三维多孔KCu7S4@C/graphene复合材料的可控制备及其储能性质的研究

Due to its excellent conductivity and high electrochemical activity, the multi-metal sulfide of KCu7S4 micro-nanowires exhibit good electrochemical performance. However, the energy storage mechanism of KCu7S4 electrode involved redox reaction as well as insertion of cations into the surface/subsurface of electrode active materials is not clear. Besides, the cycling stability of the KCu7S4 electrode is relatively low. Based on the above problems, we will further explore the energy storage mechanism of the KCu7S4 electrode material during the charge-discharge reaction process by in-situ Raman characterization, combined with data analysis and theoretical calculation. We will also try to understand the structural phase change of the active material, material changes near the electrode surface and charge transfer law. we aim to providing new ideas for optimizing the performance of the supercapacitors from the aspects of electrode material preparation and the structure design. On this basis, we will also explore the relationship between the preparation of composite material (KCu7S4@C/graphene composite prepared by self-assembly at room temperature, freezing crystallization and hydrothermal treatment) process parameters and the structure, particle size, morphology, porosity and electrochemical properties of electrode materials. We will understand the mechanics of the method for synthesizing the KCu7S4@C/graphene composite material. Moreover, we will study the influence of the microstructure of the material on its performance, establish the "structure-activity relationship" between material structure and electrochemical performance, and use it to guide the controllable preparation process, which is beneficial to obtaining high performance electrode materials for supercapacitors.

由于其优异的电导和较高的电化学活性，多元金属硫化物KCu7S4微纳米线展现出较好的电化学性能。至今KCu7S4电极在进行电化学反应储能时的微观反应机制尚不清楚，且该材料表现出相对较低的循环稳定性能。基于以上问题，本项目通过原位拉曼表征、结合数据分析计算，深入探究该材料在电化学反应过程中的储能机制，并揭示在整个电化学反应过程中，电极材料发生的结构相变、电极表面物质转变和电荷传输规律，以期从电极材料的制备和结构的设计等方面为超级电容器性能的优化提供新思路。在此基础上，研究常温自组装-冷冻结晶-水热处理制备KCu7S4@C/graphene复合材料工艺参数对电极材料结构、颗粒大小、形貌、孔隙率和电化学性能的影响，揭示该方法合成材料的机制。研究材料的微观结构对其性能的影响规律，建立材料结构与电化学性能之间的“构效关系”，并用其来指导可控制备的过程优化，以期获得性能优异的超级电容器电极材料。

本项目研究利用XRD、XPS和TEM等表征技术对KCu7S4电极材料进行了深入探究，有效地揭示该电极材料表面发生的结构演化、电荷转移和离子输运等特性，并详细讨论和揭示了KCu7S4电极材料电化学反应的储能机理。另外，通过碳材料包覆（石墨烯和碳纳米颗粒），我们获得了KCu7S4/rGO和GN/KCu7S4 纳米复合材料，最终成功优化和提升了KCu7S4电极的电荷存储能力。作为可充电水系电池负极，KCu7S4/rGO复合电极材料展现出较高的比容量、倍率性能和循环稳定性能。此外，我们制作的GN/KCu7S4超级电容器不仅表现出较高的电化学性能，而且所编制的器件展现出较高的柔韧性能，有望在未来便携、可穿戴电子产品领域获得较好的发展前景。本项目研究工作不仅有助于加深人们对多元金属硫化物储能反应机制的理解，更有助于推动多元金属硫化物在可充电电池、超级电容器等储能领域中的发展应用。