葡萄糖对微波水热合成正极材料LiFePO4的结构和性能的影响

Effect of Glucose on Structure and Properties of LiFePO_4 Cathode Material Prepared by Microwave Hydrothermal Method

以FeSO_4·7H_2O,LiOH·H_2O和H_3PO_4为原料,葡萄糖为改性剂,采用微波水热法合成具有正交晶系橄榄石结构的LiFePO_4/C复合材料。借助XRD,SEM,EDS和电化学性能测试等分析,研究葡萄糖对产物组成、结构、微观形貌和电化学性能的影响。结果表明:葡萄糖改性后,LiFePO_4结构中Fe,P和O原子间的结合增强,颗粒尺寸减小,表面有碳层包覆,电化学性能提高。LiFePO4/C在0.1C倍率下的首次放电比容量为125.6mAh/g;1.0C倍率下的首次放电比容量为106.2mAh/g,30次循环后的容量保持率为91.3%。

Orthorhombic LiFePO4/C composite material with olivine structure was prepared by microwave hydrothermal method using FeSO4·7H2O, LiOH·H2O and H3PO4as raw materials, with glucose as carbon source and modifier. The influence of glucose on the composition, structure, morphology and electrochemical performance of LiFePO4was investigated by means of XRD, SEM, EDS and constant current charge-discharge cycling. The results show that the as-obtained LiFePO4/C exhibits stronger bonding among Fe, P and O atoms, finer particle size and improved electrochemical properties than the pristine LiFePO4. From the SEM image, the LiFePO4is coated by carbon in the LiFePO4/C composite. The LiFePO4/C shows the initial discharge capacity of 125.6mAh/g at 0.1C. Even at a rate of 1.0C, it still can deliver a discharge capacity of 106.2mAh/g, the capacity retention is 91.3% after 30 cycles. © 2016, Journal of Materials Engineering. All right reserved.