안준영 (POSTECH)

서종철 (POSTECH)

안준영 (POSTECH)

최윤섭 (POSTECH)

서종철 (POSTECH)

Lithium triflate (LiOTf) plays a key role in lithium-ion batteries by affecting ionic transport in polymer electrolytes. N,N,N′,N′-Tetramethylethylenediamine (TMEDA) serves as a simplified model for polymer hosts. In this study, using ESI-IMS-MS, we investigated gas-phase structures of LiOTf-TMEDA clusters. Although the (LiOTf)₂ Li⁺·(TMEDA)₃ ion was initially presumed to be axially symmetric, CID and DFT analysis revealed an asymmetric structure, likely due to the instability of a cyclic TMEDA trimer.

To promote more defined axial symmetry, we introduced macrocyclic ligands. LiOTf was first combined with Hexacyclen, which formed distorted clusters due to its small ring size. We then synthesized 24-Crown-6 (24C6), a larger ring system, and compared its complexes with those formed using 18-Crown-6 (18C6). Among these, the (LiOTf)₂Li⁺·(24C6)₁ complex exhibited axial symmetry with close agreement between measured and calculated CCS values.

Although such coordination may reduce conductivity, it may enhance thermal and electrochemical stability, desirable for durability-oriented applications. Ongoing studies aim to probe these trade-offs and provide design insights for next-generation polymer electrolytes.