基于阳离子型MOFs衍生物的多功能碳纳米纤维用于高载硫自支撑电极的构筑

锂硫电池进行高硫负载是其发挥高能量密度的关键所在，然而目前锂硫电池自支撑硫电极在高硫含量情况下存在硫利用率低、倍率性能和循环稳定性差等问题。解决这些问题的关键技术是有效地提升高硫负载量下载体材料对多硫化物的吸附/催化转化效率。我们提出基于阳离子型MOFs构筑多功能纳米纤维自支撑硫载体的研究思路，利用简单有效的过渡金属氧酸根离子交换法，可控制备具有多金属高效催化位点及高载硫能力的多功能纳米纤维复合材料（PCNF）。多金属催化位点可以高效吸附/催化多硫化物，减少死硫生成和活性物质流失，实现高载硫电极在高倍率下的高容量稳定循环运行。拟开展：1.研究离子交换及配体调控对阳离子型MOFs微观结构性质的影响；2.研究影响PCNF孔结构和多硫化物吸附/催化转化能力等性质的关键因素和控制方法; 3.系统研究材料结构性质与高载硫锂硫电池电化学性能之间的关系，为高能量密度锂硫电池的发展提供更多有益的启示。

High sulfur loading is the key to achieve high energy density promised by Li-S batteries. However, serious problems such as low sulfur utilization, poor rate performance and cycle stability have been exposed during the scaling up of the sulfur loading for freestanding cathodes. Enhancing the adsorption/catalytic ability toward polysulfides of high sulfur loading cathode is required to address these problems. Herein, based on excellent properties of cationic MOFs, we proposed that multifunctional freestanding porous carbon nanofiber (PCNF) with efficient catalytic sites and high sulfur loading capacity will be prepared by facile transition metal-based anion exchange of cationic MOFs. And the sulfur embedded in PCNF was directly used as freestanding sulfur cathodes, enabling a high areal capacity, good rate performance and cycling stability even under high sulfur loading. The project includes: 1. The influence of anion exchange and ligands regulation on the microstructure of cationic MOFs; 2. The key factors affecting the porous structure and adsorption/catalytic ability of PCNF composite will be disclosed; 3. The relationship between characteristic of PCNF and electrochemical performances of Li-S batteries will be clarified to support more beneficial information about the development of high energy density Li-S batteries.