Multiwall carbon nanotube-hyperbranched polymaleimide core-shell nanowires with hierarchical porous and polar structure as sulfur host for sustainable lithium-sulfur batteries

Abstract

Lithium-sulfur (Li-S) batteries have gained considerable attention as a promising alternative to current advanced batteries because of their low cost, natural abundance, high energy density, and environmental benignity of sulfur. The commercial application of Li-S batteries is being seriously impeded by the shuttle effect of lithium polysulfides (LiPSs) and the sluggish reaction kinetics of solid phase transformation. Herein, a novel composite material (PPI@MWCNT-Y) with a hierarchical porous skeleton and polar channel is prepared as a sulfur host using a convenient in-situ one-pot polymerization. PPI@MWCNT-Y is composed of conductive mesoporous multiwall carbon nanotubes (MWCNTs) core and a microporous hyperbranched polymaleimide (PPI) shell formed by the self-polymerization of N,N '-1,4-phenylenedimaleimide (PDM). The mesoporous and conductive channels in PPI@MWCNT-Y improve the redox kinetics of the active materials by serving as a fast electron and Li-ions transportation pathway. The microporous structure and abundant adsorption sites (N and O atoms) within the PPI@MWCNT-Y served as physical and chemical barriers, preventing the loss of LiPSs, and suppressing the shuttle effect. Consequently, the S/PPI@MWCNT-38 composite exhibited a high discharge capacity of 1338 mAh g-1 at 0.2 C and a low-capacity decay rate of 0.088% for 400 cycles at 1 C.