Preparation And Characterization On PEO-Based Layered Silicate Composite Polymer Electrolyte

As a widely applied high-powered chargeable battery, lithium ion secondary batteries are developed into pure solid state polymer battery (polymer cathode, solid polymer electrolyte and lithium anode) with higher energy density and better safety performance. Composite solid polymer electrolyte(in short, Composite polymer electrolyte), described as polymer-lithium salt-nano particle, prepared by adding common nano particles, acts better than the original polymer-lithium salt composite polymer electrolyte, but it still can not meet the request of application. As a novel field of composite polymer electrolyte, those ones on composite polymer electrolyte prepared by adding layered silicate have showed a special future.PEO-LiClO4-layered silicate composite polymer electrolytes are prepared on the introduction of MMT and saponite in this research by solution-casting method. Factors of the concentration of silicate,the intercalating time and the time for heat treatment and so on are checked to confirm their effect on the conductivity of composite polymer electrolyte to obtain optimal techniques. Furthermore, FTIR, SEM and XRD are used to test the product with the aim to get the details of changes of surface and structure when the ionic conductivity is enhanced.Prepared PEO-LiClO4-MMT and PEO-LiClO4-saponite composite polymer electrolyte by optimal techniques present ionic conductivity of 6.5×10-5S/cm and 7.3×10-5S/cm at 20℃respectively, which are better than composite polymer electrolyte prepared by adding common nano particles. XRD tests indicate that the introduction of MMT and LiClO4 both decrease the crystallization of PEO. The addition of saponite has the similar effect, but the introduction of LiClO4 at the same time does not only lower the crystallization of PEO, but also move the characteristic absorption of PEO. FTIR tests show that the layers of MMT and saponite both interact with other components on the surface area. SEM tests present an idea that the introduction of LiClO4 is resulted in lubricity of the surface of PEO film, while the addition of MMT smooth the surface, which would help gain a low-impedance polymer interface. Besides, the experimental data on conductivity are fitted by experiential formula, indicating that although the composite polymer electrolyte owns some ion-conducting feature with hopping mechanism, the viscosity of electrolyte affects its conductivity at the same time.