A 2D covalent organic framework with ultra-large interlayer distance as high-rate anode material for lithium-ion batteries
Manman Wu, Zhao Yang, Hongtao Zhang, Jie Zhu, Yanfeng Ma, Chenxi Li, Yamin Zhang, Yongsheng Chen
Abstract
Covalent organic frameworks (COFs) have been broadly investigated for energy storage systems. However, many COF-based anode materials suffer from low utilization of redox-active sites and sluggish ions/electrons transport caused by their densely stacked layers. Thus, it is still a great challenge to obtain COF-based anode materials with fast ions/electrons transport and thus superior rate performance. Herein, a redox-active piperazine-terephthalaldehyde (PA-TA) COF with ultra-large interlayer distance is designed and synthesized for high-rate anode material, which contains piperazine units adopting a chair-shaped conformation with the nonplanar linkages of a tetrahedral configuration. This unique structure renders PA-TA COF an ultra-large interlayer distance of 6.2 Å, and further enables it to achieve outstanding rate and cycling performance. With a high specific capacity of 543 mAh·g−1 even after 400 cycles at 1.0 A·g−1, it still could afford a specific capacity of 207 mAh·g−1 even at a high current density of 5.0 A·g−1. Our study indicates that expanding the interlayer distance of COFs by rational molecular design would be of great importance to develop high-rate electrode materials for lithium-ion batteries.