Preparation And Electrochemical Properties Of Transition Bimetallic Sulfides

The fossil fuels provides energy support for the fast growth of industry and society.However,its non-renewable characteristics and long-term excessive consumption have caused serious damage to the ecological environment and inevitably affected the survival of human.With the gradual deepening of human understanding of environmental hazards and the progress of technology,pollution-free renewable energy plays a mainstay role in the energy mix,which can effectively alleviate the above hazards.Due to weather dependence and other factors,renewable energy often cannot provide continuous energy for machine.Therefore,developing energy storage devices with excellent electrochemical performance has long-term significance.In view of the advantages of supercapacitors in service life and power density,it is highly anticipated in the field of energy storage equipment.Among the components of supercapacitor,electrode materials play a key role in the performance of devices,so it is of far-reaching significance to study various electrode materials with excellent electrochemical performance.In this paper,bimetallic sulfide were selected as the research object to explore the impact of reaction conditions on electrochemical performance.Specific research contents are as follows:1.NiCo₂S₄nanospheres with hollow structure were prepared by using Cu₂O as template and ion exchange method.As supercapacitor electrode,NiCo₂S₄benefits from its unique structure and the synergistic effect of transitive bimetals,exhibiting a high specific capacity of960.9 F/g at a current density of 1 A/g,and a long cycle life is 81.5%after 2500 cycles at 20A/g.In addition,the fabricated NiCo₂S₄//activated carbon（AC）asymmetric device（ASC）delivers a high energy density of 45.7 Wh/kg at a power density of 800 W/kg,after 5000cycles,the retention rate of specific capacitance is 79.6%at 6 A/g.2.NiCo₂S₄electrode material was prepared by hydrothermal method using nickel acetate and cobalt acetate as raw materials,reduced glutathione（GSH）as morphology control agent and sulfur source.The effects of hydrothermal reaction time on the microstructure,morphology and electrochemical properties of NiCo₂S₄were investigated.The results show that:NiCo₂S₄material prepared under the action of GSH presents an"yolk-shell"structure.When the current density is 0.5 A/g,the specific capacitance is 1552.7 F/g.When the current density is 10 A/g,the specific capacitance can maintain 61.3%.After 2000 cycles,the specific capacitance retention of NiCo₂S₄electrode material can be maintained at 79.3%at 20 A/g.Using NiCo₂S₄and AC as positive and negative electrodes,an ASC device can provide a power density of 33.9 Wh/kg at 800 W/kg,and a specific capacitance retention rate of 89%after 2000 cycles at 6 A/g.3.Mn S/Ni₃S₂electrode material was hydrothermal generated on nickel foam using a ordinary and short time consuming method,and the effects of hydrothermal time and temperature on the morphology and electrochemical performance of the sample were studied.The returns show that the Mn S/Ni₃S₂electrode material has a specific capacitance of 2825.6F/g at 1 A/g and excellent rate performance,and the retention rate of specific capacitance is90%after 2500 cycles at 50 A/g.Using Mn S/Ni₃S₂as positive electrode and AC as negative electrode,Mn S/Ni₃S₂//AC can provide 30.2 Wh/kg energy density at 700 W/kg,and the specific capacitance retention rate is up to 116.0%after 3000 cycles at 5 A/g.4.Using nickel foam as the base,NiMoO₄with flake structure was grown in situ by hydrothermal method,and then vulcanized to synthesize NiMoO₄/NiMoS₄composite.The effects of hydrothermal time and thiourea addition on the morphology and electrochemical properties of the material were studied.The electrochemical test results show that the specific capacitance of the NiMoO₄/NiMoS₄electrode at a current density of 1 A/g is 1560.7 F/g,which is three times that of the precursor NiMoO₄electrode（510.5 F/g）.After 2000 cycles at40 A/g current density,the capacitance of NiMoO₄/NiMoS₄electrode can still be maintained at 76.7%of the initial specific capacitance.With NiMoO₄/NiMoS₄electrode material and AC as positive and negative electrodes respectively,NiMoO₄/NiMoS₄//AC ASC devices can provide 29.0 Wh/kg energy density at 400 W/kg,and maintain 85.6%of the initial capacitance after 2000 cycles at 5 A/g.