Brominated flame retardants coated separators for high-safety lithium-sulfur batteries

Xinxin Dong; Tao Zhu; Guoqing Liu; Jinxuan Chen; Hongfei Li; Jun Sun; Xiaoyu Gu; Sheng Zhang

doi:10.1016/j.jcis.2023.03.203

Brominated flame retardants coated separators for high-safety lithium-sulfur batteries

J Colloid Interface Sci. 2023 Aug:643:223-231. doi: 10.1016/j.jcis.2023.03.203. Epub 2023 Apr 1.

Authors

Xinxin Dong¹, Tao Zhu¹, Guoqing Liu¹, Jinxuan Chen¹, Hongfei Li¹, Jun Sun¹, Xiaoyu Gu¹, Sheng Zhang²

Affiliations

¹ State Key Laboratory of Organic-Inorganic Composites, Center for Fire Safety Materials, Beijing University of Chemical Technology, Beijing 100029, PR China.
² State Key Laboratory of Organic-Inorganic Composites, Center for Fire Safety Materials, Beijing University of Chemical Technology, Beijing 100029, PR China. Electronic address: zhangsheng@mail.buct.edu.cn.

PMID: 37060698
DOI: 10.1016/j.jcis.2023.03.203

Abstract

Lithium-sulfur batteries (LSBs) have become highly promising next-generation secondary lithium batteries owing to their high theoretical energy density and abundance of sulfur. Nevertheless, the large-scale application of LSBs is still restricted by the shuttle effect of lithium polysulfide (LiPSs) and the potential fire hazard caused by flammable electrolytes. Herein, three electrolyte-insoluble brominated flame retardants (BFRs) are selected and coated on both sides of commercial polypropylene separators by a facile slurry coating method. The effects of the three BFRs on the safety and electrochemical properties of LSBs are characterized and compared. The coating modification separators greatly improves the flame retardancy of LSBs through radical elimination mechanism. The self-extinguishing time of the electrolyte is reduced from 0.66 s/mg to 0.20 s/mg. Moreover, it is demonstrated that the oxygen (O)-containing BFRs exert a significant adsorption capacity and are more advantageous than O-free BFRs in LSBs. In addition, octabromoether (BDDP) coated separator is more effective in trapping LiPSs than decabromodiphenyl ether (DBDPO) due to higher O content, which can mitigate the shuttle effect and enhance the cycle and rate performance of LSBs. This simple coating strategy for separators with BFRs offers a strongly competitive option for the large-scale production of high-safety LSBs.

Keywords: Battery safety; Brominated flame retardants; Coating modified separator; Lithium-sulfur batteries.