高达256℃。锂硫电池测试结果表明,该类SPEs展现出相对高的首周放电比容量(881 m A·h/g),有效地抑制了多硫离子的"穿梭效应",表现出良好的电池循环性能。
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.
