Abstract:
Air oxidation method is used to prepare coating pitch as a surface modification materials for the graphite anode materials of lithium-ion battery using ethylene tar as the raw material. The effects of air flow, oxidation reaction temperature and oxidation reaction time on the physicochemical properties of coating pitch were investigated, and the physicochemical properties of the obtained coating pitch were systematically characterized using elemental analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy and nuclear magnetic resonance. The results show that, with the increase of oxidation temperature, air flow rate or oxidation time, the coking value and softening point of the produced coating pitch can be effectively improved. Under the optimal preparation conditions with the oxidation temperature of 310 °C, air flow rate of 120 L/h and oxidation time of 10 h, a high-quality coating pitch with high carbon content (
w = 93.44%), high aromaticity and less side chains (mainly short chains) can be obtained. Its softening point, coking value, quinoline insoluble content and yield (mass fraction) are 258.9 ℃, 70.19%, 0.97% and 39.99%, respectively. The modified anode material of graphite shows a significant improvement in the capacity retention rate (89.74%) after 150 cycles.