Molten salt synthesis of CoFe2O4 and its energy storage properties

Abstract

In this article, we report simple and scalable one-pot molten salt synthesis of CoFe₂O₄ as electrode material for Lithium ion batteries. X-ray diffraction studies along with Rietveld analysis showed a pure phase of CoFe₂O₄ with space group Fd-3m and crystallite size of 54 nm. As an anode material CoFe₂O₄ showed high initial discharge/charge capacity of 1556/1093 mA h g⁻¹ and a reversible capacity of 926 mA h g⁻¹ after 30 cycles with columbic efficiency of 99%. A relatively high reversible capacity of 594 mA h g⁻¹ was observed at high current density of 1C (916 mA g⁻¹) which shows the better reversibility of CoFe₂O₄ at high current density. As the current was reduced to 0.1C reversible capacity of 899 mA h g⁻¹ was retained suggesting high rate performance of CoFe₂O₄. The long-term stability test, carried out using galvanostatic charge/discharge (GC) at a current density of 0.5C, showed a reversible capacity of 369 mA h g⁻¹ at the end of 200th cycle. The structural and morphological evaluation of the sample after cycling, using ex-situ X-ray diffraction and ex-situ transmission electron microscopy, confirmed structural degradation and formation of metal nanoparticles, Li₂O and amorphous nature of electrode material. The one-pot molten salt synthesis approach is quite simple and can be extended for large-scale production of electrode materials.