l-Histidine-assisted template-free hydrothermal synthesis of α-Fe2O3 porous multi-shelled hollow spheres with enhanced lithium storage properties

Abstract

Unique α-Fe₂O₃ porous multi-shelled hollow spheres (α-Fe₂O₃ PMSHSs) have been prepared by a simple template-free hydrothermal method followed by annealing in air. For the first time, L-histidine was used as a morphology controlling agent in the synthesis process. The α-Fe₂O₃ PMSHSs had a relatively high surface area of 14.2 m² g⁻¹ and a pore volume of 0.07 cm³ g⁻¹. When used as an anode material for lithium ion batteries, the α-Fe₂O₃ PMSHSs exhibited high specific capacity, good cycling stability, and excellent rate performance. A stable and reversible capacity of 869.9 mA h g⁻¹ could be maintained at a charge–discharge current density of 400 mA g⁻¹ after 300 cycles. Superior rate capability had also been demonstrated by testing the material at different current densities. The α-Fe₂O₃ PMSHSs could deliver a capacity as high as 833.3 mA h g⁻¹ at 800 mA g⁻¹, and a capacity of 498.1 mA h g⁻¹ at 6000 mA g⁻¹. The superior electrochemical performance of the α-Fe₂O₃ PMSHSs is attributed to the hierarchical porosity, special micro/nanostructure, shorter electron and lithium ion diffusion pathways, and easy penetration of the electrolyte.