Preparation Of Biomass-based Electrode Materials And Its Application In Supercapacitors

In recent years,the energy crisis and environmental pollution caused by the excessive use of fossil fuels have seriously threatened the life of human beings.Therefore,searching for the green and clean energy,efficient and convenient energy storage devices has become an urgent task.Supercapacitors are considered to be important energy storage devices due to their high power density,fast charge and discharge characteristics,excellent cycle stability and environmental friendliness.As an important part of supercapacitors,electrode materials are the key factors that determine the performance of supercapacitors.Among the various electrode materials,biomass-based porous carbon electrode is one of the most commonly used electrode materials for electric double layer capacitors and has gained wide attention due to its large specific surface area,wide source of raw materials,developed pores,excellent chemical stability and so on.In this work,the wild rice stem-derived porous carbon materials were prepared by the simple hydrothermal treatment and high-temperature calcination using potassium hydroxide as the activator.The chemical composition and morphology of the carbon materials were characterized by infrared spectroscopy,X-ray diffraction,X-ray photoelectron spectroscopy,scanning electron microscope,transmission electron microscope,Raman spectroscopy,BET nitrogen adsorption surface area test and other test methods.The cyclic voltammetry,galvanostaticcharge/discharge and electrochemical impedance spectroscopy of the two-electrode system and three-electrode system were measured respectively in order to fully study and analyze capacitance performance and cycle performance of the wild rice stem-derived porous carbon electrode materials.We used flammulina as the carbon precursor and fully mixed it with the appropriate amount of Cu SO₄·5H₂O to prepare flammulina-based porous carbon/metal copper composite electrode materials via hydrothermal reaction and high temperature carbonization.The surface morphology and chemical structure of the composites were characterized by IR,XRD,XPS,SEM,TEM,thermogravimetric analysis and other analytical methods.The electrochemical properties of the composite electrode materials were studied in a three-electrode test system.The copper nanoparticles generated a faradic redox reaction in the electrolyte solution,which greatly improved the capacitance performance of the electrode materials.Moreover,after 3000 cycles of testing,the capacitance retention of the composite electrodes can still reach about 94%,indicating good cycle stability.We use fresh red dates as the biomass substrate and the stripped g-C₃N₄nanosheets as the doping N source to prepare nitrogen-doped red date-based porous carbon materials via simple hydrothermal treatment and high temperature calcination.The morphology and chemical structure of the porous carbon materials were characterized by IR,XRD,XPS,SEM,TEM and other analytical methods.The electrochemical properties of the composite electrode materials were studied in a three-electrode test system.The quasi-rectangular cyclic voltammetry curves and symmetrical linear galvanostatic charge-discharge curves indicate the typical electric double layer capacitance behavior of the electrode materials.The results of cycle stability and electrochemical impedance spectroscopy prove that the electrode materials have good electrochemical properties.