Study On The Preparation And Electrochemical Properties Based On Co₃O₄Nanomaterials

In recent years, the heavy use of fossil fuels has caused seriousenvironmental pollution, so the renewable clean energy is a pressing need. Li-ion batteries and supercapacitors can solve effectively the above-mentionedproblems, and many researchers paid attention to them. Li-ion batteries havebeen widely used in portable electronic devices and electric vehicles due tothe high power density, long cycle life and highly-safe performance.Supercapacitors is also characterized by high power and long life，at the sametime, virtually maintenance-free. Electrode materials play an important role onthe electrochemical performance of Li-ion batteries or supercapacitors. As theelectrode materials for lithium ion battery anode materials or supercapacitorelectrode materials, transition metal oxides present larger specific capacitythan graphite, such as Co3O4, relevant scholars pay great attention to it.Carbon cloth is widely used in the fuel cell and supercapacitor owning toits high surface area, electrical conductivity and remarkable chemical stability.Compared with other conductive substrates such as Ti foil, Cu foil, Nifoam, carbon cloth is more flexible and its network structure is very beneficialto the penetration of the electrolyte and carbon cloth. At the same time,carbon cloth has excellent electrochemical properties.Co3O4nanosheet arrays/carbon cloth was obtained by a simple electro-chemical deposition method. The electrodeposition experiments were carriedout in a15mM Co(NO3)26H2O aqueous solution and carbon cloth was used asthe current collector. The microstructures and compositions of these materialswere investigated by XRD, SEM and TEM. The interconnected and porousnanosheets form the hierarchical porous structure of the electrode, the Co3O4nanosheets are composed of many nanoparticles about10nm in size. Thestructure of the material is stable and can facilitate the Li-intercalation–de-intercalation reaction. The electrochemical properties as anode materials forlithium ion batteries have been evaluated by cyclic voltammetry, galvanostaticcharge-discharge and electrochemical impedance spectra. The Co3O4nanosheet arrays/carbon cloth electrode obtained at250℃presented a firstdischarge capacities of2.51mAh cm-2with a high coulombic efficiency of 82.1%, and1.94mAh cm-2was retained after100cycles. As the currentcollector, carbon cloth makes a significant contribution to the total capa-city of the electrode and enhance the energy density. Except the capacity ofcarbon cloth, the weight specific capacities of Co3O4nanosheets are1200,987,975,787mAh g-1in the1st,2nd,50th and100th cycles. At the sametime, we explored the synthesis technology of the eletrode，the influence ofloading density and calcination temperature on the morphology and lithiumstorage properties of the eletrode were analyzed.The supercapacitor characteristics of the Co3O4nanosheet arrays/carboncloth electrode was tested in2M KOH aqueous solution， The cyclicvoltammetry tests show that carbon cloth makes little contribution to thewhole electrode. The eletrode showed a specific capacitance of328F g-1at thecurrent density of0.5A g-1,319F g-1was obtained when the current densityincreased to0.75A g-1,160F g-1was retained at a high rate of8A g-1. Thespecific capacitance of80.1%was maintained after1500cycles. The superiorelectrochemical performance of Co3O4nanosheet arrays/carbon cloth is due tothe unique core-shell structure with excellent structural stability.