Effect Of Carbonate As Plasticizers On The P(MMA-AN)Based Gle Electrolyte

Polymer electrolytes show good properties such as safety, non-pollution, flexible design used in lithium batteries, electrochromic devices. They have been widely studied. The studies on gel electrolyte based on glycerol carbonate as plasticizer and poly(methyl methacrylate-acrylonitrile)[P(MMA-AN)] as polymer have been done as following:(1)Bis(2-oxo-1,3-dioxolane-4-yl) carbonate, bis(2-oxo-1,3-dioxolane-4-yl) oxalate and tetra(2-oxo-1,3-dioxolane-4-yl) pyromellitate had been synthesised by the substitution reaction. Bis(2-oxo-l,3-dioxolane-4-yl) carbonate was taken from glycerol carbonate and bis(triehloromethyl) carbonate as the raw materials, dichloromethane as solvent; bis(2-oxo-1,3-dioxolane-4-yl) oxalate was taken from glycerol carbonate and oxalyl chloride as the raw materials, dichloromethane as solvent; tetra(2-oxo-1,3-dioxolane-4-yl) pyromellitate was taken from glycerol carbonate, pyromellitoyl chloride and triethylamine as the raw materials, dichloromethane as solvent.IR and 1H NMR were used to characterize the compounds. The synthesis conditions were utilized to get high yield of bis(2-oxo-1,3-dioxolane-4-yl) carbonate. The reaction conditions including solvent, reactant ratio, type and amount of catalyst, reacting time were investigated. This paper also investigated the conductivity of the solid electrolytes which were synthesized by the bis(2-oxo-1,3-dioxolane-4-yl) carbonate and lithium perchlorate(LiClO4) with different proportion, the results showed that when the molar ratio of the carborate and lithium was 5.93:1, the ionic conductivity of the electrolyte reached the maxium 1.628 ×10-4 S/cm.(2)The P(MMA-AN) was prepared by the method of emulsion polymerization. The crystallization behavior of P(MMA-AN) were characterized with X-ray diffraction (XRD). The results indicated that the polymer is amorphous. The glass transition temperature of P(MMA-AN) were studied via differential scanning calorimetry (DSC). It showed that when the molar ratio of the MMA and AN was 1:1,1:2 and 1:3, the glass transition temperature of the polymer was 94.3,93.9 and 93.8℃ respectively. The thermal stability of P(MMA-AN) was tested by thermogravimetric analysis (TG), the results showed that the decomposition temperature of ploymer was higher than 300℃. Three carbonates described by (1) were added to propylene carbonate (PC) with 1 mol/L LiClO4 to prepare the liquid electrolyte. The results showed that, with the content of solid organics increase, the ionic conductivity was decreased, but the electrochemical stability window of the electrolytes were slightly increased. Films were prepared by P(MMA-AN) whose mole ratio of MMA and AN is 1:2, the films were immersed in PC solution which contained 1 mol/L LiC104 with 1% different solid carbonate to prepare the gel polymer electrolyte. The effects of impregnating time on absorption volume and ion conductivity were discussed. With the impregnating time increased, the liquid uptaking volume increased and reached a maxium of 52.11% at 60 min, and the ionic conductivity was then 9.145 × 10-4 S/cm. With time extending, the mechanical property of films descended, so 45 min was selected as immersion time. The relationship between ionic conductivity and temperature of gel polymer electrolyte were studied, the results indicated that lgσ～1000/T curve had a good linear relationship. With the temperature increasing, the ionic conductivity was increased.