For constructing next-generation lithium-ion batteries with advanced performances,pursuit of highcapacity Li-rich cathodes has caused considerable attention.So far,the low discharge specific capacity and serious capac...For constructing next-generation lithium-ion batteries with advanced performances,pursuit of highcapacity Li-rich cathodes has caused considerable attention.So far,the low discharge specific capacity and serious capacity fading are strangling the development of Fe-based Li-rich materials.To activate the extra-capacity of Fe-based Li-rich cathode materials,a facile molten salt method is exploited using an alkaline mixture of LiOH–LiNO3–Li2O2 in this work.The prepared Li1.09(Fe0.2Ni0.3Mn0.5)0.91O2 material yields high discharge specific capacity and good cycling stability.The discharge specific capacity shows an upward tendency at 0.1 C.After 60 cycles,a high reversible specific capacity of ~250 m Ah g-1is delivered.The redox of Fe3+/Fe4+and Mn3+/Mn4+are gradually activated during cycling.Notably,the redox reaction of Fe2+/Fe3+can be observed reversibly below 2 V,which is quite different from the material prepared by a traditional co-precipitation method.The stable morphology of fine nanoparticles(100–300 nm)is considered benefiting for the distinctive electrochemical performances of Li1.09(Fe0.2Ni0.3Mn0.5)0.91O2.This study demonstrates that molten salt method is an inexpensive and effective approach to activate the extra capacity of Fe-based Li-rich cathode material for high-performance lithium-ion batteries.展开更多
An acid molten salt was formed by means of mixing 1 -methyl- 3 -ethylimidazolium chloride with AlCl3 and LiAlCl4 at ambient temperature. The solubility of LiAlCl4 in the acid molten salt was measured. Variations of sp...An acid molten salt was formed by means of mixing 1 -methyl- 3 -ethylimidazolium chloride with AlCl3 and LiAlCl4 at ambient temperature. The solubility of LiAlCl4 in the acid molten salt was measured. Variations of specific conductivity, density and kinetic viscosity of molten salt with mole ratio o f MeEtlmCl/A1lCl3/LiAlCl4 were observed. A solubility maximum of LiAlCl4 with 5 4% in molar fraction was shown at a mole ratio of AlCl43/MeEtlmCl = 1 .2. An increase in density and viscosity, and a decrease in specific conductivity were found with increasing the concentrations of LiAlCl4 and AlCl3. The dependence of specific conductivity of this acid molten salt upon temperature was found to display Vogel-Tammanm-Fucher behavior. However, Arrhenius behavior was observed at two special mole ratios of MeEtImCl/AlCl3/LiAlCl4 = 1:1.5:0.05 and 1. 1.5:0. 10. The conductivity equations of this molten salt at various compositions were constructed. The ion interaction in the acid molten salt was studied using 7Li and 27Al nuclear magnetic resonance spectroscopic methods. The effect of concentrations of LiAlCl4 and AlCl3 on the ion interaction was also discussed.展开更多
The influence of cerium on the behavior of lithiumaluminium alloy anode was studied. The discharge capacity and voltage of lithium-aluminium anode can be enhanced by adding 0.5%-1.5% Ce and the surface quality of t...The influence of cerium on the behavior of lithiumaluminium alloy anode was studied. The discharge capacity and voltage of lithium-aluminium anode can be enhanced by adding 0.5%-1.5% Ce and the surface quality of the anode can also be improved. The porous LiAI-Ce alloy anode has the best charge and discharge properties.展开更多
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
Tin-doped multiwall carbon nanotubes (CNTs) were prepared by electrolysis in molten salt of LiCl (62%)-NaCl(37%)-SnCl2(1%) in mass fraction with a graphite rod as a cathode. TEM and XRD investigations show that struct...Tin-doped multiwall carbon nanotubes (CNTs) were prepared by electrolysis in molten salt of LiCl (62%)-NaCl(37%)-SnCl2(1%) in mass fraction with a graphite rod as a cathode. TEM and XRD investigations show that structure characteristic of tin-doped CNTs is webs of well-graphitized hollow tubes with outer diameters between 10 and 20 nm with presence of Sn and SnO2. The EDS elementary analysis confirms the content of tin in the products was 9%. Electrochemical Li insertion into the doped CNTs was investigated in a nonaqueous medium. Galvanostatic discharge-charge measurement revealed that their specific capacities of insertion and extraction lithium were 1762mAh/g and 1295mAh/g, respectively, in the first cycle with almost coulomb efficiency of 73%. The coulomb efficiency increased to more than 90% after the ninth cycle, and the reversible capacity was about 210 mAh/g.展开更多
