Abstract:

The modification agents for the current commercial anode material are mainly made of refined bitumen of coal and petroleum, while the quality is remarkably different and the cost is always high. To address these problems it was proposed to use low-cost coal-based heavy aromatic hydrocarbons as the precursor to prepare the modification agent through purification and polymerization processes. The modification was firstly ground and coated on the needle coke, and then the anode was obtained by a subsequent granulation process with a pyrolysis process. The rheological properties and thermogravimetric properties of the modifier were analyzed by rotational rheometer and thermogravimetric analyzer. The apparent morphology, pore structure, layer spacing, crystallinity and electrochemical properties of the modified samples were characterized by scanning electron microscope, gas adsorption apparatus, X-ray diffractometer, laser Raman spectrometer and a battery test system. The electrochemical test showed that the reversible capacity of the modified negative electrode increased from 333.02mAh/g before modification to 356.34mAh/g and 359.67mAh/g, and the initial coulombic efficiency increases by 1.72% and 1.31%. The retention rate of 98.87% over 100 cycles at 30mA/g can be obtained. The reversible capacity increased from 95.27mAh/g before modification to 147.52mAh/g and 187.30mAh/g at 300mA/g. The results indicated that the anode material prepared by adding modifier exhibited excellent specific capacity, rate performance and cycle stability. Simultaneously, the cost was low and the industrialization of preparation process was feasible.

Key words: heavy aromatic hydrocarbons, polymerization, preparation, modifier, secondary particles, anode materials, electrochemistry

摘要：

目前，商业化的负极材料改性剂主要以煤系、石油系精制沥青为原料，其品质参差不齐、价格昂贵。为改善这一现状，本文提出以价格低廉的煤系重质芳烃为原料，通过净化、聚合工艺，制得负极材料改性剂。将改性剂粉碎后与针状焦粉粒分别进行包覆、造粒工艺处理，得到改性后锂电负极材料。通过旋转流变仪和热重分析仪对改性剂的流变性能、热失重性能进行分析；利用扫描电子显微镜、气体吸附仪、X-射线衍射仪、激光拉曼光谱仪和电池检测系统对改性后样品表面形貌、孔结构、层间距、结晶性程度和电化学性能进行表征。电化学测试得出改性后的负极材料可逆比容量从改性前的333.02mAh/g增加到356.34mAh/g和359.67mAh/g，首次库仑效率增加1.72%和1.31%；30mA/g电流密度下，100周循环保持率高达98.87%以上；300mA/g电流密度下，可逆比容量从改性前的95.27mAh/g增加到147.52mAh/g和187.30mAh/g。结果表明：加入改性剂制备得到的负极材料，展现出优异的比容量、倍率性能和循环稳定性；成本低、制备工艺产业化可行性强。

关键词: 重芳烃, 聚合, 制备, 改性剂, 二次颗粒：负极材料, 电化学