纳米二氧化锰的制备与应用研究

【作者】 李青；

【导师】 周雍茂；

【作者基本信息】 中南大学 ， 冶金物理化学， 2003， 硕士

【摘要】 本文采用沉淀法制备了纳米MnO₂的前驱体，经超临界流体干燥和煅烧，得到纳米MnO₂。采用超临界流体干燥的方法，有效地解决了粒子粒径受干燥过程中温度影响大的问题。实验得出适宜反应温度为20℃，MnCl₂浓度为0.1mol·L^-1，反应时间为2小时，溶液pH值为8.3，超临界干燥温度为263℃，超临界干燥压力为6.6MP_a。 采用热重-差热法、激光粒度分析法、X射线衍射法（XRD）和扫描电镜（SEM）对纳米粉体进行了表征。结果表明，纳米MnO₂的晶型为γ型，平均粒径60nm左右。恒流放电、循环伏安等电化学方法测试结果显示，制备的纳米MnO₂的电化学性能差于电解MnO₂，但经酸化处理后，纳米MnO₂的电化学活性大大提高。浅度放电时，酸化处理后的MnO₂容量比电解MnO₂提高了24％；重负荷条件下，显示了更大的优势，放电容量提高了33％（-0.4V）和110％（-0.9V）；纳米样品中质子和电子的嵌入和脱出比电解MnO₂更易进行。研究结果表明，酸化后的纳米MnO₂比电解MnO₂更适宜作无汞可充碱锰电池的正极材料。更多还原

【Abstract】 The precursor of nanostrucured MnO2 was prepared by the method of precipitation. The nanostrucured MnO2 was obtained after the methods of Supercritical Fluid Drying (SCFD) and calcinations. The SCFD method was used, it effectively solved the problem that the particle size was largely affected by the temperature of the drying procedure. Thermogravimeteric and differential thermal analyse,X-ray diffraction, scanning electron microscophy, laser diffraction particle size analyzer were used to characterize the product.Results showed that the optimal reaction temperature was 20 C,the concentration of MnCl2 was 0.1mol-L-1,the pH value was 8.3,the optimal reaction time was 2 hours, the temperature of SCFD was 263 C,the pressure of SCFD was 6.6MPa and optimal calcining temperature was 240 C. Moreover, the crystal structure of the synthesized samples were mainly Y -MnO2 and the average particle size was 60nm. Finally,its electrochemical behaviour .were investigated by constant current diacharge,cyclic voltammerty etc.and compared with that of common particle size sample d (electrolytic manganese dioxide).It was found that the discharge capacity of the synthesized nanostrucured MnO2 was lower than that of sample d,but its electrochemical activity was greatly increased after acid treatment.The results showed the discharge capacity of sample after acid treatment improved 24% at the first discharge step; the favorable performance was more remarkable under the condition of heavy load discharge,its discharge capacity improved 33%(-0.4V) and 110%(-0.9V). Insertion and deinsertion for protons and electrons into nanostrucured MnO2 were easier than electrolytic MnO2. Nanostrucured MnO2 after acid treatment was better than electrolytic MnO2 as the anode material of the Mercury-free alkaline manganese battery.更多还原