Crystalline Free-Standing Two-Dimensional Zwitterionic Organic Nanosheets for Efficient Conduction of Lithium Ions
Ananta Dey, Vishwakarma Ravikumar Ramlal, Selvasundarasekar Sam Sankar, Tufan Singha Mahapatra, Eringathodi Suresh, Subrata Kundu, Amal Kumar Mandal, Amitava Das
Abstract
Crystalline two-dimensional organic nanosheets (2D-ONs) having atomic or near-atomic thickness with infinite lateral dimensions are of crucial significance for their possible application as a material for energy storage. The presence of nanofluidic channels with a designed array of molecular interlayers in such 2D-ONs, for a favorable lithium-ion transport, has special significance for improving the efficacy of lithium-ion batteries. However, the rational design of crystalline 2D-ONs remains a challenge because of the lack of appropriate monomers and convenient preparation methods. Herein, we report a unique lithium-ion conducting behavior of zwitterionic 2D-ONs, formed through self-assembly of a small organic molecule AM-1. Different microscopic studies confirm the near-atomic thickness (∼3.5 nm) of these 2D-ONs. Results of the single-crystal X-ray diffraction studies confirm the presence of a one-dimensional (1D) channel in crystalline 2D-ONs, which was generated during the self-assembly process of the zwitterionic monomer scaffold. The presence of immobilized ionic centers with well-defined directional channels in the 2D-ONs favors the transportation of lithium ions with a room-temperature lithium-ion conductivity of 5.14 × 10–5 S cm–1, which is rather unique for self-assembled 2D-ONs.