Synthesis of novel spherical Fe3O4@Ni3S2 composite as improved anode material for rechargeable nickel-iron batteries

- Fe3O4@Ni3S2 microspheres are fabricated through a facile method for the first time.
- Fe3O4@Ni3S2 is firstly proposed as alkaline anode materials for Ni/Fe batteries.
- Fe3O4@Ni3S2 shows enhanced high-rate capability and improved cycle stability.
- Ni3S2 can suppress the passivation and hydrogen evolution behavior of the iron anode.

Fe3O4@Ni3S2 microspheres as a novel alkaline anode material have been successfully fabricated through a four-step process for the first time. In this composite, Ni3S2 nanoparticles are coated tightly on the surface of Fe3O4 microspheres. Compared with the pure Fe3O4 and Fe3O4@NiO microspheres, the proposed Fe3O4@Ni3S2 delivers a significantly improved high-rate performance and enhanced cycling stability. At a high discharge rate of 1200 mA g−1, the specific capacity of the Fe3O4@Ni3S2 is ∼481.2 mAh g−1 in comparison with ∼83.7 mAh g−1 for the pure Fe3O4. After 100 cycles at 120 mA g−1, the Fe3O4@Ni3S2 can achieve a capacity retention of 95.1%, while the value for the pure Fe3O4 electrode is only 52.5%. The favorable electrochemical performance of the Fe3O4@Ni3S2 is mainly attributed to the beneficial impact of Ni3S2. The Ni3S2 layer as a useful additive is significantly conducive to lessening the formation of Fe(OH)2 passivation layer, enhancing the electronic conductivity, improving the reaction reversibility and suppressing the hydrogen evolution reaction of the alkaline iron anode. Owing to its outstanding electrochemical properties, we believe that the novel Fe3O4@Ni3S2 composite is potentially a promising candidate for anode material of alkaline iron-based batteries.