氧化还原电对介质对双电层电容器高比能化的作用研究

In an effort to remedy the low energy density of double-layer capacitor, redox couple media is proposed to introduce into the capacitive system. A novel supercapacitive system is constructed with activated carbon double-layer electrodes and one redox couple electrolyte, in which the Faradic reaction occurred on one side of the electrodes. The possibility of the novel supercapacitive system containing a pair of redox couples carrying opposite charges in which the Faradic reactions occurred on each side electrode simultaneously is also discussed. In this way, the energy density will be dramatically improved. The main contents of the research work include: .oInvestigating the cyclic stability and redox characteristics of redox couples; exploring the regulations and methods of improving the cyclic lifetime and energy storage of redox-mediated electrolyte..oInvestigating the kinetics of redox-media mass transport and electrode reaction process; exploring the mechanisms of improving energy density by changing the electrolyte constituents and electrode microstructure..oInvestigating the properties of the novel supercapacitive system; exploring the crucial factors determining the properties of energy density, power density and cyclic stability; studying the effect laws of redox couple media for increasing the energy density.. The novel supercapacitive system based on the double-layer electrodes and ideal redox-mediated electrolyte combines the advantages of double-layer capacitor and hybrid capacitor with high power density, long life time and high energy density, providing a new approach for exploring the high energy capacitor. The research focusing on the novel supercapacitive system will show great significance for promoting the commercial application of the supercapacitor in transportation, communication, national defense and other fields.

针对双电层电容器能量密度低的缺陷，将氧化还原电对介质引入超级电容器中，构建由单一氧化还原电对电解液和活性炭双电层电极组成的电容体系，探讨异电荷成对电对在电容体系中应用的可能性，实现在电容器的一极或两极上发生法拉第反应，增大体系的能量密度。研究高浓度氧化还原电对的循环稳定性及可逆氧化还原特性的基本规律，探讨提高电解液循环寿命和储能容量的机制和方法；明确氧化还原电对的液相传质和电极反应的动力学过程，探讨调变溶液构成和电极微观结构对提高体系能量密度的作用规律；研究电容体系性能，揭示影响功率性能、能量性能及循环寿命的控制因素，阐明氧化还原电对"高比能化"的作用机制。由双电层电极和理想的氧化还原电对电解液构成的电容体系兼具双电层电容器大功率、长寿命和混合电容器高能量密度的优点，为高比能电容体系的开发提出了新的途径，对推动电容器在交通、通讯、国防等领域的商业化应用具有重要的意义。

针对双电层电容器能量密度低的缺陷，将氧化还原电对介质引入超级电容体系中，构建由单一或两种氧化还原电对电解液和活性炭（AC）双电层电极组成的电容体系，实现在电容器的一极或两极上发生法拉第反应，增大体系的能量密度，为高比能电容体系的开发提出新的途径。经过四年研究工作，基本完成预期内容，共发表SCI收录论文6篇，得到如下成果：.（1）揭示了几种氧化还原电对Fe3+/Fe2+, VO2+/VO2+和Mn3+/Mn2+的传质和反应动力学过程，氧化还原可逆性和循环稳定性；.（2）组建了氧化还原电对AQ/H2AQ与AC电极构成的双电层电容体系，阐明了氧化还原电对AQ/H2AQ对电容性能提高的作用机制；.（3）组建了两种氧化还原电对Fe(CN)63-/Fe(CN)64-和AQ/H2AQ与AC电极构成的电容体系，阐明两种电对对电容性能提高的作用机制。.具体研究内容和结论如下：.以石墨为电极，研究了阳离子电对Fe3+/Fe2+、VO2+/VO+和Mn3+/Mn2+在酸性溶液中的液相传质和反应过程动力学。表明这三种电对均具有较好的氧化还原可逆性。Fe3+的电化学反应可逆性最好，VO2+次之，Mn2+最差。三种电对长期循环稳定性次序为Fe3+/Fe2+>VO2+/VO2+>Mn3+/Mn2+。.将氧化还原介质2,7-磺酸蒽醌(AQDS)引入到含中性电解液KNO3的电容体系中，研究了阴离子电对AQ/H2AQ对AC对称电容器性能的影响和作用机制。表明AQDS电对的氧化还原反应发生在阴极。AQDS的引入可以扩大电压窗口，达到1.8 V，也明显提高了比电容、功率密度和能量密度。.将两种氧化还原电解质2,7-磺酸蒽醌(AQDS)和K4Fe(CN)6同时加入到中性电解液KNO3中，探讨了两种电对对AC对称电容器性能的影响和作用机制。表明电对AQ/H2AQ和Fe(CN)63-/Fe(CN)64-的法拉第反应均为扩散控制，分别且同时发生在电容器的负极和正极上，使电容性能明显提高，在1 M KNO3-0.017 M K4Fe(CN)6-0.017 M AQDS的电解液中，在1.0 A g-1电流密度下，电容量、功率密度和能量密度分别达到240 F g-1、527 W kg-1和26.3 Wh kg-1。