Research On Surface Modification Method Of Electrode Materials And Its Regulation Of Impact Insulation Performance And Energy Storage Characteristics In Dielectric

In recent years,surface modification methods for constructing nanostructures have become an important way to improve the physical and chemical properties of materials.However,the interface charge effect introduced by surface modification has become a significant factor limiting the development of nanomaterials.High-performance insulating materials and energy storage media are the cornerstones and precursors of advanced electrical equipment and energy storage.The purpose of surface modification to regulate interfacial charges is to suppress or increase the generation of interfacial charges,thereby improving the corresponding material properties.Suppressing the injection and accumulation of interfacial charges is an important means to control the insulating properties of dielectrics,and increasing the interfacial charges by surface modification is an important way to improve the energy storage density of dielectrics.Efficient and convenient surface modification methods and interfacial charge regulation mechanisms are currently an important development direction and frontier research topic of this discipline.Environmentally friendly low-temperature plasma technology has significant advantages in surface modification and heteroatom doping,and has attracted the attention of researchers at home and abroad.Therefore,in this paper,two aspects of charge suppression and promotion at the solid-liquid interface are studied based on the radio frequency plasma surface modification method.On the one hand,the charge injection and transfer can be suppressed,and the impact insulation performance of the liquid medium can be improved.On the other hand,the atomic doping and morphology control of graphene can be carried out to improve the interface charge transfer and further improve the energy storage density of the material.The DFT（Density Functional Theory）calculation method was used to study the microscopic mechanism of interface regulation.The main research work is as follows:A 100 nm SiO₂ film was constructed on the copper electrode,and the surface morphology changes before and after surface modification,as well as the impact breakdown characteristics and space charge distribution of propylene carbonate,were measured.The change law of charge injection in liquid dielectrics before and after deposition of SiO₂ on the electrode surface was analyzed.The effect of electrode surface modification on charge transfer at the solid-liquid interface was investigated by DFT calculations.It was found that the impact breakdown voltage and breakdown time of the liquid were significantly improved after depositing SiO₂ film on the electrode surface.The space charge of propylene carbonate under the copper electrode has a bipolar charge injection mode,and the SiO₂ film significantly inhibits the space charge injected into the liquid from the electrode,inhibits the initial stage of the discharge development,and increases the shock voltage of the liquid.Based on the DFT calculation,the influence of the dielectric film on the liquid interface barrier and the work function of the electrode material was analyzed.The results show that after the SiO₂ film is deposited on the surface of the electrode,the charges are trapped in the SiO₂ layer,preventing the interfacial charge transfer and increasing the work function of the electrode.This result promotes the application field of plasma modification technology and also provides a new idea for improving liquid insulation performance.Three electrode materials,copper,aluminum,and stainless steel,were selected as the research objects,and the impact insulation properties of TiO₂ films on liquids with different electrode surface modifications were measured.The influence mechanism of surface modification of different electrode materials on liquid insulation was analyzed,and the influence of different films of SiO₂ and TiO₂ films on the electrode surface in improving the liquid impact insulation performance was compared.The results show that the impact breakdown voltage of the liquid under the aluminum electrode material is the lowest,the impact breakdown strength of the liquid under the copper electrode is5.8%higher than that of the aluminum electrode,and the impact breakdown voltage of the liquid under the stainless steel is 12.6%higher than that of the aluminum electrode.After the surface modification of the three electrodes,the impact breakdown voltage of the liquid is improved to different degrees,and the breakdown time is also obviously delayed.Both TiO₂ and SiO₂ films have space charge suppression effects,and the liquid lifting amplitude can reach up to 13.8%under the combined action of electrode materials and dielectric films.Based on the measurement results of liquid space charge,a method for measuring charge mobility in liquid is proposed.It was found that the charge mobility in the liquid decreased from 6.75×10^-7 m² V^-1·s^-1 to 5.14×10^-7 m²V^-1·s^-1 after electrode surface modification.The charge injection depth is reduced,from x/d=0.21 to 0.16.It is shown that the film changes the interfacial barrier between the electrode and propylene carbonate,greatly reducing the amount of space charge injection.The results reveal the microscopic mechanism of the effect of interface regulation on the insulating properties of liquids and provide a theoretical basis for the design of solid-liquid interfaces.Two solid-liquid interfaces of TiO₂ nanostructured film and TiO₂ nanoparticle doping were established respectively,and the combined effect of nanoparticle and electrode surface modification was analyzed.The results showed that the liquid breakdown voltage increased by only 6.1%after nano-doping,and only 9.4%after electrode surface modification and the combined breakdown voltage of the two increased by 14.3%.And based on the liquid space charge measurement to analyze the joint action mechanism of the two,the results show that the interface introduced by the TiO₂ nanofilm inhibits the charge injection process,thereby inhibiting the formation of the seed charge of the liquid streamer.The nanoparticle doping interface affects the charge transport process.The introduction of a potential well of 0.49 e V on the surface of the nanoparticle can capture fast-moving electrons during the development of the streamer,which is not conducive to the transport and development of the liquid streamer.The combined action of the two further enhances the breakdown voltage of the liquid.Surface modification and atomic doping of graphene-based supercapacitor electrode materials based on RF plasma,and quantitative observation of the surface morphology and physicochemical composition of the samples after plasma treatment.The results show that boron-and nitrogen-doped graphene has been rapidly synthesized at relatively low temperatures compared with conventional methods;The energy storage characteristics of boron-and nitrogen-doped graphene were characterized by the electrochemical test method,and the specific capacitances of the two were significantly improved at 0.2 A g^-1,up to 345 F g^-1 and 365 F g^-1,respectively,and there is a 2-5times increase compared to before plasma treatment.Spectral analysis and DFT calculation results show that,on the one hand,the motion of free radicals and high-energy particles excited by plasma produces an etching effect on the graphene surface,which increases the specific surface area of the pore size.In addition,the doping content and topological defects of graphene are increased,which is beneficial to the interface charge transfer between the graphene electrode and the electrolyte and improves the specific capacitance of the energy storage medium.The interface regulation diversity is realized based on RF plasma,and an efficient and facile route for the large-scale fabrication of graphene-based supercapacitors is obtained.