Microwave-assisted Synthesis of Greigite Fe₃S₄ nanosheets wrapped in an rGO Matrix as anode material for Sodium-ion batteries

School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, China

^* Corresponding author: cbcao@bit.edu.cn

Abstract

Greigite (Fe₃S₄), which have ferromagnetic in inverse thiospinel (AB₂S₄), is widely researched to use an adsorbent and biomedical field because non-toxicity and abundant in nature. Iron-based materials are known to have a high theoretical capacity because of their multivalent state including redox pairs, but still suffer from collapse and aggregate during the charge/discharge process. Here, the synthesized Fe₃S₄ nanosheet structure materials wrapped with reduced graphene oxide (Fe₃S₄NSs@rGO) were used as an anode electrode material for sodium-ion batteries (SIBs). The nano-sheet structure facilitates ion diffusion through expanded surface area, and rGO can effectively improve electrochemical conductivity and structure stability. As-prepared Fe₃S₄NSs@rGO were used as a host material to insert Na-ion via a conversion process, and the stabilized structure maintains the high capacity and long cycle performance. Thus, the Fe₃S₄NSs@rGO deliver a reversible capacity of 950 mAh g⁻¹ after 200 cycles at a current density of 1A g⁻¹ and 524 mAh g⁻¹ after 400 cycles at a current density of 2A g⁻¹, which is much higher than reported materials.