钠离子电池具有安全性高和成本低等优势,在低速电动车和大规模储能领域的应用前景被看好,开发高性能、低成本的负极材料对钠离子电池发展意义重大。煤沥青因具有碳含量高、芳化度高等特征,是硬炭负极材料的优质前驱体,但直接高温热解会产生石墨化的倾向,表现为碳层间距小,活性位点少,储钠容量低。因此,以煤沥青为原料,利用兼具活化和催化作用的NaCl为模板剂,经800℃炭化制备沥青基硬炭材料,借助X射线衍射(XRD)、Raman光谱、扫描电镜(SEM)、透射电镜(TEM)、低温氮气吸附仪、X射线光电子能谱(XPS)等表征技术探究炭材料的微观结构,并借助恒流充放电和循环伏安法等探究煤沥青作为钠离子电池负极材料的储钠性能。结果表明:NaCl的加入能够明显提高材料的比表面积,引入更多的活性位点,同时促进局部石墨片层的形成,并使其封闭孔体积显著提高;当NaCl与煤沥青的质量比为10∶1时,制备的煤沥青基多孔炭PN2具有163m2/g的比表面积,具有高斜坡比容量和高平台比容量的电化学特征,在50mA/g电流密度时可逆比容量为229.6mAh/g,当电流密度增大到2A/g时,仍能保持99mAh/g的可逆比容量,同时表现出良好的循环稳定性,200圈循环后的比容量保持率为79.51%;机理分析表明,煤沥青基多孔炭的储钠机制可归因于扩散行为和电容行为的综合控制。

Sodium ion batteries have the advantages of high safety and low cost, holding sig‐ nificant promise for applications in low-speed electric vehicles and large-scale energy storage systems.   The development of high performance and low-cost anode materials is crucial for the development of  sodium ion batteries.  Coal tar pitch with high carbon content and aromaticity is an excellent precursor  material for carbon anode materials.  However, direct high-temperature pyrolysis results in highly  graphitized carbon with small interlayer spacing and few active sites, leading to relatively low sodium  storage capacity.  In this study, coal tar pitch was employed as raw material, leveraging the activation  and catalytic effects of NaCl as template agent. The two were fully mixed at a certain mass ratio and  carbonized at 800 ℃ to prepare pitch based hard carbon materials.  X-ray diffraction (XRD), Raman  spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), low- temperature nitrogen adsorption instrument, X-ray photoelectron spectroscopy (XPS), etc.  were  used to investigate the microstructure of carbon materials, and the sodium storage performance of coal  tar pitch as an anode material for sodium ion batteries was explored using constant current charge dis‐ charge and cyclic voltammetry. The results show that the addition of NaCl significantly increase the  specific surface area of the material, fostering the generation of more active sites, and facilitating the  formation of localized graphite lamellae with an increase in the volume of closed pores.  When the  mass ratio of NaCl to coal tar pitch is 10∶1, the prepared coal-based porous carbon PN2 has a highest  specific surface area of 163 m / g, showing both increase slope and plateau capacity.  Therefore, the  reversible specific capacity of PN2 at a current density of 50 mA/g is 229. 6 mAh/g.  When the cur‐ rent density is increased to 2 A/g, the reversible specific capacity of 99 mAh/g is still maintained,  exhibiting good cycling stability with a specific capacity retention of 79. 51% after 200 cycles.  Mecha‐ nistic investigations reveal that the sodium storage behavior of coal tar pitch-based porous carbon can  be ascribed to the integrated regulation of diffusion behavior and capacitance behavior.