MOFs/生物质衍生三维自支撑Li-CO2电池正极的可控构筑及性能调控研究

Li-CO2 batteries integrate the dual characteristics of CO2 capture and efficient energy storage, which are considered to have great application prospects. However, high discharge-charge overpotential and short cycle life are the bottlenecks restricting their development. Aiming at these problems, this project plans to prepare CuM@C/3D-BioC three-dimensional self-standing electrodes by using biomass-derived three-dimensional self-standing porous doped-carbon as carriers followed by depositing Metal-Organic-Framework (MOF) materials and subsequent carbonization. By optimizing the preparation conditions, the pore structure and surface properties of the carbon carriers will be regulated, and the catalytic activity of carbon carriers and mass transfer efficiency can be enhanced. The catalytic activity of CuM@C will be regulated by adjusting the composition and proportion of raw materials to further reduce overpotential and improve the reversibility of Li-CO2 batteries. On the theoretical level, this project will study the formation mechanism of pore and defect sites in biomass-derived carbon materials and the nucleation and growth mechanism of MOFs. The evolution law of crystal structure and electronic structure of CuM@C catalyst will be elucidated. In addition, the “Structure-Activity” relationship between the morphology and composition of electrodes and the performance of batteries will be clarified; and the mechanism of electrocatalytic CO2 reduction and Li2CO3 decomposition will be revealed. At the technical level, this study will provide experimental basis for improving the preparation of three-dimensional self-supporting electrode materials, and provide theoretical guidance for exploring new Li-CO2 battery cathode materials.

Li-CO2电池具有固定CO2和高效能量储存的双重特性，被认为极具应用前景，但充放电过电位高、循环寿命短是制约其发展的瓶颈。针对此问题，本项目拟采用生物质衍生三维自支撑多孔掺杂碳材料为载体，沉积金属有机骨架材料和后续碳化处理，制备CuM@C/3D-BioC三维自支撑电极。通过对制备条件的优化，调控碳载体的孔结构及表面性质，增强载体催化活性和传质效率；通过调控原料组成及比例，调控CuM@C催化活性，进一步降低过电位和提高电池可逆性。在理论层面上，本项目将深入研究生物质衍生碳材料孔隙、缺陷位的形成机理及金属有机骨架材料的成核生长机制；掌握CuM@C催化剂晶体结构、电子结构的演变规律；阐明电极形貌结构、组成与电池性能之间的“构-效”关系；揭示电催化CO2还原和Li2CO3分解的机理。在技术层面上，本研究将为完善三维自支撑电极制备科学提供实验依据，为探索新型Li-CO2电池正极材料提供理论指导。

锂空气电池因其超高能量密度和环境友好的优点而受到广泛关注。然而，充放电过电位高、库伦效率低、循环稳定性差等问题是制约其实用化的主要障碍。正极是锂-空气电池的主要反应场所，因此，开发物质传输快、催化活性高的正极材料，是提高锂-空气电池性能的关键。本项目采用生物质为原材料，通过液相沉积-后续煅烧、熔融盐辅助煅烧等方法，获得了一系列的三维自支撑材料，并可直接用作锂-空气、锂-二氧化碳电池正极。本项目探索了不同电极材料（掺杂碳材料、过渡金属基电极、原子分散型电极）的合成规律，重点研究了这些电极材料的组成、结构及形貌的调控技术，详细探讨了不同电解液体系下的电化学性能及其充放电机理。研究表明这些电极继承了生物质天然的、独特的三维自支撑结构，有利于反应气体、电解液的快速扩散；电极中的分级孔，极大地提高了三相反应界面和提供了充足的催化活性位点，这种简单、高效、成本低廉的合成方法可能为制备低成本、高性能锂-空气电池正极提供可行的研究思路。