Mechanically robust, nonflammable and surface cross-linking composite membranes with high wettability for dendrite-proof and high-safety lithium-ion batteries

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

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.

Self-Assembly of Homo-Polyarylene Ether Into Reactive Matrix for Fabrication of Hybrid Functional Microparticles

Emulsion confinement self-assembly of block copolymer has witnessed increasing research interest in the recent decade, but the post-functionalization and application of the resultant polymeric micro/nano-particles are still in their infancy. In this work, a super-engineering polyarylene ether containing pendent nitrile and carboxyl (PAE-NC) has been synthesized and converted into polymeric microparticles for macromolecular enrichment via emulsion confinement self-assembly and subsequent surface modification. Moreover, the encapsulation capacity of PAE-NC was evaluated using hydrophobic fluorescent quantum dots (QD) as a functional probe. Particularly, we found that both the as-synthesized PAE-NC and its hydrolyzed derivatives could be converted into microparticles via emulsion confinement self-assembly. Furthermore, the co-self-assembly of red-emitting QD and PAE-NC enables the phase transfer of hydrophobic QD into hydrophilic luminescent microparticles with the persisted fluorescence emission. Based on these results, the current PAE-NC would be served as a versatile and robust matrix to fabricate advanced microparticles or microcapsules for various applications.