Olmedo-Martínez Jorge L, Meabe Leire, Basterretxea Andere, Mecerreyes David, Müller Alejandro J
POLYMAT and Polymer Science and Technology Department, Faculty of Chemistry, University of the Basque Country UPV/EHU, Paseo Manuel de Lardizabal 3, 20018 Donostia-San Sebastián, Spain.
IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain.
Polymers (Basel). 2019 Mar 9;11(3):452. doi: 10.3390/polym11030452.
Poly(ethylene oxide) (PEO) is the most widely used polymer in the field of solid polymer electrolytes for batteries. It is well known that the crystallinity of polymer electrolytes strongly affects the ionic conductivity and its electrochemical performance. Nowadays, alternatives to PEO are actively researched in the battery community, showing higher ionic conductivity, electrochemical window, or working temperature range. In this work, we investigated polymer electrolytes based on aliphatic polyethers with a number of methylene units ranging from 2 to 12. Thus, the effect of the lithium bis(trifluoromethanesulfone) imide (LiTFSI) concentration on the crystallization behavior of the new aliphatic polyethers and their ionic conductivity was investigated. In all the cases, the degree of crystallinity and the overall crystallization rate of the polymers decreased drastically with 30 wt % LiTFSI addition. The salt acted as a low molecular diluent to the polyethers according to the expectation of the Flory⁻Huggins theory for polymer⁻diluent mixtures. By fitting our results to this theory, the value of the interaction energy density (B) between the polyether and the LiTFSI was calculated, and we show that the value of B must be small to obtain high ionic conductivity electrolytes.
聚环氧乙烷（PEO）是电池固态聚合物电解质领域应用最为广泛的聚合物。众所周知，聚合物电解质的结晶度会强烈影响其离子电导率及其电化学性能。如今，电池领域正在积极研究PEO的替代物，这些替代物表现出更高的离子电导率、电化学窗口或工作温度范围。在这项工作中，我们研究了基于亚甲基单元数量在2至12之间的脂肪族聚醚的聚合物电解质。因此，研究了双（三氟甲磺酰）亚胺锂（LiTFSI）浓度对新型脂肪族聚醚结晶行为及其离子电导率的影响。在所有情况下，添加30 wt%的LiTFSI后，聚合物的结晶度和整体结晶速率均大幅下降。根据聚合物-稀释剂混合物的弗洛里-哈金斯理论预期，盐对聚醚起到了低分子稀释剂的作用。通过将我们的结果与该理论拟合，计算出了聚醚与LiTFSI之间的相互作用能密度（B）值，并且我们表明，要获得高离子电导率电解质，B值必须较小。
