Study on the Directional Synthesis of Bi ₂ S ₃ Induced by Graphene and the Mechanism of Pseudocapacitive Kinetics Regulation at the Interface

To address the issues of capacity decay and poor rate performance of Bi₂S₃ anode materials, which are caused by their intrinsically low conductivity and significant volume expansion during cycling, this study adopts a redox self-assembly strategy. Under mild hydrothermal conditions, oxygen-containing functional groups on the surface of graphene oxide (GO) induce the directed growth of Bi₂S₃ along the [001] crystallographic direction, successfully constructing a Bi₂S₃/GO composite anode with strong interfacial coupling. This structure effectively suppresses the agglomeration of Bi₂S₃ nanorods, forms a 3D conductive network, alleviates volume strain, and avoids structural damage caused by traditional high-temperature sulfidation processes. Electrochemical tests show that the 1.0-Bi₂S₃/GO composite retains a capacity of 300 mAh·g^-1 after 100 cycles at a current density of 100 mA·g^-1. At a high rate of 5000 mA·g^-1, it still exhibits a reversible capacity of 198.62 mAh·g^-1, and after current recovery, the capacity rapidly increases to 439 mAh·g^-1, with a capacity retention rate exceeding 70%. The lithium-ion diffusion coefficient reaches 8.7×10^-1 ² cm²·s^-1, which is 2.8 times higher than that of the pure phase. Mechanistic analysis reveals that the characteristic peak (τ = 0.3 s) in the distribution relaxation time (DRT) relaxation spectrum corresponds to the pseudocapacitive behavior on the GO surface, with a contribution rate of 58% at a scan rate of 2 mV·s^-1, significantly optimizing the ion storage dynamics at the interface. Additionally, the built-in electric field at the interface facilitates charge transfer, effectively shortening the relaxation time. The synergistic π-π stacking buffering network further enhances structural stability and reaction reversibility. This study, through the "directed growth-pseudocapacitance regulation-relaxation matching" triple mechanism, provides new insights for the design of high-performance sulfide-based anodes.