From Metal–Organic Framework to Li₂S@C–Co–N Nanoporous Architecture: A High-Capacity Cathode for Lithium–Sulfur Batteries

Owing to the high theoretical specific capacity (1166 mAh g –1 ), lithium sulfide (Li 2 S) has been considered as a promising cathode material for Li–S batteries. However, the polysulfide dissolution and low electronic conductivity of Li 2 S limit its further application in next-generation Li–S batteries. In this report, a nanoporous Li 2 S@C–Co–N cathode is synthesized by liquid infiltration–evaporation of ultrafine Li 2 S nanoparticles into graphitic carbon co-doped with cobalt and nitrogen (C–Co–N) derived from metal–organic frameworks. The obtained Li 2 S@C–Co–N architecture remarkably immobilizes Li 2 S within the cathode structure through physical and chemical molecular interactions. Owing to the synergistic interactions between C–Co–N and Li 2 S nanoparticles, the Li 2 S@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 –1 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 –1 at 1C, 2C, and 4C, respectively. Such a cathode structure is promising for practical applications in high-performance Li–S batteries.