预锂化对酚醛树脂硬炭结构和电化学行为的影响研究

The Effect of Prelithiation Treatment on the Structure and Electrochemical Behavior of Phenolic Resin Based Hard Carbon

为了提高酚醛树脂基硬炭的电化学性能,以间苯二酚和对苯二甲醛为原料、磷酸为促进剂制备了掺磷酚醛树脂低温热解碳,再经不同富锂化合物浸渍和高温碳化制得了预锂化的酚醛树脂硬炭,利用SEM、N2等温吸脱附、XRD、Raman和电化学测试技术解析了LiNO3、CH3COOLi以及LiOH对磷掺杂酚醛树脂硬炭结构和电性能的影响。结构表征结果显示,不同锂化物预锂化的酚醛树脂硬炭比表面积和总孔容(尤其微孔)显著降低,平均孔径明显增大,而预锂化对硬炭晶格参数无明显影响。电性能测试结果表明,预锂化的酚醛树脂硬炭可逆脱锂容量和首次库伦效率均显著升高,循环性能得到明显改善。其中,经5 wt% LiOH预锂化的样品电化学性能最佳,可逆容量和首次库伦效率分别达到425 mAh/g和72.2%,而未预锂化样品可逆容量和首次库伦效率分别仅为324 mAh/g和62.3%。

In this work, a novel prelithiation method is adopted to improve the electrochemical performance of phenolic resin based hard carbon by using resorcinol and terephthalaldehyde as the raw mate-rials and phosphoric acid as the crosslink promoter. Thus, the prelithiated hard carbons were prepared by impregnating the phenolic resin based low temperature pyrolysis carbon with dif-ferent lithium compounds and following with high temperature carbonization. The effect of com-pound LiNO3, CH3COOLi and LiOH on the structure and electrochemical properties of the obtained samples were detailly investigated using scanning electron microscope, nitrogen adsorption, X-ray diffraction analysis, Raman spectroscopy and electrochemical experiments. The structural characterization results show that the specific surface area and total pore volume (especially mi-cropore volume) of the prelithiated hard carbons were significantly reduced and the average pore size obviously increased. However, the prelithiation has no prominent influence to the microcrys-talline structure of the hard carbon. The electrochemical test show that the reversible delithiation capacity and initial coulombic efficiency of the hard carbons are significantly increased and the cycling performance are obviously improved after the prelithiation. Especially, the sample treated with 5 wt% LiOH exhibits the best electrochemical performance with a charge capacity of 425 mAh/g and initial coulombic efficiency of 72.2% while the non-prelithiated sample only delivers a charge capacity of 324 mAh/g with initial coulombic efficiency of 62.3%.