To confine the intermediate polysulfides to obstruct their dissolution from the electrolyte and increase the utilization of sulfur, a novel sulfur host for decorated nitrogen-doped carbon nanotube (NCNTs) microspheres was produced by a terse ultrasonic spraying with succedent impregnation methods. Decoration effects for Nb2O5 are better than those for Sb. Nb2O5–NCNTs microspheres are woolen-like uniform balls which are twined with CNTs and infiltrated Nb2O5 nanoparticles. Then Nb2O5–NCNTs microspheres deliver the high initial charge and discharge capacities of 1369.5 and 1335.3 mAh g–1, good cycle stability of 1201.7 mAh g–1 at 0.1 C after 200 cycles, and outstanding long-term cycle life of 846.2 mAh g–1 after 1000 cycles at 2.0 C with a very low capacity decay of 0.016% per cycle. The Nb2O5–NCNTs microspheres with remarkable effects for sulfur confinement are a potential cathode material for lithium–sulfur batteries.
For the practical application of lithium-sulfur batteries, the high areal capacity based on high loading sulfur cathode is urgently pursued. Herein, the electrochemical rate and cycling performance are significantly enhanced by the design of polar hierarchical-porous carbon container to confine sulfur species. The as-fabricated carbon container shows the following merits: providing an affordable pore volume of 4.94 cm 3 g −1 for confining sulfur and releasing volume changes; facilitating rapid electron/ion transfer pathway; allowing efficient chemisorption of polysulfides by polar active sites synergistically. As a result, the cathode displays a high rate capacity of 581 mA h g −1 at 8 C and a stable cyclability at 2 C. Importantly, the cathode with 7.2 mg cm −2 sulfur loading presents a high areal capacity of 9.75 mA h cm −2 at 0.05 C and high rate performance. Up to 7.5 mg cm −2 , the high loading cathode could still display a high areal capacity of 5 mA h cm −2 at 1 C after 80 cycles. Moreover, the container can successfully work in a pouch cell with low E/S ratio. These results show a promising way to promote the practical utilization of Li-S batteries.
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