Preparation and Zinc Storage Properties of Three-dimensional Nitrogen-doped Hierarchical Porous Carbon Nanosheets
In this work,three-dimensional nitrogen-doped hierarchical porous carbon nanosheets(N-CNs)were synthesized from coal tar pitch(CTP)by using MgO@ZIF-8 as double template and auxiliary carbon source coupled with KHCO3 in situ activation.The effects of the mass ratio of KHCO3 to CTP on the structure,chemical composition and zinc ion storage properties of N-CNs were investigated.The as-prepared N-CN3 at a mass ratio of 3∶1 of KHCO3 to CTP features a three-dimensional interconnected carbon nanosheet structure,high specific surface area(2360 m2/g)and pyrrole nitrogen content.Benefiting from the above characteristics,the N-CN3 cathode of zinc-ion hybrid capacitor(ZHCs)in 2 mol/L ZnSO4 exhibits excellent specific capacity(157.6 mA·h/g at 0.2 A/g),high energy density(126.5 W·h/kg at 176.1 W/kg)and exceptional cycle stability(only 6.4%capacity decay after 20000 cycles at 5 A/g and 100%Coulomb efficiency).The density functional theory(DFT)calculation results verified the enhance-ment of the adsorption energy to Zn2+due to the presence of pyrrole nitrogen in N-CNs,thus leading to enhanced adsorption capacity of N-CNs to zinc ions.This work prides an efficient method for the high-added value utilization of coal chemical by-products.
Zinc-ion hybrid capacitors(ZHCs)Coal tar pitch(CTP)Porous carbonMgO@ZIF-8Density functional theory calculation
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