无模板水热合成LiFePO_4/C的低温性能

Low temperature performance of template-free hydrothermal synthesized LiFePO_4/C

以LiOH、H3PO4和FeSO4为原料,用无模板水热法合成LiFePO4,与葡萄糖混合后热处理,得到正极材料LiFePO4/C。XRD、SEM测试结果表明:在无模板剂或表面活性剂的条件下,水热合成法可制得纯相、颗粒细小且分散良好的LiFePO4晶体。产物在2.3～4.2 V循环,23℃时的0.20C首次放电比容量为151.5 mAh/g,-20℃时的0.20C、0.50C首次放电比容量分别为103.5 mAh/g和84.5 mAh/g,达到23℃时0.20C放电比容量的68.3%和55.8%。产物具有良好的低温性能,是因为晶体颗粒在Li+扩散方向上具有一维纳米结构。

LiFePO4 was prepared by template-free hydrothermal synthesis using LiOH, H3PO4 and FeSO4 as raw materials, then mixed with glucose to obtain cathode material LiFePO4/C by heat treating. The results of SEM and XRD tests showed that phasepure LiFePO4 with fine grain size and good dispersion could be obtained by hydrothermal synthesis without any template or surfacrant. When the product cycled in 2.3 - 4.2 V, the 0.20 C initial specific discharge capacity was 151.5 mAh/g at 23℃ , the 0.20 C and 0.50 C initial specific discharge capacity at - 20℃ was 103.5 mAh/g and 84.5 mAh/g,respectively, which was 68.3% and55.8% of the 0.20 C one（at 23 ℃）.The fine low-temperature performance could be attributed to the one-dimensional nanometer structure of the sample along the Li＋ diffusion path.