Abstract
For practical lithium-sulfur batteries (LSBs), the high sulfur loading and lean-electrolyte are necessary conditions to achieve the high energy density. However, such extreme conditions will cause serious battery performance fading, due to the uncontrolled deposition of Li(2) S and lithium dendrite growth. Herein, the tiny Co nanoparticles embedded N-doped carbon@Co(9) S(8) core-shell material (CoNC@Co(9) S(8) NC) is designed to address these challenges. The Co(9) S(8) NC-shell effectively captures lithium polysulfides (LiPSs) and electrolyte, and suppresses the lithium dendrite growth. The CoNC-core not only improves electronic conductivity, but also promotes Li(+) diffusion as well as accelerates Li(2) S deposition/decomposition. Consequently, the cell with CoNC@Co(9) S(8) NC modified separator delivers a high specific capacity of 700 mAh g(-1) with a low-capacity decay rate of 0.035% per cycle at 1.0 C after 750 cycles under a sulfur loading of 3.2 mg cm(-2) and a E/S ratio of 12 µL mg(-1) , and a high initial areal capacity of 9.6 mAh cm(-2) under a high sulfur loading of 8.8 mg cm(-2) and a low E/S ratio of 4.5 µL mg(-1) . Besides, the CoNC@Co(9) S(8) NC exhibits an ultralow overpotential fluctuation of 11 mV at a current density of 0.5 mA cm(-2) after 1000 h during a continuous Li plating/striping process.