Nitrogen-enriched carbon-coated flower-like bismuth sulfide architectures towards high-performance lithium-ion battery anodes

Abstract

Engineering a homogeneous, stable and nitrogen-rich carbon coating on micro-/nano-sized hierarchical architectures still remains challenging due to the complex multiple procedures involved, the independent carbon and nitrogen sources, and the possibility of structure collapse at elevated annealing temperatures. In this study, nitrogen-enriched carbon-coated flower-like bismuth sulfide (N–C@Bi₂S₃) architectures were successfully synthesized by a facile hydrothermal method and post-heat treatment at mild temperatures. Due to the effective interaction between the catechol-/amine-groups and the inorganic materials, dopamine molecules were introduced and polymerized on the surface of the three-dimensional flower-like Bi₂S₃ architectures, which were then converted into a homogeneous and thin nitrogen-enriched carbon layer with an average thickness of 5.0 nm. This thin layer played key roles in accelerating the fast electronic conduction, buffering the volume change of Bi₂S₃ during cycling, and physically/chemically immobilizing the soluble polysulfide species. As expected, the as-prepared N–C@Bi₂S₃ electrode offered a high reversible capacity of 1001.7 mA h g⁻¹ (a high capacity retention of 78.5%) even after 224 cycles at 0.2 A g⁻¹, an improved rate capability of 543 mA h g⁻¹ at 2.5 A g⁻¹ and a satisfactory capacity of 616.7 mA h g⁻¹ at 1 A g⁻¹ after 950 cycles. This feasible approach of engineering a homogeneous and thin nitrogen-enriched carbon layer can also be applied to a broad range of active materials with hierarchical structures for energy storage applications.