前驱体掺杂-常温球磨还原制备Ti^(4+)掺杂LiFePO_4

Preparation of Ti^(4+)-doped LiFePO_4 by precursor-doping and room temperature reduction via ball-milling

采用共沉淀法制备了掺Ti4+前驱体FePO4·2H2O,并以乙二酸为还原剂,与Li2CO3反应在常温下球磨合成LiFePO4前驱混合物,后经热处理得橄榄石型LiFePO4。用SEM,XRD,EIS和恒流充放电等对样品进行表征。研究结果表明,3%(摩尔分数)Ti4+掺杂的LiFePO4拥有最优的电化学性能,该样品在0.1C,1C和2C倍率下的初始放电比容量分别为150,130和125mA·h/g,在1C倍率下循环100次后的放电比容量高达133mA·h/g。

Ti^4＋-doped precursors （FePO4·2H2O） were prepared via co-precipitation method. LiFePO4 precursor-mixtures were obtained by ball-milling at room temperature, using FePO4·2H2O, Li2CO3 and oxalic acid as raw materials, and then olivine-type LiFePO4 were synthesized by the following heat treatment. The samples were characterized using scanning electron microscope, X-ray diffraction, electrochemical impedance spectroscopy and galvanostatic charge/discharge test. The results show that the sample doped with 3% Ti^4＋ （molar fraction） has the most impressive electrochemical performance as follows： its initial discharge capacities are 150, 130 and 125 mA·h/g at 0.1C, 1C and 2C rates, respectively, without capacity fading even after 100 cycles at 1C rate.