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 electri-cal 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.
万方数据
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