Sulfide-reduction strategy for constructing bimetallic BiSb microrods toward high-performance potassium ion storage

In this work, we report a sulfide-reduction strategy to construct bimetallic BiSb microrods with polydopamine-derived carbon encapsulation (BiSb@PDA). The synthesis reveals that BiSbS precursors undergo a microrod growth process, and subsequent reduction under PDA-derived carbon confinement preserves their structural integrity. Benefiting from this stabilized architecture, the bimetallic BiSb@PDA microrods deliver a reversible capacity of 348 mAh g−1 after 100 cycles at 0.1 A g−1 with 88.9% retention, and maintain 264 mAh g−1 after 200 cycles at 0.3 A g−1. The performance of BiSb@PDA, characterized by its higher specific capacity compared to single-metal counterparts and acceptable retention rate, demonstrates the potential of the composite material. Comprehensive characterizations further unveil the phase-evolution mechanism of BiSb during potassiation–depotassiation process, which effectively accommodates volume changes and ensures robust potassium storage durability.