物理化学学报 >> 2011, Vol. 27 >> Issue (06): 1325-1334.doi: 10.3866/PKU.WHXB20110507

热力学,动力学和结构化学 上一篇    下一篇

固相反应合成LiCoPO4中间体的反应动力学

黄映恒1,2, 童张法1, 韦藤幼1, 李斌1   

  1. 1. 广西大学化学化工学院, 南宁 530004;
    2. 桂林理工大学南宁分校冶金工程系, 南宁 530001
  • 收稿日期:2010-11-25 修回日期:2011-02-22 发布日期:2011-05-31
  • 通讯作者: 童张法 E-mail:zhftong@sina.com
  • 基金资助:

    国家自然科学基金(20766001), 广西青年科学基金(0728101)和广西教育厅科研项目(200505083)资助

Reaction Kinetics of the Intermediate in Synthesis of LiCoPO4 by Solid-State Reaction

HUANG Ying-Heng1,2, TONG Zhang-Fa1, WEI Teng-You1, LI Bin1   

  1. 1. School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, P. R. China;
    2. Department of Metallurgy Engineering, Guilin University of Technology at Nanning, Nanning 530001, P. R. China
  • Received:2010-11-25 Revised:2011-02-22 Published:2011-05-31
  • Contact: TONG Zhang-Fa E-mail:zhftong@sina.com
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (20766001), Foundation for Young Scientists of Guangxi, China (0728101), and Research Foundation of Education Bureau of Guangxi, China (200505083).

摘要:

以磷酸二氢铵、醋酸钴和氢氧化锂为原料, 用低温固相反应合成含Li+的NH4CoPO4前驱体, 再经过高温焙烧合成LiCoPO4粉体. 应用傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)和热重-差热分析(TG-DTA)等技术对合成产物进行表征. 结果表明: 焙烧气氛影响中间体的生成, 含Li+的前驱体NH4CoPO4在210-500 °C的空气中发生脱水脱氨反应, 制备过程存在“酸碱共同体”的中间体(CoHPO4·LiCoPO4·Co2(OH)PO4·Li3PO4). 中间体生成反应遵循界面反应幂律机理, 表观活化能约50.0 kJ?mol-1, 过程机理函数为g(x)=(1-α)-1. 中间体继续脱水反应生成LiCoPO4, 平均表观活化能约为54.2 kJ?mol-1. 物系非晶化和晶化过程对中间体的存在没有直接的影响, 高温对中间体的分解产物LiCoPO4和LiCoPO4的晶体生长有利, 在550 °C以上温度中间体可分解得到完整的LiCoPO4晶体.

关键词: LiCoPO4, 含锂磷酸盐, 中间体, 固相反应, 反应机理, 反应动力学

Abstract:

A precursor NH4CoPO4 containing Li+ was synthesized using a low temperature solid-state reaction with ammonium dihydrogen phosphate, cobalt acetate, and lithium hydroxide. LiCoPO4 powder was manufactured by high temperature baking. The products were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermogravimetry-differential thermal analysis (TG-DTA). The results showed that the formation of the intermediates was effected by the baking atmosphere. NH4CoPO4 containing Li+ was dehydrated and deaminated in air at 210?500 °C and then the (CoHPO4·LiCoPO4·Co2(OH)PO4·Li3PO4) intermediate (acid-base community) was emerged during the reaction process. The intermediate formation reaction mechanism followed the interfacial reaction power-law with an apparent activation energy of 50.0 kJ·mol-1. The kinetic function was found to be g(x)=(1-α)-1. The intermediate was dehydrated to form LiCoPO4 with an average apparent activation energy of 54.2 kJ·mol-1. The formation of the intermediate was not affected by the process of crystallization or non- crystallization of the materials. High temperatures accelerated the decomposition reaction of the intermediate and then the formation of LiCoPO4 crystals. A perfect crystal of LiCoPO4 was obtained by the decomposition of the intermediate at temperatures higher than 550 °C.

Key words: LiCoPO4, Lithium orthophosphate, Intermediate, Solid state reaction, Reaction mechanism, Kinetics

MSC2000: 

  • O643