功能纳米基元构筑一体化多孔限硫载体用于高性能储能研究

Lithium-sulfur batteries are considered as one of the most promising next-generation high-energy batteries. But their development has encountered a critical bottleneck of insufficient sulfur utilization, low sulfur loading and excessive usage of electrolyte. To resolve these issues, in this project, we propose a bottom-up strategy to prepare novel electrodes, under the guidance of “lithium-sulfur reaction process” and “structural model of macroscale porous electrode”, by constructing all-in-one porous structure as sulfur host from the building blocks of functional nano-units. The hierarchical porous “ordered structure”, namely porous nitride ceramics, will be prepared by the diffusion sintering of the “units”, i.e., transition metal nitride nanomaterials, and used as electrode to support sulfur. In the so-constructed sulfur cathode, the nano-units will contribute their excellent catalysis while the integrated “ordered structure” pores will overcome the “3-highs” issues induced by the conventional granular films, i.e., high porosity, high contact resistance and high usage of inactive components. As a result, the sulfur utilization and loading will be increased as well as the electrolyte amount will be reduced, hereby a sulfur electrode with high energy density can be prepared. The sulfur reaction rate and conversion efficiency will be further elevated via controlling the intrinsic property of nano-units, the sulfur loading and electrolyte utilization efficiency increased by optimizing the architecture of all-in-one porous electrodes. This project will deeply discuss the relationship between the feature of electrode and the energy storage performance, and then illuminate the synergistic effect among the nano-units and hierarchical pores, providing scientific evidence for the design and exploration of high-energy lithium-sulfur batteries.

锂硫电池是下一代高能量密度电池的理想选择之一，但其发展面临着硫的利用率不高、有效载硫量低和电解液用量高等瓶颈。本项目根据“锂硫电化学反应过程”和“宏观多孔电极结构模型”，提出“自下而上”的“功能纳米基元构筑一体化多孔限硫载体”的新型电极研制策略，拟以过渡金属氮化物纳米材料为“基元”，通过扩散烧结形成的一体化、多级孔“序构”（氮化物多孔陶瓷）电极负载硫，发挥纳米基元对锂硫反应的优异催化作用，利用一体化多孔序构解决常规颗粒成膜所引起的高孔隙率、高接触电阻和非活性物质用量高等“三高”问题，提高硫利用率和有效载硫量，并减少电解液用量，构筑出高能量密度含硫电极。通过调控功能纳米基元的本征特征，提升硫的反应速度与转化效率；通过优化一体化多孔电极结构，提升硫的负载量和电解液的利用率。揭示电极特征与储能性能的构效关系，阐明纳米基元与多级孔隙的协同促进机制，为高能量密度锂硫电池的设计开发提供科学依据。

本项目以TiN等过渡金属氮化物纳米材料为“基元”，通过扩散烧结形成的一体化、多级孔“序构”电极负载硫。所制备的一体化多孔限硫载体的纳米基元对锂硫反应展示了优异的催化作用，其一体化多孔序构解决了常规颗粒成膜所引起的高孔隙率、高接触电阻和非活性物质用量高等“三高”问题，提高了硫利用率和有效载硫量，进而提升了含硫电极的能量密度。主要研究成果包括：（1）发展了过渡金属氮化物多孔纳米材料普适性制备方法，提出了纳米基元尺寸限硫策略，揭示了金属-氮（M-N）双活性位点催化多硫化物机理；（2）建立以TiN纳米材料为“基元”的一体化、多级孔“序构”的可控制备方法，为高性能锂硫电池提供新型正极材料体系；（3）研制出一体化高稳定双向锂沉积、溶解的金属锂负极，验证了以一体化含硫电极制备锂硫全电池的可行性。. 项目组在ACS Nano、Advanced Energy Materials、ACS Energy Letters、Nano Energy、Materials Horizons等期刊上发表高质量论文12篇；获批中国发明专利7件；培养博士生2名、硕士生11名；参与组织第四届、第五届“生物、有机与纳米电子学”（ISBONE-2021, ISBONE-2023,） 国际研讨会；获2022年第八届中国国际“互联网+”创新创业大赛主赛道金奖1项。