Metal Oxides Application In Lithium-ion Batteries And Supercapacitiors

Nowadays,there are two major theme of energy and environment all over the world.The development of new energy devices to replace traditional energy sources is one of most important means to alleviate the energy crisis and improve the environment situation.Lithium-ion batteries(LIBs)have the features of high energy density,high output voltage,long cycle life,high safety and low-discharge rate etc.Furthermore,the supercapacitors(SCs)have the characteristics of high power density,faster charge and discharge,long cycle performance and superior reversibility.At present,graphite is used as the electrode material for LIBs and electric double layer SCs,but due to the low specific capacity of graphite,which has restricted the further development of LIBs and SCs for higher capacity and superior cycle performance.For a decade,scientist workers have been exploring a new types of electrode materials to replace graphite.Among them,transition metal oxides(TMOs)have higher theoretical specific capacity owing to their rich valence change which are expected to become next-generation LIBs and SCs electrode materials.In this paper,based on nickel foam,the hierarchical TMOs'micro-nanostructure was reasonably designed to enhance the contact area between active materials and electrolyte and expose more active sites,which can accelerate electron transport rate and shorten ion diffusion distance to improve the electrochemical performance.The micro-nanostructure arrays electrode was easily prepared and do not need conductive addictive and binder,which shows a superiority.The research contents are as follows:(1)Nickel nitrate as the nickel source,sodium dodecyl sulfate as the surfactant and the porous nickel foam as substrate.Hierarchical Ni(OH)2 nanobelt array was synthesized via a facile hydrothermal grown on Ni substrate and NiO nanobelt array was obtained by post-heating.As the LIBs' anode,NiO electrode shows higher capacity remaining 1034.7 mAh/g at 0.2 C after 70 cycles.NiO nanobelt arrays exhibit excellent electrochemical performance.(2)Firstly,Nickel nitrate as the nickel source,manganese nitrate as the manganese source,hexamethylenetetramine as the precipitant and nickel foam as the substrate,NiMn2O4 microspheres consisted of many nanosheets were synthesized on Ni substrate.Then,under the electrodeposition,a layer of CoS film was coated on the surface of NiMn2O4 microspheres.The NiMn2O4@CoS electrode exhibits excellent electrochemical performance for SCs application.The specific capacitance can reach 1751F/g at the current density of 1A/g.At a higher current density of 10 A/g,the capacitance only decays 5%after 5,000 cycles.The hybrid SCs composed of NiMn2O4@CoS and stereotaxically constricted grapheme show excellent capacitive performance.When the power density is 700.51 Wkg-1,the energy density can reach 44.56Whkg-1.(3)Firstly,Zinc nitrate as the Zinc source,cobalt nitrate as the cobalt source,urea as the precipitant,ammonium fluoride as surfactant and nickel foam as the substrate.ZnO/Co3O4 nanobundles arrays were synthesized via a facile hydrothermal method grown on nickel foam substrate for SCs' application.The specific capacitance of ZnO/Co3O4 nanobundles arrays can reach 1983F/g at the density of 2A/g,and at higher current density of 10A/g,the specific capacitance still maintains 84.5%after 5,000 cycles.The ZnO/Co304 NBs-1//SCG-ASC device shows excellent capacitive performance.When the power density is 779.8Wkg-1,the energy density can reach 70.1 Whkg-1.