Synthesis Of Spinel Type Sulfides As Pseducapacitor Electrode Materials And Their Electrochemical Activities

In this thesis,we have reviewed the latest development of supercapacitor and its electrode materials,and have synthesized several spinel type sulfides as pseducapacitor electrode materials.The composition,morphology and structure of the products were characterized by means of SEM,TEM,XRD and XPS.The electrochemical performances of the products were measured by cyclic voltammetry?CV?,glvanostatic charge-discharge technique?GCD?and electrochemical impedance spectra?EIS?.The main coveragies are as followings:1.Homogeneous core–shell spinel NiCo₂S₄ nanostructures were directly grown on nickel foam substrate by a two-step hydrothermal method.The composition and morphologies of the samples were characterized by means of XRD,XPS,SEM and TEM.The homogeneous core–shell NiCo₂S₄ can be applied as super capacitor electrode material,and shows a capacitance of 1948 mF cm^-2 at a current density of 1mA cm^-2.After 5000 charge–discharge cycles,the capacitance retained 94%of the initial value.By using NiCo₂S₄ as positive electrode,and porous carbon as negative electrode,an asymmetric supercapacitor device was assembled,and the electrochemical performances of the device were measured.2.By using Cu₂O nanocubes as sacrificial template,NiCl₂·6H₂O and CoCl₂·6H₂O as raw material,hollow Ni–Co double hydroxides nanoboxes were prepared through a hyderthermal route.Then,by using the Ni–Co double hydroxides nanoboxes as precursor,spinel NiCo₂S₄ nanoboxes were prepared through sulfidization.The products were characterized by XRD,XPS,SEM and TEM.The electrochemical performances of the products were also measured.3.Fence-like spenel Mn-Co-Ni ternary sulfide was successfully prepared on nickel foam substrate by a facile two-step hydrothermal method.The as-prepared sample have an ultrahigh capacitance of 3130 mF cm^-2 at a current density of 2 mA cm^-2,even at a high current density of 32 mA cm^-2,the electrode also have a areal capacitance of 2560 mF cm^-2.By using the as-prepared Mn-Co-Ni ternary sulfide as positive electrode,porous carbon as negative electrode,an asymmetric supercapacitor device was assembled.The asymmetric supercapacitor device shows a capacitance of 1041.5 mF cm^-2 at a current density of 2mA cm^-2.