活化温度对LiMnPO_4固相反应制备过程的影响

Effect of Activation Temperature on Synthesis of LiMnPO4 Nano-crystallites via Solid State Reaction

以氢氧化锂、磷酸二氢铵和醋酸锰为原料,以聚乙二醇PEG-400为表面活性剂,经低热反应合成前驱体NH4MnPO4,再经固相反应制备LiMnPO4纳米晶体.对产物进行了表征,研究了活化温度对LiMnPO4生成过程的影响,探讨其可控制分步合成过程.结果表明,晶体生长动力学指数n=1.1,晶粒生长激活能E=20.98kJ/mol.在LiMnPO4晶粒生长过程中可通过调节温度控制LiMnPO4晶粒粒度.以LiMnPO4为材料制作析氢电极,电极因材料粒度不同在水溶液中催化析氢的程度不同,随电极材料粒度增大,析氢电极反应平衡电势负移.

The nano-crystallites of LiMnPO4 powder were successfully prepared after calcining the precursor of NH4MnPO4 at high activation temperature. The precursor was prepared with lithium hydroxide, monoammonium phosphate and manganese acetate via solid state reaction at low temperature. The effect of activation temperature on the crystallization process of LiMnPO4 was characterized by infrared spectroscopy, XRD, TG-DTA and SEM. The results showed that the synthesis of LiMnPO4 was involved in variety of kinetic competition at high activation temperature, but the calcination process was the control step of synthesis, the kinetic index number of crystal growth 1.1, and the activation energy ofnano-grain growth 20.95 kJ/mol. And the particle size of LiMnPO4 was controlled in the synthesis process at different activation temperatures, and LiMnPO4 was used as hydrogen precipitation electrode material, the electrode equilibrium potential was changed by LiMnPO4 particle size.