writer：Xinxin Dong , Tao Zhu
keywords：Brominated flame retardants，Lithium-sulfur batteries，Coating modified separator，Battery safety
source：期刊
Issue time：2023年

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.

高安全性锂硫电池溴化阻燃涂层隔膜

锂硫电池（LSB）由于其高理论能量密度和丰富的硫而成为极具前景的下一代二次锂电池。尽管如此，LSBs的大规模应用仍然受到多硫化锂（LiPSs）的穿梭效应和易燃电解质引起的潜在火灾隐患的限制。在此，选择了三种电解质不溶性溴化阻燃剂 (BFR) 并将其涂覆在商用聚丙烯的两面通过简便的浆料涂覆方法分离器。表征并比较了三种 BFR 对 LSB 的安全性和电化学性能的影响。涂层改性隔膜通过自由基消除机制大大提高了 LSB 的阻燃性。电解液的自熄时间从0.66 s/mg减少到0.20 s/mg。此外，研究表明，含氧 (O) 的 BFRs 具有显着的吸附能力，并且在 LSB 中比不含 O 的 BFRs 更有优势。此外，由于 O 含量较高，八溴醚 (BDDP) 涂层隔膜比十溴二苯醚 (DBDPO) 更有效地捕获 LiPS，这可以减轻穿梭效应并提高 LSB 的循环和倍率性能。