Lithium bis(trifluoromethanesulfonyl)imide assisted dual-functional separator coating materials based on covalent organic frameworks for high-performance lithium–selenium sulfide batteries. Issue 27 (24th June 2019)

• Record Type: Journal Article
• Authors: Yang, Yan; Hong, Xu-Jia; Song, Chun-Lei; Li, Guo-Hui; Zheng, Yi-Xin; Zhou, Dan-Dan; Zhang, Min; Cai, Yue-Peng; Wang, Hongxia
• Is Part Of: Journal of materials chemistry. Volume 7:Issue 27(2019)
• Page Start: 16323
• Page End: 16329
• Publication Date: 2019-06-24
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c9ta04614c
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : COFs with selective adsorption of LiTFSI may serve as a bifunctional separator coating material for high-performance Li–SeS2 cells. Abstract : The low transmission rate of lithium ions and the shuttling effect caused by soluble intermediate polysulfide/polyselenide ionic species have greatly limited the performance of Li–SeS2 batteries. In this work, we demonstrate that a separator coating material based on covalent-organic frameworks (COFs), TPB-DMTP-COF, can effectively resolve these issues. It is found that the TPB-DMTP-COF material can selectively adsorb lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) species in the electrolyte through the formation of hydrogen bonding of C–H⋯F and O⋯Li. The accumulation of LiTFSI in the channels of TPB-DMTP-COF leads to a narrower pore size of the material and enhanced transportation of lithium ions in Li–SeS2 cells when the material is used as the separator coating. As a consequence, outstanding performance in terms of energy storage and stability was achieved in the Li–SeS2 battery using the TPB-DMTP-COF separator coating with a specific capacity of 844.6 mA h g −1 at 0.5C and a SeS2 loading of 2 mg cm −2 . Even at a higher SeS2 loading of 4 mg cm −2, the cell demonstrated a specific capacity of 684 mA h g −1 at 1C. After 800 cycles, 416.3 mA h g −1 was still retained with a capacity decay rate of only 0.05% per cycle. This work sheds light on a new strategy toward high performance Li–SeS2 batteries by using COF based functional separator coating materials.