二氧化锰电化学电容器研究-物理化学专业论文.docx

摘 要 超级电容器，又被称为电化学电容器，是一种高效的储能器件，其具有高 比电容、高功率密度以及长循环寿命等优势。提高其电化学性能的最有效方法 就是研究其电极材料。在本文中，使用化学沉淀法合成二氧化锰并采用三种不 同的沉淀剂 Na2CO3、NaHCO3 以及 NaOH 来调节二氧化锰材料的微观结构以及 表面形貌。所得到的三种二氧化锰材料表现出不同的晶型结构、比表面和孔结 构特征。与其他两种沉淀剂所合成的二氧化锰相比，Na2CO3 沉淀剂合成的二氧 化锰具有最佳的微观结构和形貌特性。并且，这种晶型结构上的优势使其单电 极和电容器均表现出最佳的电化学性能。此外，本文还探究了水系二氧化锰超 级电容器在低温下的电化学性能。通过氧化还原、固相合成以及水热方法合成 了三种不同晶相的二氧化锰材料。其中，由氧化还原反应制得的 δ-MnO2 电极材 料在温度从 25℃降至?35℃的低温下，仍然表现出最佳的电化学性能。并且，我 们还发现低温对电极的电荷转移电阻的影响大于其对扩散阻抗的影响。在某种 程度上，这对二氧化锰超级电容器在低温下的应用是具有指导意义的。 关键词：二氧化锰；电化学电容器；赝电容 I ABSTRACT Supercapacitor, also known as electrochemical capacitor,is an efficient energy storage device with the advantages of high specific capacitance,high power density and long cycling life.Research on electrode material is one of the most effective ways to improve theirelectrochemical performance. In this paper, mesoporous manganese oxides were synthesized via a facile chemical deposition strategy. Three kinds of basic precipitants including sodium carbonate (Na2CO3), sodium bicarbonate (NaHCO3), and sodium hydroxide (NaOH) were employed to adjust the microstructures and surface morphologies of MnO2 materials. The obtained MnO2materials display different microstructures. Great differences are observed in their specific surface area and porosity properties. The MnO2 prepared with Na2CO3 precipitant exhibits the optimal microstructures and surface morphologies compared with the other two samples, contributing to their best electrochemical performances for supercapacitors when conducted either in the single electrode tests or in the capacitor measurements. Moreover, this paper also involves Investigation on the performance of aqueous manganese oxides electrochemical capacitors at low temperature.Three different crystal phases (δ,γ and α) of MnO2 were prepared by redox, solid reaction and hydrothermal routes,respectively. The δ-MnO2 prepared by a redox method exhibits the best electrochemical performances as the temperature decreased from 25℃ down to the extremely low tempera