MXene/SnS Mott-Schottky heterostructure for modulation of sulfur reduction reaction kinetics in advanced lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) offer high energy density and low cost but face challenges such as low sulfur utilization, lithium polysulfides (LiPSs) shuttling, and limited reaction kinetics. To address these issues, we rationally design a Ti₃C₂T_x/SnS Mott-Schottky heterostructure with a built-in electric field. This three-dimensional (3D) porous architecture can enhance sulfur loading, facilitate electrolyte penetration, and expose more adsorption and catalytic sites. More importantly, the built-in electric field facilitates charge transfer and directs LiPSs migration from SnS to Ti₃C₂T_x. The oriented migration of LiPSs enables rapid catalytic conversion at the Ti₃C₂T_x/SnS heterogeneous interface, enhancing electrocatalytic activity and sulfur reduction reaction kinetics. The Ti₃C₂T_x/SnS/S cathode achieves a high initial capacity (1367.1 mAh g⁻¹), excellent rate performance (602.7 mAh g⁻¹ at 3 C), and stable long cycling performance with an average capacity decay rate of only 0.029% per cycle at 2 C. Additionally, a high-sulfur-loaded 3D-printed cathode with loading of 12.7 mg cm⁻² manufactured using 3D printing exhibits an areal capacity of 15.0 mAh cm⁻², retaining 8.9 mAh cm⁻² after 70 cycles.