钒氧化物纳米管的合成、结构及电化学性能

采用流变相-纳米自组装新方法合成了钒氧化物纳米管(VO_x-NTs),并通过XRD,SEM,TEM,Raman,ESR,TG-DTA,XPS及模拟电池等技术手段对产物的结构和性能进行了表征和测试.结果表明,产物主要由钒氧化物纳米管组成,纳米管长为1～10μm,直径为30～100nm.纳米管壁由3～10个VO_x层构成,层间距为3.53nm.Raman光谱反映了V-O的伸缩或弯曲振动,层状微结构的晶格振动及模板剂的有机基团振动.无明显精细结构的室温ESR谱证明了V⁴⁺的存在,根据TGA和XPS求得产物中V的平均化合价约为+4.30.VO_x-NTs正极材料初始充电容量达到404mA.h/g,放电容量为383mA.h/g,50次循环后放电容量衰减至180mA.h/g,可归因于充放电过程中VO_x-NTs正极材料在电解液中的溶蚀作用及复合电极中“孤岛效应”的产生.

Synthesis, Structure and Electrochemical Performance of Vanadium Oxide Nanotubes

Vanadium oxide nanotubes (VOx-NTs) were synthesized in a rheological phase reaction followed by self-assembling process and characterized by XRD, SEM, TEM, Raman, ESR, TG-DTA, XPS, and simulated battery. The results show that the black products consist majority of VOx-NTs with length of 1—10 μm and diameter of 30—100 nm, whose walls consist of 3—10 VOx layers with interlayer distance of 3.53 nm. Raman spectrum indicates the stretching or bending vibration of V—O, lattice vibration of layered structure and organic group vibration of template. ESR spectrum with no superfine structure confirms the presence of V4+ and the average valence of vanadium in the product is +4.30 on the basis of TG and XPS. The initial charge and discharge capacity of VOx-NTs are 404 and 383 mA·h/g, respectively. The discharge capacity decreases to 180 mA·h/g after 50 cyclee, which can be attributed to the VOx-NTs reacting with the electrolyte and isolating from the carbon particles during the charge-discharge.