石墨烯/笼状聚合物纳微尺度协同限硫复合正极材料的原位构筑及电化学性能研究

The lithium sulfur (Li-S) battery has been regarded as the next generation of the high energydensitybatteries. However, there are two major challenges that limit the application of Li-S batteries. One is the low electrical conductivity of sulfur. Another major hurdle is the dissolution of various polysulfides in electrolyte, leading to the irreversible loss of active materials and severe decay of battery capacity. According to these existing problems, based on the studies ofsulfur-richpolymers, Here, we propose to design and in-situ synthesize graphene/cage-like polymer to confine S in nano/micro scale composites with high crosslinking density that are mainly capable of trapping the soluble polysulfides as well as delivering electrons efficiently to the sulfur. The following aspects will be involved:.1) Design the specific structure of cage-like polymers with high crosslinking density on the basis of the quantum calculations, and preparation of the graphene /cage-like polymer composites trapping S collaboratively in nano/micro size by in-situ photoinitiated polymerization..2) Investigation of the relationships between the composition and structure with electrochemical properties of the as-prepared cathode materials during charge-discharge cycles. Finally, the structure-performance relationships of the cathode materials are built up..Above expected research results will certainly provide both theoretical and practical guiding for the preparation of cathode material and according lithium sulfur battery with high cycling stability and capacity.

锂硫电池是下一代超高能量密度电池，目前主要问题是因正极材料中多硫离子溶解引起的循环稳定性差，是限制锂硫电池应用的关键所在。本申请在现有聚合物富硫材料研究基础上，进一步设计并原位制备超高交联密度的石墨烯/笼状聚合物纳微尺度协同限硫复合正极材料，重点改善正极材料的循环稳定性和导电性。主要内容包括，基于量化计算来设计超高交联密度聚合物笼状结构，用原位光引发聚合来最高限度构筑固石墨烯/聚合物纳微尺度协同限硫复合正极材料；使用原位拉曼、红外光谱和电化学方法，研究充放电过程中复合正极材料的组成、结构及电化学性能的演变规律，阐明复合材料的微观结构、组成与电化学性能之间关系。发展出一种具有高循环稳定性和高导电性的锂硫电池正极材料。

锂硫电池被认为是具有前瞻性的新一代锂电池体系，是提高锂电池能量密度的最有前途的解决方案之一。目前限制锂硫电池应用的主要问题是：1）由于硫及其放电产物的导电性差而使得硫的利用率低；2）放电中间产物多硫化物易溶解在电解液中而导致循环容量衰减过快。因此高能量密度和高循环稳定性的硫基复合正极材料的研究与开发是锂硫电池成功的关键。为此，本项目设计了多种基于石墨烯和多孔碳的碳硫复合正极材料和富硫聚合物/碳正极材料，研究了这些材料的可控制备方法和充放电过程中复合材料组成、结构及电化学性能的演变规律，最终获得具有高能量密度、长循环寿命的锂硫二次电池正极材料。此外，本项目还对单离子传导聚合物电解质和限制多硫离子穿梭的隔膜材料进行了研究。