【作者】 张亮；

【导师】 朱小红；

【作者基本信息】 四川大学 ， 材料物理与化学， 2021， 硕士

【摘要】 超级电容器作为一种近几年备受关注的电能存储器件,具有充放电速度快、循环寿命长、功率密度高以及材料安全环保可靠等特性,这些高性能表现为人类科学技术发展、解决环境和能源问题提供了可行的方案。影响超级电容器储能性能的主要因素是电极材料,本论文实验针对不同的碳源制备得到碳电极材料,对其电化学性能进行研究,使多孔碳电极材料的电化学性能更加高效、稳定,降低电极成本。主要研究内容如下:1.采用碳化结合KOH活化方法,制备了以荷花茎为碳源的生物质多孔碳电极材料。探索制备过程中活化时的温度以及活化时碳碱质量比对多孔碳电极材料电化学性能的影响。实验结果显示,当活化温度为800℃,活化碳碱质量比为1:2时,制备出的碳电极材料表现出了最佳的电化学性能。当电流密度为1 A g-1时,比电容达到248.5 F g-1,且该电极材料具备很好的倍率性能,电流密度从1 A g-1增加到10 A g-1时,比电容保持在82.5%以上。该材料的等效串联电阻、电荷转移电阻和瓦伯格阻抗均很小,这表明了有利于电化学工作时电解质离子的传输和扩散。本实验制备的多孔生物质碳电极材料比表面积较大,为1022 m2 g-1,孔体积为0.58 cm3 g-1,平均孔径为2.26 nm。由该材料制备的双电层超级电容器的功率密度是496.94 W kg-1,相应的能量密度是34.51Wh kg-1,且具有较好的循环稳定性,循环5000次后,该器件的比电容保持在90.6%。2.以不同制备条件的水热法对原材料进行活化制备实验,成功制备了以荷花茎为碳源的碳电极材料。通过实验测试数据得到了20%浓度的H2O2和CH3COOH混合溶液相较于其单独作为水热活化剂参加反应时,制备出的碳电极材料电化学性能更好,结果表明,在电流密度为1 A g-1时,该碳电极比电容为163.2 F g-1,当电流密度从1 A g-1上升到10 A g-1时,比电容保持在81.2%以上,等效串联电阻和电荷转移电阻阻值分别为0.61Ω和0.05Ω。改变活化剂的浓度和制备步骤时,结果表明20%浓度的H2O2和CH3COOH混合溶液通过直接水热法制备出的碳电极在1 A g-1时,比电容为128.7 F g-1,当电流密度从1 A g-1增加到10 A g-1时,比电容保持在75.8%以上,等效串联电阻和电荷转移电阻阻值分别为0.68Ω和0.06Ω。3.本论文实验对比采用另一类碳源无烟煤作为电极前驱体材料,通过四种制备方法成功制备出了碳电极材料,研究不同的制备方法对无烟煤基碳电极材料电化学性能的影响。实验结果表明,在所有样品中,通过碳化-KOH活化的方法制备的碳电极比电容最高,在电流密度为1 A g-1时,达到262.0 F g-1,相比而言,碳化-水热-KOH混合活化、碳化-水热活化和水热一步直接活化制备的碳电极比电容大小依次降低,分别为:254.0、83.5和19.8 F g-1。同时,由碳化-KOH活化法制备的碳电极的等效串联电阻和电荷转移电阻为所有样品中最小的,分别是0.49Ω和0.05Ω。但是,采用碳化-水热-KOH混合活化法制备的碳电极在较大的电流密度下的倍率性能最好,在1 A g-1和10 A g-1电流密度下,该样品的比电容分别为254.0 F g-1和216.5 F g-1,比电容保持率为85.2%。更多还原

【Abstract】 As a new electric energy storage device,supercapacitor has the characteristics of fast charging-discharging speed,long cycle stability,and high power density.Moreover,its materials are safe,environment-friendly and reliable.These high performances provide a feasible solution for the development of science and the solution of environmental and energy problems.The key to the performance of supercapacitors is electrode materials.In this thesis,the preparation and electrochemical performance of carbon electrode materials were studied,aiming at making the porous carbon electrode materials more efficient,stable and cheap.The main research contents are as follows:1.Porous activated carbon electrode materials derived from lotus stalk were prepared by carbonization and KOH activation method.The porous activated carbon electrode materials’ electrochemical properties,depending on the activation temperature and the ratio of carbon / KOH,were investigated.The experimental results show that when the activation temperature is 800 ℃ and the ratio of carbon / KOH is 1:2,the prepared carbon electrode material shows the best electrochemical performance.While the current density is 1 A g-1,the specific capacitance reaches 248.5 F g-1.And the electrode material has a high rate performance: when the current density increases from 1 to 10 A g-1,the specific capacitance remains above 82.5%.The equivalent series resistance,charge transfer resistance and Warburg impedance of the material are all very small,which is conducive to electrochemical ion transport and ion diffusion.The specific surface area of the biomass carbon material is 1022 m2 g-1,pore volume is 0.58 cm3 g-1,and average pore size is 2.26 nm.The energy density of supercapacitor is calculated as 34.51 Wh kg-1,and the corresponding power density is obtained to be496.94 W kg-1.Accordingly,the capacitance retention is 90.6% after 5000 cycles of charging and discharging at the current density of 1 A g-1.2.Carbon electrode materials derived from lotus stalk were also prepared by hydrothermal activation treatment.H2O2 and CH3 COOH solutions reacted separately and mixed as the hydrothermal activators.The electrochemical performance of carbon electrode prepared by 20% concentration mixed solution is more outstanding.The results show that at the current density of 1 A g-1,the specific capacitance of the electrode is 163.2 F g-1.When the current density increases from 1 to 10 A g-1,the specific capacitance remains above 81.2%.The equivalent series resistance and charge transfer resistance are 0.61 and 0.05 Ω,respectively.When the activator concentration and the preparation steps are changed,the results show that the specific capacitance of the carbon electrode material directly prepared by 20% H2O2 and CH3 COOH mixed solution is 128.7F g-1 at 1 A g-1,and the specific capacitance remains over 75.8% when the current density increases from 1 to 10 A g-1.The equivalent series resistance and charge transfer resistance are 0.68 and 0.06 Ω,respectively.3.In this thesis,carbon electrode materials derived from anthracite were successfully prepared by different methods.The effect of preparation process on electrochemical performance of electrode was studied.The experimental results show that the specific capacitance of the carbon electrode prepared by carbonization and KOH activation is the best of all samples,reaching 262.0 F g-1 at1 A g-1.In comparison,the specific capacitance of carbon electrode prepared by carbonization-hydrothermal-KOH hybrid activation,carbonization-hydrothermal activation and one-step hydrothermal direct activation are 254.0,83.5 and 19.8F g-1,respectively.Meanwhile,the equivalent series resistance and charge transfer resistance of the carbon electrode prepared by carbonation-KOH activation method are the lowest among all the samples,which are respectively 0.49 and 0.05 Ω.However,the carbonation-hydrothermal-KOH hybrid activated sample has the best rate performance at higher current densities.The specific capacitance is 254.0 and216.5 F g-1 respectively at the current density of 1 and 10 A g-1,and the specific capacitance is maintained at 85.2%.更多还原