利用碳球作为模板,通过与异丙醇氧钒的溶剂热反应制备了五氧化二钒(V_2O_5)空心球。采用扫描电子显微镜(SEM)和透射电子显微镜(TEM)等技术手段对V_2O_5空心球进行了表征。实验结果表明,V_2O_5空心球的直径约为1.5μm,壁厚约100 nm。将V_2O_5空心球作为镁二次电池的正极,在0.2 C充放电条件下,材料的首次放电比容量达140 m A·h/g,经20次循环后容量为110 m A·h/g。
The structures and electrochemical properties of the Ti1.4V0.6Ni ribbon before and after heat treatment are investigated systematically. The structure of the sample is characterized by X-ray powder diffraction analysis. Electrochemical properties including the discharge capacity, the cyclic stability and the high-rate discharge ability are tested. X-ray powder diffraction analysis shows that after heat treatment at 590 °C for 30 min, all samples mainly consist of the icosahedral quasicrystal phase (I-phase), Ti2Ni phase (FCC), V-based solid solution phase (BCC) and C14 Laves phase (hexagonal). Electrochemical measurements show that the maximum discharge capacity of the alloy electrode after heat treatment is 330.9 mA?h/g under the conditions that the discharge current density is 30 mA/g and the temperature is 30 °C. The result indicates that the cyclic stability and the high-rate discharge ability are all improved. In addition, the electrochemical kinetics of the alloy electrode is also studied by electrochemical impedance spectroscopy (EIS) and hydrogen diffusion coefficient (D).
