Synthesis Of Zinc Cobalt Electrode Materials And Their Electrochemical Performances

As an environmentally friendly energy storage device,supercapacitors have attracted the attention of researchers due to their high power density,long cycle life and fast charge and discharge characteristics.Development of High Performance Supercapacitors are one of the effective measures to solve today's environmental problems and fossil fuel shortages.Among them,the spinel structure of zinc cobaltate?ZnCo₂O₄?is a promising supercapacitor electrode material,which has higher theoretical specific capacitance and electrochemical performance than single metal oxide,but low conductivity and actual specific capacitance limit its application.In this work,ZnCo₂O₄ and its composites were studied.By studying their preparation and synthesis process,phase composition,micro-morphology and electrochemical properties,the effects of preparation process and micro-structure of electrode materials on electrochemical properties are analyzed.which provides reference for the design and research of other electrode materials.The main research contents are as follows:?1?Two kinds of electrode materials,ZnCo₂O₄ nanosheets and ZnCo₂O₄ nanowires were prepared by hydrothermal method and their phase composition,microstructure and electrochemical properties were tested.The electrochemical performance tests show that the electrochemical performance of the ZnCo₂O₄ nanosheets electrode material is excellent.The area specific capacitance is 1.86 F/cm² at a current density of 2 mA/cm².And after 1000 cycles of the charging and discharging at a current density of 20mA/cm²,the capacitance value retain 92.6%.This excellent performance is mainly attributed to the three-dimensional network structure of ZnCo2O4,which has larger specific surface area.It enables the electrolyte solution to fully contact the electrode material,shortens the ion transport channel and improves the charge transport capability.?2?The Fe³⁺doped ZnCo₂O₄ electrode material was prepared by hydrothermal method.The electrochemical test results show that after Fe³⁺doping,the electrochemical performance of the ZnCo2O4 electrode material is improved.The area specific capacitance is 0.95 F/cm² at a current density of 2 mA/cm².And after 1000cycles of the charging and discharging at a current density of 20 mA/cm²,the capacitance value retain 90.7%.This excellent properties are mainly attributed to the uniform dispersion of Fe³⁺on the periphery of the nanostructure,which leads to an increase in the conductivity of the electrode material.It facilitates the transfer of charge between the electrolyte solution and the electrode material.?3?The core-shell structure electrode materials with different morphologies of ZnCo₂O₄@CoMoO₄ and CoMoO₄@ZnCo₂O₄ were prepared by two-step hydrothermal method.The electrochemical properties of ZnCo₂O₄@CoMoO₄ electrode materials were the best.The area specific capacitance is 3.97 F/cm² at a current density of 2 mA/cm².And after 1000 cycles of the charging and discharging at a current density of 20mA/cm²,the capacitance value retain 107.1%.This excellent performance is mainly attributed to its unique core-shell structure,which can fully exploit the characteristics of the two electrode materials and show better synergistic effects.Moreover,the interlaced three-dimensional structure has a high porosity,which shortens the diffusion distance of the charge between the electrolyte ions and the electrode material,thereby exhibiting better electrochemical performance.