Application of porous bismuth-based materials in sodium ion batteries

Sodium-ion batteries (SIBs) offer a sustainable alternative to lithium-ion systems, leveraging resource availability and enhanced safety. This review describes the application of porous bismuth (Bi)-based materials in sodium ion batteries. Bismuth-based materials are emerging as promising anode candidates due to their high capacity, manageable volume expansion, and tunable porosity. Their performance is driven by a synergistic dual-mechanism Na⁺ storage combining alloying and conversion reactions. Hierarchical pore engineering (micropores for interfacial storage, mesopores for ion diffusion, macropores for high loading) effectively mitigates volume strain and extends cycle life. Advanced synthetic strategies (<i>e.g.</i>, MOF-derived pyrolysis) enable fabrication of carbon-composite architectures featuring hollow frameworks and N-doped coatings. These designs deliver exceptional rate capability and accelerated ion transport. While ether-based electrolytes and heterointerface engineering optimize interfacial stability, challenges remain in scalability, electrolyte compatibility, and full-cell integration. Future development requires ML-guided structural optimization, green synthesis, and system-level engineering to realize the potential of Bi-based anodes for wide-temperature, high-power SIBs.