基于MOFs可控生长碳纳米管阵列复合微球的设计合成及其快速储锂行为的研究

Transition metal oxides (TMO) have attracted great attention as anode materials for lithium-ion batteries (LIBs) to achieve higher energy and power densities. Unfortunately, the practical applications of TMO-based electrodes are largely hampered due to the poor electrical conductivity and the large volumetric variation during the charging-discharging processes. Herein, this project proposes a multi-step strategy for the efficient synthesis of spherical carbon nanotube (CNT) arrays/TMO/porous carbon composite as a lithium-ion battery anode material. Based on the uniform distribution of metal ions in metal-organic frameworks (MOFs), this project intends to get the growth of carbon nanotubes arrays on the surface of spherical MOFs carbonized derivatives to prepare spherical CNTs/TMO/porous carbon composites. This structures with well-dispersed TMO nanoparticles and enhanced conductivity can compensate for TMO in the conductivity, and buffer the large volumetric variation during the charging-discharging processes. This project will investigate the effect of MOFs' structures and composition on the MOFs carbonization derivatives, which is important to the controlled growth of CNT arrays. This project will precisely adjust and control the microstructure of the electrode materials and quantify their kinetic characteristics, clarify the structure-function relationship between the microstructure of the electrode materials and their electrochemical properties in detail. This study will provide the key techniques for fabricating the advanced Li-ion batteries with high rate performances and long cycling life, by analyzing the results and optimizing the experimental conditions.

针对过渡金属氧化物（TMO）作为锂离子电池负极材料在大电流密度下可逆容量低和循环稳定性较差的问题，本项目拟根据MOFs材料中金属离子均一分布、组分精控可调的特点，从MOFs前驱体分子结构的科学设计入手，以球形MOFs炭化热解衍生物为基底，利用CVD法，在其表面生长碳纳米管（CNT）阵列制得导电性高、结构稳定且易于后期加工的CNTs/TMO/多孔炭复合球形材料，实现电极材料尺寸与空间结构的科学限域，弥补锂离子负极材料在导电性、快速脱/嵌锂动力学行为上的不足。考察MOFs的结构、组成、炭化热解氛围等对其炭化衍生物结构稳定性及其表面生长CNTs机制的影响。通过精准调控电极材料的微观结构并量化其电化学性能，挖掘“材料结构-组成成分-离子运输及电化学稳定性”之间的构效关系；阐明各组分对材料整体电化学性能的协同作用及容量提升机理，优化材料体系，最终获得高倍率性能且循环稳定性好的锂离子电池负极材料。

针对绿色能源材料稳定性较差的问题，本项目以酚、醛、胺为原料合成球形聚合物，将此球形聚合物与MOFs材料复合，再经炭化得到内部结构和球体表面可控的炭球。以炭化过程中在炭球表面形成的金属单质为催化剂，在炭球表面生长碳纳米管，最终得到内部结构可控，外面均匀生长炭纳米管的新型炭复合微球。通过调变聚合物生长过程中老化温度、老化时间改变聚合物球体的密度分布，再对其有选择的溶剂刻蚀，可以实现对聚合物内部结构的调变，继而得到性能优异、结构可调的核壳以及空心炭球并研究其结构与性能的关系。阐明各组分对性能的影响规律。