阳离子调制赤铁矿层级结构的可控制备及其储锂性能研究

Controllable Fabrication of Cation-modulated Hematite Hierarchical Structures and Their Lithium Storage Properties

采用一步水热法,通过控制反应物中的阳离子(Na+)浓度,制备出了多种赤铁矿(α-Fe2O3)层级结构。通过X-射线衍射(XRD)、场发射扫描电子显微镜(SEM)、电化学测试等手段对产物的相组成、形貌结构和锂电性能进行了表征,并对其生长机理进行了探讨。研究表明:当反应物浓度较低(c(FeCl3)=0.4mol·L-1,c(NaCl)=0.2mol·L-1)时,不同反应时间下的产物均为纯相α-Fe2O3,并且呈现出笼状层级结构;而当反应物的浓度较高(c(FeCl3)=0.8mol·L-1,c(NaCl)=0.4mol·L-1)时,随反应时间的延长,产物由花状结构的FeOOH和α-Fe2O3的混合物逐渐演进为鱼卵状α-Fe2O3产物。进一步研究发现:反应体系中阳离子的浓度改变对产物的形貌结构以及相组成产生了较大的影响。此外,电化学测试研究表明:两种反应物浓度下的笼状和鱼卵状α-Fe2O3产物均具有优良的储锂性能,可用作锂离子电池的电极材料。

Various hematite （α-Fe2O3） hierarchical structures were fabricated through a one-step hydrothermal method by controlling the cation （Na＋ ） concentration in reactants. Phase composition, morphologies and structures, and lithium storage properties of the products were characterized by X-ray diffraction （XRD）, scanning electron mi croscopy （SEM）, and electrochemical testing. Their formation mechanism was also investigated. It was demonstrated that, after different reaction time, pure hematite products with cage-like hierarchical structures could always be obtained when the reactant concentration was low （c（FeCl3）=0.4 mol·L^-1 ,c（NaCl）=0.2 mol·L^-1）. In con trast, at relatively high concentration （c（FeCl3）=0.8 mol·L^-1 ,c（NaCl）=0.4 mol·L^-1 ）, the products exhibited flower-like structure with a blend of FeOOH and α-Fe2O3 phases, and finally evolved into roe-like hematite pure phase as prolonging the reaction time. Further, it was found that the alteration of the cation concentration in the reaction system exerted a great impact on the topography structure and phase composition of theproducts. Additionally, the electrochemical tests showed that the cage-like and roe-like α-Fe2O3 products, deriving from two reactions under different reactant concentrations, both possessed superior lithium storage properties, indicative of their potential applica- tion as electrode materials in lithium ion batteries.