Preparation of low-cost S-doped porous carbons for high-performance supercapacitors
Inexpensive sulfur-doped porous carbons(SSC-T,T ℃ represented carbonization temperature)were pre-pared through the hard template method by using inexpensive colloidal silica as a template,sucrose as a carbon source,and sulfuric acid as a precarbonization reagent and sulfur source.The effects of sulfuric acid and carboniza-tion temperature on the microstructure,pore structure,and specific surface area of porous carbons were investigat-ed.It was found that the carbonization temperature had a significant impact on the pore structure,surface area,and sulfur content of carbons.The sample SSC-900 obtained by carbonization at 900 ℃ has the largest surface area,pore volume,and specific capacitance,which was much higher than the SC-900 prepared without the addition of sul-furic acid,indicating that the addition of sulfuric acid can increase the surface area,pore volume,and the specific capacitance.SSC-900 had the advantages of lower cost,larger pore size,and better capacitive performance than the expensive mesoporous carbon CMK-3.In the three-electrode system with 6.0 mol·L-1 KOH as electrolyte,the specific capacitance of SSC-900 can reach 357 F·g-1 at a current density of 0.5 A·g-1,while the specific capacitance of SC-900 and CMK-3 was only 152 and 266 F·g-1,respectively.The capacitance contribution analysis showed that the double-layer capacitance(EDLC)and pseudocapacitance of SSC-900 were higher than those of SC-900.In addition,SSC-900 can maintain an initial specific capacitance of 98.4％after 10 000 cycles at a current density of 0.5 A·g-1.
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