水热法合成纳米LiFePO_4材料

Hydrothermal synthesis of LiFePO_4 nano-materials

采用水热法合成纳米Li Fe PO4材料并研究了反应溶液p H值和温度对Li Fe PO4材料颗粒形貌、微观结构和电化学性能的影响。控制Li∶Fe∶P摩尔比为3∶1∶1,按照先混合Li OH与H3PO4溶液后加入Fe SO4溶液的投料顺序,在溶液p H值为6.0以上可以得到结晶度好且比容量较高的纳米级Li Fe PO4材料。p H为6.0和180℃条件下得到的是Li Fe PO4纳米薄片,调整反应溶液p H值为中性和弱碱性,或控制反应温度在140℃以下或者200℃以上,Li Fe PO4材料可能是方形或者形貌不规则的纳米颗粒。电化学测试结果表明,颗粒形貌方形或者不规则的Li Fe PO4材料大电流放电性能优于薄片状纳米材料。

LiFePO4 nano-materials for Li-ion battery were prepared by hydrothermal method, and the effects of pH value and reaction temperature on the particle morphology, structural composition and electrochemical properties of the LiFePO4 material were investigated. With the final molar ratio of 3∶1∶1 for Li∶Fe∶P by adding FeSO4 solution into the mixture of LiOH and H3PO4 solutions, nanoparticles of LiFePO4 with wel crystal inity and high special capacity were obtained by regulating pH values to above 6.0. The flake-like LiFePO4 nano-materials were prepared at pH 6.0 and 180 ℃. The particle morphology was rectangular-like or irregular if regulating pH values to above 7.0 or control ing hydrothermal reaction temperatures to higher than 200℃ or below 140 ℃. The electrochemical results show that the high rate capability of LiFePO4 nano-materials with rectangular-like or irregular shape is better than that of flake-like nano-materials.