The Synthesis And The Electrochemical Properties Study Of Nickel-based Composites For Hybrid Supercapacitors

Faced with the increasing environmental pollution and the increasing consumption of traditional non-renewable energy,it is urgent to research and develop clean,environmentally friendly and renewable energy.However,the stability of the common renewable energy,such as wind energy,solar energy and tidal energy,is seriously affected by natural conditions,limiting the efficiency and scope of their practical application.Supercapacitors have become the focus of research because of their good storage performance,fast release of energy,long service life,good temperature characteristics and environment-friendly.Usually,the performance of supercapacitors depends on the characteristics of electrode materials.Therefore,developing high-performance electrode materials is the key to improve the performance of supercapacitors.Nickel-based materials such as NiO,Ni?OH?₂ and Ni₃S₂ have the advantages of high theoretical specific capacity,stable structure,rich source and easy preparation,and become the ideal selection of electrode materials for supercapacitors.However,the low conductivity of NiO and Ni?OH?₂ and the easy agglomeration of Ni₃S₂ all affect their comprehensive electrochemical properties as electrode materials alone.If they are combined,the synergy between substances can be realized to achieve complementary advantages and improve the comprehensive electrochemical performance of composite electrode materials.In this paper,pure nickel-based composites are formed by combining NiO and Ni?OH?₂ with Ni₃S₂ on the basis of nickel foam.The experimental scheme is designed to avoid agglomeration and improve the conductivity of materials to synthesize a uniform distribution electrode material with unique structure to improve the electrochemical performance of the electrode material,such as capacity and cyclic stability.The main contents of this paper are as follows:?1?Ni O/Ni₃S₂ composite nanomaterial directly grown on nickel foam were prepared by hydrothermal synthesis and heat treatment.The high conductivity of Ni₃S₂ improves the electrical conductivity of the composite,and makes up the shortcomings of the poor electrical conductivity of the NiO.At the same time,the interface resistance of NiO/Ni₃S₂ is reduced on the nickel foam.The unique cliff-like structure is formed and the stability of the structure is enhanced.Therefore,as an electrode material of supercapacitors,NiO/Ni₃S₂/NF shows excellent electrochemical performance.Under the current density of 2 mA cm^-2,the capacity reaches 2.28 C cm^-2,and the capacitance remains 102%after 10 000cycles.In addition,in this work,we also use NiO/Ni₃S₂ as the anode and active carbon?AC?as the cathode to assemble the hybrid supercapacitor.The hybrid capacitor also shows excellent performance.Its energy density and power density can reach 43.99 Wh kg^-1 and 2305.80 W kg^-1 respectively.After 5000 cycles,the capacity retention rate is 95.36%,and a series of LED lamps can be lit successfully.?2?A Ni₃S₂/Ni?OH?₂ composite material on nickel foam substrate was designed and synthesized by hydrothermal synthesis and electrodeposition.First,the uniform growth of Ni₃S₂ on nickel foam is synthesized to avoid agglomeration and increase its utilization.Then,Ni?OH?₂ was deposited on Ni₃S₂ surface by electrodeposition to form a hierarchical structure.During the electrochemical reaction,Ni?OH?₂ played a protective role on the underlying Ni₃S₂.Therefore,the Ni₃S₂/Ni?OH?₂/NF showed a strong cyclic stability in the electrochemical test,and the capacity retention rate was up to 113%after 30 000 cycles.At the same time,compared with pure Ni₃S₂ and Ni?OH?₂ electrodes,the capacity of Ni₃S₂/Ni?OH?₂/NF has also been improved,and the capacitance of 1.58 C cm^-2can be obtained at the current density of 2 mA cm^-2.Similarly,we use Ni₃S₂/Ni?OH?₂/NF as the anode and AC as the cathode electrode to assemble the hybrid supercapacitor.The hybrid supercapacitor can achieve the energy density of 30.23 Wh kg^-1 and the power density of 3875 W kg^-1.