氰基功能化聚乙烯亚胺交联固态聚合物电解质的制备及理化性能

Synthesis and Characterization of Cross-linked Solid Polymer Electrolyte Based on N-Cyanoethylated Polyethylenimine for Lithium-Ion Batteries

固态聚合物电解质可避免传统电解液易燃易爆等安全隐患,极大提高锂离子电池的安全性。本文通过支化聚乙烯亚胺和丙烯腈之间的迈克尔加成反应,合成了一系列具有不同氰基数的N-氰基乙基化聚乙烯亚胺(CN-PEI),通过核磁氢谱及碳氢核磁二维谱二维核磁共振和红外对CN-PEI的化学结构进行了表征。聚合物CN-PEI中引入双(三氟甲磺酰基)酰亚胺锂盐和交联剂三丙二醇二丙烯酸酯制备了交联固态聚合物电解质,我们发现氰基极性基团的引入可提高材料的离子电导率,当CN-PEI的氰基乙基化数为1时,电解质表现出最高的室温离子电导率(1.84×10^(-5)S/cm)和锂离子迁移数(0.56),固态电解质材料表现出较高的电化学稳定性,氧化电势达5.0 V(vs.Li+/Li)。

Solid polymer electrolytes have attracted much attention due to their non-volatility,low flammability and high safety.Herein,we synthesized a series of N-cyanoethylated branched polyethylenimine(CN-PEI)with different cyanoethylation numbers(0.3~5)through the Michael addition reaction between branched polyethylenimine and acrylonitrile.The polymer matrix CN-PEI was used to prepare cross-linked solid polymer electrolyte systems with lithium bis(trifluoromethanesulfonyl)imide as a lithium salt and tripropylene glycol diacrylate as a cross-linking agent.Subsequently,the chemical structure of CN-PEI was characterized by 1H-nuclear magnetic resonance(NMR),C-H correlated spectroscopy(COSY)and Fourier transform infrared(FT-IR)spectrscopy.The introduction of cyano group in PEI significantly increases the ion conductivity of the crosslinked solid electrolytes.When the cyanoethylation number of CN-PEI is 1,the electrolyte exhibits the highest ionic conductivity(1.84×10^(-5)S/cm at room temperature),lithium-ion transference number(0.56)and the solid electrolyte exhibits a high electrochemical stability,presenting an oxidation potential up to 5.0 V(vs.Li+/Li).