Studies On Supercapacitor Electrode Materials Of MnO₂ And NiCo₂S₄

Supercapacitors have high power density,long cycle life,fast charging and discharging rates,and environmentally friendly feature,which make them one kind of the most promising electrochemical energy storage devices of broad application prospects in mobile communication devices,electric cars,national defense equipments,and etc.The supercapacitor is the current research focus in the energy storage elements,and the performance of the electrode materials is the core factor influencing the performance of supercapacitors.In this thesis,we briefly review the recent progress of supercapacitors and Mn02,and then study the anodize electrodeposition of Mn02 and its graphene nanocomposite and the one-pot hydrothermal synthesis of NiCo2S4 as well as their applications as supercapacitor electrode materials.The main contents are as follows.(1)Mn(CH3COO)2 was used as a raw material to anodically electrodeposit MrnO2 in 0.1 M neutral Na2SO4 on a gold electrode.Oxygen evolution at the electrode could led to a porous structure of the Mn02 deposit and thus increase the specific area of MnO2.The specific capacitance showed its maximum at 1.5 V vs.SCE,being 223 F g'1 at 100 mV s-1.For comparing,the specific capacitance of it at 1.2 V vs.SCE,being 198 F g-1 at 5mVs-1.(2)The anodic coelectrodeposition of MnO2 and carboxylated graphene(CG)was studied on a gold electrode.The structure of the electrodeposited composite was characterized by SEM,Raman and XPS,the electrodeposition process and the amount of the electrodeposited composite were monitored/measured by electrochemical quartz crystal microbalance,and the electrochemical performance of the composite was studied by cyclic voltammetry,constant current charging/discharging measurement and ac impedanee test.The results show that the composite electrodeposited potentiostatically at 1.2 V vs SCE showed the best capacitive performance,be as high as 308 F g"1 at 5 mV s-1 in 1 M aqueous Na2SO4.(3)NiCo2S4 clusters material was synthesized by one-pot hydrothermal method.After the structure was characterized and the electrochemical performance was tested,the supercacitor performance using this material as electrode material was preliminarily explored.