Preparation of porous FeS2-C/RG composite for sodium ion batteries

•FeS2-C nanoparticles were directly obtained through one-step vulcanization of PB.•Constructing three-dimensional porous FeS2-C/RG.•Low conductivity and volume expansion of FeS2 were solved at the same time.•The high specific capacity of 655.9 mAh g−1 after 100 cycles at 0.1 A g−1.•Long cycle stability after 1000 cycles under large current density of 6 A g−1. Pyrite (FeS2) is considered to be one of the most promising anode materials for sodium ion batteries (SIBs) due to its high theoretical capacity, natural abundance, low cost and low toxicity, but the commercial process of FeS2 is always limited by its low conductivity and volume expansion during the charge-discharge process. Herein, a three-dimensional porous composite (FeS2-C/RG) is constructed using FeS2-C nanoparticles and reduced graphene oxide through one-step vulcanization of PB (Prussian blue)/GO (graphene oxide) gel. As the anode material of SIBs, FeS2-C/RG exhibits high electrochemical performance benefiting from the unique three dimensional structure and small FeS2-C nanoparticles. The initial specific capacity can reach 1196 mAh g−1 at 0.1 A g−1 and it can still remain 543.0 mAh g−1 after 100 cycles at 0.5 A g−1. Even at 6 A g−1, the capacity could maintain 291.7 mAh g−1 after 1000 cycles. The excellent rate and cycling performance of FeS2-C/RG indicate it is a promising anode material for rechargeable SIBs.