Abstract Sodium-ion batteries have been considered as the most promising candidate for large-scale energy storage applications. However, the poor cycling stability and inferior rate capability of existing cathode materials for sodium-ion batteries restrict future developments. Herein, we report a chemically bonded cathode material for sodium-ion batteries that is synthesized by freeze-drying and subsequent annealing to generate Na3V2(PO4)3/reduced graphene oxide−carbon nanotubes (NGC) composite. The NGC composite with 79 wt % Na3V2(PO4)3 shows a high initial Coulombic efficiency (>93%) and high specific capacity with superior cycling stability (∼105 mAh g−1 after 500 cycles at 1 C based on the mass of Na3V2(PO4)3). More importantly, in situ electrochemical impedance spectroscopy and ex situ X-ray diffraction, X-ray photoelectron spectroscopy, X-ray absorption near edge structure spectroscopy, and transmission electronic microscopy are employed to reveal the robust V−O−N bonding and excellent sodium storage performance of the NGC composite.

中文翻译：

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一种高效的钠离子电池，由复合碳网络中的还原氧化石墨烯键合 Na 3 V 2 (PO 4 ) 3 组成

摘要 钠离子电池被认为是最有前途的大规模储能应用候选者。然而，现有钠离子电池正极材料循环稳定性差和倍率能力差限制了未来的发展。在此，我们报告了一种用于钠离子电池的化学键合阴极材料，该材料通过冷冻干燥和随后的退火合成，以生成 Na3V2(PO4)3/还原氧化石墨烯-碳纳米管 (NGC) 复合材料。含有 79 wt% Na3V2(PO4)3 的 NGC 复合材料显示出高初始库仑效率 (>93%) 和高比容量以及优异的循环稳定性（基于 Na3V2 的质量，在 1 C 下循环 500 次后~105 mAh g-1 (PO4)3)。更重要的是，原位电化学阻抗谱和非原位X射线衍射、X射线光电子能谱、