NaV_(1-x)Al_xPO_4F的合成及电化学性能研究

Study on synthesis and electrochemical performances of NaV_(1-x) Al_x PO_4F

运用高温固相法成功合成了钠离子电池正极材料NaV1-xAlxPO4F(x=0、0.02)。通过傅里叶变换红外光谱法(FT-IR)、X射线衍射(XRD)、扫描电镜(SEM)对材料的晶体结构和形貌进行了表征,研究结果表明NaV1-xAlxPO4F为简单单斜晶型。从材料的晶体结构、恒流充放电测试和循环性能等方面分析了掺杂元素Al在改善材料性能中的作用。实验表明:掺Al后正极材料的电化学性能得到较好的改善,材料的首次放电比容量为80.4mAh/g,效率高达89.2%,可逆比容量损失只有9.7mAh/g。在循环30次后可逆比容量为68.3mAh/g,可逆容量保持率为85%。

Al doped NaV1-x AlxPO4F （x=0,0.02） for the application of cathode material of sodium-ion batteries was prepared by high temperature solid-phase method. The NaV1-x Alx PO4F powders were characterized by FT-IR, X-ray diffraction （XRD）, and the scan electronic microscopy （SEM）. The results show that the crystal system of NaV1-xAlxPO4F is monoclinic. The effects of the Al doped on improving the performances of materials were analyzed in terms of the crystal structure, charge-discharge curves and cycle performances. It＇s found that NaV1-x Alx PO4F shows an improved cathodic behavior and discharge capacity retention compared to the undoped sample, an initial reversible capacity of 80.4 mAh/g can be obtained, and the first charge-discharge efficiency is about 89.2%, the loss of capacities is 9.7 mAh/g, and it＇s also observed that the reversible capacity is 68.3 mAh/g and the reversible capacity retention of NaV0.98Al0.02PO4F is still 85 % after the 30^th cycle.