锂离子电池用溶剂型PVDF混涂隔膜制备及性能

Preparation and Properties of Hybrid Coated Separator of Solvent Type PVDF for Lithium Battery

将聚偏氟乙烯(PVDF)粉末和氧化铝(Al_(2)O_(3))加入二甲基乙酰胺中进行高速分散,得到溶剂型PVDF涂布液,将涂布液涂覆在聚乙烯多孔基膜上,通过浸渍相反转的方法得到锂离子电池用PVDF混涂隔膜。将Al_(2)O_(3)、粘结剂、助剂和水混合搅拌均匀得到水系陶瓷浆料,在上述水系陶瓷浆料中添加PVDF得到水系PVDF混涂浆料,使用研磨设备使浆料分散均匀,在聚乙烯多孔基膜单面或两面均匀涂覆水系陶瓷浆料或水系PVDF混涂浆料,直接干燥得到水系陶瓷涂覆隔膜和水系PVDF混涂隔膜。探究了三种隔膜的粘接强度、吸液保液能力等性能。结果表明,溶剂型PVDF混涂隔膜的粘接强度为11.5 N/m,是同等规格水系PVDF混涂隔膜(0.85 N/m)的13倍,而水系陶瓷涂覆隔膜几乎无粘接性能;溶剂型PVDF混涂隔膜的剥离强度达到了205 N/m,比水系PVDF混涂隔膜提高了55%,同时,对电解液的吸液率和保液率也分别提升了35%和31%。

Poly(vinylidene fluoride)(PVDF)powder and Al_(2)O_(3) were added to dimethylacetamide to get solvent type PVDF coating liquid by high speed dispersion,then the coating liquid was coated on the polyethylene porous substrate membrane and the hybrid coated separator of solvent type PVDF(s-PVDF separator)for lithium battery was prepared by a phase inversion method.Al_(2)O_(3),adhesives,additives and water were mixed for preparing the water-based ceramic slurry,PVDF was added to the above water-based ceramic slurry to obtain water-based PVDF hybrid coating slurry,the two slurries were dispersed evenly by using grinding equipment and evenly coated on one or both sides of polyethylene porous substrate membrane.Then the coated separator of water-based ceramic(w-Ceramic separator)and the hybrid coated separator of water-based PVDF(w-PVDF separator)were prepared by direct drying.The adhesive strength,liquid absorption and liquid holding capacity of the three separators were studied.The results show that the adhesive strength of s-PVDF separator is 11.5 N/m,which is 13 times for w-PVDF separator(0.85 N/m),and the w-Ceramic separator has almost no adhesion.The peel strength of s-PVDF separator is 205 N/m,which is 55%higher than that of w-PVDF separator,meanwhile,the absorption rate and retention rate of electrolyte increases by 35%and 31%,respectively.