掺碳的钠离子电池正极材料NaVPO_4F的电化学性能

Electrochemical Characteristics of C-doped NaVPO_4F Cathode Material for Sodium-ion Battery

添加适量的葡萄糖并用高温固相法合成钠离子电池正极材料NaVPO4F。用X射线衍射仪、扫描电镜等对NaVPO4F进行结构表征,采用循环伏安、交流阻抗技术等对其进行电化学性能测试,探讨了不同掺碳量对NaVPO4F结构和电化学性能的影响。恒流充放电测试结果显示,掺碳10wt%的NaVPO4F在0.1C倍率下首次充、放电容量分别达到151.5mAh·g-1和113mAh·g-1,充、放电平台分别为3.8V和3.6V,经过20次循环,放电比容量的保持率为初始的91.6%。循环伏安曲线出现明显的氧化还原峰,并分别与充、放电电位平台相对应。交流阻抗图谱显示,掺碳10wt%的NaVPO4F样品充放电阻抗较小,可逆性较好。

The cathode material NaVPO4F was synthesized by high temperature solid-state reaction, with the addition of appropriate dextrose. The structure of NaVPO4F was characterized by XRD, SEM and electrochemical performances were tested by Cyclic voltammetry, AC impedance. The effect of C-doping on the structure and electrochemical characteristics of NaVPO4F was studied. The result of Galvanostatic charge/discharge indicated that the charge/discharge capacity was the best when the C-doping amount was 10wt%. The first charge/discharge capacity of 10wt% C-doped NaVPO4F sample at 0.1C rate was 151.5 mAh·g^-1 and 113 mAh·g^-1,respectively. The charge/discharge fiats were 3.8 V and 3.6 V, respectively. After 20 cycles, the discharge capacity kept 91.6% of the original capacity. Cyclic vohammetry curve showed obvious oxidation and deoxidization peaks, corresponding to the fiats of charge and discharge. There were less impedance and better reversibility of 10wt% C-doped samples in AC impedance chart.