Electrocatalysts composed of amorphous red phosphorous nanosheets coupled with carboxylic group carbon nanotubes for Li-S batteries

The large-scale applications of lithium sulfur batteries have been limited by their rapid capacity loss, which can be attributed to the dissolution of polysulfide intermediates and subsequent irreversible shuttling effect. Several strategies have been attempted to the solve these problems by designing novel cell structure, including the modification of separator. Herein, a hybrid is obtained via a ball-milling with red phosphorous and carboxylic group carbon nanotubes (CNTs), in which bulk red phosphorous are simultaneous grounded into an overview of red phosphorous nanosheets (NP) and distribution the hybrid. Moreover, the P-O-C and P-C chemical bonds are formed between red phosphorous and CNTs upon ball-milling, which enable an intimate and robust contact between red phosphorous and CNTs, and thus facilitates the electron transfer and enhances the surface polarity of NP@CNTs. The red phosphorous nanosheets also possess a strong affinity to sulfur species, which could effectively adsorb lithium polysulfides, and boost their redox reaction catalytically-accelerate the reversible soluble/insoluble phases conversion. Benefiting from this unique nanostructures, the lithium-sulfur (Li-S) cell based on NP@CNTs hybrid modified separator has an initial discharge capacity of 895.8 mAh g- 1 at 0.3C and sustain a capacity of 704.2 mAh g- 1 after 300 cycles, corresponding to a retention rate of 78.6 %. The cell with a high sulfur loading of 8.9 mg cm- 2, it shows a discharge capacity of 7.6 mAh cm-2 and still maintains 6.5 mAh cm-2 over 100 cycles.