High-performance nanohybrid anode based on FeS2 nanocubes and nitrogen-rich graphene oxide nanoribbons for sodium ion batteries

Abstract

Sodium ion batteries (SIBs) have attracted considerable attention as an alternative to Li ion batteries (LIBs) because of the sustainable sodium resources and similar chemistry to LIBs. On the other hand, the larger and heavier sodium results in unfavorable sodium ion storage capacity. In this study, an inexpensive precursor-based conversion material, FeS2, was synthesized as a nanostructured pyrite crystal, <100 nm in size, which has a carbon coating layer, a few nanometers in thickness. The deficient electrical conductivity of the synthesized FeS2 nanocubes (FeS2-NCs) was strengthened by forming a nanohybrid structure with high-aspect ratio graphene oxide nanoribbons containing nitrogen dopants (N-GONRs). N-GONRs bind tightly the FeS2-NCs well-dispersed in the N-GONRs matrix, inducing highly improved electrochemical performance as an anode for SIBs. The FeS2-NCs/N-GONRs nanohybrid anode delivered a high reversible capacity of ∼800 mA h g−1 at 0.2 A g−1, of which approximately 60% was maintained at a 50 times higher current rate, indicating high rate capability. In addition, stable cycling performance over 200 cycles was achieved with an average capacity of ∼670 mA h g−1. The hybrid anode demonstrated its feasibility in a full cell test using an O3-type cathode material.