【摘要】 以超声波辅助沉淀法合成的纳米级球形FePO4·2H2O为原料,采用碳热还原法制备了复合金属掺杂的LiFePO4/C复合材料。通过X射线衍射(XRD),扫描电镜(SEM),恒电流充放电测试,循环伏安和交流阻抗测试表征了FePO4·2H2O和LiFePO4/C的物相、结构和电化学性能。结果表明,溶液浓度为0.1 mol/L时制备的FePO4·2H2O为分布均匀的纳米级球形颗粒。复合金属掺杂显著提高了LiFePO4的放电比容量,Ni和Nb复合掺杂的LiFePO4/C复合材料表现出了最佳的电化学性能,0.1 C倍率条件下首次放电容量158.8 mAh/g,1 C倍率下首次放电容量150.2 mAh/g,100次循环后容量保持率分别为98.30%和97.8%。Ni和Nb复合掺杂后提高了LiFePO4的锂离子扩散速率和电导率。更多还原

【Abstract】 Nanosized spherical FePO4·2H2O precursor was synthesized via ultrasonic-aided precipitation route. LiFePO4/C composites doped with various metals were prepared by carbothermal reduction. The phases, structures and the morphologies of FePO4·2H2O and LiFePO4/C were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), charging and discharging measurements, cyclic voltammogram(CV) testing and electrochemical impedance spectra(EIS). The results show that nanosized spherical FePO4·2H2O are prepared with uniform distribution when the solution concentration is 0.1 mol/L. The discharge capacity and lithium ion diffusion rate are increased by doping various metals. Especially, LiFePO4/C composites made from nanosized spherical FePO4·2H2O precursor doped with Ni and Nb shows excellent electrochemical performance. It delivers an initial discharge capacity of 158.8 mAh/g at 0.1C rate and 150.2 mAh/g at 1C rate, and capacity retention is 98.3% and 97.8%, respectively, after 100 cycles.更多还原