Achieving High-Rate and Stable Sodium-Ion Storage by Constructing Okra-Like NiS₂/FeS₂@Multichannel Carbon Nanofibers

Abstract

Transition metal sulfides (TMSs) are considered as promising anode materials for sodium-ion batteries (SIBs) due to their high theoretical capacities. However, the relatively low electrical conductivity, large volume variation, and easy aggregation/pulverization of active materials seriously hinder their practical application. Herein, okra-like NiS₂/FeS₂ particles encapsulated in multichannel N-doped carbon nanofibers (NiS₂/FeS₂@MCNFs) are fabricated by a coprecipitation, electrospinning, and carbonization/sulfurization strategy. The combined advantages arising from the hollow multichannel structure in carbon skeleton and heterogeneous NiS₂/FeS₂ particles with rich interfaces can provide facile ion/electron transfer paths, ensure boosted reaction kinetics, and help maintain the structural integrity, thereby resulting in a high reversible capacity (457 mA h g^-1 at 1 A g^-1), excellent rate performance (350 mA h g^-1 at 5 A g^-1), and outstanding long-term cycling stability (93.5% retention after 1100 cycles). This work provides a facile and efficient synthetic strategy to develop TMS-based heterostructured anode materials with high-rate and stable sodium storage properties.