Composite of sulfur impregnated in porous hollow carbon spheres as the cathode of Li–S batteries with high performance

Carbon–sulfur composites as the cathode of rechargeable Li–S batteries have shown outstanding electrochemical performance for high power devices. Here, we report the promising electrochemical charge–discharge properties of a carbon–sulfur composite, in which sulfur is impregnated in porous hollow carbon spheres (PHCSs) via a melt-diffusion method. Instrumental analysis shows that the PHCSs, which were prepared by a facile template strategy, are characterized by high specific surface area (1520 m²·g^–1), large pore volume (2.61 cm³·g^–1), broad pore size distribution from micropores to mesopores, and high electronic conductivity (2.22 S·cm^–1). The carbon–sulfur composite with a sulfur content of 50.2 wt.% displays an initial discharge capacity of 1450 mA·h·g^–1 (which is 86.6% of the theoretical specific capacity) and a reversible discharge capacity of 1357 mA·h·g^–1 after 50 cycles at 0.05 C charge–discharge rate. At a higher rate of 0.5 C, the capacity stabilized at around 800 mA·h·g^–1 after 30 cycles. The results illustrate that the porous carbon–sulfur composites with hierarchically porous structure have potential application as the cathode of Li–S batteries because of their effective improvement of the electronic conductivity, the repression of the volume expansion, and the reduction of the shuttling loss.