The Electronic Structure Control And Energy Storage Performance Of NiO Nanosheets

Supercapacitor is one of the most promising new energy storage devices.It has many advantages,such as high rate performance,long cycle life and high safety performance.Carbon materials are commonly used as electrode materials for supercapacitors,but low energy density hinders their application in practice.Transition metal oxides are considered as one of the promising electrode materials because of their low cost,abundant resources and high redox activity.Supercapacitors store energy through active sites or surface atoms provided by electrode materials,so the more active sites or surface atoms the stronger the ability of electrodes to store energy.The specific surface area（even more active sites or surface atoms can store electric energy）of the material can be increased by reasonable design of the nanostructure for the material.Meanwhile,the nanostructure can also provide an effective diffusion channel for electrolyte ions.In order to further enhance the energy storage capacity of the electrodes,the composite by two different materials are usually used synthesized,so that the composite materials retain the original advantages,while using another material to make up for the defects,thereby improving the overall electrochemical energy storage performance of the composite materials.It is well known that in order to coat the electrode material on the collector surface,binder is usually added to make the material adhere to the collector without falling off,but the addition of binder will increase the internal resistance of the electrode,thus affecting the performance of the electrode.For this reason,direct deposition of active materials on the collector surface can effectively avoid the use of adhesives and prevent the unnecessary increase of the internal resistance of the electrode.Based on the above mentioned problems,the effect of reaction kinetics on the synthesis of materials is studied in this paper.The nanostructure of materials is precisely controlled and successfully deposited on the collector surface.The electrochemical properties of the materials are studied in a series of ways.Apply foam nickel as the base material,the mesoporous NiO nanosheets and CoMoO₄ were deposited on the surface of the foam nickel by hydrothermal and heat treatment methods.The NiO/NF and CoMoO₄/NF were successfully prepared.Then,the NiO/NF electrode material was used as the substrate,and the CoMoO₄ nanosheets were deposited on the surface of the mesoporous NiO nanosheets by hydrothermal method,and the electrode of NiO@CoMoO₄/NF nanosheets was successfully prepared.The relationship between the nanostructure and electrochemical properties was also studied.The morphology and structure of the prepared materials were characterized by SEM,XRD,TEM and XPS.The electrochemical energy storage performance of the prepared electrodes was evaluated by cyclic voltammetry（CV）,galvanostatic charge-discharge（GCD）,electrochemical impedance（EIS）and life span test.The results show that the prepared NiO@CoMoO₄ nanosheets/NF electrode has better electrochemical energy storage performance.The current density of 1 A/g is the maximum specific capacity of 1097 F/g,while the current density of NiO/NF and CoMoO₄/NF is only 173 F/g and 349 F/g,respectively,which is much smaller than the electrochemical performance of the two materials after composite,which is attributed to the synergistic effect of the two materials,and the assembly of the two materials is also asymmetric super.After the capacitor,NiO@CoMoO₄ nanosheet/NF exhibits the highest energy density of 25.8 Wh/kg and power density of 894.7 W/kg,which is higher than that of single material electrode.After 3000cycles of cyclic life test,the original specific capacity can still be maintained at 100%,which is also superior to the two single materials.This further confirms the prospects of the preparation method of this material.It provides an effective strategy for precisely designing the micro-morphology of the composite and successfully depositing it on the collector surface.