Solvation Structure and Dynamics of Mg(TFSI)_(2) Aqueous Electrolyte  

作　　者：Zhou Yu Taylor R.Juran Xinyi Liu Kee Sung Han Hui Wang Karl T.Mueller Lin Ma Kang Xu Tao Li Larry A.Curtiss Lei Cheng 

机构地区：[1]Materials Science Division,Argonne National Laboratory,Lemont IL 60439,USA [2]Joint Center for Energy Storage Research(JCESR),Lemont IL 60439,USA [3]Department of Physics,Binghamton University,State University of New York,4400 Vestal Parkway East,Binghamton NY 13902,USA [4]Department of Chemistry and Biochemistry,Northern Illinois University,DeKalb IL 60115,USA [5]Physical and Computational Sciences Directorate,Pacific Northwest National Laboratory,Richland WA 99352,USA [6]Energy&Environment Directorate,Pacific Northwest National Laboratory,Richland WA 99352,USA [7]Energy Storage Branch,Energy and Biotechnology Division,Sensor and Electronics Directorate,U.S.Army Research Laboratory,Adelphi MD 20783,USA [8]Department of Chemistry and Biochemistry Northern Illinois University DeKalb IL 60115 USA [9]X-ray Science Division Argonne National Laboratory Lemont IL 60439 USA

出　　处：《Energy & Environmental Materials》2022年第1期295-304,共10页能源与环境材料（英文）

基　　金：supported by the Joint Center for Energy Storage Research(JCESR),a U.S.Department of Energy,Energy Innovation Hub。

摘　　要：Using ab initio molecular dynamics(AIMD)simulations,classical molecular dynamics(CMD)simulations,small-angle X-ray scattering(SAXS),and pulsed-field gradient nuclear magnetic resonance(PFG-NMR),the solvation structure and ion dynamics of magnesium bis(trifluoromethanesulfonyl)imide(Mg(TFSI)_(2))aqueous electrolyte at 1,2,and 3 m concentrations are investigated.From AIMD and CMD simulations,the first solvation shell of an Mg;ion is found to be composed of six water molecules in an octahedral configuration and the solvation shell is rather rigid.The TFSI^(-)ions prefer to stay in the second solvation shell and beyond.Meanwhile,the comparable diffusion coefficients of positive and negative ions in Mg(TFSI)_(2)aqueous electrolytes have been observed,which is mainly due to the formation of the stable[Mg(H_(2)O_(6))_(2)]^(+)complex,and,as a result,the increased effective Mg ion size.Finally,the calculated correlated transference numbers are lower than the uncorrelated ones even at the low concentration of 2 and 3 m,suggesting the enhanced correlations between ions in the multivalent electrolytes.This work provides a molecular-level understanding of how the solvation structure and multivalency of the ion affect the dynamics and transport properties of the multivalent electrolyte,providing insight for rational designs of electrolytes for improved ion transport properties.

关 键 词：Mg(TFSI)_(2)aqueous electrolyte molecular dynamics simulation pulsed-field gradient nuclear magnetic resonance small-angle X-ray scattering ion dynamics 

分 类 号：TM912[电气工程—电力电子与电力传动]