氧化-沉淀法合成高振实密度球形LiFePO_4/C正极材料

Synthesis of spherical LiFePO_4/C cathode material with high tap density by oxygen-precipitation method

采用氧化-沉淀法,以FeSO4.7H2O、H3PO4和H2O2为原料通过合成球形前驱体FePO4.2H2O来制备高密度球形LiFePO4/C复合材料。结果表明:当溶质浓度为0.1 mol/L,搅拌速度为500 r/min,陈化时间为36 h时,可合成振实密度高、球形度好的球状前驱体FePO4.2H2O;采用超声波浸渍液法将制备的FePO4与LiOH.H2O、蔗糖混合,通过碳热还原法合成球形LiFePO4/C。该球形LiFePO4/C正极材料的振实密度为1.68 g/cm3,在0.05 C、0.1 C和0.5 C倍率下的首次放电比容量分别为138.9、128.7和113.2 mA.h/g,经20次循环后,容量的保持率分别为99%,98.7%和98.6%。

A high tap density LiFePO4/C composite material was prepared from spherical FePO4·2H20 powder via an oxygen-precipitation method by FeSO4·7H2O and H3POawith hydrogen peroxide as the oxidizing agent. The results show that, when the concentration of reactants is 0.1 mol/L, stirring speed is 500 r/min and deposite time is 36 h, the spherical FePO4·2H20 powders with high tap density and good sphericity are obtained. The original materials of FePO4, sucrose and LiOH·H2O are mixed by steep ultrasonic oscillation. Spherical anode materials LiFePO4/C are synthesized by carbothermal reduction method. The spherical LiFePO4/C cathode material with tap density of 1.68 g/cm3 achieves high initial discharge capacities of 138.9, 128.7 and 113.2 mA.h/g at 0.05 C, 0.1 C and 0.5 C rates, respectively, and after 20 cycles discharges, the capacity retention rates are 99%, 98.7% and 98.6%, respectively.