Accumulation of Glassy Poly(ethylene oxide) Anchored in a Covalent Organic Framework as a Solid-State Li+ Electrolyte
Accumulation of Glassy Poly(ethylene oxide) Anchored in a Covalent Organic Framework as a Solid-State Li+ Electrolyte
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DOI：
10.1021/jacs.8b07670
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发表时间：
2019-01-23
影响因子：
15
通讯作者：
Horike, Satoshi
中科院分区：
文献类型：
--
作者：
Zhang, Gen;Hong, You-lee;Horike, Satoshi
分子结构的设计显示快速离子导电/传输途径在固态一直是一个重大的挑战。有机聚合物中的非晶或玻璃相由于其动态和随机的结构，可以很好地用于快速离子导电。然而，这些聚合物的主要问题是难以阐明离子传导机制，因此可设计性低。此外，离子导电聚合物的非晶态或玻璃态经常面临结构/机械稳定性的问题。共价有机框架（COFs）是一类具有周期性结构和可调功能的新型晶体有机聚合物，具有独特的离子导体/转运体的潜力。在这里，我们描述了COF作为全固态Li+导电介质的使用。采用自下而上的自组装方法对柔性、笨重、玻璃状的聚环氧乙烷（PEO）部分进行共价网状，这些部分可以通过其节段运动在刚性二维COF结构中溶剂化Li+以实现快速传输。温度相关粉末x射线衍射和热重分析表明，即使在300℃以上，周期结构仍然完整，差示扫描量热法和固态核磁共振显示，积累的PEO链具有高动态，呈现玻璃态。Li+的电导率取决于晶体状态下PEO链的动力学和长度，掺杂LiTFSI后，在200℃下，Li+的固态电导率达到1.33 X 10(-3) S cm（-1）。由于结构的坚固性，在指定温度下的高导电性在较长时间内保持完整。此外，我们展示了COF电解质在100℃下的全固态锂电池中的首次应用。
Design of molecular structures showing fast ion conductive/transport pathways in the solid state has been a significant challenge. The amorphous or glassy phase in organic polymers works well for fast ion conductivity because of their dynamic and random structure. However, the main issue with these polymers has been the difficulty in elucidating the mechanisms of ion conduction and thus low designability. Furthermore, the amorphous or glassy state of ion conductive polymers often confronts the problems of structural/mechanical stabilities. Covalent organic frameworks (COFs) are an emerging class of crystalline organic polymers with periodic structure and tunable functionality, which exhibit potential as a unique ion conductor/transporter. Here, we describe the use of a COF as a medium for all-solid-state Li+ conductivity. A bottom-up self-assembly approach was applied to covalently reticulate the flexible, bulky, and glassy poly(ethylene oxide) (PEO) moieties that can solvate Li+ for fast transport by their segmental motion in the rigid two-dimensional COF architectures. Temperature dependent powder X-ray diffraction and thermogravimetric analysis showed that the periodic structures are intact even above 300 degrees C, and differential scanning calorimetry and solid-state NMR revealed that the accumulated PEO chains are highly dynamic and exhibit a glassy state. Li+ conductivity was found to depend on the dynamics and length of PEO chains in the crystalline states, and solid-state Li+ conductivity of 1.33 X 10(-3) S cm(-1) was achieved at 200 degrees C after LiTFSI doping. The high conductivity at the specified temperature remains intact for extended periods of time as a result of the structure's robustness. Furthermore, we demonstrated the first application of a COF electrolyte in an all-solid-state Li battery at 100 degrees C.