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以三价铁盐为铁源,采用多元醇还原法在低温下制备出了具有不同长径比的棒状LiFePO4材料.通过X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、循环伏安(CV)、交流阻抗谱(EIS)和恒电流充放电测试等手段分析了不同回流反应时间下制备出的前驱体和最终的LiFePO4/C样品.结果表明:回流反应时间对LiFePO4的形貌和特性有明显的影响.通过把回流反应时间从4 h延长至16 h,材料的形貌由不规则的短棒状颗粒变为规则的长棒状颗粒,且棒的直径明显变小.当回流反应时间为10 h时,样品复合了多种形貌,有利于电子的传输,在低倍率下具有优秀的性能,0.1C放电比容量为163 mAh g-1;当回流反应时间为16 h时,样品具有最大的长径比,有利于锂离子的扩散,在高倍率下具有良好的性能,1C、3C、5C、10C、20C倍率下放电比容量分别为135、125、118、110、98 mAh g-1,循环性能良好,几乎无衰减.
Ferric rod as the iron source, the rod-shaped LiFePO4 materials with different aspect ratios were prepared by polyhydric alcohol reduction method at low temperature. The structure of the rod-shaped LiFePO4 was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope Cyclic voltammetry (CV), alternating current impedance spectroscopy (EIS) and constant current charge-discharge test were used to analyze the precursor and the final LiFePO4 / C samples prepared at different reflow reaction times.The results show that the reaction time of reflux reaction to LiFePO4 Morphology and characteristics of the material.With the extension of the refluxing time from 4 h to 16 h, the morphology of the material changes from irregular short rod-like particles to regular long rod-like particles, and the diameter of the rod is obviously smaller. When the reaction time was 10 h, the samples were compounded with many morphologies, which were conducive to the electron transport and had excellent performance at low magnification. The specific discharge capacity at 0.1 C was 163 mAh g-1. When the reaction time was 16 h , The sample has the largest aspect ratio, which is favorable for the diffusion of lithium ions and has good performance at high magnification. The specific discharge capacities at 1C, 3C, 5C, 10C and 20C magnifications are 135, 125, 118 and 110 respectively, 98 mAh g-1, cycle performance is good, almost no attenuation.