Shi Zhen, Zhou Hongru, Fan Zixin, Guo Kairui, Nie Hui, Zhou Xingping, Xue Zhigang
Key Laboratory of Material Chemistry for Energy Conversion and Storage Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China.
Small. 2024 Dec;20(52):e2407293. doi: 10.1002/smll.202407293. Epub 2024 Oct 18.
Although solid polymer electrolytes have been developed for several decades, poly(ethylene oxide) (PEO) or polymers with ethoxy (EO) segments are still one of the most promising candidates for advanced batteries. The low ionic conductivity and lithium-ion transference number as well as the deterioration of mechanical properties after coupling with lithium salts restrict its further adoption. Herein, a serial of PEO-based composite electrolytes optimized by waterborne polyurethane are prepared via blend method. With the assistance of HO, ionic type waterborne polyurethane assembles into flexible micelles, in which hydrophobic segments as the core and hydrophilic groups as the shell. Utilizing this feature of waterborne polyurethane, PEO and Li salt (LiTFSI) aqueous solution is slowly added to the organic solution of waterborne polyurethane to compound in situ, and polymer composite electrolytes are fabricated. The multilevel (hydrogen bonds with different binding energy) and multiscale (deformation of flexible micelles) dynamic interaction endows the composite electrolyte with attractive mechanical properties. The assembled Li|Li symmetric battery with the molar ratio of EO to Li salts of 8:1 exhibits excellent cycling stability up to 800 h at 0.1 mA cm, and the assembled Li|LiFePO battery can be stably cycled at 1C for >400 cycles.
尽管固体聚合物电解质已经发展了几十年，但聚环氧乙烷（PEO）或带有乙氧基（EO）链段的聚合物仍然是先进电池最有前景的候选材料之一。其低离子电导率、锂离子迁移数以及与锂盐复合后机械性能的恶化限制了它的进一步应用。在此，通过共混法制备了一系列经水性聚氨酯优化的基于PEO的复合电解质。在羟基的辅助下，离子型水性聚氨酯组装成柔性胶束，其中疏水链段为核，亲水基团为壳。利用水性聚氨酯的这一特性，将PEO和锂盐（LiTFSI）水溶液缓慢加入到水性聚氨酯的有机溶液中进行原位复合，制备出聚合物复合电解质。多级（具有不同结合能的氢键）和多尺度（柔性胶束的变形）动态相互作用赋予了复合电解质具有吸引力的机械性能。组装的锂对称电池，EO与锂盐的摩尔比为8:1，在0.1 mA cm下表现出高达800 h的优异循环稳定性，组装的Li|LiFePO₄电池在1C下可稳定循环>400次。
