Molecular dynamics simulation of LiTFSI-acetamide electrolytes: Structural properties

被引:29
作者
Li, Shu [1 ]
Cao, Zhen [1 ]
Peng, Yuxing [1 ]
Liu, Lei [1 ]
Wang, Yonglong [1 ]
Wang, Shu [1 ]
Wang, Ji-Qiang [2 ]
Yan, Tianying [1 ,3 ]
Gao, Xue-Ping [1 ]
Song, De-Ying [1 ]
Shen, Pan-Wen [1 ]
机构
[1] Nankai Univ, Inst New Energy Mat Chem, Dept Chem Mat, Tianjin 300071, Peoples R China
[2] Tianjin Inst Power Sources, Tianjin 300381, Peoples R China
[3] Nankai Univ, Inst Comp Sci, Tianjin 300071, Peoples R China
关键词
D O I
10.1021/jp710898h
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The liquid structures of nonaqueous electrolytes composed of lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and acetamide, with LiTFSI/acetamide molar ratios of 1:2, 1:4, and 1:6, were studied by molecular dynamics simulations. The simulations indicate that the Li+ cations prefer to be six-coordinate by the sulfonyl oxygen atoms of the TFSI- anions and the carbonyl oxygen atoms of the acetamide molecules, rather than by the most electronegative nitrogen atom of the TFSI- anion. Therefore, close Li+-TFSI- contact pairs exist in the system. The TFSI- anion prefers to provide only one of four possible oxygen atoms to coordinate to the same Li+ cation. Three conformations (cis, trans, and gauche) of the TFSI- anions were found to coexist in the liquid electrolyte. At high salt concentrations, the TFSI- anions mainly adopt the gauche conformation in order to provide more oxygen atoms to coordinate to different Li+ cations, while simultaneously reducing the repulsion among the Li+ cations. On the other hand, the fraction of TFSI- anions adopting the cis conformation is largest for the system with the molar ratio of 1:6, in which many clusters, mainly composed of the Li+ cations and the TFSI- anions, are immersed in the acetamide molecules. The size and charge distribution of clusters were also investigated. In the system with the molar ratio of 1:2, nearly all of the ions in the PBC (periodic boundary conditions) box aggregate into a bulky cluster that gradually disassembles into small clusters with decreasing salt concentration. The addition of acetamide molecules was found to effectively relax the liquid electrolyte structure, and the system with the molar ratio of 1:4 was found to exhibit a more homogeneous liquid structure than the other two electrolyte systems with molar ratios of 1:2 and 1:6.
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页码:6398 / 6410
页数:13
相关论文
共 72 条
[1]  
Allen M. P., 2009, Computer Simulation of Liquids
[2]   Theoretical study of CF3SO3Li, (CF3SO2)(2)NLi, and (CF3SO2)(2)CHLi ion pairs [J].
Arnaud, R ;
Benrabah, D ;
Sanchez, JY .
JOURNAL OF PHYSICAL CHEMISTRY, 1996, 100 (26) :10882-10891
[3]   VIBRATIONAL STUDIES OF LITHIUM PERCHLORATE IN PROPYLENE CARBONATE SOLUTIONS [J].
BATTISTI, D ;
NAZRI, GA ;
KLASSEN, B ;
AROCA, R .
JOURNAL OF PHYSICAL CHEMISTRY, 1993, 97 (22) :5826-5830
[4]   Structural characterization of a lanthanum bistriflimide complex, La(N(SO2CF3)2)3(H2O)3, and an investigation of La, Sm, and Eu electrochemistry in a room-temperature ionic liquid, [Me3NnBu][N(SO2CF3)2] [J].
Bhatt, AI ;
May, I ;
Volkovich, VA ;
Collison, D ;
Helliwell, M ;
Polovov, IB ;
Lewin, RG .
INORGANIC CHEMISTRY, 2005, 44 (14) :4934-4940
[5]   Development of many-body polarizable force fields for Li-battery applications: 2. LiTFSI-doped oligoether, polyether, and carbonate-based electrolytes [J].
Borodin, O ;
Smith, GD .
JOURNAL OF PHYSICAL CHEMISTRY B, 2006, 110 (12) :6293-6299
[6]   LiTFSI structure and transport in ethylene carbonate from molecular dynamics simulations [J].
Borodin, O ;
Smith, GD .
JOURNAL OF PHYSICAL CHEMISTRY B, 2006, 110 (10) :4971-4977
[7]   Li+ transport mechanism in oligo(ethylene oxide)s compared to carbonates [J].
Borodin, Oleg ;
Smith, G. D. .
JOURNAL OF SOLUTION CHEMISTRY, 2007, 36 (06) :803-813
[8]   Molecular dynamics simulations of lithium alkyl carbonates [J].
Borodin, Oleg ;
Smith, Grant D. ;
Fan, Peng .
JOURNAL OF PHYSICAL CHEMISTRY B, 2006, 110 (45) :22773-22779
[9]   Li+ cation environment, transport, and mechanical properties of the LiTFSI doped N-methyl-N-alkylpyrrolidinium +TFSI- ionic liquids [J].
Borodin, Oleg ;
Smith, Grant D. ;
Henderson, Wesley .
JOURNAL OF PHYSICAL CHEMISTRY B, 2006, 110 (34) :16879-16886
[10]   Structure and dynamics of N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide ionic liquid from molecular dynamics simulations [J].
Borodin, Oleg ;
Smith, Grant D. .
JOURNAL OF PHYSICAL CHEMISTRY B, 2006, 110 (23) :11481-11490