可实现超级电容器能量密度极大化的炭电位调变方法及机制研究

As an important kind of energy storage devices, supercapacitors (SCs) can quickly provide energy and have a long cyclic life, but can limit the amount of energy. So the most important challenge for the research and development of SCs is to increase their energy density close to the level of secondary batteries while keeping their high power at the same time. Because the energy stored in SCs is related to both working voltage and electrode capacity, the research and development of SCs are focused mainly on the discovery of new electrode materials with higher specific capacity and new electrolytes with higher voltage window till now. Although notable progresses have been made, a general and very important problem is that the high specific capacity of electrode materials and the high voltage window of electrolytes cannot be fully used when assembled into SC devices. Therefore, how to fully exert the performance of the electrode materials and electrolytes to maximize the energy density of SCs is a challenging issue remained. We found that the potential window of electrodes must be optimized to maximize the energy density of SCs, and a general way is to realize the adjustment of the electrode potential. In order to achieve the maximum energy density, this project will study various carbon materials that have been widely applied in SCs, explore their potential variation in different electrolytes, develop effective methods and technologies for tuning the electrode potential, carry out in-depth research on the mechanism and influencing factors of electrode potential tuning, understand the relationship between the electrode potential and the surface electrochemical structure of electrode materials, and finally establish the design, assembly and performance assessment methods of SCs with tuning electrode potential. It is expected that notable progresses could be made on the design and assembly of novel ultra-high energy SCs, and that the knowledge and devices obtained would provide valuable scientific basis for the applications of SCs in the fields of electric vehicles, smart electrical grid, etc.

如何在保持超级电容器高功率密度的前提下，提高能量密度使其接近电池的水平，是亟待解决的难题。超级电容器储存的能量与其工作电压和电极材料的容量相关，因此研究多集中于发展高容量电极材料和高电压窗口电解液。然而电极材料和电解液组装成器件后，电解液的可用电压窗口和电极材料的高比容量并未被充分利用，其根源在于，组装成器件后正负极未在最优电位窗口下工作。如对器件中电极材料的电位进行调变，来优化电极的工作电位窗口，就有可能实现极大化超级电容器的能量密度。因此，本项目将重点研究在不同电解液体系中炭电极材料的电位变化规律，发展有效的电位调变方法，深入研究电位调变机理和影响因素，阐明电位与电极材料表面电化学结构之间的关系，建立基于电位调变的超级电容器的设计和性能评价方法，为超高能量密度的碳基超级电容器在电动车和智能电网等应用进一步奠定科学基础。

本项目研究了各种碳电极材料在不同电解液中的变化，阐明碳材料的电位窗口在不同电解液中的变化规律、电极电位的调变机理及其影响因素，建立碳材料的电极电位与表面电化学结构的对应关系，从理论和实验出发研究了碳材料表面不同掺杂状态与电解液的相互作用规律，探索了石墨烯及相关材料在高电压有机电解液中的电化学行为及性能衰减机制，发展了荷注入调变电极材料电位的方法和技术，在电化学预包覆的方法基础上，提出来石墨烯-固态电解质固固界面新认识，实现了石墨烯-固态电解质固固界面的构筑，并利用该固固界面获得了高稳定性、低自放电的石墨烯电极材料，在建立电极电位与电极材料表面电化学结构的关系基础上，并提出了智能电化学电容器概念，并且将相关结果拓展到其他电池体系。也根据对于电化学体系的新认识，发展了脱溶剂化的具有氧化还原反应的电容器材料和电位调控的对称性电池设计，发展电极材料电位的调变方法，组装超高能量密度电位调变超级电容器，实现超级电容器能量密度的大幅提升。已经发表项目标注论文26篇，已被引用1400余次，申请发明专利6项。培养博士研究生3名、硕士研究生3名，出站博后1名。本项目完全达到并超过了本项目预期目标。