基于核磁共振技术探讨有机硅电解质物化特性

Physical and Chemical Properties of Silicone Electrolyte Materials Evaluated by Nuclear Magnetic Resonance Technology

有机硅化合物是电解质材料研究的热点之一,其物理化学特性是衡量电池性能的重要参数.本文采用多种核磁共振(NMR)技术(包括^(1)H NMR、^(13)C NMR、DOSY、^(7)Li NMR、^(19)F NMR)对有机硅化合物CN(CH_(2))_(2)Si CH_(3)(OCH_(2)CH_(2)OCH_(3))_(2)(BNS)的结构,电解液(LiPF_(6)/BNS)的溶剂化效应、扩散系数和热稳定性四个方面进行了分析评价,发现BNS和LiPF6之间具有溶剂化效应;BNS的氰基(CN)和醚键(-O-)基团可与Li+形成络合物,且氰基配位能力优于醚键,络合键的形成促进了LiPF_(6)的离解和扩散,同时也提高了LiPF_(6)/BNS的热稳定性,证明高温下LiPF_(6)的分解是电解液失败的主要原因.该研究为开发新型电解质化合物及促进其性能提升提供了理论依据.

Organosilicon compounds are one of the hot topics in research on electrolyte materials,with their physical and chemical properties standing as important parameters for measuring battery performance.In this paper,the structure of CN(CH2)2Si CH3(OCH2CH2OCH3)2 (BNS),solvation effect,diffusion coefficient and thermal stability of LiPF6/BNS were analyzed and evaluated by various nuclear magnetic resonance (NMR) methods (i.e.,1H NMR,13C NMR,DOSY,7Li NMR and 19F NMR).It was observed that there was a solvation effect between BNS and LiPF6.Cyano (CN) and ether bond (-O-)groups in BNS may help to form complexes with Li+,and the coordination ability of CN is better than that of-O-.The formation of complex bond accelerated dissociation and diffusion of LiPF6,and also improved the thermal stability of electrolyte (LiPF6/BNS).It was proved that decomposition of LiPF6 at high temperature was the main cause of electrolyte failure.The results of this study provided a theoretical basis for the development of new electrolyte compounds and improvement of their performance.