Preparation Of Ti₄O₇/C Nanofiber Composites And Their Applications In The Interlayer Of Lithium-sulfur Battery

With the rapid development of society,the demand for energy has become larger and larger,and traditional lithium-ion batteries have gradually failed to meet the demand for high energy density.Thus researchers are seeking energy storage batteries with high energy density.Among them,the lithium-sulfur battery with excellent electrochemical performance has become one of the most important research in this area.However,the lithium-sulfur battery also has many problems witch are difficult to overcome at present,among which the most important one is the“shuttle effect”of polysulfides.Recently,many researchers have found that adding a thin interlayer between the anode and the seperator of a lithium-sulfur battery can effectively block the passage of polysulfide,thus improving the cycle life of the battery.In order to solve the problems of the intermediate layer above,we adopted a one-step electrospinning method to prepare the composite Ti₄O₇/carbon nanofibers?Ti₄O₇/CNFs?.With carbon fiber as the skeleton and decorated with the polar conductive metal oxide Ti₄O₇,and then it was used as the interlayer to study the effects on electrochemical performance improvement of lithium-sulfur battery.For the preparation of Ti₄O₇/CNFs composite fiber film,we use a relatively simple one-step electrospinning method.Firstly,a composite nanofiber containing uniform distribution of anatase TiO₂ was prepared by one-step electrospinning method.And then,anatase TiO₂ reacted with carbon at a high temperature of 1000°C to form a loose Ti₄O₇/CNFs network film.Since Ti₄O₇/CNFs have strong polarity and good electronic conductivity,the Ti₄O₇/CNFs film as the interlayer of lithium-sulfur battery can not only reduce the AC impedance,but also exhibit good physical barrier and chemical adsorption effects on the polar lithium polysulfides,thereby greatly improving the cycle performance of the battery.In addition,to further improve the physical barrier and chemical adsorption effect of Ti₄O₇/CNFs intermediate layer on the basis of the above research,we improved the Ti₄O₇/CNFs film by changing the content of composite fiber and increasing the density of Ti₄O₇.First,we increase the diameter of the carbon nanofibers by increasing the concentration of the spinning solution,so that the fiber has more space to accommodate TiO₂,Then,we change the concentration of TiO₂ to explore the influence of the TiO₂content on the morphology,phase composition and electrochemical properties of Ti₄O₇/CNFs,so as to determine the optimal preparation process.What's more,we combined the electrospinning and spraying methods to prepare a composite film with different structures of Ti₄O₇/CNFs and Ti₄O₇ particle layer,which is similar to the"sandwich"structure.The film further increases the Ti₄O₇ content in the composite film and greatly increases the density of the film.When acted as an interlayer of a lithium-sulfur battery,it not only improves the cycle stability of the lithium-sulfur battery at 1 C,but also enables high-capacity cycling for a long time at a high rate of 3C.