简便制备三维多级Fe_(3)O_(4)/碳纳米纤维一体化电极及其储钠性能研究

Preparation of three-dimensional multistage iron oxide/carbon nanofiber integrated electrode and sodium storage performance

作为钠离子电池负极材料之一的铁氧化物,其理论比容量高,但在循环过程中会发生较大的体积膨胀,表现出明显的容量衰减。以柔性碳基材料为基底原位构建纳米结构的金属氧化物可作为一种缓解其体积膨胀的有效手段。本文采用化学气相沉积法在泡沫铜上原位生长了多孔碳纳米纤维(CNFs),以此为柔性导电基底,通过盐溶液浸渍与退火相结合的简便方法制备得到三维多级Fe_(3)O_(4)/碳纳米纤维(3D Fe_(3)O_(4)/CNFs)一体化电极电极,并将其用作钠离子电池负极。使用X射线光电子能谱(XPS),拉曼光谱(Raman),扫描电子显微镜(SEM)对样品进行组分分析及形貌表征。使用恒流充放电(GCD),循环伏安(CV),电化学阻抗(EIS)对其进行电化学性能表征。结果表明,尺寸在50~100 nm的纳米棒状Fe_(3)O_(4)均匀分散在多孔碳纳米纤维上,构建出富含孔隙的三维多级结构。在0.1 A/g的电流密度下,3D Fe_(3)O_(4)/CNFs一体化电极经过100圈循环后,其比容量可达893.4 mAh/g,优于CNFs电极,并表现出更快的钠离子扩散动力学,同时具有较好的电化学可逆性。本文为金属氧化物/碳基复合电极研究提供了思路与实验依据。

Iron oxide is an anode material for sodium-ion batteries and has a high theoretical specific capacity;however,it undergoes large volume expansion during cycling and exhibits considerable capacity decay.The in situ construction of nanostructured metal oxides on flexible carbon-based materials can be an effective means to mitigate their volume expansion.Herein,porous carbon nanofibers(CNFs)were grown in situ on copper foam via chemical vapor deposition as a flexible conductive substrate.Furthermore,three-dimensional multistage integrated Fe_(3)O_(4)/CNF(3D Fe_(3)O_(4)/CNF)electrodes were prepared using a simple combination of salt solution impregnation and annealing and were used as the negative electrodes in sodium-ion batteries.The compositions and morphologies of the electrodes were analyzed using X-ray photoelectron spectroscopy,Raman spectroscopy,and scanning electron microscopy.The electrochemical properties of the electrodes were characterized using constant current charge/discharge,cyclic voltammetry,and electrochemical impedance spectroscopy analyses.The results showed that Fe_(3)O_(4)nanorods with a diameter of approximately 50—100 nm were uniformly dispersed on porous CNFs to construct a highly porous 3D multilevel structure.At a current density of 0.1 A/g,the integrated 3D Fe_(3)O_(4)/CNF electrode achieved a specific capacity of 893.4 mAh/g after 100 cycles,which is higher than CNF electrodes.Additionally,the integrated electrode exhibited faster sodium ion diffusion kinetics and better electrochemical reversibility than CNF electrodes.This study provides an idea and experimental basis for the study of metal oxide/carbon-based composite electrodes.