Donor dominated triazine-based microporous polymer as a polysulfide immobilizer and catalyst for high-performance lithium-sulfur batteries

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2020-07, Vol.392, p.123694, Article 123694
• Main Authors: Xu, Jie, Yu, Fengtao, Hua, Jianli, Tang, Weiqiang, Yang, Chao, Hu, Shuozhen, Zhao, Shuangliang, Zhang, Xinsheng, Xin, Zhong, Niu, Dongfang
• Format: Article
• Language: English
• Subjects: Catalytic activity; Coating layer; Covalent triazine polymers; Li-S batteries; Theoretical calculations
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2019.123694

The π-conjugated donors behaving as “electron reservoir” present different performances in immobilizing and catalyzing polysulfides, while the fully conjugated triazine-based microporous polymer demonstrates faster electron transfer and rapid polysulfides conversion than the counterpart with a partial conjugation breakage. [Display omitted] •Triazine-based polymers functionalized as polysulfide immobilizer and catalyst.•Donor as “electron reservoir” was grafted to enhance the ability of triazine polymer.•The charge transfer between triazine unit and lithium polysulfides was improved.•The resultant Li-S batteries present excellent electrochemical performance. Triazine-based framework is an attractive organic polymer with microporous structure and high nitrogen content that could retard the shuttle of polysulfides for high-performance lithium-sulfur (Li-S) batteries. However, insight into the role of π-conjugated donor of triazine-based polymer in immobilizing and catalyzing polysulfides is still deficient. Here, two homologous conjugated buildings of triazine unit combining with perylene (CTP-1) and spirobifluorene (CTP-2) were reasonably synthesized through one-pot Suzuki-Miyaura coupling reaction with a high yield of 92% and served as the polysulfides immobilizer and catalyst to achieve high-performance Li-S batteries. Compared with the counterpart of CTP-2, the fully conjugated CTP-1 modified separator possesses a higher ionic conductivity and Li+ transference number presenting more efficient shuttle inhibition and faster kinetics in catalyzing polysulfides conversion. Theoretical calculations demonstrate that the CTP-1 with perylene donor features narrower bandgap and faster electron transfer exhibiting stronger binding ability toward polysulfides than CTP-2. This work broadens the understanding of donor dominated chemical immobilizing and catalysis of triazine-based materials in Li-S batteries, and provides guidance for the future design of organic materials in other energy storage systems.