Highly dispersed ultrasmall NiS2 nanoparticles in porous carbon nanofiber anodes for sodium ion batteries

Abstract

Although sodium-ion batteries (SIBs) show attractive advantages over current dominant lithium ion batteries (LIBs), they still face great challenges in addressing the issues of low capacity and poor cycling stability. We herein report the synthesis of a nanohybrid of ultrasmall NiS₂ nanoparticles embedded in porous carbon nanofibers (NiS₂NP/p-CNF), which is implemented by an electrospinning process accompanied by further sulfide treatment. The highly dispersed NiS₂ nanoparticles, coupled with the highly conductive porous nanofiber structure, endow the hybrids with favorable properties and structure for reducing the effects of volume expansion, providing a fast mass transport channel, and facilitating electron transfer. Systematic electrochemical studies verify that NiS₂NP/p-CNF, when studied as an SIB anode, exhibits high performance with an excellent specific capacity (500 mA h g⁻¹ at 0.1 A g⁻¹) and a competitive rate capability, maintaining 200 mA h g⁻¹ at 2.0 A g⁻¹, besides a long-term stability for 1000 cycles. The NiS₂NP/p-CNF nanofibers provide a huge potential for the development of massive sodium storage.