Molten salt synthesis of tin doped hematite nanodiscs and their enhanced electrochemical performance for Li-ion batteries

Abstract

Sn⁴⁺ doped Fe₂O₃ (hematite) nanodiscs have been synthesized by a facile mixed molten salt method. The structure, morphology and compositions of the products are characterized by X-ray diffraction (XRD), filed emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectrometry (XPS) and inductively coupled plasma (ICP). According to the time dependent experimental results, the formation mechanism of the Sn⁴⁺ doped Fe₂O₃ nanodiscs is discussed. The electrochemical properties of the Fe₂O₃ nanodiscs as an anode material are investigated in terms of their reversible capacity, and cycling performance for lithium ion batteries. The Sn⁴⁺ doped Fe₂O₃ nanodiscs (5% Sn) exhibit a reversible capacity of 899 mA h g⁻¹ at a current density of 100 mA g⁻¹ after 100 cycles. Even at 1000 mA g⁻¹, the reversible capacity of the nanodiscs still remains 490 mA h g⁻¹. The improved electrochemical performance is ascribed to the introduction of the Sn element, which decreases charge transfer resistance, enhances Li ion diffusion velocity, and thus improves its cycling and high-rate capability. These results suggest the promising application of the Sn⁴⁺ doped Fe₂O₃ nanodiscs in lithium ion batteries.