Facile synthesis of three-dimensional carbon nanotube/Fe3O4 microspheres as sulfur host for high performance lithium-sulfur batteries

Lithium-sulfur batteries were considered as a new generation of high energy density batteries, but their commercialization was limited by volume expansion, the low conductivity of sulfur and shuttle effect. To overcome these issues, we developed a three-dimensional carbon nanotube/Fe3O4 microspheres via spray drying and calcination as sulfur host materials (S/CNT/Fe3O4). In this three-dimensional microsphere structure, interwoven CNT backbone offers a robust conductive network with sufficient space for loading sulfur, and the polar Fe3O4 nanoparticles can enhance chemical adsorption of polysulfide. Benefiting from these advantages, the S/CNT/Fe3O4 cathode exhibit high initial discharge capacity (1270 mAh g−1 at 0.2 C), superior rate performance (602 mAh g−1 at 3 C), and long cyclic stability (only 0.084% capacity decay per cycle for 300 cycles at 1 C).