Multicore closely packed ultrathin-MnO2@N-doped carbon-gear yolk–shell micro-nanostructures as highly efficient sulfur hosts for Li–S batteries

Abstract

Suppressing the polysulfide shuttle effect and promoting the conductivity of electrode materials have become efficient ways to achieve high cycling stability for Li–S batteries. However, this still remains a challenge. New multicore closely packed ultrathin-MnO₂@N-doped carbon-gear yolk–shell micro-nanostructures are explored as the S host material to trap polysulfides and enhance conductivity. Such composites can accommodate S mass-loading up to 80 wt% via a valid sulfur solution infiltration approach. The cooperation of ultrathin-MnO₂ yolks with N-doped carbon internal gear shells can well suppress the polysulfide shuttle effect by strong chemical interactions and physical confinement as well as enhanced conductivity for excellent Li–S battery properties, which enable an initial gravimetric capacity of 1245 mA h g⁻¹ and a low decay rate of 0.03% per cycle over 1000 cycles at 1C. In particular, the composite delivers an initial gravimetric capacity of 1097.8 mA h g⁻¹ and volumetric capacity of 1059.6 mA h cm⁻³ at 2C rate. Specifically, the electrochemical performance of the designed composite at different electrolyte/S ratios is firstly investigated in this study, and is a promising approach with the high-performance cathode material for Li–S batteries.