Synthesis Of Iron Oxygen And Sulfur With Enhanced Electrochemical Capacitive Energy Stroge

Lithium-ion batteries（LIBs）are one of the high-energy batteries,satisfying the sustainable development of economy and society,because of its high energy density,high efficiency,long cycling time and no memory effect,Electrode materials play important role in LIBs.However,commercial graphite carbon anode material has a low theoretical capacity,it is hard to meet the demand of high energy,such as electric vehicles and smart utility grids.Therefore,a large amount of attention has been paid to explore alternative anode materials for building the next-generation LIBs.In this regard,transition metal oxides and transition metal sulfides have been studied because of its high capacity,among which iron oxygen and sulfur clearly stand out owing to their low cost,eco-friendliness,natural abundance and high capacity.The aim of this paper is to study the electrochemical performance of transition metal oxides and transition metal sulfides as anode material for LIBs.The main research contents are as follows（1）Magnetite microstructures assembled by porous nanobelts for improved lithium storage performancesHierarchical magnetite（γ-Fe₂O₃）microstructures have been synthesized by a facile and efficient templating approach involving the buttom-up formation and the subsequent thermal decomposition of the polymeric iron（III）acetate.The hierarchical microstructures of γ-Fe₂O₃ are derived from the template,which are assembled by porous nanobelts composed of nanocrystals.The approach is cost-effective and easy to the large-scale mass production.When evaluated as an anode material for lithium ion batteries,the hierarchical γ-Fe₂O₃ microstructures exhibit excellent electrochemical lithium storage performances including high reversible capacity which is 1344 mAh·g-1 at 0.1 A·g-1,the discharge capability is 408 mAh·g-1 at 5 A·g-1 and good cyclic stability which exhibits 700 mAh·g-1 after 100 cycles at 1 A·g-1,The excellent performances are explored in terms of hierarchical porous structures,which promotes the fast and effective lithium ion transport,and reduces the damage of structure resulting from the large volume change during the charge and discharge cyclings.（2）In situ sulfide synthesis of FeS/C hierarchical porous micro/nanostructure with enhanced lithium storage properties.Spindle FeS/C micro/nanostructure has been synthesized on a facile solid in situ sulfurization approach based on MOF-Fe.The FeS/C display excellent stable cycling performance,the capacity is 744 mAh·g-1 after 500 cycles at 0.1 A·g-1,good rate capacity,which is 322.2 mAh·g-1 at 10 A·g-1.They are explored on account of the fast lithium ion transport and stable structure arising from the hierarchical porous micro/nanostructure with small nanocrystals derived from MOF-Fe and the existence of carbon.（3）The preparation of Fe₃O₄@C material with enhanced lithium storage properties.A core-shell structure of Fe₃O₄@C material was designed to improve the disadvantages of Fe₃O₄.The introduction of carbon can not only enhance conductivity but also ensure the stability of structure.As is shown in the tests,compared with the sphere Fe₃O₄,the Fe₃O₄@C material exhibit more outstanding electrochemistry performance.When the current density is 0.1 A·g-1,the reversible capacity of Fe₃O₄@C material is 788.2 mAh·g-1.excellent rate capability,which is 358.8 mAh·g-1 at 10 A·g-1,and good cycling stability after 500 cycles at 0.1 A·g-1.