Synthesis And Mechanism Of Lithium Storage Of Nanocarbon Modified Transition Metal-based Materials

Due to its natural abundance,low cost,non-toxic,non-polluting characteristics,the graphitic carbon material has always been used as the commercial lithium ion battery?LIB?anode.It could exhibit a low lithium ion intercalated potential and excellent cycle performance but its intrinsic low theory capacity and poor rate performance would hinder its development for high energy electrode material.Therefore,it is necessary to develop novel anode materials with large capacity,high charge-discharge efficiency and well cycle stability.Transition metal compounds possess high theoretical capacity and the excellent rate performance,but their poor conductivity and large volume change during the process of the electrode reaction severely affect their electrochemistry performance.Currently,an effective method for enhancing the stability of material structure is to synthesize special morphology nanomaterials or combine with conductive carbon materials.Meanwhile,study on electrode reaction of structure change can help to understand the reaction mechanism,which is of great significance for the development of high-performance electrode materials.To sum up,the target of this thesis is to develop novel high performance LIB anode materials,using cheap metal salt as raw materials to synthesize nanocarbon modified metal based composite material.At the same time,explore the lithium storage mechanism of the electrode materials.The main research content is as follows:?1?Ni₃S₂ nanoslices anchored on reduced graphene oxide?denoted as Ni₃S₂@C-RGO?were designed and synthesized.Evaluated as the LIB anode,the lithium storage performance of the Ni₃S₂@C-RGO were studied,including the rate capacity and cycle performance.?2?Carbon coated Fe S and reduced graphene oxide composites with 3D structure was designed and synthesized.Explored as the anode of lithium ion battery,lithium storage performance was studied,including the rate capacity and cycle performance.?3?Urchin-like V₂O₃/C hollow nanospheres were synthesized via a template-free solvothermal method followed by a carbothermal reduction strategy,using glucose as the carbon source and control agent.The formation mechanism of its novel structure was studied by adjusting the amount of raw materials and the reaction time.As the anode material for lithium-ion batteries,the V₂O₃/C material showed excellent lithium storage performance,and can be applied in the full battery.?4?Novel composite composed of three-dimensional Fe₂N@C microspheres grown on reduced graphite oxide?denoted as Fe₂N@C-RGO?has been synthesized through a simple and effective technique assisted by a hydrothermal and subsequent heating treatment process.As the anode material for lithium-ion batteries,the lithium storage performance was explored and its mechanism were studied using in-situ XAFS technique.Additionally,catalysis performance Fe₂N-based for electrochemical hydrogen evolution was explored.