乳化/氧化协同制备高倍率钾离子电池负极用沥青基碳微球

Coordinated preparation of pitch-based carbon microspheres for anode materials of high-rate potassium-ion batteries by emulsification/oxidation

在不借助模板的情况下,以中温煤沥青为原料,在表面活性剂和分散介质辅助下,结合预氧化和乳化法成功制备了氧化沥青微球。探究了乳化温度对微球形貌的影响规律,并确定了280℃为最佳的乳化温度。制备的氧化沥青碳微球负极展现出良好的电化学性能。在0.05 A/g下的初始放电比容量为310 mAh/g,2 A/g时的容量为102 mAh/g,在1 A/g下经过1000次长循环,容量仍剩余108 mAh/g。其优异的储钾性能得益于低温预氧化形成的交联结构可以实现有序到无序的结构演变。此外,引入的含氧基团不仅使前驱体实现空间层面的交联,确保了材料在电化学脱嵌时的结构稳定性,而且还产生了丰富的空位和缺陷,从而增加储钾位点。

In this study,pitch-based carbon microspheres were successfully obtained by using a coordinated emulsification and oxidation method with coal tar pitch as the precursor and assisted by surfactant and dispersion medium without a template.The influence of emulsification temperature on the morphology of microspheres was explored,and the optimal temperature was determined to be 280℃.The prepared pitch-based carbon microspheres present excellent electrochemical performance with an initial discharge capacity of 310 mAh/g at 0.05 A/g and 102 mAh/g at 2 A/g.Their long-term cyclability was at 108 mAh/g after 1000 cycles at 1 A/g.The excellent potassium storage performance was because the cross-linking structure formed by low-temperature pre-oxidation can realize the structural evolution from order to disorder.In addition,the introduced oxygen-containing groups promoted crosslinking of precursor molecules at the spatial level,ensuring structural stability during electrochemical de-/intercalation.Nevertheless,they produced abundant vacancies and defects,thereby increasing potassium storage sites.