The Preparation And Modification Of Gel Polymer Electrolytes Containing Ionic Liquids

As the gel polymer electrolyte(GPE) combines advantages of polymer electrolyte and liquid electrolyte, GPE which contains ionic liquids has become the hot spot in recent research because of its good thermal stability and mechanical properties. But the ionic conductivity of such GPE has decreased greatly when is compared with the pure ionic liquids. which can’t satisfy the condition that conductivity of electrolyte( i.e.>10-3S·cm-1. So, it need to modify the GPE to improve its ionic conductivity and thermal stability.The two-step method was used in this paper to prepare imidazole ionic liquids [BMIM]BF4, [PMIM]BF4 and [EAMIM]BF4. Aprotic solvent PC and DMC were added to modify the property of ionic liquids,which are added into single methyl methacrylate(MMA), beta hydroxy ethyl methacrylate(HEMA), methylglycidyl ester of acrylic(GMA),methyl acrylate(MA), ethyl acrylate(EA) and butyl acrylate(BA)respectively, thus forming several kinds of gel polymer electrolytes.When mixing two kinds of monomer, several kinds of composite gel polymer electrolytes were prepared. Their structure, conductivity and thermal stability were characterized by FT-IR, AC and TG. The results show that the PMA-PC-DMC-[BMIM]BF4 has the highest conductivity of 2.818×10-3S·cm-1 in 20 ℃.With adding two kinds of monomer polymerization, the results show that the GPE PMMA-MA-PC-DMC-[BMIM]BF4 has the highest conductivity of 7.541×10-3S·cm-1 in 20 ℃and 1.214×10-2S·cm-1 in 70 ℃while m([BMIM]BF4) : m(MMAMA) is up to 7:3. In addition, the conductive behavior of the GPE follows an Arrhenius equation. The gel polymer electrolytes exhibited high decomposition temperatures of above 300℃, thermal stability of GPE is better than the electrolyte with traditional organic solvent.The two-step method was used in this paper to prepare imidazole ionic liquids [BPy]BF4, [PPy]BF4 and [EAPy]BF4. Aprotic solvent PC and DMC were added to modify the property of ionic liquids, which are added into single methyl methacrylate(MMA), beta hydroxy ethyl methacrylate(HEMA), methylglycidyl ester of acrylic(GMA), methyl acrylate(MA), ethyl acrylate(EA) and butyl acrylate(BA) respectively,thus forming several kinds of gel polymer electrolytes. When mixing two kinds of monomer, several kinds of composite gel polymer electrolytes were prepared. Their structure, conductivity and thermal stability were characterized by FT-IR, AC and TG. The results show the PMA-PC-DMC-[BPy]BF4 has the highest conductivity of4.273×10-3S·cm-1 in 20 ℃. With adding two kinds of monomer polymerization, the results show that the GPE PMMA-MA-PC-DMC-[BPy]BF4 has the highest conductivity of8.289×10-3S·cm-1 in 20 ℃ and 1.403×10-2S·cm-1 in 70 ℃ while m([BPy]BF4) : m(MMAMA) is up to 7:3. In addition, the conductivebehavior of the GPE follows an Arrhenius equation. The gel polymer electrolytes exhibited high decomposition temperatures of above 300℃.In order to improve the conductivity of gel polymer electrolyte,nano-Si O2 particles were used to modify the conductivity of GPE(PMMA-MA-PC-DMC-[BMIM]BF4, PMMA-MA-PC-DMC-[BPy]BF4).Their structure, conductivity and thermal stability were characterized by FT-IR, AC, TG, TEM and XRD. The results show that the GPE(PMMA-MA- PC-DMC-Si O2-[BMIM]BF4 and PMMA-MA-PC-DMCSi O2-[BPy]BF4) have the highest conductivity of 8.741×10-3S·cm-1 and9.862×10-3S·cm-1 in 20 ℃, 13.73×10-3S·cm-1 and 15.63×10-3S·cm-1 in70 ℃ reseparately, while m(IL) : m(MMAMA) is up to 7:3. In addition,the conductive behavior of the GPE follows an Arrhenius equation. The gel polymer electrolytes exhibited high decomposition temperatures of above 300℃.