Successful Hydrothermal Synthesis of α-Fe2O3 Hexagonal Micro-platelets and Its Application in Li-Ion Battery

摘要:

采用水热法成功合成了α-Fe2O3六边形微米片。将NaOH溶解在PEG400和蒸馏水中形成混合溶液制备Fe(OH)3，利用Fe(OH)3在碱液中的热分解和再结晶反应制得α-Fe2O3。通过XRD、SEM手段对比分析PEG400和水热反应时碱液浓度对产物成分和形貌的影响。结果显示，在制备过程中使用PEG400，且水热反应时碱液浓度为2.5 mol/L的情况下可以成功合成α-Fe2O3六边形微米片。不使用PEG400时产物为α-FeOOH纳米棒；使用PEG400时产物的成分和形貌均随着碱液浓度的增大而变化，碱液浓度从1 mol/L增加到2.5 mol/L，产物成分由α-FeOOH逐渐变为α-Fe2O3，形貌由条状变为六边形片状。可见，PEG400的使用和水热反应时碱液浓度的合理选择对形成六边形片状α-Fe2O3起到很重要的作用。将合成的α-Fe2O3六边形微米片应用于锂离子电池负极材料，其初始可逆容量为674.9 mAh·g-1

Abstract:

α-Fe2O3 hexagonal micro-platelets were prepared via a simple hydrothermal process in the presence of an organic solvent PEG400. The synthetic method was based on the hydrothermal oxidative decomposition and the recrystallization of Fe(OH)3 precursor in a basic solution of NaOH. The crystalline structures and morphologies of the as-obtained samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of the alkali environment during the hydrothermal reaction on product morphology were investigated. According to the results, α-Fe2O3 hexagonal micro-platelets could be directly prepared in a basic solution of NaOH (2.5 mol/L) when using PEG400 in the reaction system. The product morphology changes from rodlike to platelike shape when the alkali concentration increases from 1 mol/L to 2.5 mol/L. Therefore, the use of PEG400 and the hydrothermal growth alkali concentration play an important role in the formation of such platelike microstructure of α-Fe2O3. When the α-Fe2O3 hexagonal micro-platelets are used in Li-ion battery, it exhibits an initial reversible capacity of 674.9 mAh·g-1