Electrospinning Preparation And Research Of SnO₂/C Matrix Composites

With the popularization of portable electronic devices,vehicles and other products,the performance requirements of energy storage system have been further improved.In recent years,the national emphasis on new energy research has also promoted the development of energy storage systems.Lithium ion battery?LIB?as an energy storage equipment with the superiority of high energy density,strong security,and environmental friendly has been favored by researchers.The negative electrode material as one of the important components of LIB has also been widely studied.However,for the commonly used commercial anode material graphite,the low energy density and the safety problems caused by the low lithium insertion potential hinder the further development of LIB.People try to replace the commercial graphite anodes by looking for other materials,fusion doping,coating and other technologies to produce high-performance anode materials.Nanocomposite materials came into being.SnO₂ nanofiber material has become one of the most potential lithium ion battery anode materials due to its large reversible capacity,ordered configuration and large specific surface area.However,its volume expansion and pulverization problems during the LIB cycle cannot be effectively solved.Doping and modifying tin dioxide nanofiber anode materials and constructing special morphological structures are considered to be effective methods for stabilizing electrodes.In this thesis,SnO₂nanofibers are used as research objects,polyacrylonitrile?PAN?with high electrical conductivity and thermal stability is used as a stable carbon source,and electrospinning and heat treatment techniques are used to prepare SnO₂ carbon nanofibers and Ge O₂ doped SnO₂ carbon nanoparticles.Fiber and use it as a negative electrode material for lithium ion batteries.The specific research work is as follows:?1?Using electrospinning technology to prepare SnO₂/C nanofibers with PAN as a stable carbon source,using the same technology to prepare SnO₂/C nanofibers doped with different polymers?polyvinylpyrrolidone/PVP,polymethyl methacrylate/PMMA?.After heat treatment,physical and chemical properties are characterized.The experimental results show that the PVP-doped SnO₂/C nanofibers have the smallest specific surface area,strong cycle stability,and the capacity is 632.3m Ah/g at 50 m A/g after 50 cycles.?2?Based on the above processes,the effects of Ge O₂ doped SnO₂/C nanocomposites under different temperature conditions were explored.After some tabulations,it is concluded that the GSC nanocomposite at a carbonization temperature of 600? has better cycle stability and rate performance than the materials carbonized at 500? and 700?.?3?Under the premise of the above preparation of SnO₂/C nanofibers with PAN/PVP as the carbon source,electrospinning technology was used to further prepare nano-Ge O₂ doped SnO₂/C nanofibers and apply them to lithium-ion batteries for performance Characterization.The results show that the SnO₂/C nanocomposite material doped with nano-Ge O₂ has a higher specific capacity and a larger specific surface area.The first discharge capacity is 1630.96 m Ah/g,the capacity after 50cycles is 787.01 m Ah/g,and the coulombic efficiency is 98.3%.It shows that the doping of Ge O₂ effectively increases the specific discharge capacity of SnO₂/C nanomaterials,reduces the resistance of the cycle process,increases the specific area,and enhances the cycle stability of the lithium-ion battery.The research of the composite material is expected to promote the further development of anode materials for lithium-ion batteries.