Sulfur Nanoparticles-Reinforced Hierarchical Assemblies of Carbon Nanotubes: Toward the Development of Efficient Lithium–Sulfur Micro-Battery Cathodes

Abstract

Lithium–sulfur (Li–S) battery technology provides one of the most promising alternatives to conventional lithium-ion batteries (LIBs). However, these Li–S batteries suffer from polysulfide dissolution leading to a shuttle effect, insulating nature, and volume expansion associated with sulfur particles. To mitigate these challenges, we present an approach of using sulfur nanoparticle (S NP)-reinforced patterned vertically aligned carbon nanotube (S@P-VACNT)-based microstructures as S cathodes for Li–S batteries. Engineered P-VACNT microstructures offer efficient charge transport pathways, trap lithium polysulfides (LiPSs), and reduce volume expansion of S NPs, which improve the performance of Li–S batteries. The demonstrated S@P-VACNT cathodes have delivered an excellent stable average discharge-specific capacity of ∼1030 mAhg^–1 for 100 cycles at 0.1 C with an average capacity decay of only ∼0.043% per cycle. Additionally, S cathodes have shown a remarkable average discharge-specific capacity of ∼890.03 mAh g^–1 for 500 cycles at 1.0 C, with a high-capacity retention of ∼99.81%, and ∼636.46 mAhg^–1 for 1000 cycles at 2.0 C. The structural integrity of P-VACNT and LiPS trapping is confirmed by postmortem FESEM and XPS studies of cycled cathodes, respectively. The demonstrated S@P-VACNT cathodes provide an out-of-the-box solution to overcome the long-standing technical challenges associated with Li–S batteries.