Preparation Of Nickel Cobalt Based Metal Organic Frameworks And Its Application In Supercapacitor

Supercapacitors(SCs)are electrochemical energy storage devices,and their energy density needs to be improved.Metal organic framework(MOF)is a kind of coordination supramolecular material composed of coordination metal ion nodes and organic ligands,which is a rising star in the field of materials science.The electrode material is the"heart"of SCS.In this paper,a new preparation method was used to solve the problem of active sites missing caused by high temperature calcination.(1)NiCo-MOF was synthesized by room temperature ultrasonic method and compared with Ni-MOF and Co-MOF.The morphology and orientation of NiCo-MOF synthesized at room temperature were investigated,and the relationship between two-dimensional lamellar structure and electrochemical performance was explained.Under the current density of 1 A g^-1,the specific capacitance is 690 F g^-1,and the equivalent resistance is 2.73?.The experimental results show that the two-dimensional lamellar structure is conducive to the electron transport and accelerate the redox reaction,while the introduction of organic binder makes the impedance larger,and the wettability and electrolyte transport of the electrode need to be improved.(2)NiCo-LDH was grown on foamed nickel by galvanostatic deposition,which effectively avoided the introduction of organic binder.NiCo-LDH with good morphology was successfully prepared by adjusting electroplating time,electrolyte solubility,electroplating potential and current density.The electrochemical performance of NiCo-LDH was tested in 3mol L^-1 KOH electrolyte.The results show that the specific capacitance of two-dimensional lamellar NiCo-LDH nanosheets is 882 F g^-1 at 0.5 A g^-1.(3)NiCo-MOF nanosheets were prepared by using NiCo-LDH as self-sacrificial template.At 0.5 A g^-1,the specific electric capacity is up to 1289.5 F g^-1.The power density and energy density of ASC assembled with activated carbon can reach 57.8 Wh kg^-1 and 748.7W kg^-1,and the capacitance retention rate can reach 71.40%after 5000 cycles at 10 A g^-1,which shows good cycle stability.The asymmetric capacitor successfully lights 5 mm LED lamp for 7 minutes.