Ethyl-(2,2,2-trifluoroethyl)carbonate(ETFEC)is investigated as a solvent component in high-voltage electrolytes for LiNi0.5Mn1.5O4(LNMO).Our results show that the self-discharge behavior and the high temperature cycle...Ethyl-(2,2,2-trifluoroethyl)carbonate(ETFEC)is investigated as a solvent component in high-voltage electrolytes for LiNi0.5Mn1.5O4(LNMO).Our results show that the self-discharge behavior and the high temperature cycle performance can be significantly improved by the addition of 10%ETFEC into the normal carbonate electrolytes,e.g.,the capacity retention improved from 65.3%to 77.1%after 200 cycles at 60℃.The main reason can be ascribed to the high stability of ETFEC which prevents large oxidation of the electrolyte on the cathode surface.In addition,we also explore the feasibility of electrolytes using single fluoriated-solvents with and without additives.Our results show that the cycle performance of LNMO material can be greatly improved in 1 MLiPF6+pure ETFEC-solvent system with 2 wt%ethylene carbonate(EC)or ethylene sulfate(DTD).The capacity retention of the LNMO materials is 93%after 300 cycles,even better than that of carbonate-based electrolytes.It is shown that the additives are oxidized on the surface of LNMO particles and contribute to the formation of cathode/electrolyte interphase(CEI)films.This composite CEI film plays a crucial role in suppressing the serious decomposition of the electrolyte at high voltage.展开更多
2-Substituted-2,3-dihydro-4(1H)-quinazolinones were obtained in high yields by condensation of anthranilamide with aryl, alkyl or heteroaryl aldehydes or ketones in the refluxing 2,2,2-trifluoroethanol without any cat...2-Substituted-2,3-dihydro-4(1H)-quinazolinones were obtained in high yields by condensation of anthranilamide with aryl, alkyl or heteroaryl aldehydes or ketones in the refluxing 2,2,2-trifluoroethanol without any catalyst.展开更多
The one-pot aza-Diels-Alder reaction of substituted aromatic amines, ethyl glyoxylate and benzyl vinylcarbamate or N- benzyloxycarbonyl 2-pyrroline was conducted in hexafluoroisopropanol, providing the desired 1,2,3,4...The one-pot aza-Diels-Alder reaction of substituted aromatic amines, ethyl glyoxylate and benzyl vinylcarbamate or N- benzyloxycarbonyl 2-pyrroline was conducted in hexafluoroisopropanol, providing the desired 1,2,3,4-tetrahydroquinline derivatives in moderate yields.展开更多
Herein,a comprehensive study of electrochemical performances of the combined effect of fluorinated additives;fluoroethylene carbonate(FEC);and tris(2,2,2-trifluoroethyl) phosphite(TTFP) or the 2,2,2-trifluoroethyl met...Herein,a comprehensive study of electrochemical performances of the combined effect of fluorinated additives;fluoroethylene carbonate(FEC);and tris(2,2,2-trifluoroethyl) phosphite(TTFP) or the 2,2,2-trifluoroethyl methyl carbonate(TFEMC) as co-solvent,on Graphite//LiMn2O4 cells cycled at high potential is reported.On one side,each additive has a specific function,the FEC is dedicated to the negative electrode and the TTFP to the opposite one.The electrolyte mixture with(4% FEC+1% TTFP) additive has shown the best ability to reduce fading of the LiMn2O4 electrode,especially at high rates.On the other side,by studying the comparative thermal and transport properties of the formulated electrolytes with different proportions of TFEMC,we demonstrate that the difference in charge distribution of EMC and TFEMC molecules induced by the presence of fluorine atoms,modifies the solvation model of the Li+cation,and changes its behavior at the CEI interface and impact strongly the electrochemical performances.Finally,the EIS investigation of the LMO/electrolyte interfaces in the presence of TFEMC demonstrates that despite a spontaneous chemical reactivity of the TFEMC at the cathode interface over time,the conductive and good quality CEI is formed,which positively impact the cyclability.This study shows that against LMO surface phenomena,the combination in adequate proportions of fluorinated additives or solvent can be a solution not only to avoid the oxidative reactivity of LMO-cathode,but also to prevent its harmful consequences on the Li-metal or graphite-anode by controlling the solvation of lithium-ion.展开更多
基金financially supported by National Key Research and Development Program of China(Grant no.2018YFB010440)the National Natural Science Foundation of China(Grant nos.21761132030,21621091).
