柔性多孔硒碳电极的设计合成及电化学储能性能研究

There is a strong interest in thin, flexible energy storage devices to meet modern society for their potential civilian and military applications. Among various candidates, Li-Se battery is very attractive due to its high energy density and superior electrochemical properties compared to Li-S battery. However, it still suffers rather low columbic efficiency and capacity fading which are caused by the dissolution of polyselenides. In this work, we construct a novel kind of self-supporting porous Se-C cathodes for flexible Li-Se batteries. To acquire the flexible electrodes, 3D conductive interconnected graphene networks were used as the backbones of the cathodes. Then, the porous graphene-assembled composites or mesoporous carbon were filled into the pores of the graphene networks. Finally, Se8 molecules were impregnated into the porous frameworks to achieve the flexible Se-C cathodes. With this strategy，high rate capacity and outstanding cycle performance are expected since the 3D-porous graphene-based frameworks can obviously enhance the conductivity of the whole electrode and alleviate the dissolution of polyselenides. Such kind of flexible Se-C cathodes will be assembled into the Li-Se cells to character the electrochemical performance of these kind electrochemical systems. In additional, to understand the electrochemical reaction mechanical of the flexible Se-C cathodes, the charge-discharge process of the cells will be further studied by electrochemical analysis (EIS, CV, etc.) combining with the material characterizations like XRD, SEM and TEM, etc. Such novel designed Se-C cathodes can provide a new strategy to acquire the high performance flexible battery and our investigations on the electrode material, electrode structure and the electrochemical reaction mechanism, are important for further study and application of the Li-Se battery.

高性能柔性储能电化学器件的开发已成为电池科学研究的热点之一。在众多候选体系中，锂硒电池由于其较高的能量密度和优于锂硫电池的电化学性能而备受关注。但是，锂硒电池在电化学反应过程中也存在着多硒化物溶解的问题从而导致电池的库仑效率和循环寿命不高。本课题设计合成一种全新的多孔柔性硒碳电极：三维石墨烯网络被用做自支撑体，多孔石墨烯或介孔碳被填充入自支撑体的孔洞中获得高导电性的柔性碳基载体，最后将硒填充入碳基载体获得电极。通过上述设计，硒碳电极的电导率和对多硒化物溶解的抑制能力得到了明显提升，从而优化了电池的性能。为了更好地理解上述柔性硒碳电极在锂硒电池中的电化学储能机制，我们将采用交流阻抗等电化学方法，结合多种材料表征手段对硒碳电极的电化学反应过程进行深入的研究。本课题对硒碳复合材料、柔性硒碳电极结构以及电化学储能机制的研究将推动柔性电池的研发，并为锂硒电池的进一步发展打下基础。

高性能柔性储能电化学器件的开发已成为电池科学研究的热点之一。在众多候选体系中，锂硫和锂硒电池由于其较高的能量密度和优良的电化学性能而备受关注。但是，锂硫和锂硒电池在电化学反应过程中都存在着多硫化物和多硒化物溶解的问题，从而进一步导致电池的库仑效率和循环寿命不高。.为解决上述问题，项目团队采用多种不同的设计方案优化电极和电池的电化学性能：.1. 项目团队在已有研究的基础上提出了多元复合的新思路，实现了电池电化学性能和机械性能的双提升。..2.项目团队 制备了不同类型的锂硫和锂硒二次电池电极材料，借助电化学研究平台对不同类型的锂硫和锂硒二次电池电极材料的电化学性能和对电池体系的影响因素进行了分析。..3.项目团队针对电池体系轻便和柔性化的发展方向，如项目计划书所言，本课题的最终目标是设计和制备多种可用于柔性电池体系的硫碳和硒碳电极，同时优化材料的电化学性能和机械性能。研究将网状交联的设计和X-气凝胶的结构引入到柔性电池的研究中，大大加强了柔性电池的电化学性能和机械性能。..通过上述设计，硫碳和硒碳电极的电导率和对多硫（硒）化物溶解的抑制能力得到了明显的提升，从而优化了电池的性能。本课题对硫碳复合材料、柔性硫碳电极结构以及电化学储能机制的研究将推动柔性电池的研发，并为锂硫电池的进一步发展打下基础。