Design And Synthesis Of Transition Metal Oxide(Cu?Sn?Fe) Based Anode Materials And Their Lithium Storage Properties

With the rapid development of energy storage and conversion,and the widely application of new energy efficient appliances,lithium-ion batteries have received unprecedented attention.It is the key to develop simple preparation of high-capacity,long-life and high-rate anodes for power lithium-ion batteries.First,the transition metal oxides possess high theoretical capacities and varieties of phases and structures,which make they easy to obtain nano-micro structures with unique morphologies.What's more,they are wide range of sources,low cost and environmentally friendly.It is highly promising to use them as the next generation of anode materials for high-energy lithium-ion batteries.However,they still suffer from poor conductivity and volume expansion during charge-discharge cycles.In order to further improve their electrochemical performance,this work focuses on the design and synthesis of transition metal oxide-based electrode materials and their lithium storage properties.The specific contents are as follows:?1?CuO nanosheets were synthesized by a one-step hydrothermal method.When used as anodes of lithium ion batteries,CuO nanosheet electrode showed enhance electrochemical performance.The specific capacity could reach 492 mAh g^-1 at a current density of 50 mA g^-1.After cycling at high rates,the capacity of the CuO nanosheet electrode was almost not attenuated,and a reversible specific capacity of 467.6 mAh g^-1 was maintained at 80 cycles.?2?AmorphousCoSnO₃@ZnSnO₃cubeswereobtainedbycalcining CoSn?OH?₆@ZnSn?OH?₆ precursor in nitrogen.When used as anodes of lithium ion batteries,the initial discharge capacity of CoSnO₃@ZnSnO₃ was as high as 2287.1 mAh g^-1and the specific capacity remained at 613 mAh g^-1 after 100 cycles at a current density of100 mA g^-1.The ultra-high first discharge capacity and excellent cycling stability are mainly attributed to the increase of CoSnO₃@ZnSnO₃ active sites and the synergistic effect among multiple components.?3?Carbon-coated hollow spindle Fe₂O₃ composite were obtained by calcining a MIL-88A precursor?organic metal framework precursor?in air.When used as anodes of lithium ion batteries,the reversible specific capacity could reach 1207 mAh g^-1 after 200cycles at a current density of 200 mA g^-1.Even at a high current density of 1000 mA g^-1,the capacity remained at 961.5 mAh g^-1 after 500 cycles.The excellent rate and cycle performances are mainly due to the package of carbon which improves the conductivity of the material and relieves the mechanical stress caused by the volume change during charge and discharge.?4?Carbon-doped nanobipyramid Fe₂O₃@C composites with different phases were obtained by calcining a MIL-88A precursor?organic metal framework precursor?in nitrogen.When used as anodes of lithium ion batteries,??-Fe₂O₃@C exhibited excellent electrochemical performances.After 50 cycles at a current density of 200 mA g^-1,the reversible capacity of??-Fe₂O₃@C was 875.5 mAh g^-1.What's more,a reversible capacity of 631.6 mAh g^-1 was maintained after 150 cycles at a high current density of 1000 mA g^-1.The excellent electrochemical performance is mainly due to the electrode-derived FeOx@C nanosheets during the charge and discharge.