Molecular Stacking Patterns Enhance Organic Small-Molecule Electrochemical Stability and Enable Ion Separation.

Abstract

Organic small-molecule materials, leveraging their multisite nature, low molecular weight, sustainability, and element-rich composition, are promising candidates for electrochemical ion extraction applications. However, restricted structural stability, caused by ion-intercalation-induced volume expansion and resulting capacity decay, has hindered further application. Here, based on a structural stacking approach to form an integrated intermolecular force network and lithiophilic ion channels, phenazine (PNZ) is utilized to demonstrate the significant functional relevance of molecular stacking structures in enhancing organic small-molecule electrochemical stability. By fostering integrated intermolecular forces, the uniquely orthogonal molecular-structured PNZ is capable of effectively addressing the challenges related to volume expansion, pulverization, and dissolution. Moreover, this stacking creates ion-transport channels with high affinity for monovalent ions, enhancing Li⁺ transport efficiency and enabling selective Li/Mg ion separation. This work provides significant insights into molecular structural stacking characteristics, contributing to the discovery and design of stable and efficient small-molecule materials for electrochemical applications.