<b>Thermal Properties and Ionic Conductivity in Salt-Containing POEM/PEO Polymer Blend Electrolytes</b>

Polymer blend electrolytes are one possible pathway to developing solid electrolytes with improved properties when compared to the widely studied poly(ethylene oxide) (PEO) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) system. However, many previously studied polymer blend electrolytes are not fully miscible at varying salt concentrations across the full blend composition window. In this study, we design a polymer blend electrolyte system that is fully miscible and characterize its thermal and ion transport properties. Poly (oligo ethylene oxide methacrylate) (POEM) is an ion conducting polymer with ethylene oxide side chains that can be varied in length. Our polymer blend electrolyte system contains PEO, POEM, and LiTFSI where we vary POEM monomer chemistry to determine the effect of side chain length and molecular weight on blend properties. All PEO/POEM/LiTFSI blends were miscible, regardless of POEM monomer structure, blend composition, or salt concentration. We characterize the blend properties using differential scanning calorimetry (DSC) and variable-temperature electrochemical impedance spectroscopy (EIS). Using the blend glass transition temperature and a modified Fox Equation, we are able to determine the salt partitioning within the system and quantify changes in the segmental dynamics of the polymer blend. We find that while Li ions are primarily solvated by PEO, the POEM monomer structure determines the extent. Through EIS, we find that longer side chains more easily solvate the Li ionsand have higher ionic conductivities. This study shows that engineering the solvation structure and segmental dynamics of salt-doped polymer blend can lead to developing electrolytes with improved ion transport properties for battery applications.

相较于当前被广泛研究的聚环氧乙烷（poly(ethylene oxide), PEO）与双(三氟甲基磺酰)亚胺锂（lithium bis(trifluoromethanesulfonyl)imide, LiTFSI）体系，聚合物共混电解质是开发性能更优异的固体电解质的可行路径之一。然而，此前已被研究的诸多聚合物共混电解质，在全共混组成范围内的不同盐浓度下，无法实现完全互溶。本研究设计了一种可实现完全互溶的聚合物共混电解质体系，并对其热学与离子传输性能进行了表征。聚(寡聚环氧乙烷甲基丙烯酸酯)（Poly(oligo ethylene oxide methacrylate), POEM）是一种带有环氧乙烷侧链的离子导电高分子，其侧链长度可调节。本研究的聚合物共混电解质体系由PEO、POEM与LiTFSI组成，通过调控POEM单体的化学结构，探究侧链长度与分子量对共混体系性能的影响。无论POEM单体结构、共混组成或是盐浓度如何，所有PEO/POEM/LiTFSI共混体系均实现了完全互溶。本研究采用差示扫描量热法（differential scanning calorimetry, DSC）与变温电化学阻抗谱（variable-temperature electrochemical impedance spectroscopy, EIS）对共混体系的性能进行表征。结合共混体系的玻璃化转变温度与修正福克斯方程（modified Fox Equation），我们可以确定体系内的盐分配情况，并量化聚合物共混体系的链段动力学变化。研究发现，尽管锂离子主要由PEO溶剂化，但POEM单体结构决定了溶剂化程度。通过EIS测试我们发现，侧链越长越易溶剂化锂离子且离子电导率更高。本研究表明，通过调控盐掺杂聚合物共混体系的溶剂化结构与链段动力学，可开发出用于电池领域、离子传输性能更优异的电解质材料。

搜集汇总

背景与挑战

背景概述

该数据集聚焦于盐掺杂POEM/PEO聚合物共混电解质的热性能和离子电导率研究，通过设计完全可混溶的PEO/POEM/LiTFSI系统，探究POEM单体侧链长度和分子量对共混物性能的影响。研究使用DSC和EIS进行表征，分析了盐分配、链段动力学与离子传输的关系，发现较长侧链更易溶剂化锂离子并提高电导率，为开发电池用高性能电解质提供了实验数据。