Promising Au&CNTs@N-Doped Hierarchical Carbon\nComposite for High-Performance Lithium–Sulfur Batteries

Abstract

A lithium–sulfur battery with\nan ultrahigh specific capacity\nof 1675 mAh g^–1 is witnessed to be one of the most\npromising high-energy-density storage devices. However, the commercialization\nis restricted by the poor conductivity of sulfur, the “shuttle\neffect” of polysulfides, and the volume expansion during the\ncharge/discharge process. Herein, Au&CNTs@N-doped hierarchical\nporous carbon material was prepared in view of structural design,\nchemical modification, and metal catalysis. Sulfur can be effectively\naccommodated and protected in the hierarchical porous carbon host;\nbesides, the overall conductivity and structural stability of the\ncarbon/sulfur composite are able to be enhanced by carbon nanotubes\ninterconnected between hollow carbon spheres. Furthermore, the redox\nreaction kinetics of lithium polysulfides and the chemical adsorption\nto polysulfide are enhanced by Au atoms and doped N heteroatoms. As\na result of the multifunctional features, Au&CNTs@ND-C/S exhibits\nan initial discharge capacity of 1256 mAh g^–1 at\nthe current density of 0.8 A g^–1, with 1031 mAh\ng^–1 remaining after 50 cycles. Overall, the multifunctional\nAu&CNTs@N-doped hierarchical carbon materials can effectively\nfacilitate the electrochemical performance of the sulfur cathode through\nphysical confinement, chemical adsorption, and catalytic enhancement.