基于自支撑氮掺杂多孔碳材料的高能量密度锂-硫电池柔性设计

High-energy-density Lithium-sulfur battery provides opportunities for the development of lightweight flexible energy storage devices. However, the low mass load decreases the overall energy density of the battery. Increasing the ratio of sulfur can reduce utilization of active materials and mechanical flexibility, increase the shuttle effect, and further affect the electrochemical performance and mechanical properties of the battery. This project intends to design self-supporting nitrogen-doped carbon materials with 3D hierarchical porous structure, which can be used to improve electron/ion transport while increasing mass upload. The shuttle effect is limited by secondary structure and nitrogen doping, and high-performance flexible lithium-sulfur battery system can be developed by combining with mechanical structure design of devices. By studying the influence of microstructure on battery performance, the relationship between load quantity and electron/ion transport property is revealed, and the principles of flexible battery structure design is explained, which is expected to be helpful in designing flexible lithium-sulfur battery with high energy density and stability.

高能量密度锂-硫电池为轻薄柔性储能器件的发展提供了机遇。然而，活性物质负载量较低使得电池总体能量密度大打折扣，而增加硫的比例会降低活性物质利用率和机械柔性，增加穿梭效应，影响电池的电化学性能和力学性能。本项目拟设计具有三维多级孔结构的氮掺杂自支撑碳材料，在增加活性材料负载量的同时改善电子和离子传输性能，利用二级结构和氮掺杂限制穿梭效应，并结合电池力学结构设计，制备高性能柔性锂-硫电池。通过研究微观结构对电池性能的影响，揭示电极中负载量和电子/离子传输性能的关系，探明柔性电池结构设计原则，为制备具有高能量密度、稳定性能的锂-硫电池柔性器件提供思路。

作为具有高能量密度的下一代电池体系，锂-硫电池中多硫化锂的穿梭效应以及负极中的枝晶问题严重影响着电池的库伦效率、循环稳定性以及安全性，而且高容量和高柔性的相互制约使得高能量密度柔性电池设计极具挑战。本项目针对柔性锂硫电池中内部关键材料和电池结构进行了全面探索，设计了具有柔性自支撑结构的三维多孔骨架，通过精细组分和微观结构调控，制备了适用于锂-硫电池正极和负极的负载基底，系统研究了微观结构对多硫化锂穿梭效应和金属锂的成核生长的影响，进一步结合电池力学结构设计，解决柔性电池中高容量高柔性不能兼容的问题，为制备高能量密度、高稳定性的柔性锂硫电池提供借鉴。