Of Peg-pan Solid Polymer Electrolyte

Solid polymer lithium batteries (SPLB) not only have the excellent performance of liquid lithium battery, but also can resolve the possible problems of leakage and blast owing to no free liquid electrolyte in SPLB. It is also very convenient to design the shape at will. Therefore, Solid polymer lithium batteries have become a novel orientation about the development of lithium ion technology.Now the ion conductivity of solid polymer electrolyte (SPE) can reach the magnitude of 10^-4S/cm, which is very close to that of the practical request(10^-3 S/cm). But it is still lower than that of liquid electrolyte (10²S/cm), which causes the fall of high rate discharge and low temperature performance of lithium battery. However, the mechanical strength and thermodynamic stability of the polyether matrices were found to be poor and these polymer electrolytes often creep under applied pressure while using in practical electrochemical devices.Focusing on the filter of polymer as matrix for polymer electrolyte, the synthesis of PEG-PAN copolymer, the fabrication of the SPEs and optimizing the performance of the SPEs, the paper intends to resolve some of the key problems mentioned above and to prepare a SPEs with good performance.Firstly, the PEG-PAN copolymers were synthesized by free radical solvent polymerization. The formation and construction of copolymer were confirmed by FT-IR, NMR, GPC and elemental analyze.Secondly, the transparent and flexible SPEs were fabricated by solvent casting. The formation and characterization of SPEs were confirmed by FT-IR, DSC and SEM.Finally, by controlling and adjusting the AN wt% content and doping PEO with high molecular weight, the performance of SPEs was optimized. The ionic conductivity of PEG-PAN solid polymer electrolytes was found high to be 6.79 X 10-4S/cm at 25 ℃which is close to the level of that of the practical polymer electrolyte. The conductivity and interfacial resistance remain almost constant even at 80℃ which means the SPE isdimensionally and mechanically stable regardless of operating temperature. The SPEs were electrochemically stable up to about 4.8V versus Li/Li+, which means the SPEs have suitable electrochemical stability to allow the use of high-voltage electrode couples such as LiCoO₂, LiNiO₂ and so on positive electrode.