微波合成法制备LiFePO_4及其电化学性能

Electrochemical performance of LiFePO_4 prepared by microwave synthesis for Li-ion battery

分别以草酸锂、草酸亚铁、磷酸二氢铵为锂源、铁源和磷源,苯蒽二元共聚物为还原剂合成前驱体,采用微波合成的方法制备了锂离子电池正极材料LiFePO4。采用扫描电镜(SEM)对产物进行物相表征,并采用恒流充放电的方法考察了样品作为锂离子电池正极材料的电化学性能。结果表明,650℃下制备的样品为纯橄榄石结构的LiFePO4,颗粒粒度为1～2μm;在2.5～4.2V电压范围内以0.2C倍率充放电时,首次放电比容量达到158.3mAh/g,经过20次充放电循环容量仍保持为157.9mAh/g,具有较好的倍率放电性能和容量保持能力。

Positive material LiFePO4 was synthesized by microwave-synthesis method,with Li2C2O4,FeC2O4,NH4H2PO4 as the raw materials,and benzanthracene copolymer as reducing agent.The products were characterized by scanning electron microscopy(SEM).Electrochemical properties of samples were investigated by constant-current charge/discharge method.Results showed that the sample synthesized at 650 ℃ was pure olive-type structure LiFePO4 with a particle size of 1~2 μm,and its initial discharge capacity was 158.3 mAh/g at 0.2 C in the voltage range of 2.5~4.2 V,which remained well after 20 cycles.The LiFePO4 prepared with this method had good rate performance and capacity retention performance.