Yaohui Qu

Confining selenium in nitrogen-containing hierarchical porous carbon for high-rate rechargeable lithium–selenium batteries

A novel nitrogen-containing hierarchical porous carbon (NCHPC) was prepared by a simple template process and chemical activation and a selenium/carbon composite based on NCHPC was synthesized for lithium–selenium batteries by a melt-diffusion method. The Se–NCHPC composite was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), and transmission electron microscopy (TEM) measurements. It is found that the elemental selenium was dispersed inside the hierarchical pores of NCHPC. It is demonstrated from cyclic voltammetry (CV) and galvanostatic discharge–charge processes that the Se–NCHPC composite has a large reversible capacity and high rate performance as cathode materials. The Se–NCHPC composite with a selenium content of 56.2 wt% displays an initial discharge capacity of 435 mA h g−1 and a reversible discharge capacity of 305 mA h g−1 after 60 cycles at a 2 C charge–discharge rate. In particular, the Se–NCHPC composite presents a long electrochemical stability at a high rate of 5 C. The results reveal that the electrochemical reaction constrained inside the interconnected macro/meso/micropores of NCHPC would be the dominant factor for the enhancement of the high rate performance of the selenium cathode, and the nitrogen-containing hierarchical porous carbon network would be a promising carbon matrix structure for lithium–selenium batteries.

A simple SDS-assisted self-assembly method for the synthesis of hollow carbon nanospheres to encapsulate sulfur for advanced lithium–sulfur batteries

The hollow carbon nanospheres (HCNSs) were prepared using a simple SDS-assisted self-assembly method, and a sulfur–carbon composite based on HCNSs was synthesized for lithium–sulfur batteries by a vapor phase infusion method. The sulfur–HCNS composite was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetry (TG) measurements. It is found that the elemental sulfur was dispersed inside the pores of carbon spheres. It is demonstrated from the galvanostatic discharge–charge process and cyclic voltammetry (CV) that the sulfur–HCNS composite has a large reversible capacity and an excellent cycling performance as cathode materials. The sulfur–HCNS composite with a sulfur content of 47.6 wt% displays an initial discharge capacity of 1031 mA h g−1 and a reversible discharge capacity of 477 mA h g−1 after 100 cycles at 0.5 C charge–discharge rate.

Synthesis of sulfur/activated carbon aerogels composite with a novel homogeneous precipitation method as cathode materials for lithium–sulfur batteries

A novel homogeneous precipitation method has been reported for synthesizing sulfur/activated carbon aerogels (S–ACAs) composite as cathode materials for lithium–sulfur batteries by a solution-based decomposition reaction of ammonium polysulfide ((NH4)2Sx). This novel sulfur deposition route represents a low-cost and recyclable approach to obtain S–ACAs composite cathodes possessing good electrochemical performance for lithium–sulfur batteries.