Synthesis Of Porous Carbon Materials For High Performance Supercapacitors

Electrode material is the key to supercapacitor research.The electrode materials of supercapacitors mainly include graphene,carbon nanotubes and activated carbon.Activated carbon is a potent candidate for carbon materials due to its electrochemical reversibility and adjustable pore size.Nevertheless,low energy density and high production costs limit the use of activated carbon as an electrode material.Therefore,there is a need to develop novel and effective methods for synthesizing activated carbon to save costs and achieve green environmental protection requirements,thereby promoting its practical application.In view of the excellent properties of porous carbon materials,biomass waste can be used as a low-cost and environmentally friendly raw material to synthesize porous carbon materials.In addition,biomass contains nitrogen,sulfur,phosphorus and several metal elements such as iron and copper.These elements all provide tantalum capacitors to improve electrochemical performance.In this subject,we use grapefruit peel as a source of porous carbon,by grinding or dissolving with heteroatom-containing compounds,and finally using a one-step carbonization or activation method to introduce micropores and mesopores to obtain carbon materials with ideal properties.The main works of this topic are as follows:?1?We prepared the carbon precursor by mixing the grapefruit skin with ammonium persulfate.After pre-carbonization at 500 °C,the KOH activator was added at 500 °C to 800 °C and activated in a nitrogen-protected environment for 2 h to prepare the nitrogen-sulfur co-doping.Heteroporous carbon material.After a series of experiments,our synthesized porous carbon material has a specific surface area of 1193 m2 g^-1,a nitrogen content of 5.89%,a sulfur content of 0.46%,and a multi-stage pore structure with numerous micropores.And mesopores.At the same time,the specific capacitance of the material is 310 F g^-1(current density is 0.5 A g^-1).After 10,000 cycles,the material had a cycle retention of 98.8%(current density of 2 A g^-1)in a 6 M KOH electrolyte.For all solid state symmetrical supercapacitors,our materials have an energy density of 21.4 W h kg^-1 at a power density of 259.9 W kg^-1.?2?We use biomass grapefruit skin as a carbon precursor to extract hemicellulose from grapefruit skin,which is mixed with zinc chloride and activated.The prepared porous activated carbon material has high specific capacitance and good rate performance.The sample HPAC^-1-500 exhibited a specific capacitance of 302.4 F g^-1 at a current density of 0.5 A g^-1 with a specific surface area of 1361 m2 g^-1.After 10,000 cycles,the material had a cycle retention of 98.6% at 2 A g^-1.In the two-electrode system,the prepared porous activated carbon material has an energy density of 11.7 W h kg^-1 at a power density of 349.9 W kg^-1.