Preparation Of Ni/Co Metal Compound Electrode Materials For Supercapacitor Performance

Supercapacitors have attracted extensive attention due to their high-power density,high specific capacity and rapid charging and discharging ability.As we all know,the type of electrode materials plays a very important role in supercapacitors,including different kinds of carbon materials,conductive polymers and transition metal compounds.When the transition metal compounds are used as electrode materials,reversible reactions among various oxidation states can be effectively used to significantly increase their energy density.Unfortunately,transition metal compounds tend to collapse in volume in alkaline solutions,leading to their poor stability and reduced electron conversion rates.In order to further improve the performance of transition metal compound electrode materials,the energy storage performance of supercapacitors can be improved by adjusting the conductivity,morphology,structure and specific surface area of the materials.In this paper,based on Ni/Co metal compounds,the synergistic effect between transition metal elements is used to design electrode materials with excellent performance.The specific work is as follows:1.The synergistic advantage of different metal ions in two or more metal compounds improves electrochemical performance compared with single metal compounds.The improvement of energy storage capacity of polymetallic compounds is due to the redox reaction of different active centers,and the polyvalence of transition metals can improve the conductivity.At the same time,the corrosion resistance of the base material is improved,and the cycle performance of the electrode material is greatly enhanced.In this paper,nickel foam（NF）was first electroless plated nickel phosphorus alloy to improve its corrosion resistance in alkaline solution.After the preparation of Co-ZIF-67,the growth of Ni Mo-LDH was achieved by controlling the hydrothermal reaction time.Finally,NF/Ni-P@NCM-LDH composite with spheroidal nanosheet structure was successfully synthesized as a binder-less electrode.The composite has the morphology of spheroidal nanosheet,showing excellent electrochemical performance and cycling stability.The detailed study shows that the electrode material has high specific capacitance and good cycle life due to the abundant active sites and thin structure of the nanosheet.NF/Ni-P@NMC-LDH//AC ASC achieved an energy density of 91.2 Wh·kg^-1 at a power density of 727.9 W·kg^-1,and maintained a capacity of 86.97%after 5000 cycles.Thus,this work provides a simple and effective way to manufacture ingenious collaborative nanostructures with good energy storage capacity.2.The capacitance performance of electrode materials can be improved by combining the same metal oxides with different morphology and microstructure,and the performance can be effectively improved by adjusting the morphology of transition metal compounds.In this paper,a simple and safe method is developed to prepare Ni（OH）₂-B/S composites with thicker and more densely distributed hydrangea nanosheet structure after vulcanization.Firstly,the borides were doped during the hydrothermal preparation of Ni（OH）₂,after which the morphology of the composites was regulated by varying the amount of sodium sulfide,and the electrochemical performance were significantly enhanced.When the molar ratio of nickel nitrate to sodium tetraborate and sodium sulfide in the precursor solution is 1:1 and1:12,the obtained Ni（OH）₂-B/S shows the best electrochemical performance.When the current density is 1 A·g^-1,the composite material can obtain a high specific capacitance of1550 F·g^-1.Moreover,Ni（OH）₂-B/S also has good cycling performance（71.4%after 10000cycles）.In addition,the Ni（OH）₂-B/S//AC ASC has an energy density of 60.5 Wh·kg^-1 at a power density of 825 W·kg^-1.The prepared Ni（OH）₂-B/S composites are simple to prepare,exhibit low toxicity,can be produced on a large scale,and the raw materials used are well stocked,which are expected to be effective for supercapacitor production and other energy storage applications.3.Materials based on zeolite imidazole framework（ZIFs）have uniform pores,large specific surface area and simple structure.In particular,the electrical conductivity of Co-based ZIF-67 is much higher than that of Zn-based ZIF-8,making cobalt-based ZIF-67widely studied as an energy storage material.In this paper,the precursor of Co-ZIF-67 with regular cube structure was first synthesized,and then nickel-coated carbon nanotubes（CNT）and NiLa-LDH were introduced by controlling the hydrothermal reaction time to prepare an electrode material with nanosheet structure on carbon nanotubes.The electrochemical study showed that,Co-ZIF-67@CNT@NiLa-LDH composite has high specific capacitance of1710 F·g^-1 at a current density of 1 A·g^-1.Co-ZIF-67@CNT@NiLa-LDH//AC asymmetric supercapacitors exhibit excellent capacitive performance(150.1 F·g^-1 at current density of 1A·g^-1),wide operating voltage window（1.7 V）,and excellent stability.This research lays the foundation for the design of a ZIFs derivative for capacitive energy storage devices.