NiS/FeS binary nanoparticles confined in interconnected carbon framework with regulated pore structure enabled by citric acid for enhanced sodium storage properties.

Recently, pyrite iron disulfide (FeS) has emerged as a promising anode candidate for sodium-ion batteries (SIBs) due to its high theoretical capacity, affordability, non-toxicity and abundant resource in nature. However, the utilization of FeS still confronts the challenges of inferior rate capability and cycling instability for sodium storage, stemming from its low electronic conductivity and substantial volume changes during cycling. Herein, to address these obstacles, NiS/FeS binary nanoparticles encapsulated within a network of interconnected N-doped porous carbon framework (NiS/FeS@NPC) are prepared by a successive solid-state ball milling, carbonization and sulfurization strategy with coordination complex of nickel iron Prussian blue analogue (NiFe-PBA) as precursor.