Preparation And Properties Of Pei Based Gel Polymer Electrolyte Doped With Hnts

The electrolytes of lithium-ion battery can be divided into liquid electrolytes, all solid state polymer electrolytes and gel polymer electrolytes, according to the shape. Although the ionic conductivity of liquid electrolytes is high, it is easy to leak, so there are security risks in the practical application. While there is no leakage of electrolytes in all solid state polymer electrolytes, the security is improved, but the ionic conductivity is relatively low, so it is difficult to meet the practical application needs.The pattern of gel polymer electrolytes is between the liquid electrolytes and the all solid state electrolytes, so it not only solves the safe hidden danger of the liquid electrolytes' leakage, but also provides a liquid environment for the transmission of ions in the liquid electrolytes, thus the ionic conductivity of the electrolyte is greatly improved on the basis of all solid state electrolytes. In this way, gel polymer electrolyte can be expected to have a good development and application prospects in lithium-ion batteries.Polyetherimide (PEI) has high temperature stability, good toughness, strength and excellent mechanical properties,so it can be expected that Choosing PEI as the polymer matrix can play a very good supporting role. HNTs is a kind of natural clay silicateminerals, which has straight anda hollow tubular structure. Added into polymer electrolytes, HNTs can provide more channels for the transfer of ions in the electrolyte.In this paper, firstly, organic modification on Surface of halloysite nanotubes (HNTs) was carried out. The surface of HNTs contains a large amount of -OH, which can be used as the starting point of HNTs modification. In this paper, the ion exchange method was used, taking hexadecyl trimethyl ammonium bromide (HDTMA) as the surfactant to graft a layer of long organic chains on the surface of HNTs, in order to improve the compatibility between HNTs and polymer matrix and organic solvents. The HNTs and modified HNTs were characterized by HRTEM, FTIR, TGA, specific surface area and diameter measurement, and finally verified the success of organic modification of HNTs.The nanofiber membranes based on PEI polymer matrix with different contents of HNTs and modified HNTs were prepared by electrospinning, which were used as framework materials of gel polymer electrolyte. Then infiltrating the matrix materials into liquid electrolytes, and gel polymer electrolytes are obtained after activation process.Characterize the nanofiber films bySEM, HRTEM, FTIR and it was found that the fiber surfaces were smooth and the morphology was good, besides the average fiber diameter of the fiber membranes was decreased after the addition of HNTs. The results of Basic structure property testing of skeleton materials show that the prepared nanofiber membranes have high porosity, saturated electrolyte uptake and retention rate, creating a superior structural basis for the preparation of good performance gel polymer electrolytes. Assembling these gel electrolytes into various forms of button cells, and test their electrochemical performances. The results show that compared with the commercial Celgard 2500 diaphragm, the gel electrolytes prepared in this study have better electrochemical performances, especially the performances of PEI based gel polymer electrolytes doped with 1% modified HNTs, in which the ionic conductivity is up to 5.45×1.-3S·cm-1, lithium ion transfer number reaches 0.675, interface impedance value of the cell is only 90?, and at the same time, the cycle stability is excellent.