Kalybekkyzy Sandugash, Kopzhassar Al-Farabi, Kahraman Memet Vezir, Mentbayeva Almagul, Bakenov Zhumabay
National Laboratory Astana, Department of Chemical and Materials Engineering, School of Engineering and Digital Sciences, Nazarbayev University, Nur-Sultan 010000, Kazakhstan.
Institute of Batteries LLC., Nur-Sultan 010000, Kazakhstan.
Polymers (Basel). 2020 Dec 23;13(1):15. doi: 10.3390/polym13010015.
Conventional carbonate-based liquid electrolytes have safety issues related to their high flammability and easy leakage. Therefore, it is essential to develop alternative electrolytes for lithium-ion batteries (LIBs). As a potential candidate, solid-polymer electrolytes (SPEs) offer enhanced safety characteristics, while to be widely applied their performance still has to be improved. Here, we have prepared a series of UV-photocrosslinked flexible SPEs comprising poly(ethylene glycol) diacrylate (PEGDA), trimethylolpropane ethoxylate triacrylate (ETPTA), and lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) salt, with the addition of polydimethylsiloxane with acrylated terminal groups (acryl-PDMS) to diminish the crystallinity of the poly(ethylene glycol) chain. Polysiloxanes have gained interest for the fabrication of SPEs due to their unique features, such as decrement of glass transition temperature (T), and the ability to improve flexibility and facilitate lithium-ion transport. Freestanding, transparent SPEs with excellent flexibility and mechanical properties were achieved without any supporting backbone, despite the high content of lithium salt, which was enabled by their networked structure, the presence of polar functional groups, and their amorphous structure. The highest ionic conductivity for the developed cross-linked SPEs was 1.75 × 10 S cm at room temperature and 1.07 × 10 S cm at 80 °C. The SPEs demonstrated stable Li plating/stripping ability and excellent compatibility toward metallic lithium, and exhibited high electrochemical stability in a wide range of potentials, which enables application in high-voltage lithium-ion batteries.
传统的碳酸盐基液体电解质存在与高易燃性和易泄漏相关的安全问题。因此，开发锂离子电池（LIBs）的替代电解质至关重要。作为一种潜在的候选材料，固体聚合物电解质（SPEs）具有增强的安全特性，但其性能仍有待提高才能得到广泛应用。在此，我们制备了一系列紫外光交联的柔性SPEs，其由聚乙二醇二丙烯酸酯（PEGDA）、三羟甲基丙烷乙氧基三丙烯酸酯（ETPTA）和双（三氟甲烷磺酰）亚胺锂（LiTFSI）盐组成，并添加了具有丙烯酸化端基的聚二甲基硅氧烷（acryl-PDMS）以降低聚乙二醇链的结晶度。聚硅氧烷因其独特的特性，如玻璃化转变温度（T）的降低以及改善柔韧性和促进锂离子传输的能力，而在SPEs的制备中受到关注。尽管锂盐含量高，但通过其网络结构、极性官能团的存在及其无定形结构，在没有任何支撑骨架的情况下实现了具有优异柔韧性和机械性能的独立、透明的SPEs。所开发的交联SPEs在室温下的最高离子电导率为1.75×10 S cm，在80°C时为1.07×10 S cm。这些SPEs表现出稳定的锂电镀/剥离能力和对金属锂的优异兼容性，并在很宽的电位范围内表现出高电化学稳定性，这使其能够应用于高压锂离子电池。
