Preparation And Properties Of Hybrid Gel Polymer Electrolytes With Silicon Crosslinked Structure

Gel polymer electrolytes(GPEs)have advantages which are the liquid electrolyte of high ionic conductivities and the solid electrolyte of no leakage.It has the potential to prepare flexible,thinn,small electrochemical devices.In this paper,the hybrid GPEs with silicon crosslinked structure was prepared by sol-gel method and the properties of GPEs were investaged.Using isocyanate propyl triethoxysilane(ICS)and poly(propylene glycol)bis(2-aminopropyl ether)(2-APPG)as raw materials,the PI-x-n GPEs were prepared by sol-gel method.FTIR and NMR confirmed that the isocyanate groups of ICS reacted with the amino groups of 2-APPG to form urea groups and silicon crosslinked structure.The molar ratio of the etheroxy groups in polymer matrix to the lithium ion,that is,[O]/[Li+]has a significant effect on the performances of the hybrid GPEs.The ESW of PI-100-22 is 10 V and ionic conductivity is 7.09x10-4 S/cm at room temperature.ECDs assembled with PI-100-22 have excellent coloring efficiency(267.4 cm2/C),reasonable voltage stability(applied 5 V voltage for 8 cycles)and good cycle performance(150 cycles)The pyromellitic anhydride(PMDA)is introduced into PI x-n GPEs and formed imide structure.The structure and the effect of 2-APPG molecular weight on structure and properties of API-x GPEs were investaged.Compared with other API-x electrolytes,API-100 electrolytes have wide ESW(10 V),maximum room temperature conductivity(1.03x10-3 S/cm)and maximum lithium ion migration numbers(0.65).The ECDs assembled with API-100 have excellent coloring efficiency(167.7 cm-/C),high voltage stability(applied 5 V voltage for 100 cycles)and good cycle performance(450 cycles)Introducing KH560 into API-x GPEs,the GPE-x GPEs are prepared by the reaction of the epoxy group of KH560 with the carboxyl group of the amic acid.The effect of the molar ratio of ICS/KH560 on the structure,thermal properties and electrochemical properties of GPE-x and the performances of the GPE-50 in the ECDs were investigated.The results of FTIR showed that when KH560 was introduced,the characteristic peaks of the epoxy group and the carboxyl group of the amic acid disappeared,indicating that the KH560 reacted successfully with the carboxyl group of amic acid,thereby removing the amic acid in electrolyte.The TGA results show that GPE-50 electrolytes have good thermal stability(almost 0 weight loss at 100?).Electrochemical characterization results confirmed that the room temperature conductivity(3.1×10-4 S/cm)of GPE-50 is slightly lower than that of PI-100-22(7.09×10-4 S/cm)and API-100(1.03×10-3 S/cm),but it also has good electrochemical stability(10 V).ECDs assembled with GPE-50 have better coloring efficiency(276.9 cm2/C),better high voltage stability(125 cycles when applied 5 V voltage)and better cycle performance(600 cycles)compared to ECDs assembled by PI-100-22 and API-100 electrolytes.