CAJ | 학술논문

以H_3PO_4、Fe_2O_3和LiOH·H_2O为原料,用H_2还原合成了橄榄石型LiFePO_4材料.采用Rietveld全谱拟合法检测不同温度和时间下LiFePO_4的转化率,通过研究其转化率与时间、温度的关系,确定了H_2还原合成LiFePO_4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"H_2气氛低温合成,N2气氛高温生长"机制合成了LiFePO_4/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%.
이H_3PO_4、Fe_2O_3화LiOH·H_2O위원료,용H_2환원합성료감람석형LiFePO_4재료.채용Rietveld전보의합법검측불동온도화시간하LiFePO_4적전화솔,통과연구기전화솔여시간、온도적관계,학정료H_2환원합성LiFePO_4적반응궤리、반응급수화속솔상수,병급출료공제보취적전화온도화각계단적활화능.근거동역학연구적결과,채용"H_2기분저온합성,N2기분고온생장"궤제합성료LiFePO_4/C복합재료.해재료구유단일적감람석결구,과립척촌세소균균,0.1C배솔하,수차방전용량체152.5 mAh/g,방전효솔위95.4%,순배30차후,전지적용량보지솔체98.4%.
The LiFePO_4/C composite materials were synthesized by hydrogen reduction with H_3PO_4,Fe_2O_3 and LiOH·H_2O as raw materials.Rietveld method used to detect the transformation ratio of LiFePO_4 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, LiFePO_4/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.