高容量/高倍率碳素电极的自组装制备及其储能机理研究

The energy density, power density and uniformity of the present energy storage systems are difficult to be increased to a great extent due to the limitation of the electrode materials and their fabrication technology. The layer-by-layer (LBL) technique can be used to prepare nano-film materials with precise control at the molecular level and has good superiority and potentiality in the new energy field. This project is design for the preparation of carbon electrode with high capacity & high rate assembled using layer-by-layer technique, which are based on functionalized carbon materials that include stable pseudo-capacitive functional groups. The as prepared carbon assemblies will then be compounded with other electrode materials (sulfur, for example) to further explore the application of LBL technique in the new energy field. Based on various characterization methods and electrochemical measurements, the assembling mechanism of the functionalized carbon materials and the influence of LBL conditions on the performance of the carbon electrode will be studied, and then the optimum techniques of LBL carbon electrodes can be obtained. The redox reactions of the LBL carbon electrode in electrolyte and its energy storage mechanism will be also researched, and finally a theoretical model describing the dynamic behavior of the LBL carbon electrode will be presented. The research work in this project, will put forward on theoretical basis of the application of LBL techniques in the new energy field,.and provide theoretical guidance for the design and fabrication of energy storage systems with high energy density and high power dengsity.

现有储能体系由于电极材料容量或倍率的局限与电极制备工艺的缺陷，导致其能量密度与功率密度难以大幅提高，器件性能的均一性也难有效保证。自组装技术可在分子层面控制材料制备过程，在新能源领域具有巨大应用潜力。本项目提出采用表面官能团化碳素作为原料，通过层层自组装技术来制备兼具高容量与高倍率且性能均一的新型纳米碳素电极材料；同时还将研究由碳素组装体与高容量硫复合所得电极的电化学性能，进一步探索和拓展自组装技术在能源领域的应用。项目还将利用各种表征手段与电化学测试技术，研究官能团化碳素基元的组装机理，揭示组装条件对材料理化性能影响规律；在深入研究材料制备工艺与其电化学行为关系基础上，找到具有优异储能性能的组装体制备技术，并阐明其储能机理，建立起电极的电化学反应过程模型和反应速度理论。项目的研究，可为自组装技术在新能源领域的应用奠定理论基础,并为兼具高能量密度与高功率密储能体系的设计与制备提供理论指导。

为提高现有储能体系的能量密度与功率密度，本项目从改进电极材料容量、倍率特性以及电极制备工艺出发，利用自组装技术开展了高能锂离子电池用碳基复合负极材料的探索研究。项目首先采用独特工艺制备获得了具有低维结构的碳素材料（碳纤维、石墨烯），然后采用自组装技术制备碳纳米管/石墨烯(CNT/GNS)复合负极材料，并探索其微观结构和储锂性能；针对氧化锡(SnO2)负极材料存在导电性和循环性能差的缺陷，利用自组装技术制备氧化锡/碳纳米管(SnO2/CNT)和氧化锡/石墨烯(SnO2/GNS)两种复合材料，并详细研究它们的电化学储锂性能。通过研究合成条件对电极材料理化性能的影响，得到了优化的工艺条件，建立了自组装碳素复合电极的电化学反应过程模型。此外，项目还利用自组装思路制备了碳素自组装体与锰基、硫基材料等其他同类型高容量电极材料，并研究其在锂离子电池中的应用。实验结果证明了自组装碳基体结构由于具有高效的导电网络和稳定的结构，且可以很好地容纳充放电过程中的体积膨胀，对锡、锰、硫等高容量锂电电极材料具有优良的改善作用，可以得到容量高、循环稳定、大倍率性能良好的复合电极材料。