超高比表面积氮掺杂多孔碳材料的制备及其超级电容性能

以蔗糖为碳源,尿素为氮源,草酸钾为活化剂,通过简单的研磨和高温碳化制备了具有超高比表面积(大于3 000 m²·g^-1)的氮掺杂多孔碳材料。采用多种手段对多孔碳材料的微观形貌、比表面积、孔结构和表面氮物种进行了表征,探究了不同温度下草酸钾和尿素对碳材料的比表面积、氮含量和超级电容性能的影响。结果表明,仅使用草酸钾作为活化剂制备的碳材料KC-800 的比表面积为 1 114 m2·g^-1,而同时使用草酸钾和尿素制备的样品 KNC-800 的比表面积高达 3 033 m²·g^-1。在以 6.0mol·L^-1 KOH 为电解液的三电极体系中,当电流密度为 0.5 A·g^-1时,KNC-800 的比电容为 405 F·g^-1,而 KC-800 的比电容仅为248 F·g^-1。这表明草酸钾和尿素的加入显著提高了多孔碳材料的比表面积和超级电容性能。电容贡献分析表明,KNC-800的双电层电容值和赝电容值均高于KC-800。KNC-800在电流密度为0.5 A·g^-1时经过10 000次循环后仍能保持98.3%的初始比电容,表现出优异的循环性能。

Preparation of nitrogen-doped porous carbons with ultra-high surface areas for high-performance supercapacitors

N-doped porous carbons with ultra-high surface area was prepared by simple grinding and carbonization using sucrose as the carbon source, urea as the nitrogen source, and potassium oxalate as the activator. The effects of potassium oxalate and urea at different temperatures on the specific surface area, nitrogen content, and capacitive performance of carbons were investigated. The results showed that the specific surface area of KC- 800 prepared using only potassium oxalate as an activation agent was 1 114 m²·g^-1, while the specific surface area of KNC-800 prepared using both potassium oxalate and urea was as high as 3 033 m²·g^-1. In a three-electrode system, the specific capacitance of KNC-800 was 405 F·g^-1 at the current density of 0.5 A·g^-1, while the specific capacitance of KC-800 was only 248 F·g^-1, indicating that the synergistic effect of potassium oxalate and urea can significantly improve the specific surface area and capacitive performance. The capacitance contribution analysis showed that both the electrical double-layer capacitance and pseudocapacitance values of KNC-800 were higher than those of KC-800. KNC-800 maintained an initial specific capacitance of 98.3% after 10 000 cycles at 0.5 A·g^-1, demonstrating excellent cycling performance.