基于钠离子嵌入反应的高比能超级电容器负极材料钛酸钠的制备及改性研究

Supercapacitors (SCs) have attracted significant research attention as efficient energy storage devices in recent years due to their interesting properties like a higher power density than batteries and a higher energy density than conventional electrolytic capacitors. Electrode materials play a vital role on the electrochemical performance of SCs. To further increase the energy density of SCs, it is proposed here that one can construct a new SC based on sodium ions insertion reaction by utilizing Na2Ti3O7 or Na2Ti6O13 and activated carbon as negative and positive electrode, respectively. The morphology of Na2Ti3O7 or Na2Ti6O13 will be controlled by hydrothermal, solvothermal or sol-gel method. The effect of reaction temperature, time and concentration on the preparation will be studied. Different ions doped Na2Ti3O7 or Na2Ti6O13 will be obtained through the solid reaction of pre-coated TiO2 nanoparticles with sodium salts. The best doping ions and doping ratio can be determined by experimental analysis. This new hybrid capacitor will provide the high energy density, power density and long cycle life by using Na2Ti3O7 or Na2Ti6O13 with the improved ions and electronic conductivity. This research would lay the foundation for designing and fabricating high-performance SCs.

超级电容器作为一种新型电化学储能装置，能提供比普通电容器更高的能量密度，比电池更高的功率密度和更长的循环寿命，受到了人们的广泛关注。电极材料是影响超级电容器性能的关键因素之一，其对所组成的超级电容器的性能具有举足轻重的作用。本项目为提高超级电容器的能量密度，拟构建一种基于钠离子嵌入反应的新型超级电容器，并通过水热、溶剂热及溶胶-凝胶等方法可控制备其负极材料Na2Ti3O7及Na2Ti6O13，调控反应温度、时间、浓度，确定最佳的工艺制备参数；通过预先包覆的纳米TiO2与钠盐的反应过程中，掺杂不同离子，确定最佳的离子掺杂种类及掺杂比，提高Na2Ti3O7及Na2Ti6O13的Na+离子扩散系数和电子导电性，有效改善其倍率特性，进而提高所组成电容器的功率密度和能量密度，以期获得兼具高比能量、高比功率和长寿命的新型超级电容器关键技术，为开发高性能的超级电容器提供理论指导。

层状结构的钛酸钠（Na2Ti3O7）作为一种绿色、低成本的储钠材料，循环性能稳定，安全性能好，高低温性能优异，以其作为负极的动力钠电池及钠离子电容器具有广阔的应用前景。本课题紧密围绕提高钛酸钠电子导电率、改善离子扩散速率这两个亟待解决的国际性难题，从钛酸钠材料的制备、组成、结构与性能的关系入手，开展了系统深入的研究工作，取得了一系列在国际上产生重要影响的创新性成果。发展了一种构筑钛酸钠纳微结构的“湿化学方法”，揭示了在化学钠化过程中纳米晶的生长规律；提出了碳复合、引入缺陷、掺杂降电位等三种结构与性能优化策略，解决了粒径不可控、电子导电率低、传荷阻抗大等难题；同时也构筑了柔性一体化的电极结构；显著提高了钠离子电池的功率密度，实现了快速充放电特性；组装成高性能的钠离子电容器。将具有高电子和钠离子导通能力的Na2Ti3O7@CNT、Na2Ti3O7/碳布柔性电极、Na2Ti3O7/3D石墨烯泡沫作为电池型负极，分别以花生壳衍生碳和石墨烯作为电容型正极，优化组装成非对称电化学电容器器件，即钠离子电容器。能量密度和功率密度（基于正负极活性物质总量）分别高达111.2 Wh kg–1和11200 W kg–1。