Na_3V_2(PO_4)_3/C复合材料的制备及电化学性能研究

Synthesis and electrochemical performance of Na_3V_2(PO_4)_3/C as cathode materials for sodium ion batteries

利用不同的方法合成了Na_3V_2(PO_4)_3/C复合材料,通过X射线衍射、红外光谱、扫描电镜、循环伏安、交流阻抗等方法对Na_3V_2(PO_4)_3/C材料进行了结构表征及性能测试。通过改变合成方法,考察了不同合成路径对于材料结构、微观形貌及电化学性能的影响。研究发现,利用水热法合成的Na_3V_2(PO_4)_3/C复合材料的颗粒呈类球形,粒径尺寸为50nm。电化学性能测试表明,0.1C倍率下,其首次放电比容量接近理论值,达到117.3mAh/g,50次循环后容量保持率为97.3%。2C倍率下,其放电容量仍能达到81.6mAh/g,循环10次后容量未见衰减。

In this study,the Na3V2（PO4）3/C composites were successfully synthesized by different methods.The structure and electrochemical properties of Na3V2（PO4）3/C composites were investigated by Fourier transform infrared spectrum,X-ray diffraction,scanning electron microscope,cyclic voltammetry and electrochemical impedance spectroscopy.The effect of synthetic method on the structure and performance of the cathode material was investigated.Na3V2（PO4）3/C composite with a particle size of 50 nm was successfully synthesized via a hydrothermal method.This study demonstrates that growth of large particles can be effectively inhibited in the hydrothermal method,and the composite show a smaller and more uniform particle size.The electrochemical tests show that the initial discharge capacity of the composite was 117.3mAh/g at 0.1Crate and the capacity retention rate was 97.3% after 50 cycles.Even at a high charge-discharge rate of 2C,it still delivered a discharge capacity of 81.6mAh/g and maintained this capacity after 10 cycles.