Simultaneously Encapsulating Co/Co2P Nanoparticles Inside and Growing Vertical Graphene Nanosheets Outside for N-Doped Carbon Nanotubes as Efficient Sulfur Carriers for High-Performance Lithium Sulfur Batteries

Agglomeration of carbon nanotubes (CNTs) extremely hampers utilization of active surface area and impedes sulfur loading, which limit their application in high-energy-density lithium-sulfur (Li-S) batteries. Herein, N-doped carbon nanotubes with Co/Co2P nanoparticles encapsulated inside and vertical graphene (VG) nanosheets grown outside (CCP@NCNT@VGs) are prepared as efficient sulfur carriers for Li-S batteries. The Co/Co2P nanoparticles encapsulated in the NCNTs could strongly anchor polysulfide and efficiently catalyze the conversion of polysulfides to Li2S, while the 3D hierarchical conductive network constructed by the vertical graphene nanosheets and NCNT quickly transfer electrons and improve the conversion kinetics of polysulfides. The as-synthesized hierarchical structure combines conductivity with anchoring and catalysis, significantly elevating the electrochemical performance of the Li-S batteries. Hence, even at a high mass loading of 7 mg cm(-2), the CCP@NCNT@VGs/S electrode with limited electrolyte/sulfur ratio (4 mu L mg(-1)) exhibits a high areal capacity of 7 mAh cm(-2), showing great application potential in the field of energy storage.

Automated summary

A highly efficient sulfur carrier for Li-S batteries, N-doped carbon nanotubes (CNTs) with Co/Co2P nanoparticles encapsulated inside and vertical graphene (VG) nanosheets grown outside (CCP@NCNT@VGs), has been successfully prepared, which significantly improves the electrochemical performance of the batteries.