Research On Fabrication And Performance Control Of Multi-dimensional Composite Micro/Nano Electrodes Strutures For Supercapacitor

With the rapid development of science and technology and the improvement of human living standards,we have put forward higher requirements for the new generation of energy storage devices from their characteristics to energy storage performance（such as high performance,flexibility and miniaturization）.As a typical energy storage device,supercapacitors have ultra-high power density,long cycle life,safety and stability,which have been widely used in different scenarios such as car start-stop systems,electric buses,and wearable electronic devices.However,compared with other energy storage devices such as lithium-ion batteries,the smaller energy density of supercapacitors has also restricted the wider application of supercapacitors.Studies have shown that the energy density of supercapacitors is directly related to the electrode material and electrode microstruture（such as surface morphology and reasonable pore distribution）.Under the conditions of ensuring high power density and good cycle stability,this paper develops a method for preparing composite electrodes with micro-nano structures,combing by multi-dimensional materials through multiple manufacturing method,to achieve the improving energy density.The growth mechanism,unique physical and chemical characteristics of these micro-nano structures are thoroughly studied,and their use as electrodes of supercapacitors is tested.Energy storage characteristics.The main contents of this article include:（1）A controllable preparation method for surface morphology control is proposed,which improves the problem of low conductivity of transition metal sulfides.In this paper,an appropriate amount of zero-dimensional graphene quantum dots are added during the preparation of one-dimensional NiCo₂S₄ nanowires and the morphology evolution of NiCo₂S₄growth was induced by graphene quantum dots.In order to verify the universality of the graphene quantum dots regulating surface morphology evolution method,graphene quantum dots were added to the growth process of two-dimensional CuCo₂S₄ nanosheets.Such layered structures with rough surfaces all show improved electrical conductivity and increased capacitance,while partially improving the cycle stability of transition metal sulfides and achieving the purpose of regulating the energy storage performance of the electrodes.（2）A controllable three-dimensional core-shell composite structure method is proposed is proposed to effectively improve the stability of the transition metal sulfide cycle.In this paper,the effective fusion of multiple micro-nano structure preparation processes to form a three-dimensional core-shell micro-nano structure.By controlling the parameters of electrodeposition,the core-shell micro-nano structure is regulated to achieve the purpose of regulating the energy storage characteristics of the composite electrode.Compared with the nanowire array,this three-dimensional core-shell structure shows a larger specific surface area,improves the cycling performance of transition metal sulfides and reduces the internal strain and pressure caused by the volume change during the cycle,which in turn greatly delays the electrode loss.After 10,000 cycles,there is almost no loss in capacitance,which is far superior to other excessive metal sulfide electrodes.This three-dimensional core-shell structure makes full use of the material characteristics while making full use of the contribution of micro-nano structures to electrochemical performance.（3）A scalable preparation of ultra-high-load thin-film electrode preparation ideas to solve the problem of blocked ion transmission under high load.The two-dimensional reduced graphene oxide film as an electrode material exhibits excellent electrochemical characteristics,but the electrochemical performance decreases linearly with the increase of the film thickness.Because two-dimensional materials are easily stacked during the preparation process,their two-dimensional characteristics cannot be maintained,their ion transmission is restricted,and their electrochemical performance is significantly reduced.This paper proposes a method for preparing a reduced graphene oxide layered porous film supported by a three-dimensional carbon fiber conductive frame structure.Such a micro/nano structure exhibits excellent electrochemical performance.When the load reaches 4 mg cm^-2,the specific capacitance can still be maintained at 220 F g^-1,and the electrode capacitance can reach 880 F cm^-2,which is much higher than the capacitance reported in other literatures,which is also based on reduced graphene oxide electrodes.At the same time,the electrode exhibits excellent mechanical properties.After being folded 180°,the electrochemical performance remains almost unchanged,showing great potential for use in flexible electronics.This method proposes a low-cost,large-scale,high-load thin-film electrode preparation method,which effectively improves the problem of limited ion transmission under high loads,and provides ideas for the practical application of thin-film electrodes.