类Yolk-Shell结构炭/石墨微球新型动力锂电池负极材料的研究

To fulfill the demand of high additional value utilization for coal tar of Shanxi province, meanwhile to search way for the issue that the low energy and power density of present anode materials can not meet the practical demand of electric vehicles, in this project, we attempt to develop a novel high-performance anode material with coal tar as precursor. The well-designed anode material is composed of carbon/ graphite microsphere with Yolk-Shell structure, and contains carbon coated transition metal oxides (MOx@C) and hollow carbon nanostructures (HCNs). The preparation processes mainly include the pre-processes, such as doping with transition metal nanoparticles or their salts, liquid phase carbonization and emulsification into microspheres. The composition and texture of the material will be adjusted by control the conditions of pre-oxidation, carbonization, graphitization and post-oxidation. This project will study the scientific principles of synergistic effect between the three kinds of mechanisms of lithium storage in transition metal oxides, hollow carbon nanostructures and graphite layers, as well as its structure foundation and implementation methods. We hope to get the structure-performance relationship which could realize the combination of three mechanisms. This project is expecting to fabricate carbon/ graphite composite microsphere with reasonable structures and composition which could satisfy the demands of high reversible capacity, good rate capability, cyclic stability and high apparent density of high-performance anode materials. The establishment and completion of the project tries to build a base in both theory and practice for elevating the additional value of coal tar and developing high performance coal tar-based anode materials for power lithium-ion batteries.

针对山西煤焦油高附加值化需求，以及现有负极材料能量和功率密度低等还不能完全满足动力锂电池实际需求的现状，本项目拟设计一种包含碳包覆过渡金属氧化物（MOx@C）和碳纳米空腔（HCNs）的类Yolk-Shell 结构的炭或石墨复合微球负极材料。主要以煤焦油为原料，经与过渡金属盐或纳米颗粒的掺杂、液相碳化、乳化成球等工艺，通过控制预氧化、碳化、石墨化和后氧化处理等过程实现对材料结构的调控。项目将研究复合材料中金属氧化物储锂、纳米空腔储锂和石墨层间储锂三种储锂机制协调作用的科学原理以及实现上述原理的复合材料的结构基础和制备方法，得到实现三种储锂机制融合的构效关系。本项目预期制备出组成和结构合理的炭或石墨复合微球，期望满足动力锂电池负极材料要求的高储锂容量、倍率、循环稳定和高堆积密度等性能。项目的设立和完成可为提高煤焦油附加值和以煤焦油为碳源制备高性能动力锂电池碳基负极材料提供理论和实践基础。

背景：山西煤焦油沥青高附加值化需求，现有负极材料能量和功率密度低等还不能满足动力锂电池未来需求。研究新型沥青基高性能负极材料是解决山西省煤炭产业困境的一个可行方向。在申请书基础上，本项目主要研究了以下内容：1）过渡金属纳米颗粒及其掺杂沥青，实现从少量到批量的制备，并分析其组成结构及其电化学性能；2）过渡金属纳米颗粒掺杂沥青微球的制备；3）不同金属氧化物纳米颗粒（Fe3O4, Co3O4,Fe2O3, Cr2O3, Mn3O4,SnO2等）及其碳复合材料的制备及电化学性能研究；4）含纳米空腔结构的中空碳球的制备及其储锂机制研究；5）掺杂金属氧化物热处理过程中对碳材料（石墨烯）结构演变影响规律探索；6）批量（百克级）含丰富纳米空腔结构石墨化样品的制备及其电化学性能研究；7）沥青调制过程涉及的尾气处理装置，喷雾干燥过程涉及的蒸汽回收装置的设计和制造，以及相关工作的专利申报等。.取得的重要结果，关键数据及其科学意义如下：1）探索出采用喷雾干燥工艺可实现百克级粒径20nm左右的NiOOH纳米颗粒和1~10微米掺杂沥青球的制备工艺开发，掺杂沥青表现出较强的磁性，所制备石墨化产品是中空石墨化微球或包含大量的纳米空腔结构，表现出优良的储锂容量和倍率性能，100mA/g的电流密度下比容量可以有400mAh/g以上，超过目前石墨产品的最高值，有实用价值，为制备更高能量密度的石墨负极打下坚实的基础。2）开发出多种金属氧化物纳米颗粒，及其碳基复合材料的制备方法，并研究组成结构和粒径调控规律和电化学性能；3）创造性地采用双模板法，含有丰富纳米空腔结构（5-10nm）的中空碳球，并研究了其储锂机制，取得863mAh/g的比容量，分析了其储锂机制，为制备更高储锂容量的碳材料提供了理论基础；4）研究了金属氧化物与碳源（葡萄糖和石墨烯）分子的反应过程，并分析了多孔石墨烯层的形成机制。