Synthesis And Properties Of Metal Organic Framework Materials For Supercapacitor

As new type of electrochemical energy storage device,supercapacitors have attracted much more attention due to its high power density,excellent cycle stability and less environmental pollution.Metal-organic framework compound（MOF）materials can be used to design electrode materials with high specific surface area and controllable pore size.In this paper,porous carbon composite materials with Co doped（Co@PC）were synthesized by using MOF ZIF-67 as templates.The Co@PC composite materials were modified by using porous Ni（OH）₂,and Ni（OH）₂/Co@PC nanocomposites have been prepared with excellent electrochemical performance.ZIF-67 precursor presents regular dodecahedron diamond structure with the side length of about 600 nm.The specific surface area was as high as 1149 m² g^-1.The ZIF-67 precursor presents nanoporous structure characteristics with a pore size of about1.0 nm and 1.4 nm with a total pore volume of 0.011619 cm³ g^-1.Porous carbon composite materials（Co@PC）were prepared by using as ZIF-67 precursor,which also shows a dodecahedron diamond structure with a high specific surface area of 303 m² g^-1.The composite materials were measured as the supercapacitor electrode materials that the discharge specific capacity was 146 F g^-1 at the current density of 0.5 A g^-1.Ni（OH）₂/Co@PC nanocomposites were synthesised by modifying Co@PC composites surface with porous Ni（OH）₂ by using electrochemical deposition method.A high specific capacity of 952.4 F g^-1 has been obtained at the current density of 0.5 A g^-1,which was about 6.5 times higher than Co@PC materials.When the current density increased 10times(5 A g^-1),the specific capacity can maintain as high as 850 F g^-1,which is about 89%of the specific capacity(952.4 F g^-1)at 0.5 A g^-1.Asymmetric supercapacitor have been assembled by using Ni（OH）₂/Co@PC nanocomposites and carbon material,which shows a high energy density of 33.6 Wh kg^-1 at the power density of 516.3 W kg^-1,and the energy density can still maintain as high as 27.5 Wh kg^-1 when the power density of the capacitor was 2025.0 W kg^-1.In addition,the asymmetric supercapacitor presents a higher capacity retention rate of 83.7%after 10000 cycles at the current density of 2 A g^-1.