摘要
以H3PO4、Fe2O3和LiOH.H2O为原料,用H2还原合成了橄榄石型LiFePO4材料。采用Rietveld全谱拟合法检测不同温度和时间下LiFePO4的转化率,通过研究其转化率与时间、温度的关系,确定了H2还原合成LiFePO4的反应机理、反应级数和速率常数,并给出了控制步骤的转化温度和各阶段的活化能。根据动力学研究的结果,采用"H2气氛低温合成,N2气氛高温生长"机制合成了LiFePO4/C复合材料。该材料具有单一的橄榄石结构,颗粒尺寸细小均匀,0.1C倍率下,首次放电容量达152.5 mAh/g,放电效率为95.4%,循环30次后,电池的容量保持率达98.4%。
The LiFePO4/C composite materials were synthesized by hydrogen reduction with H3PO4 ,Fe203 and LiOH · H2O as raw materials. Rietveld method was used to detect the transformation ratio of LiFePO4 under the conditions of different temperatures and times. By studying the relationship between the transformation ratio and time and temperature, the reaction mechanism, reaction order and reaction rate constant were ascertained. Furthermore, the transformation temperature for the controlling procedures and activity energy were provided. According to the research results, LiFe- PO4/C was synthesized by adopting the mechanism of low-temperature synthesis in hydrogen atmosphere and high-temperature growth in nitrogen atmosphere. The material shows a single olivine-type structure with fine and uniform grain size. It has an initial discharge capacity of 152.5 mAh/g and a discharge efficiency of 95.4% at 0.1C multiplying power. The discharge capacity remains 98.4% after the material cycling 30 times.
出处
《矿冶工程》
CAS
CSCD
北大核心
2010年第1期65-68,72,共5页
Mining and Metallurgical Engineering
