TiO2-聚吡咯纳米复合材料的电化学制备及其在锂硫电池中的应用

采用电化学沉积的方法,以阳极氧化法制备的二氧化钛纳米管阵列为基底,制备出高度有序的TiO_2-聚吡咯(PPy)纳米阵列,再通过共热法,将单质硫颗粒负载到基底阵列中,得到S/PPy/TiO_2纳米阵列结构复合材料。扫描电镜(SEM)、透射电镜(TEM)、能谱(EDX)、傅里叶变换红外光谱(FT-IR)和热重分析(TGA)表征结果表明,TiO_2纳米管高度有序平行排列,管径约120nm,聚吡咯均匀沉积在纳米管壁上,复合材料中硫的质量分数约为61.9%。电化学测试结果表明,在0.1C电流密度下,S/PPy/TiO_2纳米复合材料首次循环比容量达1155mAh·g-1,100次循环后比容量为648.4mAh·g-1,库伦效率保持在96.8%。高容量下良好的循环稳定性能显示出S/TiO_2/PPy纳米阵列结构复合材料作为锂硫电池正极材料的优势。

Electrochemical Synthesis of TiO2-polypyrrole Nanocomposites and an Application to Lithium Sulfur Battery

To obtain highly ordered TiO2-PPy composite with nanotube array structure,PPy was electrochemi-cally deposited onto anodized substrate of TiO2 nanotube arrays.Then sulfur was loaded into the TiO2-PPY arrays by co-heating sulfur with TiO2-PPy composite to form S/PPy/TiO2 nanocomposites.The resultant samples were charac-terized by scanning electron microscope (SEM),transmission electron microscope (TEM),X-ray spectroscopy (EDX),Fourier transform infrared spectroscopy (FT-IR)and thermo-gravimetric analysis (TGA).The results showed that TiO2 nanotubes were arranged in parallel with highly ordered and uniform tube-array structure that has a diameter of~120 nm.PPy uniformly covered on the wall of TiO2 nanotubes in the S/PPy/TiO2 nanocomposites which have the sulfur mass percentage of 6 1 .9%.Electrochemical test revealed an initial discharge specific capacity of 1 1 5 5 mAh·g-1 at the current density of 0.1C.And the specific capacity still remains in 648.4 mAh·g-1 with a high cou-lombic efficiency of 96.8% after 100 cycles.The high capacity and excellent cycling performance exhibit the advantage of S/TiO2/PPy composite with nanotube array structure as cathode for lithium sulfur battery.