温度对碳球形貌及超级电容性能的影响

以三氯乙烷和二氯乙烷为原料, 金属钠为还原剂, 在溶剂热条件(100~150 ℃)下使氯代乙烷中的碳氯键和碳氢键发生断裂制备了碳纳米球, 并对制备的碳纳米球进行了表征. X射线衍射结果表明, 样品为类石墨结构, 衍射信号宽且弱, 表明样品的结晶性较差; 拉曼光谱分析结果也表明样品具有较高的无序度. 样品的SEM与TEM分析结果表明, 在较高的反应温度下, 碳球具有更好的单分散性, 碳球的粒径随温度的升高而增大; 选区电子衍射结果表明碳球内部为无定形的类石墨结构. 以碳纳米球为负极材料的锂离子电池测试结果表明, 50周循环后比容量为941 mA·h/g, 库仑效率接近100%, 放电容量保持率为103.7%, 具有良好的循环稳定性. 测试了不同温度下制备样品的超级电容器性能, 发现120 ℃下制备的碳纳米球具有较高的比电容和较低的内阻值, 比电容高达130 F/g, 经过1000周循环充放电后比电容衰减比例低于14%, 具有较高的稳定性.

Effect of Temperature on Morphology and Supercapacitor Performance of Carbon Nano-spheres†

Abstract Sodium was used as reductant to break the C—Cl bond and C—H bond in the solvent, trichloroethane(C₂H₃Cl₃) and dichloroethane(C₂H₄Cl₂), under solvothermal condition(100—150 ℃) to prepare carbon nano-spheres(CNSs). The X-ray diffraction pattern shows that the sample has a graphite-like structure. The diffraction signal of the sample is wide and weak, indicating that the sample has a poor crystallinity and an amorphous structure. The Raman spectra shows that the sample has a relative high degree of disorder. The results of SEM and TEM show that the CNSs have better monodispersion at higher reaction temperatures. The particle size of the CNSs increases with increasing temperature, and the results of electron diffraction in the selected area indicate that the CNSs are internally amorphous graphite structure. The results of the lithium-ion battery test using the CNSs as the negative electrode material show that the specific capacity after 50 cycles is 941 mA·h/g, and the Coulomb efficiency is close to 100%, the discharge capacity retention rate is 103.7%, indicating that the CNSs have good cycle stability. The performance of CNSs prepared at different temperatures as supercapacitor material was tested. The CNSs prepared under 120 ℃ show higher specific capacitance and lower internal resistance. The specific capacitance is up to 130 F/g. The attenuation of specific capacitance is less than 14% after 1000 cycles, which shows higher stability.