【作者】 黄萍；

【导师】 杨武；

【作者基本信息】 西北师范大学 ， 分析化学， 2016， 硕士

【摘要】 二氧化钌（RuO₂）等贵金属氧化物由于其优异的电化学性能被成功应用于超级电容器电极材料。但是昂贵的成本和有毒的特性限制了它的广泛应用。因此人们致力于研究开发其它廉价金属氧化物,如氧化镍,氧化钴,氧化锰等,作为更为优异,性价比较高的超级电容器电极材料。其中氧化锰以其成本低廉,绿色无污染,较高的理论比电容,较宽的工作电位窗口等优点,有望成为替代二氧化钌的过渡金属氧化物。锰元素在自然界中储量丰富,且具有多种氧化态（MnO₂,Mn₂O₃,Mn₃O₄等）。但是,二氧化锰（MnO₂）导电性差,循环稳定性低,严重影响了它的电容性能。研究者们期望通过添加导电性良好的碳材料来改变二氧化锰（MnO₂）的导电性。四氧化三锰（Mn₃O₄）则是在常温下只有专一结构的黑锰矿,受到研究者关注。氧化锰制备方法多样,但是多数都会受到高温高压的限制,制备条件苛刻,难以大量生产。因此,本文探索研究采用低温、简便的方法制备二氧化锰和四氧化三锰及其复合材料,采用IR,XRD,SEM等技术手段对合成材料的结构和形貌进行了表征,考查了它们的电容性能。具体内容如下:第一章:简要介绍了超级电容器的构造,储能原理及其特点,对超级电容器电极材料的制备方法和研究进展进行了系统的综述。第二章:以氧化石墨烯为原料,高锰酸钾为锰源,乙二醇为还原剂,采用水热法,在80℃还原制备得到了二氧化锰纳米颗粒/还原石墨烯及四氧化三锰纳米颗粒/还原石墨烯复合材料。在Mn和C的摩尔比为1:0.8时复合材料的电容性能最佳,当电流密度为1A/g时,比电容值为184F/g。结构分析表明,复合材料中接近无定型结构的MnO₂纳米颗粒均匀分散于石墨烯表面,这种结构有利于电解液的扩散,提高电极材料的比电容。第三章:以高锰酸钾为锰源,乙二醇为还原剂,十二烷基磺酸钠为结构调控剂,采用水热法制备得到MnO₂纳米片材料。结构分析表明该纳米材料为比表面积较大的分散纳米片,为结晶度程度较低的无定型结构。电化学测试表明,当电流密度为1A/g时,比电容为184F/g,电流密度升高,比电容保持率较高,说明材料有很好的倍率性能。当电流密度为5A/g时,循环充放电1600圈,比电容没有发生衰减,说明材料具有良好的循环稳定性。第四章:以高锰酸钾为锰源,葡萄糖为还原剂,分别采用水热法和微波辅助方法制备得到了不同形貌的Mn₃O₄纳米材料。微波辅助法合成的Mn₃O₄呈均匀分布的八面体纳米块状,结晶度高于水热法合成的Mn₃O₄。水热法制备的Mn₃O₄为单分散的纳米棒和无特定纳米块混合结构。电化学测试表明水热法制备得到的纳米棒和纳米块混合形貌的Mn₃O₄具有更好的电化学特性,比电容高于微波辅助合成的Mn₃O₄。更多还原

【Abstract】 Ruthenium dioxide（RuO₂） and other precious metal oxides have been applied to supercapacitor electrode materials successfully due to their excellent electrochemical performance. But high cost and innate toxicity limit their wide application. Therefore, scientists are engaging in finding and developing new types of electrode materials for supercapacitor with higher cost performance ratios based on other base metal oxides such as nickel oxide, cobalt oxide and manganese and so on. Owing to low cost, environment-friendliness, high theoretical specific capacitance and wide working potential window, manganese oxide is expected to become an alternative of ruthenium dioxide.Manganese is abundant in nature, and has a variety of oxidation states such as（MnO₂, Mn₂O₃ and Mn₃O₄）. However, poor electroconductivity and cycle stability of MnO₂ seriously weaken its capacitance performance. Conductive carbon materials are usually added into MnO₂ to improve its electric conductivity. Mn₃O₄ has also attracted the wide attention as the electrode material for supercapacitor, that has an unique structure of hausmannite at room temperature. At present there have been many methods to be employed for preparing manganese oxides, but most of them need to be carried out at high temperature and high pressure. Weighty conditions limit their mass production. The preparation methods for manganese oxide varied, but most will be subject to the conditions of high temperature and high pressure. Therefore, in this thesis, we tried to study and develop some simple, easily-operated and environment-friendly methods to prepare nanoscale manganese oxides and relevant composites, characterized their structures and morphologies with IR, XRD, SEM TG etc. and investigated their electrochemical capacitance performances. The thesis consists of four parts:Chapter 1. The structures, principles for energy storage and characters of supercapacitors were introduced briefly and the advances on study of preparation methods of the electrode materials for supercapacitors were reviewed in detail.Chapter 2.With graphene oxide as raw materials, potassium permanganate as source of manganese source and glycol as a reductant agent, some nanocomposites of grapheme and MnO₂ nanoparticles were successfully prepared by using a hydrothermal method at 80℃. When the molar ratio of Mn: C equaled to 1:0.8, the nanocomposite had the best capacitance performance and specific capacitance reached 224F/g at the current density of 0.5A/g. The structural analysis had proved that approximate amorphous MnO₂ nanoparticles dispersed uniquely on grapheme sheets in the composite, which was very advantageous to diffusion of the electrolyte in order to enhance specific capacitance of the electrode material.Chapter 3. Using KMnO₄ as the source of manganese, ethylene glycol as the reducing agent, SDS as a structural controller, MnO₂ nanoflakes were synthesized by a hydrothermal method. Electrochemical tests showed that when the current density was 1 A/g, the specific capacitance value is 184 F/g. At a current density, the prepared material still maintained a high specific capacitance retention rate, indicating that material has a good ratio capability. When the current density was 5 A/g, after circulation charge and discharge for 1600 cycles, the specific capacitance did not decay, which suggested the material has good cycle stability. The excellent electrochemical performance is attributed to a well-dispersed nanoflake of morphology with a low crystallinity and high specific surface area.Chapter 4. Using potassium permanganate as manganese source, glucose as the reducing agent, Mn₃O₄ nanomaterials with different morphologies were fabricated respectively by hydrothermal method and microwave assisted method. Mn₃O₄ nanocrystals obtained by the microwave assisted procedure showed a morphology of octahedral nanoblock, and the materials prepare by the hydrothermal method consisted of nanorods and irregular structural nanoblocks. Electrochemical test indicated that the specific capacitance of the hydrothermal preparation of Mn₃O₄ was higher than the microwave assisted synthesis of Mn₃O₄.更多还原