水热-炭化法制备菱角壳基硬炭及其储锂性能

Water chestnut-based hard carbon prepared by hydrothermal-carbonization method as anode for lithium ion battery

生物质硬炭材料由于具有大层间距、可控的孔隙和缺陷结构,非常适合应用于动力锂离子电池(LIB)的负极材料。本文以生物质菱角壳为前驱体,通过水热除杂和高温炭化法制备出高纯度的菱角壳基硬炭负极材料(HT-x)。该方法更加安全环保,而且节省材料的制备时间。采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、拉曼光谱(Raman)、透射电子显微镜(TEM)等表征其形貌、微晶结构及微结构,并采用恒电流充放电、循环伏安技术研究了其电化学储锂性能。结果表明:水热除杂具有较好的效果,同时碳化温度对材料的微观结构和储锂性能影响较大。样品HT-1100具有大的层间距(d002=0.39 nm)和适中的比表面积(76.82 m^2/g),在0.1 C (1 C=250 mA/g)电流密度下,可逆放电比容量最高可达405.6 mA·h/g,首次库仑效率为57.32%;并具有良好的倍率性能,在4C电流密度下比容量仍可以达到167.6 mA·h/g;在0.4 C电流密度下循环300圈后容量保持在382.5 mA·h/g,显示出非常优异的循环性能。菱角壳基生物质硬炭材料用于锂离子电池负极材料研究,为实现菱角壳生物质变"废"为宝,最终实现绿色和高效资源化利用提供了实验支持。

With their large layer spacing and controllable pore and defect structures, hard biomass carbon materials are suitable anode materials for lithium ion batteries(LIB). In this paper, impurities were removed from a water-chestnut shell precursor by hydrothermal treatment, which is safer and more environmentally friendly than pickling and saves material preparation time. The hard carbons derived from the water chestnut shells were prepared as the anode materials at different high temperatures(HT-x). The morphologies, microcrystalline structures, and microstructures of the specimens were characterized by scanning electron microscopy, X-ray diffraction analysis, Raman spectroscopy, and transmission electron microscopy. As clarified in the results, the impurities were substantially removed from the precursor. The carbonization temperature significantly affected the microstructure and lithium storage performance of the material. Sample HT-1100 exhibited a large layer spacing(d002=0.39 nm) and a moderate specific surface area(76.82 m^2/g). Under a current density of 0.1 C(1 C=250 mA/g), the reversible discharge specific capacity of this sample reached 405.6 mA·h/g. The rate performance was also high, with a specific capacity of 181.3 mA·h/g at 4 C. After 300 cycles at a current density of 0.4 C, the capacity remained at 382.5 mA·h/g, showing excellent cycle performance.By applying hard carbon derived from water chestnut shells as the anode material in LIB, we provide experimental support for converting a waste product into a valuable commodity, ultimately realizing green and efficient resource utilization.