Hierarchical Porous Carbon Prepared By Nano-ZnO Template For Supercapacitor

Electrode material is the key to supercapacitors.Hierarchical porous carbons with high specific surface area have both high specific capacitance and good rate performance,which were the most commonly used electrode material for supercapacitors.In this paper,when we used nano-ZnO as hard template to prepare mesoporous carbons,we found that nano-ZnO had strong inner activation effect to produce pores at high temperature,based on which hierarchical porous carbons with high specific surface area can be prepared.A series of hierarchical porous carbons with excellent performance were prepared using nano-ZnO as both a hard template and an activation agent.The main research results were as follows:1?Nitrogen-doped hierarchical porous carbons with high specific surface area were simply prepared using ZnO nanoparticles as hard template and gelatin as carbon precursor by a serial process of liquid phase mixing,carbonization and removal of the templates with HCl aqueous solution.The effects of carbonization temperature(700-950?)on the inner activation of nano-ZnO templates was investigated.With the temperature increasing,the activation effect and the specific surface area are enhanced(The specific surface area and pore volume of the carbon increase up to 2464 m2 g-1 and 3.436 cm3 g-1,respectively.),and the nitrogen content decreases.Furthermore,the carbon material obtained at 750? exhibits maximum specific capacitance(258 F g-1 at 0.1 A g-1)and good rate stability(195 F g-1 at 50 A g-1)in 6 mol L-1 KOH aqueous electrolytes.2?Nitrogen-doped hierarchical porous carbons were simply prepared by pyrolyzing the Ethylenediaminetetretraacetic Acid Disodium Zinc Salt Hydrate in a tube furnace at 600-900? under nitrogen atmosphere.During the pyrolysis process,the nano-ZnO was formed,which could act as a template and an activator.By washing the templates in the pyrolysis products,the nitrogen-doped hierarchical porous carbons with high specific surface area were obtained.With the temperature increasing,the specific surface area gradually rised.The carbon material obtained at 650 ? exhibits a large specific surface area(1020 m2 g-1)and a high nitrogen content(7.46 at%).Based on the high specific surface area and high nitrogen content,the sample prepared at 650? exhibits a high capacitance of 258 F g-1 and 388 F g-1 in 6 mol L-1 KOH aqueous electrolytes and 3 mol L-1 H2SO4 aqueous electrolytes,respectively.3?Hierarchical porous carbons were prepared using disodium Zinc salt EDTA hydrate as the precursor of the nano-ZnO template and phenol-formaldehyde resin as carbon precursor through a process of solid phase mixing,carbonization and removal of the template with HCl aqueous solution.The hierarchical porous carbon,which has a high specific surface area(2176 m2 g-1)and pore volume(2.054 cm3 g-1),exhibits high capacitances in 6 mol L-1 KOH aqueous electrolytes(197 F g-1 at 0.1 A g-1)and in 1 mol L-1 Et4NBF4/AN electrolyte(135 F g*1 at 0.1 A g-1).Furthermore,the carbon material reveals good rate stability in 6 mol L-1 KOH aqueous electrolytes(160 F g-1 at 100 A g-1)and in 1 mol L-1 Et4NBF4/AN electrolyte(97 F g-1 at 100 A g-1).4?Hierarchical porous carbons were prepared using disodium zinc citrate as the precursor of nano-ZnO template and phenol-formaldehyde resin as carbon precursor by solid mixing,carbonization and washing process.The specific surface area of the obtained carbon sample reaches 1552 m2 g-1 and the pore volume is 1.351 cm3 g-1.The carbon material exhibits high capacitance(158 F g-1 at 0.1 A g-1)and good rate stability(97 F g-1 at 100 A g-1)in 6 mol L-1 KOH aqueous electrolytes.