基金supported by the Nature Science Foundations of Hebei Province (B2016210071, B2016210111)the Natural Science Foundation of Hebei Education Department (QN2016057, ZD2015082, ZC2016045)+3 种基金the National College Students’ Innovative Entrepreneurial Training Project of Chinasupported by the Chinese National 973 Program (2015CB251106)the Joint Funds of the National Natural Science Foundation of China (U1564206)Major achievements Transformation Project for Central University in Beijing
文摘For constructing next-generation lithium-ion batteries with advanced performances,pursuit of highcapacity Li-rich cathodes has caused considerable attention.So far,the low discharge specific capacity and serious capacity fading are strangling the development of Fe-based Li-rich materials.To activate the extra-capacity of Fe-based Li-rich cathode materials,a facile molten salt method is exploited using an alkaline mixture of LiOH–LiNO3–Li2O2 in this work.The prepared Li1.09(Fe0.2Ni0.3Mn0.5)0.91O2 material yields high discharge specific capacity and good cycling stability.The discharge specific capacity shows an upward tendency at 0.1 C.After 60 cycles,a high reversible specific capacity of ~250 m Ah g-1is delivered.The redox of Fe3+/Fe4+and Mn3+/Mn4+are gradually activated during cycling.Notably,the redox reaction of Fe2+/Fe3+can be observed reversibly below 2 V,which is quite different from the material prepared by a traditional co-precipitation method.The stable morphology of fine nanoparticles(100–300 nm)is considered benefiting for the distinctive electrochemical performances of Li1.09(Fe0.2Ni0.3Mn0.5)0.91O2.This study demonstrates that molten salt method is an inexpensive and effective approach to activate the extra capacity of Fe-based Li-rich cathode material for high-performance lithium-ion batteries.
文摘An acid molten salt was formed by means of mixing 1 -methyl- 3 -ethylimidazolium chloride with AlCl3 and LiAlCl4 at ambient temperature. The solubility of LiAlCl4 in the acid molten salt was measured. Variations of specific conductivity, density and kinetic viscosity of molten salt with mole ratio o f MeEtlmCl/A1lCl3/LiAlCl4 were observed. A solubility maximum of LiAlCl4 with 5 4% in molar fraction was shown at a mole ratio of AlCl43/MeEtlmCl = 1 .2. An increase in density and viscosity, and a decrease in specific conductivity were found with increasing the concentrations of LiAlCl4 and AlCl3. The dependence of specific conductivity of this acid molten salt upon temperature was found to display Vogel-Tammanm-Fucher behavior. However, Arrhenius behavior was observed at two special mole ratios of MeEtImCl/AlCl3/LiAlCl4 = 1:1.5:0.05 and 1. 1.5:0. 10. The conductivity equations of this molten salt at various compositions were constructed. The ion interaction in the acid molten salt was studied using 7Li and 27Al nuclear magnetic resonance spectroscopic methods. The effect of concentrations of LiAlCl4 and AlCl3 on the ion interaction was also discussed.
文摘The influence of cerium on the behavior of lithiumaluminium alloy anode was studied. The discharge capacity and voltage of lithium-aluminium anode can be enhanced by adding 0.5%-1.5% Ce and the surface quality of the anode can also be improved. The porous LiAI-Ce alloy anode has the best charge and discharge properties.
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.
文摘Tin-doped multiwall carbon nanotubes (CNTs) were prepared by electrolysis in molten salt of LiCl (62%)-NaCl(37%)-SnCl2(1%) in mass fraction with a graphite rod as a cathode. TEM and XRD investigations show that structure characteristic of tin-doped CNTs is webs of well-graphitized hollow tubes with outer diameters between 10 and 20 nm with presence of Sn and SnO2. The EDS elementary analysis confirms the content of tin in the products was 9%. Electrochemical Li insertion into the doped CNTs was investigated in a nonaqueous medium. Galvanostatic discharge-charge measurement revealed that their specific capacities of insertion and extraction lithium were 1762mAh/g and 1295mAh/g, respectively, in the first cycle with almost coulomb efficiency of 73%. The coulomb efficiency increased to more than 90% after the ninth cycle, and the reversible capacity was about 210 mAh/g.
