Porous Liquids as Electrolyte: A Case Study of Li<sup>+</sup> and Mg<sup>2+</sup> Ion Transport in Crown Ether-Based Type-II Porous Liquids
Sun Hae Ra Shin, Hyung‐Seok Lim, Kee Sung Han, Alexander Robinson, Aaron Hollas, Bhuvaneswari M. Sivakumar, Samantha I. Johnson, Jaehun Chun, Wei Wang, Vijayakumar Murugesan, Praveen K. Thallapally
Abstract
We demonstrated an enhanced ion transport properties of type-II porous liquid-based electrolyte in which crown ether provides internal porosity and are capable of coordinating and transporting Li+ and Mg2+ ions. We investigated the solvation structure and transport properties of the porous liquid electrolytes with different functional groups and cavity sizes. Among the electrolytes studied, the 12-crown-4 (12C4)-based porous liquid electrolyte exhibited the most enhanced ionic conductivity due to size match between the crown ether cavity and the Li+ ion. Nuclear magnetic resonance and Fourier transform infrared analyses revealed that addition of crown ethers reduces the Li+ ion–solvent interaction, resulting in the formation of Li-crown ether complexes. Molecular simulations complement such observations by describing the detailed solvation environment at molecular scale, including complexation between Li+ and Mg2+ ions and 12C4. The strategy described here using crown ether-based porous liquids should be applicable to design versatile electrolytes for various metal-ion batteries.