From Metal-Organic Framework to LiS@C-Co-N Nanoporous Architecture: A High-Capacity Cathode for Lithium-Sulfur Batteries.

Owing to the high theoretical specific capacity (1166 mAh g), lithium sulfide (LiS) has been considered as a promising cathode material for Li-S batteries. However, the polysulfide dissolution and low electronic conductivity of LiS limit its further application in next-generation Li-S batteries. In this report, a nanoporous LiS@C-Co-N cathode is synthesized by liquid infiltration-evaporation of ultrafine LiS nanoparticles into graphitic carbon co-doped with cobalt and nitrogen (C-Co-N) derived from metal-organic frameworks. The obtained LiS@C-Co-N architecture remarkably immobilizes LiS within the cathode structure through physical and chemical molecular interactions. Owing to the synergistic interactions between C-Co-N and LiS nanoparticles, the LiS@C-Co-N composite delivers a reversible capacity of 1155.3 (99.1% of theoretical value) at the initial cycle and 929.6 mAh g after 300 cycles, with nearly 100% Coulombic efficiency and a capacity fading of 0.06% per cycle. It exhibits excellent rate capacities of 950.6, 898.8, and 604.1 mAh g at 1C, 2C, and 4C, respectively. Such a cathode structure is promising for practical applications in high-performance Li-S batteries.