Preparation Of Nanofibre Composite Membrane For Lithium Ion Battery

Lithium ion secondary battery has many advantages,including long cycle life,extremely high energy density,fast charge and discharge.The performance of lithium-ion battery depends on its electrode material.For a long time,carbon material is used to be the negative material of commercial lithium-ion battery.Carbon material has stable structure and small volume change in the process of charging and discharging,but the upper limit of capacity theory is only 372mAh/g,which restricts the development of lithium-ion battery.In recent years,transition metal oxides have emerged in the field of lithium-ion battery anode materials because of their high specific capacity(more than 700 mAh/g),economic and environmental protection,but their volume changes are very large during the charging and discharging process,which reduces the cycle performance of the battery.In order to seek higher performance lithium-ion batteries,nano and structure composite modification methods can be usedElectrospinning technology is a method to prepare polymer nanofibers by using high-voltage electrostatic as the driving force.The nanofiber membrane has many advantages,including large bottom area,high porosity,enhanced adsorption capacity,increased filtration and adhesion.It can absorb more liquid electrolytes and accelerate the transport speed of lithium ion in the channel.In this paper,PAN nanofiber membranes are prepared by electrospinning technology.Metal inorganic salts such as FeCl3 and SnCl2 are added to PAN,and by carbonizing them,the metal oxide/carbon nanofiber composite membranes are obtained.A number of performance parameters of the fiber membranes are tested,including assenbling a button battery to test its performanceFirstly,PAN nanofiber membrane were prepared,and the better spinning parameters are determined by comparing the morphology of Pan nanofibers prepared at different spinning speed,spinning voltage and pan concentration.The results shows that when the concentration of polyacrylonitrile is 10%and 15%,the spinning flow rate is 0.5ml/h,the spinning voltage is 20kV,the morphology of nanofiber membrane turns to be the best.Then FeCl3/PAN and SnCl2/PAN nanofiber membranes were prepared by adding FeCl3 and SnCl2 of different concentrations into the spinning solution.Their effects on the spinning process and morphology of Pan were investigated by SEM,TGA,FTIR,DSC,DSC and DSC.The nanofiber membranes prepared by 3%FeCl3/10%PAN,5%SnCl2/10%PAN have good appearance,less spindles,uniform fiber diameter and straightness.Also,the carbonization process parameters were obtainedLastly,Fe2O3/C and SnO2/C nanofiber films were prepared by carbonization of the better nanofiber films.The structure and morphology of the films were analyzed by SEM,FTIR,TGA and carbon content test.After carbonization,the Fe2O3/C fiber film turned from yellow to black,which was brittle and had no toughness,and its carbon content of the fiber film decreased seriously,so it is not suitable to be used as negtive material of high performance lithium-ion battery After carbonization,the color of SnO2/C nanofiber film changeed from white to black,and it still kept the softness of the film.The carbon content changed little.The charge discharge performance test shows that it can be used as the negtive material of high-performance lithium-ion battery.