Piperazine-Linked Phthalocyanine Covalent Organic Frameworks for Efficient Anodic Lithium Storage
Rong Jiang, Xiaoyang Wang, Chunhui Shi, Yike Li, Qianqian Xu, Xiya Yang, Chunli Li, Chang Liu, Zhixin Liu, Kang Wang, Jianzhuang Jiang, Yongjun Feng
Abstract
Organic anode materials have been considered as promising electrodes for achieving low-cost and sustainable lithium-ion batteries (LIBs). However, organic materials face challenges, such as inadequate cycling stability and sluggish reaction kinetics, leading to an unsatisfactory LIB performance. Covalent organic frameworks (COFs) possess a porous and designable structure coupled with exceptional stability, making them promising candidates for anode electrodes in LIBs to address the challenges. Herein, two piperazine-linked conjugated phthalocyanine-based COFs (named CoPc-BTM-COF and CoPc-DAB-COF) were fabricated from reacting hexafluorophthalocyanine cobalt(II) (CoPcF 16 ) with 1,2,4,5-benzenetetramine (BTM) and 3,3′-diaminobenzidine (DAB), respectively. Powder X-ray diffraction and electron microscopy analyses in combination with theoretical simulation reveal their crystalline nature with sql net and AA arranged stacking pattern. The pore sizes of these two Pc-COFs are 1.62 and 1.90 nm according to theoretical simulation and N 2 sorption measurement, which facilitates their rapid transport of Li + ions. The immersion experiments disclose their remarkable stability. These advantages, together with their conjugated nitrogen-rich skeletal structures, lead to outstanding anodic Li + storage capabilities, exceptional rate performance, and favorable cycling stability. In particular, both Pc-COFs exhibit high capacities of 877 and 669 mAh g –1 at 100 mA g –1, superior to most reported organic LIB anodes, showing promising application potential in high-performance LIBs.