Abstract
We investigated the surprising ionic conductivity trend of a series of hybrid complexes based on lithium iodide (LiI) associated with different size of crown ethers. Through a combination of experimental and theoretical methods, LiI hybrid complexes were characterized to rationalize the unexpected tendency of ionic conductivity. Our findings revealed that the solvation structure of the lithium iodide (LiI) complex of crown ethers is influenced by the size of the crown ether. Consequently, the solvation structure of the complex affects the transport properties. Notably, we observed a unique sandwich-like complex is formed between two 12C4 molecules and the Li cation during classical NVT molecular dynamics (MD) simulation, which is rarely observed with larger crown ethers. Based on this observation, we postulate that the idiosyncratic structure of [Li ⊂ 12C4][I] increases the ratio of SSIP solvation structure, ultimately resulting in higher ionic conductivity compared to [Li ⊂ 15C5][I], despite 15C5 is a larger crown ether than 12C4. We also propose a hypothesis, based on the MD simulation, that adjusting the size of crown ether molecules can potentially enhance the transference number.