Abstract:

Sodium has the advantages of being an abundant resource and having a low cost; thus, sodium ion batteries are considered as one of the best candidates for replacing lithium ion batteries in the future. However, the radius of the sodium ion is larger than that of the lithium ion, and the de-intercalation of the sodium ion will seriously damage the crystal structure of most electrode materials during the charging and discharging process, which considerably limits its charge-discharge specific capacity, cycle performance, and rate performance. However, finding appropriate electrode materials is one of the difficulties in fabricating high-performance sodium ion batteries. Among the many candidate materials, vanadate materials can improve the stability of material structures by introducing cations to increase the coordination numbers of vanadium, thus improving the electrochemical performance of sodium ion batteries. In this paper, an in situ phase separation method to fabricate V₂O₅/Fe₂V₄O₁₃ nanocomposite materials is reported. First, we synthesized hydrated crystalline Fe₅V₁₅O₃₉(OH)₉·9H₂O nanomaterials using a water bath heating method; then, we in situ constructed two-phase nanocomposite V₂O₅ and Fe₂V₄O₁₃ from the single phase by further high-temperature treatment. The morphology, composition, and structure of the electrode materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy(FTIR), as well as other methods. The V₂O₅/Fe₂V₄O₁₃ nanocomposite materials were found to have a more stable structure, higher initial discharge capacity (342 mAh·g^-1 at a current density of 0.1 A·g^-1), longer cycle life, and better rate performance than V₂O₅ nanowires. Therefore, this research on V₂O₅/Fe₂V₄O₁₃ nanocomposite materials has broadened ability to develop new high-performance anode materials for sodium ion batteries.

Key words: Sodium ion battery, Anode material, V₂O₅/Fe₂V₄O₁₃, Electrochemistry