Ethylene carbonate(EC)is an important electrolyte used in lithium-ion batteries due to its excellent electrochemical performance.However,propylene carbonate(PC)differs from EC by only one methyl substituent and exhibi...Ethylene carbonate(EC)is an important electrolyte used in lithium-ion batteries due to its excellent electrochemical performance.However,propylene carbonate(PC)differs from EC by only one methyl substituent and exhibits markedly poorproperties.The EC-PC disparity is still poorly understood at the molecular level.In this study,we demonstrated that femtosecond broadband sum frequency generation vibrational spectroscopy(SFG-VS)with simultaneous measurement of multiple polarization combinations provides a powerful probe for investigating the physicochemical processes at the electrode-electrolyte interface during the charge-discharge cycles of lithium batteries.Using monolayer graphene as the working electrode,we observed the distinct reaction outcomes of EC and PC on the electrode surface.The interfacial reaction of EC occurred only in the first charge-discharge cycle,while the interfacial reaction of PC was ongoing along with the charge-discharge cycles,which explains why EC is a better electrolyte choice than PC.This study provides direct experimental evidence in elucidating the differences in interfacial performance between EC and PC,facilitating a deeper understanding of battery interface reactions and guiding the design of high-performance lithium-ion batteries.展开更多
Graphite thin film anodes with a high IR reflectivity have been prepared by a spin coating method. Both ex situ and in situ mi- croscope FTIR spectroscopy （MFFIRS） in a reflection configuration were employed to inve...Graphite thin film anodes with a high IR reflectivity have been prepared by a spin coating method. Both ex situ and in situ mi- croscope FTIR spectroscopy （MFFIRS） in a reflection configuration were employed to investigate interfacial processes of the graphite thin film anodes in lithium-ion batteries. A solid electrolyte interphase layer （SEI layer） was formed on the cycled graphite thin film anode. Ex situ MFTIRS revealed that the main components of the SEI layer on cycled graphite film anodes in 1 tool L 1 LiPF6/ethylene carbonate ＋ dimethyl carbonate （1：1） are alkyl lithium carbonates （ROCOzLi）. The desolvation process on graphite anodes during the initial intercalation of lithium ion with graphite was also observed and analyzed by in situ MFTIRS.展开更多
基金supported by the National Natural Science Foundation of China(No.21925302)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0450202).
文摘Ethylene carbonate(EC)is an important electrolyte used in lithium-ion batteries due to its excellent electrochemical performance.However,propylene carbonate(PC)differs from EC by only one methyl substituent and exhibits markedly poorproperties.The EC-PC disparity is still poorly understood at the molecular level.In this study,we demonstrated that femtosecond broadband sum frequency generation vibrational spectroscopy(SFG-VS)with simultaneous measurement of multiple polarization combinations provides a powerful probe for investigating the physicochemical processes at the electrode-electrolyte interface during the charge-discharge cycles of lithium batteries.Using monolayer graphene as the working electrode,we observed the distinct reaction outcomes of EC and PC on the electrode surface.The interfacial reaction of EC occurred only in the first charge-discharge cycle,while the interfacial reaction of PC was ongoing along with the charge-discharge cycles,which explains why EC is a better electrolyte choice than PC.This study provides direct experimental evidence in elucidating the differences in interfacial performance between EC and PC,facilitating a deeper understanding of battery interface reactions and guiding the design of high-performance lithium-ion batteries.
基金supported by the National Natural Science Foundation of China (21003102, 21021002)the Fundamental Research Funds for the Central Universities (2012121035)the National Basic Research Program of China (2009CB220102)
文摘Graphite thin film anodes with a high IR reflectivity have been prepared by a spin coating method. Both ex situ and in situ mi- croscope FTIR spectroscopy （MFFIRS） in a reflection configuration were employed to investigate interfacial processes of the graphite thin film anodes in lithium-ion batteries. A solid electrolyte interphase layer （SEI layer） was formed on the cycled graphite thin film anode. Ex situ MFTIRS revealed that the main components of the SEI layer on cycled graphite film anodes in 1 tool L 1 LiPF6/ethylene carbonate ＋ dimethyl carbonate （1：1） are alkyl lithium carbonates （ROCOzLi）. The desolvation process on graphite anodes during the initial intercalation of lithium ion with graphite was also observed and analyzed by in situ MFTIRS.
