Abstract:

Dry electrode technology is one of the currently advanced manufacturing technologies for lithium-ion batteries, but there are few reported literatures on this technology. Besides, the content of the binder polytetrafluoroethylene (PTFE) in the recent studies is greater than 5%. Therefore, ternary dry electrode films of 140μm and 180μm were prepared with different contents of PTFE by hot pressing method after homogenization of the materials. The influence and mechanism of PTFE content on the physical and electrochemical properties of ternary materials were studied, such as fibrosis, membrane structure morphology, optical contact angle, tensile strength, resistivity, charge discharge, etc. The results indicated that macroscopically, the content of PTFE did not affect the homogenization of the material fibrillation. Microscopically, the number of fine fibrous binders observed in the cross-section of the film by scanning electron microscopy was significantly higher than that on the surface. The film with 2.5% of PTFE exhibited the smallest optical contact angle of approximately 68°, the lowest resistivity of 10.35Ω·cm, and a relatively high tensile strength of 4.512MPa. The film with 180μm thick had the best rate performance, with a discharge capacity of 149.13mAh/g at 1C. Based on the above research, it is believed that dry electrode technology is a highly feasible industrial electrode preparation technique.

Key words: dry electrode, polytetrafluoroethylene, Li-ion battery, ternary electrode

摘要：

干法电极技术是目前先进的锂离子电池制造技术之一，但目前研究报道的文献较少，且研究中黏结剂聚四氟乙烯（PTFE）质量分数均大于5%。为此，本文采用物料均纤维化后热压法制备了不同PTFE质量分数的140μm及180μm三元干法电极膜片，探究了PTFE的质量分数对三元材料纤维化、膜片结构形貌、接触角、拉伸强度、电阻率、充放电等物理和电化学性能的影响及其机制。结果表明，宏观上PTFE质量分数不影响物料的均纤维化，微观上膜片扫描电镜截面中的细纤维状黏结剂数量远多于表面，2.5% PTFE膜片具有最小的接触角68°左右、最低的电阻率10.35Ω·cm和较高的拉断力4.512MPa，180μm厚的膜片具有最好的倍率性能，1C放电容量达到149.13mAh/g。通过以上研究，认为干法电极技术是一种非常可行性的产业化电极制备技术。

关键词: 干法电极, 聚四氟乙烯，锂离子电池, 三元电极