Preparation And Electrochemical Performance Of Three-dimensional Carbon Foam-based Supercapacitor Electrode Materials

Three-dimensional?3D?carbonaceous electrode materials have interconnected electronic channels for realizing charge exchange during electrochemical reactions,thus have a wide range of applications in the field of energy storage.Among them,carbon foam?CF?has attended great attention due to its unique 3D porous structure,simple preparation process,and excellent electrical conductivity.However,the low specific capacitance prevents CF from meeting the increasing electrochemical performance requirements of supercapacitors.Therefore,increasing the specific capacitance of CF is the only way to expand its application prospects.At present,the strategies for increasing the specific capacitance of CF include design of the composition and structure of CF-based composite.Here,CF was composited with0D Mn₃O₄ nanoparticles,1D V₂O₅ nanoneedle,and 2D SnS₂ nanosheets.The effect of the mass of reactants on the structure and electrochemical performance is investigated,which provides an important reference for broadening the application of CF in supercapacitors.CF was prepared by the carbonization method,and then Mn₃O₄ nanoparticles were combined with highly conductive CF by a one-step hydrothermal method to prepare a Mn₃O₄@CF composite.The 0D@3D hierarchical structure of Mn₃O₄@CF composite using CF as 3D growing skeleton prevent agglomeration of Mn₃O₄nanoparticles and increase the number of reactive sites of Mn₃O₄ nanoparticles.The synergistic effect between CF and Mn₃O₄ improves the electrochemical performance of CF.Mn₃O₄@CF-1,Mn₃O₄@CF-2 and Mn₃O₄@CF-3 composites were prepared by adjusting the mass of the reactants in the processes of hydrothermal reaction.The Mn₃O₄ nanoparticles grow uniformly on the CF surface with a diameter of 18 nm in Mn₃O₄@CF-2 composite.Mn₃O₄@CF-2 composite has a specific capacitance of212.8 F/g at a current density of 1 A/g,which is much higher than that of CF monomer?79.1 F/g?and Mn₃O₄ monomer?112.7 F/g?.In addition,CF as a conductive skeleton shortens the charge transfer path.Compared with Mn₃O₄monomer,the conductivity of Mn₃O₄@CF-2 composite has been greatly improved.The V₂O₅@CF composites with 1D@3D hierarchical structure were prepared based on CF by a one-step hydrothermal method.V₂O₅@CF-1,V₂O₅@CF-2 and V₂O₅@CF-3 composites were prepared by adjusting the mass of the reactants in the processes of hydrothermal reaction.The V₂O₅ nanoneedles grow uniformly on the CF surface with a diameter of 90 nm in V₂O₅@CF-2 composite.The V₂O₅@CF-2composite has a specific capacitance of 317.2 F/g at a current density of 1 A/g,which is much higher than the CF monomer?54.5 F/g?.In addition,the impedance of V₂O₅@CF-2 composite is much smaller than that of V₂O₅ monomer.The symmetrical coin supercapacitor based on V₂O₅@CF-2 composite has the highest energy density of 10.6 W h/kg,when the power density is 499.9 W/kg.The excellent electrochemical performance of V₂O₅@CF-2 composite comes from the synergistic effect between the composite system with unique 1D@3D hierarchical structure:?1?CF could be a conductive skeleton in the composite system.Electrons can be quickly transferred on CF,and 1D V₂O₅ nanoneedle arrays obtain the electrons to participate in the electrochemical reaction from CF,which greatly reduces the impedance of the material;?2?CF could be a growing skeleton in the composite system.1D V₂O₅ nanoneedle arrays can be grown vertically and uniformly on the CF surface,which is beneficial for the connection with the electrolyte.V₂O₅@CF composite gets more reactive sites and reduces the electrolyte transmission resistance,thus the specific capacitance of V₂O₅@CF composite has be greatly increased.Based on CF,SnS₂@CF composites with 2D@3D hierarchical structure were prepared by a one-step hydrothermal method.Combining SnS₂ with CF can make both obtain the complementary electrochemical advantages and achieve the purpose that the electrochemical performance of the SnS₂@CF composites is far higher than that of any monomers.The synergistic effect between SnS₂ and CF greatly improve the electrochemical performance of CF.SnS₂@CF-1,SnS₂@CF-2 and SnS₂@CF-3composites were prepared by adjusting the mass of the reactants in the processes of hydrothermal reaction.The SnS₂ nanoplates grow uniformly on the CF surface with a thickness of 20 nm in SnS₂@CF-2 composite.The SnS₂@CF-2 composite has the highest specific capacitance of 283.6 F/g at the current density of 1 A/g.After10,000 cycles,the specific capacitance maintains 76.8%of the initial specific capacitance.The symmetrical coin supercapacitor based on SnS₂@CF-2 composite has the maximum energy density of 13.9 W h/kg,when the power density is 551.7W/kg.After 10,000 cycles,the specific capacitance of symmetrical coin supercapacitor can still be maintained 71.3%of the initial specific capacitance.To sum up,CF was used as the matrix to prepare Mn₃O₄@CF composites with0D@3D structure,V₂O₅@CF composites with 1D@3D structure,and SnS₂@CF composites with 2D@3D structure.The synergistic effect between hierarchical materials greatly improved the electrochemical performance of CF.