镁离子掺杂对LiFePO4/C复合正极材料性能的影响

摘要

为了提高正极材料LiFePO4的电化学性能,采用两步固相法合成LiFe1-xMgxPO4/C(x=0、0.01、0.02、0.03、0.04)复合正极材料,并对所得样品进行XRD、SEM、以及充放电循环性能测试.测试结果表明:掺杂少量的Mg2+并没有影响材料的结构,所得样品都为单一的橄榄石型;充放电结果表明掺杂Mg2+为0.02的样品即LiFe0.98Mg<,002>PO4/C电化学性能最佳,在0.2C倍率下首次放电比容量为149.32 mAh/g,经过50个循环,仍然有138.37 mAh/g,衰减仅率为7.33%.%To improve the performance of LiFePO4, single phase LiFe1-xMgx PO4/C (x=0, 0.01, 0.02, 0.03, 0.04) cathodes were synthesized by two-step solid-state method. The samples were characterized by X-ray diffraction ( XRD)、 scanning electron mi-crescopy (SEM) and charge-discharge test. The results indicate that the prepared samples have ordered olivine structure and doping of the low concentration Mg2+ does not affect the structure of the samples. The electrochemical capabilities evaluated by charge-discharge test show that the sample with 2% (molar fraction) Mg2+ has good electrochemical performance delivering about an initial specific ca-pacity of 149.32 mAh/g at 0.2 C-rate. And after 50 cycles, its retains 138.37 mAh/g.