The significant effect of octa(aminophenyl)silsesquioxane on the electrospun ion-selective and ultra-strong poly-m-phenyleneisophthalamide separator for enhanced electrochemical performance of lithium-sulfur battery

In this paper, a novel ion-selective and ultra-strong poly-m-phenyleneisophthalamide (PMIA)-based gel polymer electrolyte (GPE) containing fluorinated emulsion and octa(aminophenyl)silsesquioxane (OAPS) nanoparticles is rationally designed for lithium-sulfur batteries by electrospinning. Under the significant effect of OAPS, the PMIA-based GPE acts as a multi-functional separator with exceedingly high electrolyte uptake, exceptional thermal stability and robust mechanical strength. Particularly, the -NH2 groups of OAPS provide an electronegative environment, which facilitate the lithium ions migration while inhibit the negative polysulfide anions transfer. Thus, the PMIA-based GPE exhibits an effective electrostatic shielding effect to restrain lithium polysulfide on cathode side, while vigorously stimulating the transmission of lithium ions. As a great result, the lithium ions migration, the interface impedance and the reversible rate capacity of the assembled lithium-sulfur battery obtain a marked improvement. Meantime, the cell with the PMIA-based separator, adopting conventional sulfur-carbon black as cathode materials, delivers a high initial capacity of 851.1 mAh.g(-1) with capacity retention of 458.3 mAh.g(-1) after 800 cycles at 0.5 C rate, accompanied by a low capacity decay of 0.057% per cycle. Therefore, the prepared PMIA separator imbedding with OAPS can be deemed as an extraordinary potential candidate for the application in high-performance lithium-sulfur cells.