Hydrothermal carbon-based nanostructured hollow spheres as electrode materials for high-power lithium–sulfur batteries†
Carbon hollow spheres were produced using a sustainable approach, i.e. hydrothermal carbonization, using monosaccharides as carbon precursors and silica nanoparticles as hard-templates. Hydrothermal carbonization is an eco-efficient and cost-effective route to synthesize nanostructured carbonaceous materials from abundant biomass-derived molecules. After further thermal treatment under an inert atmosphere and removal of the silica-based core by chemical etching, porous hollow spheres depicting 5–8 nm thin shells were obtained. Subsequently, carbon–sulfur composites were synthesized via a melt diffusion method and used as nanostructured composites for cathodes in lithium–sulfur (Li–S) cells. The morphology of the hollow spheres was controlled and optimized to achieve improved electrochemical properties. Both high specific energies and high specific powers were obtained, due to the unique nanostructure of the hollow spheres. These results revealed that using optimized carbonaceous materials, it is possible to design sustainable Li–S cells showing promising electrochemical properties.