Preparation, Mechanical Properties And Application Of Tin Dioxide Nanofibers

Nanomaterials is a new subject with rapid development.Due to the large specific surface area and surface energy of nanomaterials（structures）and the resulting small size effect,nanomaterials have become a frontier issue in the field of materials science.Due to the improvement of application demand,people have more comprehensive performance and application requirements for materials,which to a certain extent has promoted the research of composite materials.The small size,large specific surface area and high surface energy of nano-materials,combined with the synergistic effect of composite materials,make nano-composites have more excellent physical and mechanical properties of traditional materials,and show great application value in energy storage and environmental protection.As a typical wide bandgap n-type semiconductor material,SnO₂ has good application prospects in catalysis,micro-nano electronic devices,battery cathode materials and gas sensors.In the past few decades,the chemical and physical properties of SnO₂ nanostructures have been extensively studied.However,little attention has been paid to the mechanical properties of one-dimensional SnO₂nanostructures.In this article,SnO2 and SnO2@C nanofibers were prepared by electrospinning and heat treatment.The mechanical properties of single nanofibers were characterized and simulated by atomic force microscopy（AFM）and finite element simulation（FEM）to study the mechanical properties of single nanofibers.And the application of SnO₂ and SnO₂@C nanofibers as anode materials in lithium ion battery was studied.The main research contents include:（1）SnO₂ and SnO₂@C nanofibers with core-shell structure were prepared by electrospinning and subsequent heat treatment.The morphology was characterized by scanning electron microscopy（SEM）and transmission electron microscopy（TEM）,and the effect of carbonization temperature on the preparation of nanofibers was investigated.（2）Three-point bending experiments of SnO₂ nanofibers were carried out under peak force quantitative nanomechanics（PFQNM）mode by AFM.The relationship between nanofibers size and elastic modulus was studied by AFM.The effect of Poisson’s ratio and aspect ratio on the mechanical behavior of SnO₂ nanofibers was studied by FEM simulation of the deformation process of nanofibers.（3）The relationship between elastic modulus and fiber size of SnO2@C nanofibers with core-shell structure was studied by means of AFM.The deformation behavior of SnO2@C nanofibers during three-point bending was simulated by FEM.The effects of Poisson’s ratio,carbon layer thickness and fiber length-diameter ratio on the mechanical behavior of SnO2@C nanofibers were studied.（4）The electrochemical properties of SnO2@C nanofibers were characterized by AC impedance,cyclic voltammetry and constant current charge-discharge techniques.The application of SnO2@C nanofibers in flexible lithium ion batteries was investigated.