Cao Yingnan, Sun Weiwei, Guo Chaofei, Zheng Lu, Yao Mengyao, Wang Yong
Department of Chemical Engineering, School of Environmental and Chemical Engineering, Shanghai University, 99 Shangda Road, Shanghai, People's Republic of China, 200444.
Key Laboratory of Organic Compound Pollution Control Engineering, Ministry of Education, Shanghai University, 99 Shangda Road, Shanghai, People's Republic of China, 200444.
ACS Nano. 2022 Jun 28;16(6):9830-9842. doi: 10.1021/acsnano.2c03857. Epub 2022 Jun 5.
Covalent organic polymers are attracting more and more attention for energy storage devices due to their lightweight, molecular viable design, stable structure, and environmental benignity. However, low charge-carrier mobility of pristine covalent organic materials is the main drawback for their application in lithium-ion batteries. Herein, a yolk-shell bimetal-modified quinonyl-rich covalent organic material, Co@2AQ-MnO, has been designed and synthesized by loading of petal-like nanosized MnO and coordinating with Co centers, with the aim to improve the charge conductivity of the covalent organic polymer and activate its Li-storage sites. As investigated by FT-IR, XPS, and electrochemical probing, the quinonyl-rich structure provides abundant redox sites (carbonyl groups and π electrons from the benzene ring) for lithium reaction, and the introduction of two types of metallic species promotes the charge transfer and facilitates more efficient usage of active energy-storage sites in Co@2AQ-MnO. Thus, the Co@2AQ-MnO electrode exhibits good cycling performance with large reversible capacity and excellent rate performance (1534.4 mA h g after 200 cycles at 100 mA g and 596.0 mA h g after 1000 cycles at 1000 mA g).
共价有机聚合物因其重量轻、分子可设计性、结构稳定和环境友好性，在储能设备方面正吸引着越来越多的关注。然而，原始共价有机材料的低载流子迁移率是其在锂离子电池中应用的主要缺点。在此，通过负载花瓣状纳米MnO并与Co中心配位，设计合成了一种核壳结构双金属改性的富含醌基的共价有机材料Co@2AQ-MnO，旨在提高共价有机聚合物的电荷传导率并激活其锂存储位点。通过傅里叶变换红外光谱（FT-IR）、X射线光电子能谱（XPS）和电化学探测研究发现，富含醌基的结构为锂反应提供了丰富的氧化还原位点（羰基和苯环的π电子），两种金属物种的引入促进了电荷转移，并有助于更有效地利用Co@2AQ-MnO中的活性储能位点。因此，Co@2AQ-MnO电极表现出良好的循环性能，具有大的可逆容量和优异的倍率性能（在100 mA g下循环200次后为1534.4 mA h g，在1000 mA g下循环1000次后为596.0 mA h g）。
