The Preparation Of Porous Carbon/Nickel-based Composites As Electrode Materials For Supercapacitors

Supercapacitors have attracted extensive attention in the field of electrochemical energy storage devices due to their advantages of fast charging and discharging capacity in recent years.However,electrode materials directly determine most of the functional indicators of supercapacitors.In order to improve electrochemical performance and meet practical application requirements,it is urgent to find ideal electrode materials.Porous carbon materials have been developed for a variety of applications due to their reproducibility,unique structure and low cost.Also,transition metals.Oxygen/sulfides are widely used as electrode materials for supercapacitors due to their large capacity and controllable morphology.In this paper,by constructing three-dimensional hierarchical porous carbon-based materials,improving the ion diffusion rate,and selecting appropriate composite materials to optimize the reaction conditions,several different morphologic transition metal oxygen（sulfur）compound materials are synthesized,and their supercapacitor performance is further explored as follows:（1）Biomass-based carbon electrodes with precise and controllable biological structures have attracted increasing attention due to their wide availability,reproducibility and low cost.In this study,we used Osmanthus as a raw material in the preparation of nitrogen-doped porous carbon by using a simple carbonization/activation method.It was observed that the prepared biomass carbon had a three-dimensional hierarchical porous,including micropores and mesopores,and the highest specific surface area was 2078.3 m²g^-1.The electrochemical performance of Osmanthus fragrans mainly depends on its microporous/mesoporous performance.At a current density of 0.5 A g^-1,the specific capacitance of the sample reaches 351 F g^-1,and the capacity retention rate is 93.51%after 10,000 charge-discharge cycles.At a specific density of 700 W kg^-1,the specific density reached 13.86 Wh kg^-1.（2）We modified graphene oxide sheets with polydopamine,used abundant oxygen-containing groups to adsorb metal ions in a hydrothermal process,and obtained graphene-supported Ni Mo O₄ nanorod composite materials after pyrolysis.Ni Mo O₄nanorods were uniformly dispersed on the surface of a reduced graphene oxide layer under strong electrostatic adsorption.The specific capacitance of the composite material measured at a current density of 1 A g^-1 was 856 F g^-1(514 C g^-1).When the power density of the device is 800 W kg^-1,its energy density is 45 Wh kg^-1.After 5000times of charging and discharging,the capacity retention rate is by 73%.（3）Metal organic framework as excellent template materials as well as the precursor is often used in super capacitor electrode materials,Ni-MOF as basal material,using solvent hot method,through simple in-situ sulfide,designed the unique morphology of Ni-Co sulfide,unique three-dimensional topography can provide more reaction sites to ensure efficient electron transfer.The composite electrode material has a high specific capacitance of 1636 F g^-1(1 A g^-1)in a 3-M KOH system.Moreover,the device composed of activated carbon exhibits an energy density of 53 Wh kg^-1 and a power density of 810 W kg^-1 in a two-electrode system.