| For the past two decades,supercapacitors have received considerable attention,owing to their high power density,extremely long cycle life and fast charging/discharging rates.Porous carbon materials are the most promising electrode for EDLCs due to their high electrical conductivity,electrochemical inertness and high specific surface area.Among the porous carbon-based materials,activated carbons with high surface area and developed pore structure,as an intriguing candidate for supercapacitor application.Activated carbons are synthesized from variety of materials,and biomass materials have become the hot choice due to unique structure,low cost,renewable,and environment friendly.In this paper,many attempts have been made to develop porous carbon materials and N-doped porous carbon material prepared by fungus（auricular）through KOH hydrothermal and activation method and in situ N-doping method,respectively.The morphology and microstructure of the materials were investigated in depth by SEM,TEM,XRD,BET,XPS,Roman and TGA.In addition,the electrochemical performances of the as-obtained nanoporous carbons were measured in a three-electrode system and two-electrode system,respectively.（1）Fungus（auricular）was used as the carbon source to prepare mesoporous material（HTA）through hydrothermal treatment and carbonization process.The results suggest that electrochemical properties of carbon materials significantly improved through hydrothermal treatment,at low scan rate of 2 mV·s-1,HTA has a specific capacitance of 183 F·g-1,indicating that the HTA has high specific capacity and excellent rate capability as supercapacitor electrode material.（2）We use fungus as the carbon source through KOH hydrothermal and activation method to obtain porous carbon material（KHTA）,the addition of a small amount of KOH not only promotes biopolymers polymerization in fungus,but also realize uniform activation of carbon materials in the activation process afterwaed.The prepared material has high specific surface and appropriate pore distribution,and the material has excellent electrochemical properties.The data of the electrochemical tests reveal that KHTA-0.1-800-1 has ultra-high volumetric capacitance of 360 F·cm-3 at 2 mV·s-1 due to its low pore volume,and it exhibits high specific capacitance of 323 F·g-1at 2 mV·s-1with an excellent rate capability of 64%retention at 500 m V·s-1.In addition,Only 1%of the initial capacitance is lost after 10000cycles at 200 m V·s-1.Notably,in a two-electrode symmetric supercapacitor,KHTA-0.1-800-1energy density as high as 21.6 Wh·kg-1at a high power density of 86.2 W·kg-1was achieved in 1 mol·L-1 Na2SO4 electrolytes.Thus,the synthesized KHTA-0.1-800-1 material could be a highly promising electrode material for advanced supercapacitors.（3）N-doped carbon material（NAC）was prepared by in situ doping method using fungus as carbon source and NH4Cl as nitrogen source.NAC has high specific capacity at the scan rates of 2 mV·s-1,the highest specific capacitance of NAC could reach 208.3 F·g-1.Therefore,doping N atoms can effectively improve the specific capacitance of carbon materials.（4）N-doped porous carbon material（ZnNAC-2）was prepared by in situ doping method using fungus as carbon source,NH4Cl as nitrogen source,and ZnCl2 as activator.The activation of ZnCl2 can increase ratio of material internal medium and large pore,and adding proper amount of N atoms can improve the wettability of carbon material.Therefore,the porous carbon materials can significantly improve the specific capacity and rate characteristics.ZnNAC-2 achieves a high specific capacitance of 264 F·g-1at a scan rate of 2mV·s-1.When the scan rate is increased to 500 mV·s-1,the specific capacitance is still 165.3F·g-1,and the capacity retention rate is 62.3%,indicating that ZnNAC-2 has high specific capacitance and good rate capability.At the same time,ZnNAC-2 has good cycle stability,the material in the 6 mol·L-1 KOH solution,at a scan of 100 mV·s-1,after 5000 cycles,the capacitance decreased only 3%. |
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