Song Jian, Lin Li, Cui Fengchao, Wang Heng-Guo, Tian Yuyang, Zhu Guangshan
Key Laboratory of Polyoxometalate and Reticular Material Chemistry of Ministry of Education, Faculty of Chemistry, Northeast Normal University Changchun 130024 China
Chem Sci. 2024 Jun 19;15(29):11480-11487. doi: 10.1039/d4sc02506g. eCollection 2024 Jul 24.
In recent years, solid-state lithium metal batteries (SSLMBs) have become a new development trend, and it has become a top priority to design solid-state electrolytes (SSEs) that can rapidly and stably transport lithium ions in a variety of climatic environments. In this work, an integrated "rigid-flexible" dual-functional strategy is proposed to develop a cationic covalent organic framework (EO-BIm-iCOF) with well-defined flexible oligo(ethylene oxide) (EO) chains as an SSE for SSLMBs. As expected, the synergistic effects of the rigid cationic framework and flexible EO chains not only promote the dissociation of LiTFSI salts, but also greatly improve the transport of lithium ions, which endows LITFSI@EO-BIm-iCOF SSEs with a high Li conductivity of 1.08 × 10 S cm and ionic transference number of 0.69 at room temperature. Besides, the molecular dynamics (MD) simulations have also elucidated the diffusion and transport mechanism of lithium ions in LITFSI@EO-BIm-iCOF SSEs. Interestingly, the assembled SSLMBs wherein LiFePO is paired with LITFSI@EO-BIm-iCOF SSEs display decent electrochemical properties at higher and lower temperatures. This work provides a great development prospect for the application of cationic COFs in solid-state batteries.
近年来，固态锂金属电池（SSLMBs）已成为一种新的发展趋势，设计出能在各种气候环境中快速稳定传输锂离子的固态电解质（SSEs）已成为当务之急。在这项工作中，提出了一种集成的“刚柔”双功能策略，以开发一种阳离子共价有机框架（EO-BIm-iCOF），其具有定义明确的柔性低聚环氧乙烷（EO）链，作为SSLMBs的SSE。正如预期的那样，刚性阳离子框架和柔性EO链的协同效应不仅促进了LiTFSI盐的解离，还大大改善了锂离子的传输，这使得LITFSI@EO-BIm-iCOF SSEs在室温下具有1.08×10 S cm的高Li电导率和0.69的离子迁移数。此外，分子动力学（MD）模拟也阐明了锂离子在LITFSI@EO-BIm-iCOF SSEs中的扩散和传输机制。有趣的是，LiFePO与LITFSI@EO-BIm-iCOF SSEs配对组装的SSLMBs在较高和较低温度下都表现出良好的电化学性能。这项工作为阳离子COFs在固态电池中的应用提供了广阔的发展前景。
