目前硬炭大规模生产主要受到制备工艺的限制。以兰炭为原料,经硫酸铵一步水热处理后进行1400℃高温炭化,制备兰炭基硬炭,采用X射线衍射(XRD)、拉曼光谱(Raman)、氮气吸附、扫描电镜(SEM)和透射电镜(TEM)等方法分析了兰炭基硬炭的微观结构及表面官能团等在硫酸铵水热处理与高温炭化过程中的演变规律,并通过恒流充放电、恒电流间歇滴定以及循环伏安测试等方法研究不同兰炭基硬炭用作钠离子电池负极材料的电化学性能,探索微观结构对负极材料电化学储钠性能的影响机制及兰炭基硬炭的电化学储钠机理。结果表明:通过调节硫酸铵水热处理温度可以精准调控兰炭基硬炭中各碳相的相对含量,从而达到提高其储钠性能的目的;当水热处理温度为260℃时,得到的样品(NLC-260)具有较高含量的伪石墨结构(32.4%)以及适量的无序结构(36.4%),表现出最佳的电化学性能,在20mA/g的电流密度下可逆容量可达294.0mAh/g,首次库伦效率高达83.0%,经1000次循环后容量保持率仍可达79.6%。

At present, the large-scale production of hard carbon is mainly limited by the complex preparation process. This paper presents a straightforward methodology for the synthe- sis of hard carbon using semi-coke as the raw material. The hard carbon was prepared by a one- step hydrothermal treatment with ammonium sulfate, followed by high-temperature carboniza- tion at ℃. X-ray diffraction (XRD), Raman spectroscopy (Raman), nitrogen adsorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to analyze the evolution of microstructure and surface functional groups of the semi-coke-based hard carbon during the hydrothermal treatment and high-temperature carbonization. Additionally, the electrochemical performance of different semi-coke-based hard carbon as anode materials for sodi- um-ion batteries was thoroughly examined by constant current charging and discharging, con- stant current intermittent titration and cyclic voltammetry tests, aimed to elucidate the influence of microstructure on the electrochemical sodium storage performance of anode materials and the electrochemical sodium storage mechanism of semi-coke-based hard carbon. The study reveal that the relative content of each carbon phase in the semi-coke-based hard carbon can be precisely reg- ulated to enhance its sodium storage performance by adjusting the temperature of the hydrother- mal treatment. The sample (NLC-260) obtain at a hydrothermal treatment temperature of ℃ exhibited a high content of pseudo-graphite structure (32.4%) and a moderate amount of disor- dered structure (36.4%), resulting in superior electrochemical performance. At a current density of mAh/g, the reversible capacity reach mAh/g, with a first Coulombic efficiency of 83.0%. Remarkably, the capacity retention rate remain as high as 79.6% even after cycles.