高能量密度纳米电介质电容器的研究

In order to develop high energy-density dielectric capacitors based on the design and architecture of electrolytic capacitors, the thickness ratio of aluminum metal electrode to anodic alumina dielectric is reduced by the fabrication of nanostructures, achieving an improved energy density as high as electrochemical capacitors. The strategy can provide an opportunity to create novel devices with improved energy storage properties while maintaining the extremely high power density characteristic of dielectric capacitors. In this study, we will make use of the self-assembly of regular nanopore arrays available from porous anodic alumina (PAA) to form self-aligned nanocapacitors. An aluminum electrode with ordered nanocolumn arrays will be fabricated by utilizing the PAA template. Then the Al/Alumina anode with ordered nanocolumn arrays having lower thickness ratio of aluminum electrode to alumina dielectric can be obtained by anodizing the aluminum electrode in a barrier film-forming solution. Finally, the dielectric nanocapacitor arrays with Al/Alumina/Conductive polymer structures will be achieved after a layer of conductive polymer film is coated onto the dielectric alumina film. In this research project, the performances of the capacitor such as charge-discharge cycle life, impedance characteristics, frequency characteristics and temperature characteristics will be investigated. The theoretical model for describing the relationships between the energy density of the capacitor and the morphological parameters of ordered nanocolumn arrays of aluminum electrodes will be established. The current-voltage characteristics of the Al/Alumina/Conductive polymer system will be studied. The formation mechanism of the electronic currents through anodically dielectric film will be explored. The dielectric breakdown characteristics and breakdown mechanisms for the system of Al/Alumina/Conductive polymer and that of Al/Alumina/Electrolyte will be explored. In addition, the anodization behaviors of other valve metals or alloys will be disclosed and the dielectric properties for their anodic oxide films will be also examined. These research efforts will provide a theoretical basis and shed a new light on the development of novel dielectric capacitor with high energy density.

为开发能量密度达到电化学电容器水平的电介质电容器，在高比容量的电解电容器基础上，利用纳米技术降低铝电极与氧化铝电介质的厚度之比，来增大电容器的能量密度，从而在保持电介质电容器固有的极高功率密度的同时，获得所需的高能量密度。本项目采用多孔氧化铝纳米模板技术，制备具有有序纳米圆柱阵列的铝电极，通过阳极氧化法在其表面生成氧化铝电介质膜，再在氧化膜上覆盖导电高分子膜，从而得到铝/氧化铝/导电高分子体系的纳米电介质电容器阵列。主要研究纳米电容器的充放电性能、阻抗特性、频率特性、温度特性等性能，建立电容器能量密度与铝电极纳米结构参数之间的理论模型；研究铝/氧化铝/导电高分子体系的伏安特性，探讨氧化铝电介质膜内电子电流的形成机制及规律；研究铝/氧化铝/导电高分子体系的击穿行为及击穿机理；研究其他阀金属或合金的阳极氧化规律及其阳极氧化膜的介电性能，为寻求更高能量密度的电介质膜材料提供理论基础和前进方向。

兼具高功率密度和高能量密度、长循环寿命的绿色新型电容器一直是人们追求的目标。本项目从电介质电容器固有的高功率密度特点出发，通过纳米技术和新电介质材料提高其能量密度，以期制备具有电化学电容器能量密度水平的电介质电容器。本项目利用PAA模板的自组织纳米孔洞阵列，在铝电极表面得到相应的纳米圆柱阵列，然后通过阳极氧化法形成一层氧化铝电介质膜，最后在电介质膜上覆盖一层导电高分子作为对电极，得到纳米电容器阵列结构。主要研究内容包括：有序纳米孔洞阵列PAA模板的研究；其他阀金属（钛、钨）阳极氧化膜的研究；阳极氧化铝电介质膜的研究及纳米电容器阵列物理模型的建立；有序铝纳米柱阵列电极的制备及铝/氧化铝/电解液体系的电容性能研究；导电高分子PANI和PEDOT对电极的制备及电化学性能研究等。经过四年的研究，本项目主要在以下方面取得突破：明确了实现铝高场阳极氧化的条件；制备了超薄、V型或超大孔间距（超过2 μm）的PAA模板；实现了大孔间距、大面积铝箔的纳米软模板压印技术；实现了大孔间距PAA膜快速生长，生长速率是传统磷酸溶液中的30-60倍；开发了不同孔径的通孔PAA模板的简易高效制备方法，并通过纳米模板技术成功制备出不同直径的有序纳米圆柱阵列的铝电极；在其他阀金属阳极氧化膜的研究方面，解决了阳极氧化钛长纳米管阵列的制备难题，以及纳米管与钛基底的界面间结合力弱的问题，通过改性得到了比容高达76.12 mF cm-2（0.5 mA cm-2）的氧化钛电极材料；建立了电容器能量密度与铝电极纳米结构参数之间的物理模型，得到了纳米电容器能量密度的变化规律和理论最大值；研究了铝/氧化铝/电解液体系的电容性能，对于长度为16.5 μm的铝纳米柱阵列，当氧化电压为50 V时，能量密度高达2.37 mJ cm-2。本项目的研究为新型电能储存和转换器件的开发提供了理论基础和前进方向。