Regulating Li+ Transport and Interfacial Stability with Zwitterionic COF Protective Layer Towards High-Performance Lithium Metal Batteries

• Ethidium cations act as 'anion capturers' to immobilize TFSI−, promoting the formation of a LiF/Li3N-rich solid electrolyte interphase. • Ion–dipole interactions between ethidium groups and solvent molecules boost Li+ desolvation, enhancing ion transport kinetics. • Sulfonate groups exhibit an ion-sieving effect that selectively attracts Li+ while excluding TFSI−, facilitating LiTFSI dissociation and accelerating Li+ migration. • The Z-COF protective layer enables stable Li plating/stripping for over 6300 hours and high-capacity retention in full cells, demonstrating practical potential for high-performance lithium metal batteries.