Post-Modification\nApproach for Self-Exfoliated Synthesis\nof Pyridinium Sulfobetaine Covalent Organic Frameworks for Enhanced\nLithium-Ion Conductivity

While\ncovalent organic frameworks (COFs) have been extensively\ninvestigated in the field of organic electrolyte materials, there\nis potential for further enhancement of their room-temperature ionic\nconductivity. This study introduces a novel methodology to induce\nself-exfoliation in the parent COF during synthesis through a postmodification\ntechnique. This process yields covalent organic nanosheets that feature\npyridinium sulfobetaine groups, referred to as PS-CON. Due to the\nstrategic arrangement of pyridinium cations and sulfobetaine anions,\nthe charge distribution in PS-CON varies substantially, leading to\na significant enhancement in lithium-ion dissociation. The methodically\norganized one-dimensional pore channels, along with the linear structure\nof the pyridinium sulfobetaine groups, facilitate the lithium-ion\ntransport. PS-CON demonstrated a remarkable ionic conductivity of\n2.19 × 10<sup>–4</sup> S cm<sup>–1</sup>and a low\nactivation energy (0.26 eV) coupled with a broad electrochemical stabilization\nwindow (4.05 V). Furthermore, the symmetrical cell (Li|Li@PS-CON|Li)\ndemonstrates stable Li plating/stripping for more than 1200 h, which\nhighlights the vast potential of pyridinium-sulfobetaine based zwitterionic\nnanosheets as high-performance organic electrolytes.