Carbonyl-containing polymers have been considered promising candidates as hosts in solid polymer electrolytes (SPEs) due to the reasonable chelating coordination with Li⁺, better antioxidation for high-voltage cathodes, and higher ion transference number compared with polyether SPEs. In this work, four polyesters of poly(octamethylene succinate), poly(hexmethylene succinate) (PHS), poly(butylene succinate), and polycaprolactone were investigated. In these SPEs with different −C═O/–CH₂– ratios, PHS had the highest conductivity (σ) of 1.24 × 10^–4 S/cm because of the excellent ability to deionize bis(trifluoromethane)sulfonimide (LiTFSI) up to 88.3 ± 3.2% at 70 °C and the lowest activation energy of Li⁺ ionic conduction. The effect of Li⁺/–C═O ratios (r) on the ionic conductivity can be clarified into low-, middle-, and high-concentrated regions. The decrease of PHS crystallinity due to LiTFSI solvation provided ion transport paths and mainly contributed to the improvement of ionic conductivity in the middle-concentrated region, while the solvation degree dominantly facilitated ionic conduction in the high-concentrated region and at higher temperatures. By combining the DFT simulation and polymer thermal analysis, we found the transition of Li⁺ coordination from multichain to single-chain bindings provided more flexible segment movement. It also proved that the sequence design of active groups in a polymer chain would be a promising strategy for stable and high-performance SPEs.

中文翻译：

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LiTFSI 溶剂化对聚酯基固体电解质离子电导率的影响

与聚醚 SPE 相比，含羰基聚合物由于与 Li ⁺合理的螯合配位、对高压正极更好的抗氧化性以及更高的离子迁移数而被认为是固体聚合物电解质（SPE）中的主体的有前途的候选者。在这项工作中，研究了聚（八亚甲基琥珀酸酯）、聚（六亚甲基琥珀酸酯）（PHS）、聚（丁二酸丁二醇酯）和聚己内酯这四种聚酯。在这些具有不同−C=O/–CH ₂ – 比例的SPE中，PHS具有最高的电导率(σ)，为1.24 × 10 ^–4 S/cm，因为它具有优异的双(三氟甲烷)磺酰亚胺(LiTFSI)去离子能力，可达70 °C 时为 88.3 ± 3.2%，Li ⁺离子传导的最低活化能。 Li ⁺ /–C=O 比率 ( r ) 对离子电导率的影响可以分为低浓度、中浓度和高浓度区域。 LiTFSI溶剂化导致PHS结晶度降低，提供了离子传输路径，主要有助于中浓度区域离子电导率的提高，而溶剂化程度主要促进高浓度区域和较高温度下的离子电导率。通过结合DFT模拟和聚合物热分析，我们发现Li ⁺配位从多链到单链结合的转变提供了更灵活的链段运动。它还证明，聚合物链中活性基团的序列设计将是稳定和高性能 SPE 的一种有前途的策略。