Abstract:

One-dimensional porous titanium dioxide@carbon nanofibers (P-TiO₂@CNFs) composite with a lamellar branch structure was prepared by in situ electrospinning and concentrated alkali hydrothermal etching methods, and then employed as the anode material of sodium-ion batteries. The lamellar branching structure could effectively shorten the ion diffusion pathway and increase the contact area between electrolyte and active material. The porous structure provided more reactive sites, thus accelerating the charge transfer kinetics. Finally, the chemical bonding between TiO₂ and carbon nanofibers could reinforce the structural stability of the composites. The surface morphology, microstructure, crystal structure, specific surface area, pore size and valence state of P-TiO₂@CNFs were analyzed. The galvanostatic charge and discharge measurements and rate performance tests were performed on the NEWARE battery test system. The experimental results demonstrated that P-TiO₂@CNFs exhibited excellent reversible capacity of 197mAh/g at 2.0A/g after 2000 cycles, and high specific capability of 61.7mAh/g at an ultrahigh current density of 30.0A/g.

Key words: electrospinning, titanium dioxide, porous structure, chemical bond, sodium ion battery

摘要：

通过静电纺丝法和浓碱水热刻蚀法原位制备出具有片状分枝结构的一维多孔二氧化钛@碳纳米纤维（P-TiO₂@CNFs）复合材料，并将其作为钠离子电池的负极材料。P-TiO₂@CNFs的片状分枝结构能够有效缩短离子扩散路径并增加电解液与活性物质的接触面积；多孔结构提供了更多的反应活性位点，从而加快了电荷转移动力学；二氧化钛与碳纳米纤维之间的化学键能够增加复合材料的结构稳定性。实验对P-TiO₂@CNFs的表面形貌、微观结构、晶体结构、比表面积、孔径、元素价态等进行了分析，并在新威尔电池测试系统上进行恒电流充放电测量和倍率性能测试，实验结果表明P-TiO₂@CNFs表现出优异的循环性能和倍率性能，在2.0A/g的电流密度下循环2000次仍能保持197mAh/g的比容量，在超大电流密度30.0A/g下电极仍然能够保持61.7mAh/g的比容量。

关键词: 静电纺丝, 二氧化钛, 多孔结构, 化学键, 钠离子电池