文摘Ethyl-(2,2,2-trifluoroethyl)carbonate(ETFEC)is investigated as a solvent component in high-voltage electrolytes for LiNi0.5Mn1.5O4(LNMO).Our results show that the self-discharge behavior and the high temperature cycle performance can be significantly improved by the addition of 10%ETFEC into the normal carbonate electrolytes,e.g.,the capacity retention improved from 65.3%to 77.1%after 200 cycles at 60℃.The main reason can be ascribed to the high stability of ETFEC which prevents large oxidation of the electrolyte on the cathode surface.In addition,we also explore the feasibility of electrolytes using single fluoriated-solvents with and without additives.Our results show that the cycle performance of LNMO material can be greatly improved in 1 MLiPF6+pure ETFEC-solvent system with 2 wt%ethylene carbonate(EC)or ethylene sulfate(DTD).The capacity retention of the LNMO materials is 93%after 300 cycles,even better than that of carbonate-based electrolytes.It is shown that the additives are oxidized on the surface of LNMO particles and contribute to the formation of cathode/electrolyte interphase(CEI)films.This composite CEI film plays a crucial role in suppressing the serious decomposition of the electrolyte at high voltage.
文摘2-Substituted-2,3-dihydro-4(1H)-quinazolinones were obtained in high yields by condensation of anthranilamide with aryl, alkyl or heteroaryl aldehydes or ketones in the refluxing 2,2,2-trifluoroethanol without any catalyst.
基金the National Natural Science Foundation of China(No.30672540)NSF of Beijing(No.7072048)for financial support.
文摘The one-pot aza-Diels-Alder reaction of substituted aromatic amines, ethyl glyoxylate and benzyl vinylcarbamate or N- benzyloxycarbonyl 2-pyrroline was conducted in hexafluoroisopropanol, providing the desired 1,2,3,4-tetrahydroquinline derivatives in moderate yields.
基金“La region Centre Val de Loire” for financial support to the researchers involved in this study on OBAMA project under “Lavoisier Ⅱ” regional program。
文摘Herein,a comprehensive study of electrochemical performances of the combined effect of fluorinated additives;fluoroethylene carbonate(FEC);and tris(2,2,2-trifluoroethyl) phosphite(TTFP) or the 2,2,2-trifluoroethyl methyl carbonate(TFEMC) as co-solvent,on Graphite//LiMn2O4 cells cycled at high potential is reported.On one side,each additive has a specific function,the FEC is dedicated to the negative electrode and the TTFP to the opposite one.The electrolyte mixture with(4% FEC+1% TTFP) additive has shown the best ability to reduce fading of the LiMn2O4 electrode,especially at high rates.On the other side,by studying the comparative thermal and transport properties of the formulated electrolytes with different proportions of TFEMC,we demonstrate that the difference in charge distribution of EMC and TFEMC molecules induced by the presence of fluorine atoms,modifies the solvation model of the Li+cation,and changes its behavior at the CEI interface and impact strongly the electrochemical performances.Finally,the EIS investigation of the LMO/electrolyte interfaces in the presence of TFEMC demonstrates that despite a spontaneous chemical reactivity of the TFEMC at the cathode interface over time,the conductive and good quality CEI is formed,which positively impact the cyclability.This study shows that against LMO surface phenomena,the combination in adequate proportions of fluorinated additives or solvent can be a solution not only to avoid the oxidative reactivity of LMO-cathode,but also to prevent its harmful consequences on the Li-metal or graphite-anode by controlling the solvation of lithium-ion.
