Electrochemical Storage Materials Based On Pore Structure

Problems including environmental pollution and energy shortage have been brought by the rapidly growing economy world spread,which promotes the development of energy storage devices.As electrical energy storage devices,supercapacitors have attracted considerable interest due to the high power density and long cycle life.Materials with pore structures possess larger specific surface area,which can facilitate the processing of redox reactions.Therefore,they can be used as electrode materials for supercapacitors.Both metal-organic frameworks and porous carbon own pore structure,and the pore size of metal-organic frameworks is tunable.By combining metal organic framework or porous carbon with other materials,high electrical storage performance can be achieved.In this thesis,cobalt-vanadium-nickel ternary metal-organic framework,cobalt-nickel selenide/porous carbon and sulfur-doped-nickel-based metal-organic framework composites（S-Ni-BDC）were prepared,respectively.The crystal structures and elemental distributions of the prepared electrode materials were characterized by characterizations including X-ray diffraction,scanning electron microscopy,X-ray photoelectron spectroscopy.The electrochemical properties of the electrode materials were investigated by cyclic voltammetry and galvanostatic charge/discharge method.Electrochemical results show that the obtained Co₁V₂Ni₁-MOF with a cobalt/vanadium/nickel molar ratio of 1:2:1 has the best electrochemical storage performance among the prepared cobalt-vanadium-nickel ternary metal-organic framework in different composition ratios.The specific capacitance of Co₁V₂Ni₁-MOF can achieve 838.32 F g^-1at the current density of 0.5 A g^-1,and it can maintain 88.3%of the initial specific capacitance after 1000 cycles of charging and discharging,showing a good capacitive performance.The prepared cobalt-nickel selenide with a metal molar ratio of 1:1 showing the best electrochemical performance,was further combined with porous carbon derived from ZIF-8 as the precursor,obtaining Co₁Ni₁Se@CZIF composite.A capacitance retention of 95.1%can still achieved after 1000 cycles.Nitrogen adsorption-desorption measurements showed that the obtained Co₁Ni₁Se@CZIF composite exhibits a typical mesoporous structure.In addition,when the amount of 1,4-benzenedimethanethiol added into Ni-BDC was 12.9 mg,the resultant S-Ni-BDC-12.9had a specific capacitance of 938.10 F g^-1at a current density of 0.5 A g^-1,with the corresponding power density and energy density of 150.1 W kg^-1and 46.9 Wh kg^-1,respectively.Electrochemical results show that the sulfur doping can improve the specific capacitance of the electrode material,achieving a better electrochemical storage performance.Experimental results all indicate that the electrode materials with pore structures own great application prospects in the field of supercapacitors.