Defect Modulation Of Porous Carbon And Its Effect On Energy Storage Properties

In the thesis,Mn（NO₃）₂modification,hydrogen-assisted low-temperature passivation and plasma etching were used to modulate the structural defects of peanut meal-based porous carbon as raw material.On this basis,a"constitutive"relationship between the defect concentration of porous carbon and its energy storage properties was proposed.The porous carbon was comprehensively modified via simple carbonization with the aid of low dosage Mn（NO₃）₂.The resultant CMPC_xexhibit significantly increased specific surface area compared to untreated porous carbon,with a maximum increment of 873 m²g^-1.Under a critical dosage of Mn（NO₃）₂,i.e.,a mass ratio of Mn（NO₃）₂solution to porous carbon of 0.2,the resultant CMPC₂has remarkably increased sp²carbon content and appropriate Mn O loading.Notably,CMPC₂delivers a high specific capacitance of 370 F g^-1at 1.0 A g^-1and superior rate performance(207 F g^-1at 100 A g^-1)in three-electrode system using 6 M KOH electrolyte,with dramatically enhanced pseudocapacitive behavior.As an asymmetric supercapacitor electrode,CMPC₂has large specific capacitance of 309 and 227 F g^-1at 0.25 and 20 A g^-1in 6 M KOH electrolyte,respectively.And capacitance retention of 94.87%can be retained after10,000 cycles at 10 A g^-1,demonstrating excellent cycle stability.Furthermore,CMPC₂based supercapacitor yields impressive energy densities of 31.9 and 8.3 W h kg^-1at the power densities of 492.3 W kg^-1and 9.6 k W kg^-1in 1 M Li₂SO₄electrolyte,respectively.Using PB-1 as a precursor,the microstructure of porous carbon was modulated by the coupling effect of Mn（NO₃）₂modification and hydrogen-assisted low-temperature passivation.The catalytic graphitization of Mn（NO₃）₂can change the order of porous carbon,and the subsequent hydrogen passivation can remove the highly reactive heteroatom functional groups of porous carbon.The resulting porous carbon has essentially the same specific surface area,pore size distribution and heteroatomic groups,while the defect concentration is not uniform.The specific capacitance and rate of porous carbon showed a pattern of increasing and then decreasing with the increase of defect concentration.In a three-electrode system with a 6 M KOH electrolyte,PHC₄（I_D/I_G=1.61）has a high specific capacitance of 312.5 F g^-1at 0.5 A g^-1and excellent rate performance(232.6 F g^-1at 100 A g^-1).A series of porous carbons with the same specific surface area,pore size distribution and heteroatom group,but with increasing defect concentration,were successfully etched by a simple Ar plasma irradiation technique.The specific capacitance of the porous carbon increased and then decreased with the increase of the defect concentration,and reached the extreme value at I_D/I_G=1.64.In a three-electrode system with 6 M KOH electrolyte,PC-Ar₆exhibits a high specific capacitance of 506.2F g^-1and excellent rate performance(265.3 F g^-1at 100 A g^-1).In the EMIMBF₄electrolyte,the PC-Ar₅based supercapacitor can reach an energy density of 90.1 Wh kg^-1at a power density of 515 W kg^-1and still maintain an energy density at an ultra-high power density of 13.8 k W kg^-1of 22 Wh kg^-1.There are 30 figures,13 tables and 149 references...