Salt-Concentration Dependence of the Glass Transition Temperature in PEO-NaI and PEO-LiTFSI Polymer Electrolytes
Salt-Concentration Dependence of the Glass Transition Temperature in PEO-NaI and PEO-LiTFSI Polymer Electrolytes
复制标题
DOI：
10.1021/ma401686r
复制
发表时间：
2013-11-12
期刊：
影响因子：
5.5
通讯作者：
Wilde, Gerhard
中科院分区：
文献类型：
--
作者：
Stolwijk, Nicolaas A.;Heddier, Christian;Wilde, Gerhard
我们测量了玻璃化转变温度T-g作为聚合物电解质体系中的盐浓度的函数，该体系由与碘化钠（NaI）或锂双（三氟磺酰亚胺）（LiTFSI）络合的聚（环氧乙烷）（PEO）组成。在相同组成下，PEO-Nal的Tg通常大于LiTFSI的Tg。本T-g值明显高于以前报道的参考数据。观察到的非线性浓度依赖性也不同于早期的研究。这些发现暂时归因于本工作中保持的更严格的制备和测量条件，从而使有机溶剂残留和水污染保持在低水平。聚合物的高分子量也可能有一些影响。在从熔体淬火后通过差示扫描量热法进行测量。我们发现，在液氮中的非原位浸没淬火导致较低的结晶度比在量热计环境中的原位淬火。此外，随着盐含量的增加，结晶度的强烈降低引起了更浓的电解质在T-g附近的热容的明显步骤。
We measured glass transition temperatures T-g as a function of the salt concentration in polymer electrolyte systems consisting of poly(ethylene oxide) (PEO) complexed either with sodium iodide (NaI) or lithium bis(trifluorosulfonylimide) (LiTFSI). At homologous compositions, T-g of PEO-Nal is found to be generally larger than that of LiTFSI. The present T-g values are markedly higher than previously reported reference data. Also the observed nonlinear concentration dependence differs from earlier studies. These findings are tentatively attributed to the more stringent preparation and measuring conditions maintained in the present work, thereby keeping organic solvent residues and water contamination at low levels. Also the high molecular weight of the polymer may have some influence. The measurements were performed by differential scanning calorimetry after quenching from the melt. We find that ex situ immersion quenching in liquid nitrogen leads to lower degrees of crystallinity than in situ quenching in the calorimeter environment. In addition, the strong decrease of the crystallinity with increasing salt content gives rise to pronounced steps in the heat capacity near T-g for the more concentrated electrolytes.