Spherical CoS 2 with high load capacity as cathode carrier material of lithium sulfur batteries for improving the volume energy density

High-efficiency electrocatalysts for Li–S batteries have great significance for improving their electrochemical performance and cycle stability. Here, a hollow CoS 2 nanosphere as a novel electrocatalyst for the cathode host material of high-performance Li–S batteries was obtained by a two-step strategy of solvothermal and sulfuration. Different from the traditional light carbon materials, the tap density of CoS 2 @S composite material has reached 1.17 g cm −3 . The high tap density of CoS 2 @S nanospheres composite guarantees the high volume energy density. Specifically, a hollow nanosphere has a large internal space which provides the possibility for a large load of the active material (80.66 wt%). Besides, electrochemical kinetics evaluation indicated CoS 2 nanospheres are beneficial for promoting Li–S electrochemical heterogeneous conversion and accelerating the diffusion of lithium ions in the cathode, both of which can help to keep the battery cycle stable and long life. Moreover, the chemical interaction between Co ions and polysulfides can effectively anchor the adsorbed polysulfides, which can help immobilize sulfur species and restrain the shuttle effect. Such a rationally prepared CoS 2 nanosphere is significant for promoting the electrochemical performance of the sulfur cathode due to high-volume energy density and rapid kinetic transformation promoting action. As a result, the CoS 2 @S composite exhibits high volume energy density and excellent performance under high sulfur load (4.8 mg cm −2 ) and low E / S ratio (electrolyte/sulfur = 10 μL mg −1 ) based on of the composite as cathode host materials. This work provides a new idea for the exploration of cathode host materials with high volume energy density and high electrochemical performance for lithium–sulfur batteries.