Na₃V₂(PO₄)₂O₂F (NVPOF) is a promising cathode material for sodium-ion batteries (SIBs) due to its high working plateaus, small volume change and large theoretical capacity. However, the electrochemical performance is strongly hampered by its intrinsic inferior kinetics. Herein, NVPOF nanorods are uniformly anchored onto reduced-graphene oxide (rGO) nanosheets by a simple electrostatic assembly method followed by thermal-annealing treatment. The synthesized NVPOF@rGO nanocomposite is applied as cathode material of SIBs. With the assistance of rGO, NVPOF@rGO has improved surface kinetics and reduced polarization, leading to an enhanced rate capability and long cycle stability. The in-situ XRD results indicate that the desodiation process of NVPOF@rGO is related to two-Na/two electrons full extraction process and the crystal phase is changed from Na₃V₂(PO₄)₂O₂F into Na₂V₂(PO₄)₂O₂F (1st charge plateau) and then to NaV₂(PO₄)₂O₂F (2nd charge plateau), and the sodiation process is the reverse process. The diffusion coefficient of sodium ions is increased greatly with the assistance of rGO nanosheets for NVPOF@rGO nanocomposites. This superior electrochemical performance is attributed to the synergetic effect between rGO nanosheets and the NVPOF nanorod by enhanced electronic conductivity and the improved electrochemical kinetics. Our results may provide a simple route to improve the electrochemical performance for the cathode materials of SIBs.

Na ₃ V ₂（PO ₄）₂ O ₂F（NVPOF）由于其高工作平稳性，小体积变化和大理论容量而成为一种有前景的钠离子电池正极材料。但是，电化学性能因其固有的劣质动力学而受到严重阻碍。在此，NVPOF纳米棒通过简单的静电组装方法随后进行热退火处理而均匀地锚固在氧化石墨烯（rGO）还原的纳米片上。合成的NVPOF @ rGO纳米复合材料被用作SIBs的阴极材料。在rGO的帮助下，NVPOF @ rGO改善了表面动力学并降低了极化，从而提高了倍率能力和长周期稳定性。原位X射线衍射（XRD）结果表明，NVPOF @ rGO的脱脱过程与二钠/两电子全萃取过程有关，且晶相由钠变为_将3 V ₂（PO ₄）₂ O ₂ F转换为Na ₂ V ₂（PO ₄）₂ O ₂ F（第一个电荷平稳段），然后转换为NaV ₂（PO ₄）₂ O ₂F（第二电荷平稳段），并且成胶过程是相反的过程。借助rGO纳米片用于NVPOF @ rGO纳米复合材料，钠离子的扩散系数大大提高。优异的电化学性能归因于rGO纳米片和NVPOF纳米棒之间的协同作用，其通过增强的电子电导率和改善的电化学动力学来实现。我们的结果可能为改善SIBs阴极材料的电化学性能提供一条简单的途径。