Se-doping induces bulk MoS2-Se composites with increased interlayer spacing for enhances lithium-ion batteries

Abstract

Molybdenum disulfide (MoS2) is considered a promising candidate for anodes in lithium-ion batteries (LIBs), however, its practical application is hindered by inferior cyclic stability and poor capability. Given the analogous coordination environments of selenium and sulfur within the same main group, selenium doping (Se) is explored to augment interlayer spacing and conductivity, thereby accelerating diffusion kinetics and enhancing capacitance contribution. In this study, we fabricate composites of Se-doped bulk MoS2 (B-MoS2-Se) through a combination of heat treatment and subsequent selenization process. Se doping not only enhances interlayer spacing but also forms a binary alloy, MoS2−xSex. The expanded interlayer spacing mitigates resistance to Li+ diffusion, improving the kinetics of Li+ reactions, while the binary alloy MoS2−xSex concurrently enhances the conductivity of bulk MoS2. By intricately integrating these advantages, the B-MoS2-Se-1 electrode demonstrates exceptional long-term cycling performance (390 mA h g−1 at 1.0 A g−1 after 2000 cycles) and remarkable rate capability (172.4 mA h g−1 at 5.0 A g−1), showcasing its significant potential for practical applications in LIBs.