K_2Ti_4O_9制备TiO_2-B纤维快速嵌锂负极材料

TiO_2-B fibres derived from K_2Ti_4O_9 as fast lithium intercalation negative material

以四钛酸钾(K2Ti4O9)经离子交换得到的四钛酸(H2Ti4O9.xH2O)为前驱体,经过不同温度热处理得到不同结晶度的氧化钛纤维。对样品进行XRD、Raman、FE-SEM及TEM等结构形貌表征,发现600℃烧结可得到纯相、高结晶度的TiO2-B材料。并考察了其作为锂离子电池负极材料的容量、倍率和稳定性。嵌锂性能测试发现,TiO2-B相材料的首放容量可以达到225mA.h.g-1,比相近结构的锐钛矿(anatase)相材料高50mA.h.g-1,即22.5%的容量。与相似结构anatase材料的倍率结果对比发现,TiO2-B纤维倍率性能更高,主要是TiO2-B纤维的开放结构使其锂离子扩散系数达到1.92×10-7 cm2.s-1,是anatase相材料的8倍。1C稳定性测试发现循环80次后容量仍然高于anatase,且最终容量稳定在159mA.h.g-1,比anatase材料的64mA.h.g-1高1.5倍。

TiO2-B fibers were obtained by heat treatment of the precursor of tetratitanate（H2Ti4O9· xH2O）,which was derived from potassium tetratitanate（K2Ti4O9）via ion exchange.Structure characterization showed that TiO2-B fibers sintered at 600℃ still maintained pure phase and high crystallinity.Lithium insertion performance indicated that the capacity performance of this TiO2-B material sintered at 600℃ was up to 225 mA·h·g-1,and was 50 mA·h·g-1（i.e.22.5%）higher than that of the anatase material with similar structure.The TiO2-B fibers exhibited excellent rate performance mainly because the open structure of the TiO2-B fibers led to fast lithium-ion diffusion coefficient of 1.92×10-7 cm2·s-1,which was nearly 8 times higher than that of anatase material.1 C stability test showed that the capacity of TiO2-B fiber was 159mA.h.g-1 after 80cycles,which was about 1.5times higher than the capacity of anatase material（64mA.h.g-1）.