Hydrothermal Preparation Of Nickel-based Sulfide And Its Supercapacitor Performance

Supercapacitor is a kind of energy storage equipment between ordinary capacitor and battery.It has become a research hotspot because of its advantages such as fast charging and discharging speed,high power density and long service life.Supercapacitors can be divided into double-layer capacitors and pseudocapacitors.Pseudocapacitors have attracted wide attention because of their faraday redox reaction ability,which can achieve higher energy density than double-layer capacitors.Among them,the nickel-based sulfide in the pseudocapacitor electrode material has higher electrochemical activity.In order to improve the performance of supercapacitors,this paper studies nickel-based sulfides by adjusting the morphology and designing the structure.The details are as follows:（1）Layered Ni₃S₂ nanorod/nanosheet arrays were prepared by hydrothermal vulcanization method.Ostwald curing process of stratified Ni₃S₂ nanorod/nanosheet arrays was determined by a series of time-and temperature-dependent controls.The array has a high areal capacitance of 5540 m F cm^-2 at 2 m A cm^-2,much higher than the Ni₃S₂nanosheet arrays(1469.6 m F cm^-2).The capacitance retention rate of the layered Ni₃S₂nanorod/nanosheet electrode was 78.9%at 10 m A cm^-2 after 1000 times of charge and discharge.This work provides a promising method for the preparation of layered Ni₃S₂nanorod/nanosheet arrays as high-performance electrochemical capacitors.（2）A mixed layered Ni₃Sn_xS_2-x nanomaterial was synthesized by solvothermal method.By adjusting the concentration of Sn element,the morphology and structure of the nanomaterial were transformed from vertical nanosheet arrays to composite arrays of vertical and horizontal nanosheets,and the phase transition was transformed from Ni₃S₂to Ni₃Sn₂.After the introduction of Sn element,many electrochemical active sites and mixed layered structures are generated,making the optimized Ni₃Sn_xS_2-x as the electrode material of supercapacitor,with a high capacitance of 2377.78 m F cm^-2 at 1 m A cm^-2.At20 m A cm^-2,the capacitance retention rate is 137.86%after 5000 cycles.In addition,the magnetic properties of the material are changed due to the change of phase,which has a significant impact on the electrochemical properties.This work proves that Ni₃Sn_xS_2-xnanomaterial is a good energy storage material.（3）Ni Co₂S₄/Ni₉S₈ nanocone composite were prepared on nickel foam by a one-step hydrothermal method.Ni Co₂S₄/Ni₉S₈ nanocone shape with well-arranged morphology and uniform dispersion was synthesized by adjusting time.This good morphology and the multiple valence states provided by bimetallic compounds make the optimized material as electrode material of three-electrode supercapacitor with super high areal capacitance.The optimized material can be used as electrode material of three-electrode supercapacitor.When the current density is 5,8,10,20,50,80 and 100 m A cm^-2,the areal capacitance is 11200,9910.4,9150,7724,5762,4593.6 and 3872 m F cm^-2,respectively.At 80 m A cm^-2,the capacitance retention rate was 44.76%after 3000cycles.The preparation method of the material has certain guiding significance for the development of electrochemical energy storage technology.