Synergistic enhancement of chemisorption and catalytic conversion in lithium-sulfur batteries via Co3Fe7/Co5.47N separator mediator.

ABSTRACT

Lithium-sulfur batteries (LSBs) show considerable potential in next-generation high performance batteries, but the heavy shuttle effect and sluggish redox kinetics of polysulfide hinder their further applications. In this paper, to address these shortcomings of LSBs, Co3Fe7/Co5.47N heterostructure were prepared and constructed from their Fe-Co Prussian blue analogue precursors under the condition of high temperature pyrolysis. The obtained Co3Fe7/Co5.47N display excellent immobilization-diffusion-conversion performance for polysulfides by synergistic effect in successfully hindering the shuttle effect of polysulfides. When the Co3Fe7/Co5.47N heterostructure were applied to modify the commercial polypropylene (PP) separator, the batteries displayed fantastic rate capacity and cycling stability. Specifically, the Co3Fe7/Co5.47N-PP batteries exhibit an extremely satisfactory initial specific capacity of 1430 m Ah/g at 0.5C, wonderful rate capacity of around 780 m Ah/g at 3C and superior per cycle decaying rate of 0.08 % for 500 cycles at 0.5C. When the current density reaches to 2C, the batteries still exhibit 501 m Ah/g after 900 cycles with 0.015 % per cycle decay rate. Besides, even in the high loading of sulfur (3.0 mg cm-2) at 0.5C, the superior cycling stability (0.075 % per cycle decay rate after 200 cycles) and high specific capacity (741 mAh/g after 200 cycles) can still be performed. Thus, this work provides a facile method for high-powered and long-life Li-S batteries with eminent entrapping-conversion processes of polysulfides.