FeSb2S4 anchored on amine-modified graphene towards high-performance anode material for sodium ion batteries

Abstract

Sodium ion batteries (SIBs) have been considered as promising alternatives to lithium ion batteries (LIBs), due to the earth-abundance and low cost of Na metal, as well as the similar chemistry between SIBs and LIBs. For the advancement of SIBs, the challenges are still remained in anode materials. Metal sulfides with high theoretical specific capacity have been explored as SIB anodes adequately. However, the exploration of high-performance SIBs is hindered by the disadvantages of metal sulfides anodes, including low reversible capacity, limited cycling lifespan and inferior rate performance. Herein, we report a new bimetallic sulfide, FeSb2S4 anchored on amine-modified graphene (FeSb2S4/EN-rGO) as an advanced anode for SIBs, which shows a reversible capacity of 782.5 mAh g−1 at 0.1 A g−1 after 100 cycles and remains a high capacity of 515.7 mAh g−1 at 5 A g−1 after 500 cycles with a low capacity loss rate of 0.04% per cycle. Moreover, both experimental and theoretical calculation results reveal that the strong chemical interaction between amine-modified graphene and FeSb2S4 as well as discharge products (Na2S) is the crucial reason for enabling the stability of anode micro-architecture. Furthermore, the evolution mechanism of the reactions between FeSb2S4 and Na ions is disclosed by ex-situ XRD diffraction. This work opens up a new door for the rational design of bimetallic sulfide anodes for sodium ion batteries with high capacity and rate performance as well as superior cycling stability.