Spectroscopic and DFT studies to understand the liquid formation mechanism in the LiTFSI/acetamide complex system.
It is interesting that although both lithium bis(trifluoromethane sulfone) imide (LiN(SO2CF3)2, LiTFSI) and acetamide (CH3CONH2) are solid, their mixture is a liquid in an appropriate molar ratio range at room temperature. The liquid formation mechanism of the LiTFSI/acetamide complex has been investigated by FT-IR and FT-Raman spectroscopy. The spectroscopic studies show that the Li+ ions coordinate with the C=O group of acetamide whereas the SO2 group in TFSI- anions interacts with the NH2 group of acetamide via hydrogen bonding. These interactions lead to the breakage of the hydrogen bonds between acetamide molecules and to the dissociation of LiTFSI, resulting in the formation of this molten salt. Furthermore, it has been found that moderate interaction between LiX and RCONH2 (R = -NH2, -CH3 and -CF3) is favorable for forming a LiX/RCONH2 molten salt system with low eutectic temperature and high conductivity based on density functional theory (DFT) calculational and experimental comparison for different R groups in RCONH2 and different lithium salts.
Hu
Yongsheng
Y
Laboratory for Solid State Ionics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100080, China. yshu402@yahoo.com
Wang
Zhaoxiang
Z
Li
Hong
H
Huang
Xuejie
X
Chen
Liquan
L
D000081:Acetamides / Q000737:chemistry*; D000838:Anions; D002244:Carbon / Q000737:chemistry; D008094:Lithium / Q000737:chemistry; D008968:Molecular Conformation; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D014732:Vibration
D000081:Acetamides; D000838:Anions; D009942:Organometallic Compounds; D002244:Carbon; C030686:acetamide; D008094:Lithium; D009584:Nitrogen; D010100:Oxygen