锂离子电池用勃姆石/PP复合隔膜

Boehmite/PP composite separator for Li-ion battery

为提高锂离子电池隔膜的热安全性,研究勃姆石(γ-AlOOH)/聚丙烯(PP)复合隔膜的性能。以不同粒径的勃姆石粉为涂覆材料、聚偏二氟乙烯(PVDF)为黏结剂、9μm厚的PP隔膜为基底,制得B1(D_(50)=0.741μm)、B2(D_(50)=1.172μm)两种复合隔膜。勃姆石/PP复合隔膜的综合性能比PP隔膜更好。PP隔膜在140℃下的收缩率超过57%,而B1复合隔膜小于3%,并在180℃下保持完整;复合隔膜的拉伸、穿刺强度均优于PP隔膜,B1复合隔膜拉伸强度较PP隔膜提高18.8%,B2复合隔膜穿刺强度较PP隔膜提高54.4%;复合隔膜的电解液润湿性良好,B2复合隔膜30 s后完全润湿,而PP隔膜润湿面积小于1/2;B2复合隔膜组装的电池内阻增大8.7%,但循环伏安(CV)测试显示,电池内部反应未受影响。

In order to improve the thermal safety of separator for Li-ion battery,the performance of boehmite(γ-AlOOH)/polypropylene(PP)composite separator was studied.Two kinds of composite separator B1(D50=0.741μm)and B2(D50=1.172μm)were prepared by using different particle size boehmite as coating material,polyvinylidene fluoride(PVDF)as binder and PP separator with thickness of 9μm as the substrate.The comprehensive performance of boehmite/PP composite separators was better than that of PP separator.The shrinkage of PP separator was more than 57%at 140℃,while composite separator B1 was less than 3%,which kept undamaged at 180℃.The tensile strength of composite separator B1 and punch strength of composite separator B2 were 18.8%and 54.4%higher than that of PP,respectively.The composite separators also showed well electrolyte wettability.Composite separator B2 was completely wetted after 30 s,while the wetting area of PP separator was less than 1/2.The impedance of the battery assembled with composite separator B2 was increased by 8.7%,but on its internal reaction little effect was proved by cyclic voltammetry(CV)test.