The Preparation Of Nickel-iron-based Electrode Materials And Their Applications In Supercapacitors

Supercapacitors are considered to be the most attractive next-generation devices in electrochemical energy storage systems,also known as electrochemical capacitors.Supercapacitors have excellent characteristics in terms of power density,cycle life and safety performance,and have great potential value in the future development.It can be used in portable electronic devices,memory backup systems,energy management,hybrid electric vehicles and industrial-scale power supplies.However,due to the low energy density of supercapacitors,it is limited in practical use,which restricts its application and development in industry.Electrode material is the most important component of supercapacitor.The performance of electrode material is directly related to the performance of capacitor.Therefore,supercapacitor electrode material has become a research hotspot.The main research contents are as follows:?1?Ni-Fe-O composites under different reaction conditions were prepared by a simple one-step hydrothermal process.As observed from SEM images,the surface morphology were found to be significantly changed by adjusting the reactive ion ratio,reaction time,reaction temperature and p H.As reaction time and reaction temperature increase,the material begins to agglomerate and forms semi-spheres.As the p H increases,the semi-spheres begin to break and form irregular particles.Electrochemical tests show that the electrochemical performance of the material is best when ion ration of Ni:Fe=2:1,reaction time 2h,reaction temperature 100?,p H=5.7with a specific capacity of 268.6F g^–1at 5mv/s.This may be related to the formation of a uniform spherical shape,which can provide a larger specific surface area,increase the diffusion pores of the electrolyte ions,and therefore improve the electrochemical performance of the composite electrode material.These studies on the effects of various reaction conditions on the surface morphology and electrochemical performance of Ni-Fe-O can provide a reference for the controlled synthesis of morphology.?2?A novel bimetallic Ni-Fe-Se nanomaterial for supercapacitors electrode were prepared by a simple two-step hydrothermal process.The Ni-Fe-Se sample consists of octahedrons partly covered with some particles.This novel electrode material has high specific surface area and high conductivity and therefore exhibits high specific capacitance of?909.7 F g^–1 at 0.5 A g^–1 and still retains 550.0 F g^–1 at a 20-fold current density as well as a high capacitance retention of?74.1%after 5000 cycles at 10 A g^–1.An asymmetric supercapacitor was assembled using Ni-Fe-Se as the positive electrode and active carbon as negative electrode,which exhibits a high energy density of 20.1 W h kg^-1 at the power density of 813 W kg^-1 and a high capacitance retention of 90%after 5000 charge/discharge cycles,demonstrating that Ni-Fe-Se material is promising for high performance supercapacitor.