水热合成LiFePO_4/C材料电化学性能的颗粒尺度敏感性

Particle size sensitivity of electrochemical performance for hydrothermally synthesized LiFePO_4/C cathode material

通过控制水热法过程中的水热反应加热速度,制备了3种不同颗粒尺度的LiFePO4/C锂离子电池正极材料。结果表明,加热速度越快,LiFePO4/C平均粒径越小,分布越集中。当加热速率从5℃/min升至15℃/min时,材料颗粒半径从336nm减小到200nm,0.1 C放电容量从154 mAh/g增至162mAh/g,而20C放电容量则从75mAh/g显著增大至127mAh/g。LiFePO4/C材料的电化学性能表现出明显的尺度敏感性,特别是在高倍率充放电条件下。

A series of LiFeO4/C cathode materials with different particle size was synthesized via adjusting the heating rate during the hydrothermal process.When the heating rate was increased from 5 to 15℃/min,the av-erage particle radius of sample reduced from 336 nm to 200nm.As results,the discharge capacity and particu-larly the high rate discharge ability of sample were improved.The capacity output of LiFeO4 at 20Cwas greatly increased from 75 to 127mAh/g as the reduction of particle size.The results confirm an obvious particle size sensitivity of electrochemical performance for LiFePO4 material,which is more evident when the material oper-ated at high rates.