均匀设计优化湿法制备PE-UHMW锂离子电池隔膜

摘要

The ultra-high molecular weight polyethylene (PE-UHMW) lithium ion battery separators were prepared by wet method [thermally induced phase separation (TIPS)],using liquid paraffin (LP) as diluent and ultra-high molecular weight polyeth-ylene (PE-UHMW) resin with 1.2 million viscosity molecular weight in average as raw material. The PE-UHMW resin can be dis-solved by LP under the heat and shear of a twin-screw of twin screw extruder,then is processed to be film. The separator is cooling and the solid-liquid phase separates at the same time. The membrane is finished after extraction paraffin from the film. Paraffin is re-mained in the crystal or between crystals,the gaps are formed after the extraction of paraffin. The preparation process was optimized by uniform design,while the results was analyzed by DPS software. The results show that when the extrusion temperature is 225℃, the screw speed is 36 r/min,the solution concentration is 24% and the cooling temperature is 55℃,the the air permeability of PE-UHMW lithium ion battery separator is 820 s/(100 mL),the tensile strength is 173 MPa and the puncture intensity is 5.05 N (the separator thickness is 20 μm),which increases by 53%,21% and 11% compared with the optimal value,respectively,the thermal shrinkage is 1.2%,which decreases by 57% compared with the optimal value.%以黏均分子量为120万的超高分子量聚乙烯(PE-UHMW)树脂为原材料,液体石蜡为稀释剂,采取湿法[热致相分离法(TIPS)]制备PE-UHMW锂离子电池隔膜.该方法以液体石蜡为溶剂,在挤出机双螺杆剪切和热的作用下,将PE-UHMW溶解,再通过挤出机挤出成型、冷却后进行固液相分离,然后将液体石蜡萃取出来制得膜,依靠液体石蜡在晶体间或晶体中萃取后形成孔隙.使用均匀设计试验对PE-UHMW锂离子电池隔膜的加工工艺进行了优化,采用DPS软件对均匀设计试验结果进行了回归分析.结果表明,当口模温度为225℃、螺杆转速为36 r/min、溶液浓度为24%、冷却温度为55℃时,PE-UHMW锂离子电池隔膜的透气率为820 s/(100 mL),拉伸强度为173 MPa,穿刺强度为5.05 N (隔膜厚度为20 μm),与实验最优值相比,分别提高了53%,21%和11%;热收缩率为1.2%,与实验最优值相比下降了57%.