Synthesis And Electrochemical Properties Of Cobalt-based Bimetal Oxide Materials

Transition metal oxides,as electrode materials of supercapacitors,have high theoretical specific capacitance and various oxidation state.The unitary metal oxides are difficult to be applicable to supercapacitors due to their low electric conductivity and poor cycle stability.In this paper,binary metal oxides and their composite were used as research objects,and they were synthesized through a hydrothermal and followed calcination treatment.Crystalline structure of the materials was confirmed using X-ray diffraction.Micromorphology of the materials was analyzed using scanning electron microscopy.Elemental composition of the materials was analyzed using EDS spectrometer.Electrochemical performance of the materials was analyzed using the CS350 electrochemical workstation.The main research contents are as follows:(1)The synthesis and electrochemical properties of ZnCo2O4 materials were studied.ZnCo2O4 electrode material was synthesized by a hydrothermal and calcination treatment,using urea as precipitant and NH4F as morphology modifier.The effects of reaction time,reaction temperature,the amount of urea,and calcination temperature on the structure,morphology,and electrochemical performance of ZnCo2O4 materials were studied.The results show that these factors have a certain effect on the structure,morphology,and electrochemical performance of ZnCo2O4.Among them,the calcination temperature has the greatest effect on the crystallization process of ZnCo2O4.In comparison,the synthesized ZnCo2O4 material with reaction time of 7 h,reaction temperature of 120℃,urea addition amount of 5.5 mmol,and calcination temperature of 400℃ has more excellent electrochemical performance.The wrinkle structure on the surface of the microsphere provides enough space for the electrolyte to fully contact the material.The pore structure on the surface of the microsphere allows the ions in the electrolyte to fully penetrate into the inside of the electrode material,so that more reactions can occur.(2)The synthesis and electrochemical properties of NiCo2O4 materials were studied.By changing the raw materials,the flower-like NiCo2O4 electrode material was synthesized using the above methods and conditions for synthesizing ZnCo2O4.The flower-like NiCo2O4 material is composed of nanosheets,and the surface of the nanosheets has many small pore structures.The large grid space between nanosheets and nanosheets facilitates the contact between the electrolyte and the material,and the pore structure on the nanosheets facilitates the transfer of ions between the electrode and the electrolyte,which can generate more ion exchanges and is beneficial to charge storage.(3)The synthesis and electrochemical properties of ZnCo2O4/NiCo2O4 composite were studied.The flocculent ZnCo2O4/NiCo2O4 composite was synthesized by following the above-mentioned methods and conditions for synthesizing ZnCo2O4.The results show that the ZnCo2O4/NiCo2O4 composite has more excellent electrochemical performance than the pure ZnCo2O4 and NiCo2O4 materials.The reasons may be:1)The flocculated structure not only facilitates the contact between the material and the electrolyte,but also facilitates the penetration of ions in the electrolyte;2)The ZnCo2O4/NiCo2O4 composite combines the advantages of ZnCo2O4 and NiCo2O4 and their synergistic and multifunctional effects are beneficial to the improvement of electrochemical performance.