Porosity Engineering of N‐Doped Carbon Framework Decorated With Ultrafine FeS ₂ Nanoparticles via Mechanochemical Coordination Synthesis for High‐Rate and Durable Sodium Storage

Pyrite iron disulfide (FeS ₂ ) emerges as a potential anode material for sodium‐ion batteries (SIBs) because of its superior theoretical capacity and cost‐effectiveness. Nevertheless, its practical application is hindered by poor electronic conductivity and significant volume changes during cycling, resulting in limited rate capability and rapid capacity fading. To overcome these challenges, a highly porous nitrogen‐doped carbon framework decorated with ultrafine FeS ₂ nanoparticles (FeS ₂ /NC) was synthesized via a facile and scalable mechanochemical method followed by carbonization and sulfurization. By adjusting the amount of NaCl as a removable pore‐forming agent, an interconnected three‐dimensional porous carbon framework was constructed. This architecture facilitates efficient ion and electron transport, alleviates mechanical stress during sodiation/desodiation, and improves structural stability. Benefiting from this optimized structure, the FeS ₂ /NC‐1 anode demonstrates outstanding sodium storage performance (394 mAh g ⁻¹ at 5 A g ⁻¹ ) and durable cycling stability (a capacity retention of 107.6% after 2500 cycles). This study demonstrates an effective porosity engineering strategy for designing high‐performance FeS ₂ ‐based anodes and provides a practical pathway toward durable and high‐rate SIBs.