π-Conjugated electrochemically stable covalent quinazoline network for lithium ion storage

Abstract

Covalent organic frameworks (COFs) have been widely used as electrode materials for lithium ion batteries due to their adjustable structure, abundant porous structure and large specific surface area. In this work, 2D porous covalent quinazoline organic network (CQN) materials, with abundant mesoporous and nitrogen-containing active sites, were synthesized by a simple ionic thermal reaction. Due to the abundant active sites in the structure of CQN, CQN anodes show excellent electrochemical capacity (975 mAh g−1) and at 1.0 A g−1current density, the capacity retention rate is 82 % after 1000 cycles. The theoretical calculation results show that the N of the quinazoline group is an effective active site. However, due to hindrance by H+, the Li+ diffusion channel is mainly a 2D interlayer. Furthermore, the structure of the CQN material is similar to that of nitrogen-doped graphene and has good electronic conductivity; thus, leading to outstanding rate performance.