Dendritic Fe2O3 single crystal for high performance lithium-ion batteries by turning the concentration of the iron source

Abstract

Lithium-ion batteries (LIBs) are widely used due to their high capacity, high safety, and low cost. The anode material exhibits significant volume changes and subsequent reversible capacity decay during the lithiation/delithiation process, therefore, the performance of lithium-ion batteries is determined by the anode material. In this work, dendritic Fe₂O₃ single crystal with different precursor concentrations was prepared by hydrothermal method. The composition and microstructure of the samples were analyzed and tested using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy techniques. The electrochemical performance was tested using cyclic voltage measurement and electrical impedance spectroscopy. The leaves of dendritic Fe₂O₃ were too small when the iron source concentration was too low to provide enough Fe³⁺, and excessive Fe³⁺ led to the leaves of dendritic Fe₂O₃ being too thick. The most suitable branch size and thickness of dendritic Fe₂O₃ single crystals were grown for 0.007 mol/l Fe³⁺ concentration (sample L4), and its electrode showed the best electrochemical performance. The sample L4 has a capacity of up to 734 mAh∙g⁻¹ for 200 cycles at 100 mA∙g⁻¹, and has a specific capacity retention rate of 95.4% after high current 3000 mA∙g⁻¹. This work is believed to facilitate understanding single crystal growth mechanisms and promote the development of high-performance lithium-ion batteries.