Ion Selective Covalent Organic Framework Enabling Enhanced Electrochemical Performance of Lithium–Sulfur Batteries

• Published in: Nano letters Vol. 21; no. 7; pp. 2997 - 3006
• Main Authors: Cao, Yu, Wu, Hong, Li, Gang, Liu, Cheng, Cao, Li, Zhang, Yiming, Bao, Wei, Wang, Huili, Yao, Yuan, Liu, Shuo, Pan, Fusheng, Jiang, Zhongyi, Sun, Jie
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 14.04.2021
• Subjects: lithium−sulfur battery; polysulfides shuttle; ion selectivity; modified separator; covalent organic framework
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.1c00163

Ion selective separators with the capability of conducting lithium ion and blocking polysulfides are critical and highly desired for high-performance lithium–sulfur (Li–S) batteries. Herein, we fabricate an ion selective film of covalent organic framework (denoted as TpPa-SO3Li) onto the commercial Celgard separator. The aligned nanochannels and continuous negatively charged sites in the TpPa-SO3Li layer can effectively facilitate the lithium ion conduction and meanwhile significantly suppress the diffusion of polysulfides via the electrostatic interaction. Consequently, the TpPa-SO3Li layer exhibits excellent ion selectivity with an extremely high lithium ion transference number of 0.88. When using this novel functional layer, the Li–S batteries with a high sulfur loading of 5.4 mg cm–2 can acquire a high initial capacity of 822.9 mA h g–1 and high retention rate of 78% after 100 cycles at 0.2 C. This work provides new insights into developing high-performance Li–S batteries via ion selective separator strategy.