Shi Jiangwei, Su Mengfei, Li Hang, Lai Dawei, Gao Feng, Lu Qingyi
State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, Collaborative Innovation Center of Advanced Microstructures, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China.
Department of Materials Science and Engineering, Jiangsu Key Laboratory of Artificial Functional Materials, Collaborative Innovation Center of Advanced Microstructures, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210023, P. R. China.
ACS Appl Mater Interfaces. 2022 Sep 21;14(37):42018-42029. doi: 10.1021/acsami.2c10917. Epub 2022 Sep 12.
Modifying the separator of lithium-sulfur batteries (LSBs) is considered to be one of the most effective strategies for relieving the notorious polysulfide shuttle effect. Constructing a stable, lightweight, and effective LSB separator is still a big challenge but highly desirable. Herein, a stable and lightweight imide-based covalent organic framework (COF-TpPa) is facilely fabricated on reduced graphene oxide (rGO) through an oxygen-free solvothermal technique. With the directing effect of rGO and changing the side functional group of the monomer, the morphology and the pore tailoring of COF-TpPa can be simultaneously achieved and two-dimensional (2D) COF nanosheets with different functionalities (such as -SOH and -Cl) are successfully constructed on rGO films. The specific functional groups inside the COF's pore channels and the narrowed pore size result in efficient absorption and restriction of LiS for weakening the "shuttle effect". Meanwhile, the 2D COF nanosheets on the rGO is a favorable morphology for better exploiting pores inside the COF materials. As a result, the COF-SOH-modified separator, consisting of rGO and COF-TpPa-SOH, exhibits a high specific capacity (1163.4 mA h/g at 0.2 C) and a desirable cyclic performance (60.2% retention rate after 1000 cycles at 2.0 C) for LSBs. Our study provides a feasible strategy to rationally design functional COFs and boosts their applications in various energy storage systems.
改性锂硫电池（LSB）的隔膜被认为是缓解臭名昭著的多硫化物穿梭效应最有效的策略之一。构建稳定、轻质且有效的LSB隔膜仍然是一项巨大挑战，但却非常必要。在此，通过无氧溶剂热技术在还原氧化石墨烯（rGO）上轻松制备了一种稳定且轻质的基于酰亚胺的共价有机框架（COF-TpPa）。借助rGO的导向作用并改变单体的侧官能团，可同时实现COF-TpPa的形貌和孔剪裁，并成功在rGO薄膜上构建了具有不同功能（如-SOH和-Cl）的二维（2D）COF纳米片。COF孔道内的特定官能团以及变窄的孔径导致对LiS的有效吸收和限制，从而减弱“穿梭效应”。同时，rGO上的2D COF纳米片具有良好的形貌，有利于更好地利用COF材料内部的孔。结果，由rGO和COF-TpPa-SOH组成的COF-SOH改性隔膜对LSB表现出高比容量（在0.2 C时为1163.4 mA h/g）和理想的循环性能（在2.0 C下1000次循环后保留率为60.2%）。我们的研究提供了一种合理设计功能性COF的可行策略，并推动了它们在各种储能系统中的应用。
