Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, United States.
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
ACS Macro Lett. 2023 Jul 18;12(7):874-879. doi: 10.1021/acsmacrolett.3c00285. Epub 2023 Jun 21.
The phase behavior of polymer blend electrolytes comprising poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA)/lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was determined using a combination of light and small angle neutron scattering (SANS) experiments. The results at a fixed temperature (110 °C) are presented on a PEO concentration versus salt (LiTFSI) concentration plot. The blends are miscible at all PEO concentrations in the absence of salt. With added salt, a region of immiscibility is obtained in PEO-lean polymer blend electrolytes; blends rich in PEO remain miscible at most salt concentrations. A narrow region of immiscibility juts into the miscible region, giving the phase diagram a chimney-like appearance. The data are qualitatively consistent with a simple extension of Flory-Huggins theory with a composition-dependent Flory-Huggins interaction parameter, χ, that was determined independently from SANS data from homogeneous blend electrolytes. Phase diagrams like the one we obtained were anticipated by self-consistent field theory calculations that account for correlations between ions. The relationship between these theories and measured χ remains to be established.
采用光散射和小角中子散射（SANS）实验相结合的方法，研究了包含聚（环氧乙烷）（PEO）/聚（甲基丙烯酸甲酯）（PMMA）/双（三氟甲烷磺酰基）亚胺锂（LiTFSI）的聚合物共混电解质的相行为。在固定温度（110°C）下的结果以 PEO 浓度与盐（LiTFSI）浓度的关系图呈现。在没有盐的情况下，所有 PEO 浓度下的共混物都是混溶的。加入盐后，在 PEO 贫聚合物共混电解质中获得了不混溶区域；富含 PEO 的共混物在大多数盐浓度下仍然混溶。不混溶区域狭窄地突入混溶区域，使得相图呈现出烟囱状。数据与 Flory-Huggins 理论的简单扩展定性一致，该理论具有独立于 SANS 数据从均相共混电解质确定的组成依赖性 Flory-Huggins 相互作用参数 χ。我们获得的相图与考虑离子相关性的自洽场理论计算所预期的相图相似。这些理论与测量的 χ 之间的关系尚待建立。
