Preparation Of Nitrogen/Oxygen Co-doped Carbon-based Supercapacitor Electrode Materials And Research On Surface Modification Of Carbon Materials

Traditional fossil energy has always been the"cornerstone"for people to live on,but in recent years,the extensive use of traditional fossil energy has brought great challenges to environmental pollution,which has also forced people to develop high-performance new sustainable energy storage systems.As one of the new type of energy storage devices with special application prospect—supercapacitors have many unique advantages;compared with traditional batteries,their cycle life is longer,the charge/discharge rate is higher,and the power density is higher.What’s more,it is safe and environmentally friendly to use.However,the preparation of electrode materials and the regulation of their microstructures are also very important;the reasonable design of their microstructures largely determines the performance of the capacitor’s energy storage.In our work,we mainly carry out research work from two aspects:surface modification of carbon materials and heteroatom doping（nitrogen/oxygen co-doping）of carbon-based nanomaterials.The detailed research contents are as follows:1.Explored a low-temperature solid-phase pressure to promote the modification of electrode materials.This method can realize the surface functionalization of carbon materials and the adjustment of the pore structure.In a closed autoclave at 200℃,only oxalic acid and activated carbon materials need to be mixed to obtain oxalic acid-modified carbon nanomaterials.The specific surface area of the prepared electrode material increased from the initial 1604 to 1814 m²g^-1;the specific capacitance increased to 187 Fg^-1(C_initial=100 Fg^-1).After the stable performance cycle test（5000 cycles）,the capacitance retention rate can still reach 73%(tested at 4 Ag^-1).2.Using D-anhydrous glucose/D-fructose as a carbon source,melamine as a nitrogen source and Na HCO₃as a porogen,a nitrogen/oxygen co-doped carbon nanomaterial used in high-performance capacitors was successfully synthesized.The specific capacitance of the electrode material could be able to increase to 156 Fg^-1(6 M KOH electrolyte three-electrode system,1 Ag^-1).Our synthesis method can successfully realize the non-formaldehyde in the whole synthetic preparation process,which opens up a new and green road for the preparation of electrode materials.3.Nitrogen/oxygen co-doped porous carbon nanosheets were prepared by dual template method without aldehyde formation for supercapacitors.We use Mg（OH）₂and polyether F127as hard and soft templates respectively;D-anhydrous glucose and melamine are used as carbon source and nitrogen source respectively.Under slightly alkaline conditions（provided by disodium hydrogen phosphate）,high-performance nitrogen/oxygen co-doped carbon nanomaterials were successfully prepared without hydroformylation;the specific capacitance can reach 128 Fg^-1(1 Ag^-1),and the test system is 6 M KOH/three electrode system.In our research work,we also found that disodium hydrogen phosphate is also a good polymerization inducer,which further broadens the way for the green and non-formaldehyde production of electrode materials.A novel,green and environmentally friendly process method for the synthesis of electrode materials without aldehydes is provided,which successfully realizes the release of no harmful substances such as formaldehyde during the preparation of electrode materials,which is of great significance.