Wang Bi-Heng, Xia Tian, Chen Qun, Yao Ye-Feng
Material Science Department & Physics Department & Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Electronic Science, East China Normal University, North Zhongshan Road 3663, Shanghai 200062, China.
Polymers (Basel). 2020 Feb 9;12(2):391. doi: 10.3390/polym12020391.
Polyethylene oxide-based solid polymer electrolytes (SPEs) are of research interest because of their potential applications in all-solid-state Li batteries. However, despite their advantages in terms of compatibility with the electrodes and easy processing, polyethylene oxide (PEO)/Li complexes often suffer from low conductivity at room temperature. Understanding the conduction mechanism and, in turn, developing strategies to improve the conductivity have long been the main objectives underlying research into PEO/Li complex electrolytes. Here, we prepared several special PEO/Li complex samples where the PEO/Li complex structures were located on the surfaces of PEO crystals and consisted of high content chain ends. We found two different Li species in the PEO/Li complex structures via solid-state nuclear magnetic resonance (NMR). The 2D Li exchange NMR showed the exchange process between the different Li species. The exchange dynamics of the Li ions provide a molecular mechanism of the Li transportation in the surface of PEO crystal lamella, which is further correlated with the ionic conduction mechanism of the PEO/Li complex structure.
基于聚环氧乙烷的固体聚合物电解质（SPEs）因其在全固态锂电池中的潜在应用而受到研究关注。然而，尽管聚环氧乙烷（PEO）/锂络合物在与电极的兼容性和易于加工方面具有优势，但在室温下其电导率往往较低。理解传导机制并进而开发提高电导率的策略长期以来一直是PEO/锂复合电解质研究的主要目标。在此，我们制备了几种特殊的PEO/锂复合样品，其中PEO/锂复合结构位于PEO晶体表面且由高含量链端组成。通过固态核磁共振（NMR），我们在PEO/锂复合结构中发现了两种不同的锂物种。二维锂交换NMR显示了不同锂物种之间的交换过程。锂离子的交换动力学提供了PEO晶体薄片表面锂传输的分子机制，这进一步与PEO/锂复合结构的离子传导机制相关。
