Preparation And Properties Of Organic - Inorganic Hybrid Polyacrylate Polymer - Based Gel Polymer Electrolytes

Gel polymer electrolyte (GPE) is one kind of potential electrolyte and provided with high ionic conductivity, better compatibility with electrode, free shape flexibility and safety etc. But the GPE still has existed one fatal problem:the increased mechanical property and better membrane self-standing usually are based on the sacrifice of ionic conductivity. Therefore, how to make the GPE has high ionic conductivity at the same time has good film-forming property and high mechanical properties which has become the focus of the researchers.This paper is based on the two respects:1) polyhedral oligomeric silsesquioxane (POSS) nano-cage can endow GPE with similar modification caused by other inorganic nano-particles; the organic substituents on the cage corners make POSS more compatible with GPE. So POSS as hybrid modification filler is added into the GPE with polymethyl methacrylate (PMMA) matrix.2) In order to incorporate inorganic nano-particle into GPE in the form of chemical bond to improve electrolyte performances, the monomers of methyl methacrylate (MMA) and vinyl trismethoxy silane (VTMS) are chosen to synthesize the novel self-doped polymer of h-poly(methyl methacrylate-vinyl trismethoxy silane)(h-P(MMA-VTMS)), and then the obtained polymer is used as matrix to prepare GPE. The properties of polymers were studied by Fourier Transform Infrared spectra(FTIR), Nuclear Magnetic Resonance spectroscopy(NMR), X ray diffraction(XRD), Differential scanning calorimetry(DSC), and Thermo gravimetric analysis(TGA); The relationship between temperature and ionic conductivity of the GPE were studied by alternating current impedance. Following results were obtained:1) POSS addition amount was a critical factor for the ionic conductivity of prepared GPE. When POSS content was7.5wt%, the thermal stability was sufficient at the elevated temperature; the ionic conductivity of GPE reached up to1.33×10-3S/cm; the mechanism of conductivity was the typical Arrhenius behavior; the lithium ion transference number was up to0.33; the deposition/dissolution of litium was highly reversible; the electrochemical stability window was high enough with5.25V and the compatibility of electrolyte with lithium electrolyte was satisfying.2) By the characterization of the resulted polymer, the composition and structure are conformed to the design concept, and the self-doped polymer is amorphous and the better thermal stability. From the investigation of the prepared GPE, it is thermal stable in the temperature range from30℃to100℃; the ionic conductivity reaches to the level of10-4/cm at room temperature; For the50wt%GPE system, the variation of the ionic conductivity displays an Arrhenius behavior in the temperature range from30℃to55℃; the higher lithium ion transference number is0.42; the compatibility with lithium metal anode is better; the electrochemical stability is stable up to5.20V versus Li/Li+.