Preparation And Electrochemical Performance Of Composite Materials Based On Zeolitic Metal Organic Frameworks

The rise of portable electronics and new energy electric vehicles has raised the demand for safe and efficient energy storage equipment.Supercapacitors with long cycle life,high energy density and high power density play an important role in the field of energy storage and are potential energy storage devices.However,The performance of the device depends greatly on its electrode material.As a kind of electrode material,metal oxides have many kinds and a higher theoretical specific capacitance.But some inherent disadvantages of the single material itself make it unable to be widely used in capacitors.So,it is necessary to design and prepare multicomponent,high performance metal oxides,and combine the advantages of each single component.Recently,a large number of reports have indicated that multi-component,layered composite metal oxides can combine the advantages of each single component,and can effectively improve the electrochemical performance of supercapacitors.Taking this as point,this paper prepared samples by calcining precursor.Using zeolite-like metal-organic skeleton as template,the metal nitrates were loaded onto the skeleton by solvothermal method to prepare the precursors.The annealed precursors were used as research samples,and then their applications in supercapacitors were studied.The main work of this paper is as follows:?1?A three-dimensional porous nanomaterial Co₃O₄/ZnCo₂O₄/CuO with hollow polyhedral structure and highly enhanced electrochemical performance was synthesized successfully by a zeolitic metal organic framework-67 as template.The influence of the mass ratio of zinc nitrate and copper nitrate on the electrochemical propertie of the composite was discussed,and the optimized Co₃O₄/ZnCo₂O₄/CuO-1compositeelectrodeexhibitedhighelectrochemicalperformance.The Co₃O₄/ZnCo₂O₄/CuO-1 holds the shape of the ZIF-67 template well and the shell has multi-compositions.And,the Co₃O₄/ZnCo₂O₄/CuO-1 electrode exhibited a specific capacitance of 890.2 F g^-11 at a current density of 1 A g^-1.The assembled CZC-1//AC asymmetric supercapacitor?ASC?can be reversibly cycled in a large potential range of 0-1.6 V and deliver a high energy density of 35.82 Wh kg^-11 as well as the maximum power density of 4799.25 W kg^-1.In addition,two ASC devices in series can successfully light up various colors LED.?2?A rational design and synthesis of ternary ZnO/ZnCo₂O₄/NiO wrapped by nanosheets was studied.The polyhedral ZnO/ZnCo₂O₄/NiO with core-shell structure were prepared using ZIF-8 as template by in situ growth and solvent thermal method.The effects of the molar ratio of nickel nitrate and cobalt nitrate on the morphology,structure and electrochemical properties of the composites were discussed in detail.The ZnO/ZnCo₂O₄/NiO-2 electrode exhibited a high specific capacitance of 1136.4 F g^-11 at 1 A g^-11 and excellent cycle stability of 86.54%after the 5000 cycles.The assembled ZZN-2//AC asymmetric supercapacitor can realize the energy density of46.04 Wh kg^-11 and the power density of 7987.5 W kg^-11 in the large voltage range of0-1.6 V.After charging for some time,the capacitor device can light up the LED and the LED can last for more than 20 minutes,showing the practical application value of the material.?3?Ternary ZnO/Co₃O₄/NiO with layered core-shell structure was successfully prepared by seed method,solvent thermal method and calcining.At the same time,the effect of load on the morphology and electrochemical properties of product was studied,the optimized ZnO/Co₃O₄/NiO-2 composite electrode exhibited better electrochemical performance.When the current density is 1 A g^-1,ZnO/Co₃O₄/NiO-2shows high specific capacitance of 1600 F g^-1,In addition,at the current density of 10A g^-1,after 10000 cycles of charging and discharging,the capacitance value can still maintain 93.75%of initial capacitance.The voltage window of assembled ZCN-2//AC asymmetric supercapacitor can reach 1.6 V,and the maximum energy density can reach 95.82 Wh kg^-1.After 5000 charge-discharge cycles at a 10 A g^-1current density,the cycling stability can reach 94.53%of the initial value.And after a charge,two ASC devices in series can successfully light up a LED light.