The Preparation Of Zinc Manganese Oxide Micro-nano Structure And Its Electrochemical Properties

Super capacitors have become popular in the field of energy research due to their rapid charge and discharge,long cycle performance,and environmental friendliness.Spinel zinc-manganese oxide?ZnMn₂O₄?material has its unique properties as a composite transition metal oxide.The advantages of good safety,low cost,and environmental protection have made it widely studied in the fields of photocatalysts,gas sensors,battery electrode materials,etc.,but the research on supercapacitor electrode materials and industrial mass production are not yet in-depth.In this paper,zinc and manganese oxides were prepared by three different synthesis methods.The effects of supercapacitor chemistry and calcination temperature on morphology and performance were studied.At the same time,we explored that Zn₂Mn₄O₈?H₂O with crystal water had the excellent electrochemical performance because of the phase transformation of spinel-layer phase in the aqueous electrolyte.The main work contents are as follows:?1?Spinel phase Zn₂Mn₄O₈?H₂O nanoparticles?Zn Mn-NPs?was prepared by the means of KOH solution coprecipitation method at room temperature.Electrochemical datas showed that ZnMn-NPs at 0-1.2V voltage window under the cyclic voltammograms test transform into the layer?-MnO₂-based composite nanosheets from spinel phase.The capacitances of ZnMn-NPs-1.2V in MgSO₄and Na₂SO₄ electrolytes were about 182 F·g^-1 and 324 F·g^-1 at 0.1A·g^-1.The composite showed the excellent electrochemical performance.?2?On the basis of the research of first chapter,we continued to explore samples of different calcining temperature under the cyclic voltammograms tests in high potential window about the phenomenon of spinel-layer phase transformation.The crystal size of the samples obtained after calcination at 400 C,600 C and 800C changed from 14.1nm of ZnMn-NPs to 32.5nm,34.7 nm and 38.5nm,respectively.It was found that the ZnMn₂O₄ particles with relatively large crystal size were obtained under the calcination condition of 800 C,and the same phase transition was almost invisible under the same conditions.According to the electrochemical performance test,we concluded that it had the poor capacitance of 71.8 F·g^-1 at 0.1A·g^-1 and better cyclic stability compared with Zn₂Mn₄O₈?H₂O in MgSO₄ electrolyte solution.?3?ZnMn₂O₄ nano materials were gained by two kinds of ways about ammonia water titration method under normal temperature and solvent and solvothermal method.Comparing the morphology and properties of different two synthesis methods.The test results showed that ZnMn₂O₄ prepared by ammonia water titration method had the capacitance of 444 F·g^-1 and 251 F·g^-1 at 1 A·g^-1.And ZnMn₂O₄ prepared by compared by solvothermal method had the capacitance of 182 F·g^-1 in MgSO₄ electrolytes.The former had more excellent capacitance and more simple preparation method.These datas can lay the foundation of improving the performance and mass industrial production.