Facile Synthesis of Lithium Sulfide@Carbon Nanocomposite via Precursor Solution Infiltration-Decomposition for High-Performance Lithium Sulfide Batteries

Lithium–sulfur batteries (LSBs) based on lithium sulfide (Li 2 S), or Li 2 S-LSBs, are promising candidates for next-generation energy storage due to their high theoretical capacity, lower costs, and environmental benefits compared to lithium-ion batteries. However, synthesizing Li 2 S-infiltrated mesoporous carbon nanocomposites (Li 2 S@C) to mitigate the low conductivity of Li 2 S has been challenging because of its high melting point and poor solubility. To address this, we developed an efficient synthesis method for Li 2 S@C nanocomposites under mild conditions. Li 2 S was first reacted with carbon disulfide (CS 2 ) in ethanol at ambient temperature, forming a highly soluble lithium trithiocarbonate (Li 2 CS 3 ) solution, which was easily infiltrated into mesoporous Super P carbon (SP) to form a Li 2 CS 3 @C nanocomposite. Thermal decomposition of Li 2 CS 3 at 400 °C produced Li 2 S@SP-400 nanocomposites with finely dispersed Li 2 S particles (∼11 nm) confined within the SP matrix. The Li 2 S-LSBs exhibited a high discharge capacity of 821 mA h g –1 (Li 2 S) (equivalent to 1190 mA h g –1 (S) based on sulfur content) and demonstrated superior rate and cycling performance compared to commercial Li 2 S, noninfiltrated Li 2 S-400 nanoparticles, and sulfur nanocomposites (S@SP) prepared by melt infiltration. This simple, scalable method offers a promising route for commercializing high-energy-density Li 2 S-LSBs.