高振密球形FePO_4·XH_2O的合成研究

Synthesis research on iron phosphate with spherical structure and high tap density

以硝酸铁和磷酸为原料,用浓碱溶液调节反应pH值,合成化学式为FePO4.X H2O的磷酸铁。研究液相沉淀法合成FePO4.X H2O的机理,以及反应pH值、温度、时间等因素对FePO4.X H2O合成的影响。用扫描电镜对FePO4.X H2O进行表面形貌结构表征。结果表明:在溶液pH=2.0,60℃反应15 h后合成由纳米微晶团聚而成的球形FePO4.X H2O,振实密度可高达1.3 g/cm3以上;以其为铁源合成的磷酸铁锂振实密度高达1.4 g/cm3以上,首次放电比容量155.3 mAh/g,首次效率高达97%,具有良好的电性能。

Iron nitrate, phosphoric acid and concentrated alkaline solution were used as raw materials to synthesis FePO4-X H2O. The reaction mechanism of liquid phase precipitation method and the influence of pH, temperature, reaction time on the synthesis of FePO4O4 X H2O were researched. Morphology of prepared material was characterized using SEM. The results show that tap density of the material prepared at pH=2.0, T=60 ℃ for 15 h is up to 1.3 g/cm3, with spherical structure gathered by nanocrystal. The tap density of lithium iron phosphate synthesized with the prepared FePO4· X H2O is up to 1.4 g/cm3.The results of charge-discharge test show that the first discharge specific capacity is 155.3 mAh/g at 0.2 C rate, with 97% efficiency. And the matedal exhibit excellent cyclic reversibility.