碳包覆Na2Ti6O13纳米管的电化学性能研究

以金红石型TiO2和NaOH为原料,由水热反应制备Na2Ti6O13纳米管.然后,在含有0.1 mol.L-1NaOH的葡萄糖水溶液中反应4 h制得碳包覆的Na2Ti6O13纳米管.X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等分析表明,该碳包覆Na2Ti6O13纳米管外径约14～19 nm,内径约2～5 nm,长度为数百纳米,有一层厚度约为2 nm的碳层包覆在纳米管外壁.以其作为锂离子电池负极材料,恒电流充放电测试表明,在50 mA.g-1电流密度下首周可逆容量达到161 mAh.g-1,循环100周后容量保持在147 mAh.g-1.相比于Na2Ti6O13纳米管,提高了20%以上.电流密度升至1600 mA.g-1充放电,碳包覆Na2Ti6O13纳米管可逆容量仍有70 mAh.g-1左右,远高于Na2Ti6O13纳米管,表现出良好的倍率性能.

Electrochemical Performances of Carbon-coated Na2Ti6O13 Nanotubes

With rutile TiO2 and NaOH as starting materials,the Na2Ti6O13 nanotubes were prepared by a hydrothermal reaction.The carbon-coated Na2Ti6O13 nanotubes were obtained by treating the Na2Ti6O13 nanotubes for 4 h in glucose aqueous solutions containing 0.1 mol·L-1 NaOH.The as-prepared samples were characterized by X-ray diffraction,scanning electron microscopy and transmission electron microcopy.The results showed that the dimensions of carbon-coated Na2Ti6O13 nanotubes were 14~19 nm of outer diameter,2~5 nm of inner diameter,and several hundreds nanometers of length with a carbon layer of about 2 nm being coated on outer surface of the nanotubes.As an anode material for lithium ion battery,the carbon-coated Na2Ti6O13 nanotubes exhibited an excellent cycle performance and high rate discharge capability compared with the Na2Ti6O13 nanotubes.At 50 mA·g-1,the reversible capacities of the carbon-coated Na2Ti6O13 nanotubes were 161 mAh·g-1 in the initial cycle and 147 mAh·g-1 after 100 cycles.When the discharge-charge current density was 1600 mA·g-1,the reversible capacity of the carbon-coated Na2Ti6O13 nanotubes still reached 70 mAh·g-1,much higher than that of Na2Ti6O13 nanotubes.