新型碳基增强无纺布型高储硫正极/双亲隔膜复合包的设计制备及其基础研究

Lithium-sulfur battery system has a very high theoretical energy density, which is the most potential of a secondary battery in a variety of energy storage systems. However, lithium-sulfur batteries also exist in low sulfur conductivity, polysulfide dissolution and migration and other issues. The project mainly focuses on improving sulfur utilization and cycle reversibility. A non-woven fabric with three-dimensional pore structure was adopted as substrate, combined with ALD deposition technique, we will design and prepare a new kind of amphiphilic membrane with non-woven fabric, a new kind of sulfur cathode material with high sulfur loading, and innovative design a new composite package by the heat sealing property of non-woven, which is consist with the two materials: a high sulfur positive and amphiphilic membrane. The surface element composition, chemical state and microstructure of our prepared materials will be systematically investigated. The preparation conditions were optimized by the parameters such as specific capacity, cycle performance and magnification performance measured by lithium sulfur battery, finally the goal is to obtain a high sulfur positive / amphiphilic membrane composite package. Through the analysis of the performance of the composite package, identify the reactive center, reveal its reactive mechanism, and explore the reaction mechanism of inhibition of polysulfide shuttle and lithium dendrite production. The research of this project will provide a new research idea for the design and preparation of new membrane materials, high sulfur cathode materials and simplified battery modules, which has important theoretical significance and application value.

锂硫电池系统具有极高的理论能量密度,在多种储能系统中是最具潜力的一种二次电池。 但锂硫电池中也存在硫的电导率极低、多硫化物溶解迁移等问题。本项目围绕提高硫利用率和循环可逆性方面展开工作。拟采用三维孔结构的无纺布为基底材料,结合ALD沉积技术设计制备一种双亲性(一面亲硫、一面亲锂)无纺布型隔膜材料、一种碳基增强无纺布型高储硫正极材料,并创新设计将两种材料热封压制成一种高储硫正极/双亲隔膜复合包。实验将系统考察所制隔膜材料、正极材料表面元素组成、化学态及微观结构,通过对组成锂硫电池测得的比容量、循环性能、倍率性能等参数,优化制备条件,最终制备高储硫正极/双亲隔膜复合包。通过对复合包的电池性能分析,识别反应活性中心,揭示其反应活性机理，探究抑制多硫化物穿梭和锂枝晶生产的反应机理。本项目的研究将为设计制备新型隔膜材料、高储硫正极材料及简化电池组件提供了新的研究思路,具有重要的理论意义和应用价值。

锂硫电池具有极高的理论比容量，是最有前途的下一代储能系统之一。但由于硫和Li2S的绝缘性、正极的体积膨胀、多硫化物的穿梭效应以及锂枝晶在负极上的生长等不可避免的缺点，严重阻碍了其实际应用。为了深入探究关键科学问题的影响因素及对策，本项目围绕抑制锂枝晶和多硫化物穿梭两大科学问题开展工作，具体包括：.1）针对多硫化物穿梭效应造成电池活性物质不可逆损耗和容量快速退化的关键问题，研究组对以往工作进行了系统分析及总结，从而提出一系列优化策略。.2）以多种类型的无纺布、聚烯烃类隔膜为基底，通过氧化物、氮化物、COF等材料进行表界面修饰，构筑亲锂、亲硫修饰改性隔膜，大量实验结果表明添加COF涂层可减小无纺布的孔径，抑制多硫化物穿梭的同时促进锂离子的均匀传导，从而提升隔膜的电化学性能，提高锂硫电池的循环稳定性。.3）采用简单的过滤法制备了双亲性TB-COF/SP功能化改性PP隔膜。其中，TB-COF是一种亲锂且亲硫的用于化学吸附多硫化物的改性剂，SP是硫氧化还原动力学的促进剂。TB-COF中的三嗪基能有效地锚定Li+，硼氧基能较强地吸附多硫化物阴离子。SP的加入弥补了TB-COF材料自身较差导电性的缺陷，加速了硫物种的电子交换。.4）开发出一种独特的流变调控UV聚合策略用于快速制备电解质。与传统的原位UV固化工艺相比，流变调控UV引发聚合工艺采用了流变调控聚合物浆料，适用于薄膜印刷和卷对卷连续制造工艺。.5）开发了一种Co4N纳米颗粒修饰的天然木材衍生碳载体（Co4N/WCP），该载体具备优异的锂硫电池电化学反应催化活性且可实现锂金属均匀沉积，还可以同时作为硫正极载体和锂金属负极载体，且在对应的锂硫全电池中表现出优异的电化学性能。本研究不仅为开发长寿命锂硫电池提供了解决方案，也为进一步探索其他类型的锂硫电池纳米催化剂和载体结构提供了有益参考。.本项目执行期内，共计发表论文11篇，其中6篇标注为第一资助，影响因子>6.0的论文7篇；申请发明专利2件，授权实用新型专利1件。