Ga掺杂FeNb11O29材料的制备及其电化学性能

FeNb₁₁O₂₉由于其高的理论充电容量(400 mAh·g^-1),作为锂离子电池(LIBs)负极材料具有很大的应用前景。然而,目前报道的FeNb₁₁O₂₉实际容量仅有168~273 mAh·g^-1。因此,有必要进一步提高其电化学性能。本文介绍了一种制备Ga掺杂FeNb₁₁O₂₉材料的方法,成功合成了Ga_xFe_1-xNb₁₁O₂₉(x=0.1,0.2)。结果表明,Ga_0.2Fe_0.8Nb₁₁O₂₉的电导率比FeNb₁₁O₂₉提高了两个数量级。X射线衍射结果显示,Ga掺杂不会改变FeNb₁₁O₂₉的正交剪切ReO₃晶体结构。扫描电镜结果显示,材料的微观形貌没有发生明显改变。电化学实验表明,Ga_0.2Fe_0.8Nb₁₁O₂₉具有较好的电化学性能,在电流密度为0.1 C时,Ga_0.2Fe_0.8Nb₁₁O₂₉充电容量为290 mAh·g^-1,当电流密度达到5 C时容量仍能保持145 mAh·g^-1,此外,Ga_0.2Fe_0.8Nb₁₁O₂₉具有良好的循环稳定性,在电流密度为5 C时循环1 000圈之后,容量保持率为91.0%,而不掺杂的FeNb₁₁O₂₉的充电容量仅有107 mAh·g^-1,容量保持率仅为55.9%。利用Ga掺杂改善FeNb₁₁O₂₉负极材料的电化学性能在锂离子电池中具有广阔的应用前景。

Fabrication and Electrochemical Performances of Ga-Doped FeNb11O29 Materials

FeNb₁₁O₂₉ is a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity (400 mAh·g^-1). However, the reported practical capacities of FeNb₁₁O₂₉ are only 168 mAh·g^-1 to 273 mAh·g^-1. Therefore, it is very necessary to further improve the electrochemical performance of FeNb₁₁O₂₉. A simple and effective Ga-doped method was demonstrated in this study, which enhanced the electrochemical performances of FeNb₁₁O₂₉ materials successfully. XRD results show that Ga-doped doesn't change the orthogonal shear ReO₃ crystal structure of FeNb₁₁O₂₉. Scanning electron microscopy characterization indicats that no significant change in morphology is observed. Ga³⁺ could replace Fe³⁺ in FeNb₁₁O₂₉, the electronic conductivity of Ga_0.2Fe_0.8Nb₁₁O₂₉ is enhanced by two orders of magnitude compared with FeNb₁₁O₂₉. Consequently, Ga_0.2Fe_0.8Nb₁₁O₂₉ exhibits excellent electrochemical performances. At the current density at 0.1 C, the charge capacity of Ga_0.2Fe_0.8Nb₁₁O₂₉ reaches 290 mAh·g^-1, which remains 145 mAh·g^-1 when the current density rose to 5 C. Moreover, Ga_0.2Fe_0.8Nb₁₁O₂₉ presents outstanding cycling stability with a capacity retention of 91.0% at 5 C after 1 000 cycles. In contrast, undoped FeNb₁₁O₂₉ only possesses a charge capacity of 107 mAh·g^-1 with a capacity retention of 55.9% at 5 C after 1 000 cycles. The research indicates that the electrochemical performances of FeNb₁₁O₂₉improves significantly by Ga-doped, and Ga_0.2Fe_0.8Nb₁₁O₂₉ has wide application in LIBs in the future.