writer：Tao Zhu, Shuheng Wang, Jiasu Li, Dongli Chen, Xiaoyu Gu, Jun Sun, Bin Xu, Sheng Zhang
keywords：Flame-retardancy，Micro-nano particles，Chemical adsorption，Interlayer，Lithium-sulfur battery
source：期刊
Issue time：2022年

  Lithium-sulfur batteries (LSBs) are widely accepted representatives of next-generation energy storage with high energy density. However, the high flammability of polypropylene (PP) separators and ether electrolytes deteriorates the safety of LSBs. Moreover, the severe shuttle effect of lithium polysulfides (LiPSs) induces the capacity degradation and poor cycle stability of LSBs. In this work, we unprecedentedly synthesize multifunctional micro-nano-sized particles (ACNP) that are constructed on PP separators to improve the safety and electrochemical performance of LSBs. The ACNP is obtained by the electrostatic assembly of ammonium polyphosphate and chitosan. The presence of ACNP decreases the burning process and improves the thermal stability of separators and electrolytes. Besides, the temperature of pouch cells during combustion is decreased after the addition of ACNP or ACNP@super-P(SP) interlayers. Moreover, the abundant N-containing and O-containing groups in the ACNP layer effectively inhibit the shuttle effect of LiPSs via chemical adsorption, increase the affinity to electrolytes, and facilitate the Li+ diffusion and redox kinetics. The SP enhances the conductivity of the interlayer, thus enhancing the capacity and cycle stability of LSBs. It is expected that this work provides a universal strategy to enhance the safety of separators as well as the batteries.

   锂硫电池（LSB）是被广泛接受的具有高能量密度的下一代储能代表。然而，聚丙烯（PP）隔膜和乙醚电解质的高可燃性使LSB的安全性恶化。此外，多硫化锂（LiPSs）的严重穿梭效应诱发了LSB的容量下降和循环稳定性差。在这项工作中，我们史无前例地合成了多功能微纳大小的颗粒（ACNP），这些颗粒被构建在PP分离器上，以改善LSB的安全性和电化学性能。ACNP是由聚磷酸铵和壳聚糖的静电组装得到的。ACNP的存在减少了燃烧过程，提高了分离器和电解质的热稳定性。此外，加入ACNP或ACNP@super-P(SP)夹层后，燃烧过程中袋式电池的温度下降。此外，ACNP层中丰富的含N和含O基团通过化学吸附有效地抑制了LiPSs的穿梭作用，增加了与电解质的亲和力，促进了Li+扩散和氧化还原动力学。SP增强了层间的导电性，从而提高了LSB的容量和循环稳定性。预计这项工作将提供一个通用的策略来提高分离器以及电池的安全性。