Pomegranate-like microclusters organized by ultrafine Co nanoparticles@nitrogen-doped carbon subunits as sulfur hosts for long-life lithium–sulfur batteries

Abstract

For further development of lithium–sulfur (Li–S) batteries, it is necessary to construct sulfur hosts with high sulfur utilization/loading ratios and moderate the shuttling effect of lithium polysulfides. Herein, we synthesized uniform pomegranate-like microclusters (MCs) via carbonization of a Prussian blue analogue; the MCs consist of homogeneously inlaid ultrafine Co nanoparticles in nitrogen-doped carbon subunits (Co-NPC). The hierarchical pore structure and high conductivity of the Co-NPC-MCs can immobilize sulfur species, and the ultrafine Co nanoparticles and doped nitrogen exert catalytic effects to improve the electrochemical performance of Li–S batteries. Therefore, the S/Co-NPC-MCs cathode exhibits a high initial capacity of 1192 mA h g⁻¹ and 941 mA h g⁻¹ after 200 cycles at 0.5C. It also exhibits excellent rate capacities at high rates of 1C and 2C; the reversible capacities remain at 650 mA h g⁻¹ and 574 mA h g⁻¹ after 400 cycles, respectively, demonstrating its great potential for practical applications.