Indirect Synthesis And Electrical Properties Of Transition Metal Oxides

Supercapacitor is a kind of excellent electrical storage devices due to its high energy efficiency and low pollution,and the quality of electrode materials is the key to the development of supercapacitors.Some transition metal oxides have been receiving vast attention of researchers owing to their abundant resources,low cost,wide working potentials and good electrochemical energy storage performance.Graphene,with a two-dimensional structure,possesses large specific surface area and good electrical conductivity.The combination of transition metal oxides and graphene can enlarge the specific surface area and further improve the conductivity of transition metal oxides.In this thesis,the indirect synthesis of transition metal oxide materials and their electrochemical properties were studied.The morphology of the product can be controlled to some extent by indirect methods.Three transition metal oxides were prepared by indirect approaches,including tricobalt tetroxide,cobalt monoxide and trimanganese tetraoxide-manganese monoxide.The prepared transition metal oxides were combined with reduced graphene oxide?rGO?in different mass ratios to obtain the composites with different component ratios.The microscopic structure and chemical composition of the prepared transition metal oxides and composites were characterized by scanning electron microscopy and X-ray diffraction.The electrochemical performance was tested by cyclic voltammetry and galvanostic charge and discharge tests.The results showed that when the mass of the reduced graphene oxide is 5%of the mass of transition metal oxides,the specific capacitance of the tricobalt tetroxide/rGO composite can reach 168 F g^-1 at a current density of 0.5A g^-1,and the specific capacitance can achieve 106%of the initial capacitance after1000 cycles of charge and discharge tests;moreover,the reversible capacity of the composite assembled lithium-ion battery could be maintained at 0.409 A h g^-1 after 200 cycles.cobalt monoxide/rGO and trimanganese tetraoxide-manganese monoxide/rGO composite also showed well-performed stability.Experimental results show that the prepared composite material has certain electrical storage performance and high cycle stability.