Preparation Of Gel Polymer Electrolyte Battery Applied Research

Now commercialized lithium-ion batteries mainly employ organic liquid electrolyte which is easy to flow and volatilize and combustible. So these batteries have the safety problems such as leakage swelling fire even explosion. To avoid these dangerous things happening, liquid lithium-ion batteries all adopt rigid metal shell such as steel and aluminum as out covering. If liquid electrolyte can be replaced by solid polymer electrolyte the safety of batteries can be improved greatly, and can adopt plastic materials as shell which make batteries'peocessing flexible and increase their weight specific energy.Physical cross-linking gel polymer electrolyte was fabricated by the method of high-temperature and quick solidification. Its ionic conductivity can reach 3.32 x10-3 S/cm, which meets the request of conductivity of electrolyte for lithium-ion batteries, i.e. >10~3 S/cm. The first charge and discharge specific capacity of the button-cell made of that gel electrolyte are 127 and 120 mAh/g respectively, and its charge and discharge efficiency can reach 94.49%, but its cycling performance is not good.Chemical cross-linking gel polymer electrolyte was fabricated by the method of in-situ thermal polymerization. After mixing monomer cross-linking agent initiating agent and liquid electrolyte as certain ratio, the mixing electrolyte solution is injected into the battery, then the sealed battery was heated at some temperature for some time to make it polymerize as gel polymer electrolyte. The better composition is: monomer 1 2%, cross-linking agent 2 2%, initiating agent 1 1% and liquid electrolyte 96%. The better heating-temperature is 70 C, and the better heating time is 2h. The ionic conductivity of thus made gel polymer electrolyte is 1.34x 10-3S/cm, which meets the lithium-ion battery'request. By comparing gel electrolyte and liquid electrolyte Li-ion batteries, we concluded: the former's discharge performances at low-rate and high temperature are better, but its discharge performances at high-rate and low temperature are rather poor. Even so, considering the specialproperties such as safety light-weight and flexible process of the polymer lithium-ion batteries, this research on gel polymer electrolyte is more worthy.