Construction Of Manganese Oxide/Graphene Composite Electrode And Its Electrochemical Performance

Supercapacitor is one of the most ideal energy storage device.However,the energy density of supercapacitors needs to be further improved due to the increasing requirements of microelectronic devices on the performance of energy storage devices.Electrode material is a key factor to determine the capacity of supercapacitor,so the development of a new reliable electrode is expected to deal with the above problems.It is reported that the highly stable electrode with a double layer energy storage mechanism and the electrode with redox reaction mechanism are the two most widely studied electrode materials.On the basis of their research,this work combines the advantages,and constructs a composite electrode material with high stability and high specific capacity.In this paper,a composite electrode material based on graphene and manganese oxide is designed.Specifically,the 3D porous polyimide（PI）foam with high water absorption is selected as the precursor material of graphene,and manganese acetate is used as the precursor material of manganese oxide.Through direct laser scanning,the high content manganese oxide loaded graphene composite electrode material（LIG/Mn O-Mn₃O₄）is efficiently and rapidly prepared.The morphology and structure of the composite electrode materials are analyzed by scanning electron microscopy（SEM）,X-ray photoelectron spectroscopy（XPS）,Raman spectroscopy and other characterization techniques.The content of manganese oxide in the composite electrode material is analyzed by thermogravimetric analysis（TGA）and inductively coupled plasma（ICP）test,and the electrochemical performance is tested by electrochemical workstation.In addition,PVA/Li Cl gel electrolyte is used to assemble the symmetrical interfingered supercapacitor,and its performance in the device was further explored.The main research conclusions are as follows:The density of PI foam in this work was determined to be 10 kg m^-3by comparing the quality of graphene generated after laser scanning of PI foam with different densities,and the film-forming property and water absorption of PI foam under different parameters.The relationship between the price states of manganese oxide generated at different laser power and scanning speed,and their effects on the electrochemical properties of composite electrode materials were compared and analyzed.Under the optimal laser parameters and doping concentration,manganese oxide/graphene composite electrode with a load of 8 mg cm^-2 is successfully prepared,which reached the level of commercial grade.The electrochemical performance of the LIG/Mn O-Mn₃O₄ electrode is tested.The results demonstrated that the ultra-high specific capacitance of 1525 m F cm^-2 was obtained at the current density of 0.5 m A cm^-2,and the excellent cycle stability of 94.75%was maintained after 6000 charge-discharge cycles.Furthermore,a symmetrical supercapacitors（SCs）assembled with LIG/Mn O-Mn₃O₄ composite electrode materials also possess excellent electrochemical performance,which shows the highest area specific capacitance of 410.19 m F cm^-2,the highest energy density and power density of82.04 u Wh cm^-2 and 400 u W cm^-2,respectively.In conclusion,this article utilized a highly water-absorbent PI foam as the precursor material for graphene.This achieved uniform and high-content dispersion of Mn O-Mn₃O₄ nanomaterials within the graphene,significantly enhancing the utilization rate of pseudo-capacitive materials.Furthermore,it inhibited the agglomeration between graphene layers.