【摘要】 具有钠超导三维结构的氟磷酸钒钠（Na₃V₂（PO₄）₂F₃,NVPF）因其拥有高工作电压和理论比容量而被应用于钠离子电池正极材料。本研究以偏钒酸铵（NH4VO3）为钒源，磷酸二氢铵（NH₄H₂PO₄）为磷源、氟化钠（NaF）为氟源和钠源、无水柠檬酸为还原剂，分别添加0.2、1.0、2.0 g和0 g聚乙烯吡咯烷酮K30（PVP）进行碳包覆，用水热-微波法成功制备出氟磷酸钒钠正极材料NVPF/C-1、NVPF/C-2、NVPF/C-3和NVPF，采用X-射线衍射（XRD）、X射线光电子能谱（XPS）、傅里叶红外光谱（FT-IR）、扫描电镜（SEM）以及透射电镜（TEM）对其进行结构和形貌表征，通过恒流充放电测试其电化学性能。实验结果表明，NVPF/C-2呈直径为350～500 nm的球形，其电荷转移电阻为219.4Ω，钠离子扩散系数是NVPF的33倍，在1.0 C电流密度下初始放电容量为104.0 mA·h·g^-1，经过100次充放电后容量维持在74.3 mA·h·g^-1。此外，结果表明PVP能够有效控制NVPF的微粒粒径以及团聚现象，同时其本身存在的大量官能团可有效降低NVPF的电荷转移电阻，提高了钠离子扩散系数，进而有效提升NVPF的电化学性能。更多还原

【Abstract】 Na₃V₂（PO₄）₂F₃（NVPF）, with a three-dimensional structure of sodium superconductivity, has been applied as a cathode material for sodium ion batteries due to its high operating voltage and theoretical specific capacity. In the present study, Na₃V₂（PO₄）₂F₃ cathode materials including NVPF/C-1, NVPF/C-2, NVPF/C-3 and NVPF are successfully prepared by hydrothermal microwave method, with adding 0.2, 1.0, 2.0 g and 0 g polyvinylpyrrolidone K30（PVP） for carbon coating, respectively, which uses ammonium metvanadate as vanadium source, ammonium dihydrogen phosphate as phosphorus source, sodium fluoride as fluorine source and sodium source, and anhydrous citric acid as reducing agent. The structure and morphology of the prepared materials are characterized by X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, Fourier infrared spectroscopy（FT-IR）, scanning electron microscope（SEM） and Transmission electron microscope（TEM）, and the electrochemical properties are obtained by using constant current charge/discharge test. The experimental results show that NVPF/C-2 is spherical and 350～500 nm in diameter, whose charge transfer resistance is 219.4 Ωdiffusion coefficient of Na⁺ is 33 times as that of NVPF. The initial discharge capacity is 104.0 mA·h·g^-1at current density of 1 C, and the capacity is maintained at 74.3 mA·h·g^-1after 100 times of charging and discharging. In addition, the results also show that PVP can effectively control the particle size and agglomeration of NVPF; in the meantime, a large number of functional groups in PVP can effectively reduce the charge transfer resistance of NVPF and improve the diffusion coefficient of Na+, which can effectively improve the electrochemical performance of NVPF.更多还原