Preparation Of Carbon Materials Derived From Zanthoxylum Schinifolium Husk And Research On Performance Of Supercapacitors

Supercapacitors（SCs）have received intense attention of researcher because of their much higher energy density than conventional dielectric capacitors and higher power density than secondary batteries.In addition,supercapacitors have been applied in ener-gy conversion systems and acceleration systems of hybrid electric cars extensively.It is well known that the capacitive performance of supercapacitors largely depends on the microstructure and electroactive structure of materials.Pure carbon materials are widely used in commercial supercapacitors due to high specific surface area and more active sites.As the carbon source,biomass is not only the source wide and low price,but also has rich heteroatomic functional groups.The higher pseudo capacitance and synergetic effect can be obtained by combining carbon materials with metal oxides or metal sulfides.Therefore,the addition of metal materials in carbon materials can im-prove the material’s conductivity and ion transport rate.In this study,the multilayer and porous carbon material with high specific surface area was prepared by simple two-steps method using southern Zanthoxylum schinifo-lium husk（ZSH）as carbon precursor,which have abundant electron transmission net-work and surface active electrochemical sites.Meanwhile,the capacitive property of carbon materials were adjusted by controlling the dose of activator,and metal oxide with high capacitance is compounded with porous carbon.So that metal oxide on the electronic transmission network can get better activation during charging and dis-charging.We mainly done the following work.（1）Synthesis of multilayer porous carbon and their research in supercapacitors.Porous carbon materials with different activator ratios were synthesized by two-steps method（carbonization-activation）.The influence factors of the dose of acti-vator on carbon materials were studied,and the electrochemical performance of the carbon materials were investigated detailly.The electrochemical measurements dem-onstrate that NC possess a high specific capacitance（SC）performance,well cycle sta-bility and rate capability.To be specific,the SC of NC when the ratio of NC to activa-tor is 1:3 is the largest,up to 333.7 F g^-1 at 0.5 A g^-1,and as high as 294 F g^-1 even at large current density of 2 A g^-1.Furthermore,the NC maintains 97.9%of its initial SC after 5000 cycles at 0.5 A g^-1.Moreover,the asymmetric super-capacitors with NC as positive electrode and negative electrode are of prominent energy density of 16 Wh kg^-1 at the power density of 300.6 k W kg^-1,and superior cycling stability of 98.5%initial value retention after 5000 cycles.（2）Synthesis of nickel oxide modified carbon material for high performance su-percapacitor.Composites of Ni O/NC with different mass ratios were synthesized by hydro-thermal-sintering,and electrochemical performance of composites were investigated.The Ni O nano-flowers with high specific surface not only deposit on the surface of NC by SEM characterization,but also disperse in its pores.Which can prevent Ni O from agglomerating on the surface of NC and increase the specific surface area.That indi-cated only Ni O and C in the composites by XRD characterization.At the current den-sity of 0.5 A g^-1,the specific capacitance of composite electrodes with the mass ratio of1:20 is up to 1850 F g^-1.The capacitance only decreased by 5.63%after charg-ing/discharging of 1000 times continuously.And the materials demonstrated well con-ductivity,charging/discharging can be carried out up to 15 A g^-1.The results show that the capacitance and electrochemical performance of composites have been improved to a certain degree compare with NC.（3）Synthesis of cobalt oxide modified carbon materials and research on perfor-mance of supercapacitorsThe precursor of the composites were obtained by Hydro-thermal synthesis with CTAB（Hexadecyl trimethyl ammonium Bromide）,and composites of Co O/NC were synthesized by by calcining in N₂ atmosphere.Electrochemical properties of compo-sites with different molar ratios of Co O and NC were investigated.The components of composites indicated only Co O and C by XRD characterization.CTAB could increase active sites of surface on the carbon materials and regulated the morphology of cobalt oxide were showed by SEM characterization,so the specific surface area was in-creased.The capacitance of composites is 724 F g^-1 at 0.5 A g^-1 when the molar ratio of NC to Co O is 1:1,while the capacitance the pure NC is 333.7 F g^-1.The capacitance of the composite electrode（molar ratio of NC to Co O is 1:1）maintains 91%after charg-ing/discharging 1000 cycles with the current density of 0.5 A g^-1.Moreover,the mate-rials can still be charged and discharged with current density up to 15 A g^-1,which have a well conductivity.The results show that the specific capacitance and electrochemical performance of composite electrodes are better than that of NC electrode.The results of this experimental show that NC with excellent electrochemical performance,which has the basis for the selection of electrode materials for superca-pacitor.Electrochemical properties of Ni O/NC and Co O/NC compared with NC had been improved obviously.