多孔氮氟共掺杂碳气凝胶的制备及其在锂硫电池中的应用

Preparation of Nitrogen and Fluorine Co-Doped Porous Carbon Aerogel and Its Application for Lithium-Sulfur Batteries

锂硫电池以其超高的理论能量密度,已成为最具发展潜力的新一代电化学储能技术,但硫正极存在电导率低、体积膨胀、多硫化物穿梭效应等技术瓶颈问题,制约了其实际应用。通过甲醛和3-氨丙基三乙氧基硅烷的醛胺缩合和溶胶-凝胶化反应合成了席夫碱二氧化硅凝胶,经与聚四氟乙烯乳液冷冻干燥、热处理同步刻蚀二氧化硅以及碳化制备了多孔氮氟共掺杂碳气凝胶(NF-CA)。以NF-CA为载体制备的NF-CA/S正极材料表现出优异的循环性能和倍率性能,0.2 C循环初始放电比容量高达1322 mA∙h/g,1 C循环200圈可逆比容量可保持564 mA∙h/g,2C倍率下可逆比容量高达598mA∙h/g。

Lithium-sulfur batteries are recognized as a promising new generation of electrochemical energy storage technology due to their ultrahigh theoretical energy density.Despite these advantages,some major technical issues have to be solved for practical applications,such as low electrical conductivity,volume expansion,and the shuttle effect of polysulfides of sulfur electrodes.In this work,a Schiff base silica gel was synthesized through the aldehyde amine condensation of formaldehyde and 3-aminopropyltriethoxysilane,followed by a sol-gel transformation.By employing a freeze-drying process with polytetrafluoroethylene emulsion and subsequent thermal treatment,a porous nitrogen and fluorine co-doped carbon aerogel(NF-CA)was fabricated through a simultaneous etching of silica and carbonation mechanism.After loading sulfur as active material,the NF-CA/S cathode demonstrated superior electrochemical performance.Specifically,it manifested an impressive initial discharge capacity of up to 1322 mA∙h/g at 0.2 C rate,retained a reversible capacity of 564 mA∙h/g after 200 cycles at 1 C rate,and exhibited a notable reversible capacity of 598 mA∙h/g under 2 C rate.