Study On Modified Preparation And Sodium Storage Performance Of Graphene/Fe₂O₃ Anode Materials

Sodium-ion storage devices have received widespread attention because of their abundant sodium resources,low cost and high energy density.The electrochemical redox reaction of metal oxides provides a new way to construct a high-capacity negative electrode for sodium ion storage devices.However,due to the slow kinetics of the most anode materials and the irreversible changes in the internal structure of the material in the cycle,it will cause problems such as poor rate performance,low coulombic efficiency,and unsatisfactory cycle stability of sodium ion energy storage devices,which makes sodium ion energy storage devices still face great challenges in practical applications.This paper focuses on the metal oxide Fe₂O₃,which is rich in materials,low in cost,high in theoretical specific capacity,and environmentally friendly.To study the Fe₂O₃anode material for efficient sodium storage,the graphene/Fe₂O₃nanocomposite anode material for sodium storage was prepared using the high conductivity and high specific surface area of graphene two-dimensional layered structure.At the same time,the microstructure of the composite electrode material is optimized by methods such as pre-oxidation and nitrogen doping,thereby effectively improving its sodium storage electrochemical performance.Optimized composite electrode materials were used as the negative electrode to assemble sodium ion batteries(sodium-ion battery,SIB)and sodium ion supercapacitors(sodium-ion supercapacitors,SIS).The research results show that this anode material has obtained good application effect.This paper also studies the energy storage mechanism of ferric oxide composite materials and sodium storage devices through various electrochemical methods,providing factual basis and theoretical basis for the practical application of ferric oxide composite materials and sodium ion energy storage devices.The research content of this paper is as follows:(1)The graphene/Fe₂O₃(GF)composite nanomaterials were prepared and synthesized by one-step reduction hydrothermal method.The uniformly sized Fe₂O₃nanoparticles were evenly distributed on the graphene sheets,forming rich pores,avoiding the agglomeration of nanoparticles,and providing rich active sites and large Na storage space.The coating of graphene sheets effectively enhances the conductivity of the material.At the same time,the mutual bonding between the graphene surface and Fe₂O₃shortens the electron transmission path and further enhances the electron conduction.Electrochemical studies show that GF has good storage sodium performance.In the hydrothermal process,by adding hydrogen peroxide,the effect of the pre-oxidation process on the electrochemical performance of GF composite nanomaterials was further explored.The results show that the graphene/Fe₂O₃composite(HGF)prepared after pre-oxidation can obtain better sodium storage electrochemical performance,and provides a high reversible discharge capacity of 597.1m Ah g^-1at a current density of 0.1 A g^-1.(2)A nitrogen-doped graphene/Fe₂O₃(N-GF-300)composite was designed and prepared by low temperature water bath and annealing treatment,in which Fe₂O₃nanoparticles with a homogeneous size of about 30 nm were uniformly anchored on the graphene nanosheets.The doping of nitrogen on the graphene sheet structure enhances the connection between the Fe₂O₃nanoparticles and the graphene nanosheets,improves the conductivity and cushions the volume expansion of the material,thereby achieving SIB high capacity and stable cycling performance.The test results show that it provides a high reversible discharge capacity of 638 m Ah g^-1at a current density of 0.1 A g^-1,and maintains a capacity of 428.3 m Ah g^-1after 100 cycles under the condition of 0.5 A g^-1,moreover,the loss rate per turn is only 0.08%,which confirms the cycle stability of N-GF-300 used as SIB negative electrode.Organic asymmetric SIS were assembled using N-GF-300 as the negative electrode and graphene as the positive electrode,and explore its electrochemical performance and energy storage mechanism from the device.Through various electrochemical tests,its research results show that the asymmetric N-GF-300//graphene SIS exhibits high energy density and power density in organic solutions.When the power density is 1365 W kg^-1,the energy density can reach 58 Wh kg^-1.