Atomic tuning of Ti_xCr_1−xN catalysts to enhance the polysulfide trapping and conversion in lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries face critical challenges, including sluggish polysulfide redox kinetics and the shuttle effect. This study presents a novel self-supporting carbon nanofibers (CNFs) decorated with Ti_xCr_1−xN (TCN) solid–solution nanoparticles (CNFs@TCN) as Li₂S₆ host for Li–S batteries. By leveraging electrospinning and high-temperature nitridation reaction, we engineered a flexible electrode with tunable Ti/Cr ratios. Density functional theory (DFT) calculations and experimental analysis reveal that the TCN solid–solution phase optimizes electronic structure via Cr substitution, enhancing polysulfide adsorption and catalytic conversion kinetics. The CNFs@TCN-1/2 cathode (Ti:Cr = 1:2) exhibits exceptional performance of high initial capacity (1359 mAh·g⁻¹), ultralow capacity decay (0.012% per cycle at 2 C), and remarkable rate capability (803 mAh·g⁻¹ at 3 C). Under high sulfur loading (6.12 mg·cm⁻²) and lean electrolyte (electrolyte/sulfur (E/S) ratio = 9.3 μL·mg⁻¹), it delivers an areal capacity of 4.87 mAh·cm⁻². This work demonstrates atomic-level d-band engineering of bimetallic nitrides as a powerful strategy to suppress shuttle effects and boost sulfur redox kinetics in practical Li–S batteries.