机械活化辅助多元醇法合成锂离子正极材料LiFePO_4  

Synthesis of LiFePO_4 Cathode Materials by Mechanical-Activation-Assisted Polyol Processing

作　　者：曹雁冰[1,2] 段建国[1] 姜锋[2] 胡国荣[1] 彭忠东[1] 杜柯[1] 

机构地区：[1]中南大学冶金科学与工程学院,长沙410083 [2]中南大学材料科学与工程学院,长沙410083

出　　处：《物理化学学报》2012年第5期1183-1188,共6页Acta Physico-Chimica Sinica

基　　金：国家科技支撑计划项目(2007BAE12B01);中央高校基本科研业务费专项资金(2012QNZT018);湖南省科技计划项目(2009GK3150)资助~~

摘　　要：以LiH2PO4和还原铁粉为原料,通过机械液相活化法获得了棒状形貌的[Fe3(PO4)2·8H2O+Li3PO4]前驱体,然后在三甘醇(TEG)介质中采用多元醇工艺制备了LiFePO4材料.为提高其电导率,以聚乙烯醇(PVA)为碳源,对纯相LiFePO4进行碳包覆改性.通过X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、恒电流充放电和电化学阻抗谱(EIS)等测试方法对制备的材料进行了表征.结果表明:采用机械活化辅助多元醇法可在低温下合成结晶良好的LiFePO4,碳包覆改性的LiFePO4/C材料导电性能得到改善,电荷转移阻抗减小,1C、2C倍率下放电容比量分别为139.8、129.5mAh·g-1,具有良好的倍率性能和循环稳定性.A low-temperature approach for efficient preparation of LiFePO 4 was developed.The rod-shaped[Fe 3（PO 4） 2 ·8H 2 O＋Li 3 PO 4 ]precursor was prepared,using a mechanochemical liquid-phase activation technique,from LiH 2 PO 4 and reduction iron powder.Pure LiFePO 4 was then synthesized in boiling tetra（ethylene glycol）（TEG）by polyol processing with the as-prepared precursor.In order to improve the electrical conductivity,carbon coating of the pure LiFePO 4 was carried out,using poly（vinyl alcohol）（PVA）as the carbon source.The products were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,galvanostatic charge-discharge test and electrochemical impedance spectroscopy（EIS）.The results show that well-crystallized LiFePO 4 was successfully synthesized by polyol processing at low temperature.Carbon coating significantly improves the conductive properties of LiFePO 4 and reduces charge-transfer impedance.The obtained LiFePO 4 /C composite delivers specific discharge capacities of 139.8 and 129.5 mAh·g-1 at 1C and 2C rates,respectively,displaying good cycling performance and rate capability.

关 键 词：正极材料 LIFEPO4 机械活化 多元醇法 碳包覆 

分 类 号：TM912[电气工程—电力电子与电力传动]