Preparation And Electrochemical Properities Of Sipn Gel Polymer Electrolyte

As one of key materials, polymer electrolytes draw lots of researchers'attention with the wide application of lithium ion battery. In this paper, lithium 2-acrylamido-2-methylpropanesulfonate (LiAMPS), vinyl triethoxysilane (VTES) and polyethylene glycolallylmethyl ethers (AMPEO) were chosen as the monomers of copolymerization, the binary and ternary linear polymer were synthesized by free radical polymerization in organic solution. Single-ion transport type SIPN polyelectrolyte membrane was obtained through the thermally initiated free-radical polymerization of crosslinker monomer poly(etheylene glycol) dimethacrylate (PEG(400)DMA), mixture composed of PEG(400)DMA and the copolymer purified using azobisisobutyronitrile (AIBN) as a thermal initiator. The structure and morphology of SIPN membrane was investigated by FTIR, H1-NMR, scanning electron microscope (SEM), X-ray diffraction (XRD). The thermal property of dried membranes were tested, the liquid absorption and the electrochemical properties of membranes were also measured. The conductivity, electrochemical stability and ion transference number, interfacial resistances were measured through AC impedance, linear sweep voltammetry and chronoamperometry respectively.The results of FTIR and H¹-NMR indicate that the production synthesized in this paper is the copolymer of LiAMPS, VTES and AMPEO. The membranes prepared are transparent. The results of XRD manifest the structure of membrane is amorphous. From the SEM images of membrane, we can conclude that the compatibility of the linear copolymer and the crosslinking network is good and the membrane is homogeneous phase. AMPEO introduced to reduce the system of linear polymers the glass transition temperature. The thermogravimetry analysis shows that the initial thermal weight loss begin at about 200℃and the membranes have a good thermal stability.The effects of feeding radio in the process of synthesizing the linear copolymer, the amount of crosslinker PEGDMA and the length of AMPEO chain to the liquid uptake and conductivity were discussed. It can be conclude that the liquid uptake and conductivity increase with the increasing of LiAMPS content, when the content of AMPEO is above 28.6%, the trend reverse. Fixing the ratio of LiAMPS and VTES is constant, the liquid uptake and conductivity increases at first then decreases with the increase of the AMPEO content and reaches the maximum when the AMPEO content is 44.4%. Meanwhile, lengthening the AMPEO chain is helpful to improve the the liquid uptake and conductivity. Increasing the linear copolymer content in membrane induce the liquid uptake decrease. The conductivity increases with the increasing of the plasticizer content. The relationship between conductivity and temperature follows Arrhenius type equation during the investigated temperature range.The liquid uptake varies with the different composition of membrane, the maximum value is 176%. The ion conductivity of gel membrane is 2.6×10^-5 S/cm at 30℃, electrochemical stability window is up to 4.5 V⁵.5 V, the ion transfer number is 0.86. Interfacial resistances were measured by measuring the AC impedance of Li / SIPN GPE / Li cell system, the results indicate there is large interfacial resistance in the interfacial zone between electrode and polymer electrolyte,signal disturbance by placing five times a week, the interfacial resistance tends and open circuit potential to be stable with increase of time.