Design,Preparation And Capacitive Performance Of Paper Based Porous Carbon Materials

As a new energy storage device,supercapacitor has attracted wide attention due to its irreplaceable advantages,such as high power performance,good reversibility and superior safety.Electrode material is the key factor that determines the performance of supercapacitor.Therefore,the development of cheap and good electrode material has been the focus of supercapacitor research.In this paper,several types of papers were used as carbon precursors for the synthesis of activated carbon electrode materials with different pore structures.They were further investigated as electrode materials of aqueous supercapacitors.The details are as follows:1.Porous carbon materials derived from waste printing paper for high rate performance supercapacitors:Porous carbon electrode materials were prepared by two step method of pre-carbonization and KOH activation.The as-prepared carbons were systematically characterized by nitrogen adsorption/desorption,X-ray diffraction（XRD）,scanning electron microscopy（SEM）,Raman spectroscopy and X ray photoelectron spectroscopy（XPS）.The prepared carbon materials exhibit large specific surface areas and good conductivities as high as 2616.1 m² g^-1 and 198.8 mS cm^-1,respectively.They were used as electrode materials of supercapacitors in the most common aqueous electrolytes,including 6 M KOH,1 M H₂SO₄,and 1 M Na₂SO₄,and showed excellent capacitive performance in all the investigated electrolytes,such as very high specific capacitances(e.g.385.0,370.1,317.7 F g^-1 in KOH,H₂SO₄ and Na₂SO₄ electrolyte at 0.2 A g^-1,respectively),outstanding rate capabilities(e.g.198F g^-1 at 60 A g^-1 in H₂SO₄),high energy densities(e.g.21.9 Wh kg^-1 in Na₂SO₄),high power capability(at 28 000 W kg^-1,remains 5.83 Wh kg^-1 in Na₂SO₄),good recyclability（about 94%retention after 10 000 cycles）.2.Preparation and capacitance properties of graphene/porous carbon composite material:In view of the wide application and excellent performance of porous carbon materials in supercapacitors,we have successfully prepared a graphene/porous carbon composite material（GAPC）by a facile one-step method.Among them,the carbon source is low price,widely available and recyclable bibulous papers.In this study,the morphology,structure and surface properties of the GAPC samples were investigated by SEM,TEM and N₂adsorption/desorption.They showed much more remarkable capacitance increment in comparison with pure carbon sample without graphene and ZnCl₂ activation when tested in 6 M KOH aqueous solution.At a current density of 0.2 A g^-1,the GAPCs electrode showed a high specific capacitance of 204 F g^-1,which is much larger than that of the pristine APs(72 F g^-1),highlighting the promise of the composite materials for high power applications.3.Preparation and electrochemical properties of waste printing paper based carbon/quinone composites:To further improve the capacitive performance of the paper-based porous carbons,we introduced the redox active quinones into the prepared carbons.The prepared carbon/quinone composite materials are investigated as the electrode material of the supercapacitor in H₂SO₄electrolyte.The electrochemical test shows that the voltage range has a great effect on the pseudocapacitive performance of Quinone.When the current density is 3 A g^-1,the capacitance couldreach 519.6 F g^-1 in the voltage range of-0.4-0.4 V,and the capacitance value is only 311.76 F g^-1 in the voltage range of 0-1 V.However,the experimental results show that the anthraquinone has better matching with the pore structure of the waste printing paper based carbon materials.At the ratio of anthraquinone/carbon=1,the capacitance could be up to an ultrahigh value of 744 F g^-1 at the current density of 1 A g^-1.When the current density increases to 40 A g^-1,the capacitance of this material can remain to be 357 F g^-1.