Facile Synthesis Of Cobalt-based Metal Oxide Electrode Materials And Their Electrochemical Properties

Rechargeable lithium-ion batteries（LIBs） have revolutionized not only portable electronics, electric vehicles（EVs） but also energy storage systems（ESSs）, due to their high energy density, low self-discharge, long lifespan and small memory effect. In order to meet the new requirements, the development of anode material for lithium-ion battery with high specific capacity, high rate and excellent stability possess a pivotal position. As one type of promising electrode material, mixed transition metal oxides have drawn considerable attentions because they exhibit a higher theoretical specific capacity than that of commercial graphite(372 m A h g^-1). However, the low electric conductivity and volume expansion/contraction of materials cause aggreation and pulverization during the lithiation/delithiation processes. It is well known that the size and morphology-dependent effects of nanomaterials affects the related adjustment of nanostructures for anode materials. As a result, the hierarchical configuration is engineered to modify the electrochemical behaviours and attain materials that are qualified for LIB appl ications.Thus this research chose cobalt-based metalt-based metal oxide as the object and tried to obtain hierarchical structure of MCo₂O₄ by microwave assisted method and solvthermol synthesis. The microscopic morphology and phase compostion were characterized by X-ray diffraction, scan electron microscope, transmission electron microscope, and X-ray photoelectron spectroscopy, while their electrochemical performance were measured. Furthemore, the relationship between battery performance and structure were discussed.Urchin-like CuCo₂O₄ were syhthesized with formamide as solvent by using microwave assisted method with β-cyclodextrin as a template. Study the effects of reaction temperature and the amount of β-cyclodextr on the morphology. Explore the proposed formation mechanism of urchin-like CuCo₂O₄. One-dimensional nanorods assembled urchin-like structure can effectively relieve the problem of structural strain in the process of charge and discharge. Stable capacity of 699 m Ah g^-1 were observed over 600 cycles at the current density of 2 A g^-1.Hierarchical ZnCo₂O₄ microspheres were prepared using DMF/Ethanol as solvent, and increasing the amounts of PVP result in the distribution of particle on the surface of microspheres. Study the effects of solvents and the amount of PVP on the morphology, which limiting the size of products and leading to porous structure. The micro-/nanostructured ZnCo₂O₄ assembled by nanoparticles exhibits remarkable electrochemical performances, preserving an excellent reversible capacity of 671 m A h g^-1 after 300 cycles at a high current density of 3 A g^-1. The superior performance of hierarchical ZnCo₂O₄ microspheres can be attributed to their structural features, including nanosized building blocks and porous architectures, which can modify the electrochemical behaviours as anode materials for highly reversible lithium-ion batteries.