基于功能基团调控的二维碳基复合材料及其非对称超级电容器性能研究

Asymmetric supercapacitors featuring both high power and energy densities, hold a great promise in the future electrical energy storage fields. Enhancing the reaction kinetics of positive electrode materials and to narrow the kinetics gap between two electrodes (positive and negative electrodes) play a vital role in boosting the energy density of devices while to maintain high power density. For this propose, two-dimensional carbon-based composites will be employed as the positive electrodes for asymmetric supercapacitors. This project will mainly address critical issues including the precise design of the functional groups on two-dimensional carbon surface, the tuning of coupling effect between different components, and electrochemical charge storage mechanism of two-dimensional carbon-based composites. The surface-initiated polymerization and molecular-grafting strategies will be developed to precisely design two-dimensional carbon materials with unique functional groups. Benefiting from unique interaction between the functional groups and active components, the two-dimensional carbon-based composites with tuned surface structure and composition will be constructed by methods such as hydrothermal treatment, coprecipitation process, and/or physics field-induced assembly. The coupling mechanism and synergistic effects between different components will be clarified, and the effect of pseudocapacitive contribution derived from two-dimensional carbon-based composites on improving power and energy densities of devices will be investigated and revealed. The kinetics process between positive and negative electrodes will be further matched and optimized, leading to an excellent electrochemical performance. Overall, this project will establish the science foundation and provide new lights into the design and fabrication of novel electrodes for high-performance asymmetric supercapacitors.

非对称超级电容器作为一类兼具高功率密度和高能量密度的新型储能器件，显示出巨大的应用潜力。提高正极材料反应动力学速率，减小正负电极动力学差异，是实现该器件功率密度和能量密度协同提升的关键。本项目拟以二维碳基复合材料为正极，主要围绕二维碳材料表面功能基团精准设计、各组分耦合效应调控、电化学储能机理等关键问题开展研究。通过表面聚合、分子接枝等策略，研究建立二维碳材料表面功能基团精准调控的新技术方法。利用功能基团与活性组分的独特作用，有机耦合水/溶剂热、共沉淀、外场诱导组装等技术，从分子水平实现二维碳基复合材料表面结构与组成的可控构筑。重点阐明各组分之间的相互耦合机制和协同作用规律，研究揭示二维碳基复合材料表面赝电容效应的调控机制以及对器件功率密度和能量密度的影响规律，进一步匹配和优化正负电极的动力学过程。本项目的实施，将为高性能非对称超级电容器用电极材料的设计与构筑提供重要的科学基础和理论依据。

非对称超级电容器作为一类兼具高功率密度和高能量密度的新型储能器件，在新能源领域显示出广阔的应用潜力。然而，由于这类超级电容器正极材料的氧化还原反应速率远小于碳负极材料对电解液离子的吸附/脱附过程，导致其储能效率尚未达到高效规模化应用的标准。提高正极材料反应动力学速率，减小正、负电极动力学差异，是实现该器件功率密度和能量密度协同提升的关键。. 有鉴于此，本项目以氧化石墨烯为基本结构单元，利用其表面电负性特征，提出氧化石墨烯表面限域生长策略，实现了超薄和多褶皱镍/钴层状双氢氧化物（NiCo-LDH）纳米片的可控制备，基于石墨烯与二维活性组分的界面协同作用，可显著提升其反应动力学和电荷存储能力。进一步，本项目采用聚乙烯亚胺、乙二胺等分子接枝策略对石墨烯进行功能化，建立了高活性与高稳定性石墨烯基复合材料的普适性制备方法，并考察了其作为非对称超级电容器正极材料的电化学性能。实验和理论计算结果表明，基于不同晶型/组成构建的异质结构可通过电子转移作用，协同重构界面处的电荷分布，显著改善了碳基复合材料的氧化还原反应动力学，呈现出优异的倍率性能。为深入理解功能分子/基团对无机活性组分的结构调控作用，基于原位液相透射显微表征技术，系统研究了二维金属氧化物（CoO、NiCoOx等）形态的原位演变过程。. 此外，针对碳负极材料本征活性差、比电容低等问题，本项目基于沸石咪唑骨架材料（ZIF-8）在功能化碳材料表面原位生长、聚乙烯醇-聚苯胺超分子组装等技术策略，制备了多种氮掺杂碳材料，系统研究了氮原子掺杂在提升碳材料电化学性能方面的独特作用。通过正、负电极的容量和动力学匹配与优化，构筑非对称超级电容器，实现了功率密度和能量密度的协同提升。上述研究成果为高性能储能器件的实际应用提供了理论和工程基础。在本项目的资助下，项目负责人以第一/通讯作者在Nat Mater、Adv Funct Mater、ACS Appl Mater Interfaces、Chem Eur J等期刊上发表SCI/EI论文12篇，申请和授权发明专利5件等。