Bi-MOF-derived N-C/Bi hybrids: Isolation and conductive for high-capacity, long-cycling Si anodes

Silicon (Si) anodes have consistently been a focal point of research in lithium-ion batteries. Nonetheless, challenges that include volumetric expansion during cycles, together with intrinsic low conductivity, remain inadequately addressed. Here, we report a spatially confined “silicon/bismuth@nitrogen-doped amorphous carbon” (Si/Bi@NC) anode material to address these challenges, which is derived from bismuth-based metal-organic frameworks (Bi-MOFs). Through coordinated pyrolysis of polyvinylpyrrolidone (PVP) and Bi-MOF, N-doped carbon matrices and metal Bi are synergistically generated, respectively, which spatially isolate silicon nanoparticles while enhancing electrical conductivity. The incorporation of metal Bi not only reduces charge-transfer resistance but also establishes efficient lithium-ion transport pathways via the in situ formation of the pre-lithiated Li_xBi phase. Because of this, dual functional conductivity and volume buffering structure, the Si/Bi@NC exhibits an excellent long cycling lifespan (520.0 mAh g⁻¹ after 700 cycles at 1 A g⁻¹) and rate capability (552.7 mAh g⁻¹ at 5 A g⁻¹). In addition to outlining the creative and prospective uses of bismuth-based composites formed from Bi-MOF in new energy storage devices, this study offers a methodical approach to material development for creating silicon composite electrodes with superior electrochemical qualities.