The Preparation And Electrochemical Properties Of Graphene/Transition Metal Oxide(Sulfide) Composites

Supercapacitors are considered as a promising energy storage device due to its high power density,fast charge/discharge speed,high rate performance,long cycle life,wide operating temperature limit,and eco-friendly.As the most important component of supercapacitors,electrode materials are the main factors affecting their electrochemical performance.Transition metal oxides/sulfide and hydroxides as the representative of pseudocapacitive materials,which exhibits superior specific capacitance and high energy density.Nevertheless,their rate capability,which rely on fast faradic redox reactions are inhibited because of the restriction of electrical conductivity.Therefore,composite materials made of conductive materials such as carbon materials as the base network are often used to balance conductivity and high capacity.Although there have been many reports about transition metal oxide(sulfide)compound composite materials used as electrode materials,they still have problems such as easy pulverization of electrode materials,poor electrolyte ion infiltration,and weak bonding between composite components.It is very necessary to develop a composite material with good interface connection.In this paper,two types of ternary composite materials are prepared by designing graphene composites with special morphologies(layered and striped),using the characteristics of mesophase components to tightly constrain the pseudocapacitance materials,and preparing two types of ternary composite materials,while ensuring good electrical conductivity.,Improve the rate performance and capacity performance of the material.In this paper,the composition ratio and synthesis conditions of the component materials are optimized,The composition,morphology,and performance in supercapacitors of these materials were verified by various characterizations and electrochemical methods.The main research contents are as follows:(1)MnO_x pillared reduce graphene oxide layered material(G/MnO_x)was obtained through reduction treatment of MnO₂ pillared graphene oxide block precursor(GO/MnO₂).Then the electrochemical additive K₃[Fe(CN)₆]was absorbed between the layers of G/MnO_x through a simply vacuum adsorption method and the FP-G/MnO_x was obtained.As an electrode in supercapacitor,the FP-G/MnO_x-45-8 exhibits a good specific capacitance of 253 Fg^-1 at 2 mV s^-1 and rate capability of 140 Fg^-1 at 500 mV s^-1.(2)NiS_x anchored reduce graphene ribbon and PANI composites(GR/PANI/NiS_x)was obtained by successfully anchoring the NiS_x to the reduce graphene ribbon substrate and PANI interlayer(RG/PANI)through a simply hydrothermal method.Then the highly conductive GR/15PANI/12NiS_x was obtaind by optimizing the ratio of component.As an electrode in supercapacitor,the GR/15PANI/12NiS_x achieves a high specific capacitance of 2404 Fg^-1 at 2mV s^-1 and a good rate capability of 605 Fg^-1 at 200 mV s^-1.