Abstract
Expanding the structural diversity of crystalline two-dimensional polymers (2DPs) is highly desired but remains a considerable challenge. Herein we report the first synthesis of novel crystalline secondary amine-linked triazine-based 2DPs (SAT-2DPs) by using benzidine or 4, 4 ''-diamino-p-terphenyl and cyanuric chloride under solvothermal conditions. We find the structures of diamine-based monomers play a crucial role in deciding whether the synthesized material is crystalline 2DPs nanosheets or amorphous nanoparticles, which is unexpected and provides an important understanding of the 2D polymerization mechanism. The obtained SAT-2DPs not only show a lateral size of micrometers and an ultrathin thickness of a few nanometers, but also demonstrate high crystallinity with a unique ABC stacking configuration, excellent solvent dispersibility and superior thermal stability. In addition, the resultant SAT-2DPs are used to guide uniform lithium-ion deposition due to their abundant nitrogen atoms and ordered open channels. The assembled asymmetric coin cells (Li|Cu) with SAT-2DPs realize the average coulombic efficient up to 99.3% during discharge-charge cycles. This work provides valuable insights into the synthesis of new 2DPs for various applications.