Confinement of sulfur species into heteroatom-doped, porous carbon container for high areal capacity cathode

Abstract

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 cm3 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.