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为了降低目前商用聚乙烯锂离子电池隔膜在闭孔温度下的热收缩比率、同时提高复合隔膜的电化学性能,通过浸没沉淀法在聚乙烯(PE)隔膜两侧涂覆聚偏氟乙烯-共-六氟丙烯(PVDF-HFP)微孔涂层.通过改变强沉淀剂和弱沉淀剂的比例,研究混合沉淀剂与溶剂的溶度参数差异(Δδ)对于微孔涂层结构的影响.随着Δδ逐渐增加,固-液相分离产生的微孔结构逐渐扩展,涂层由致密表面结构向球状颗粒聚集的微孔结构转变.微孔涂层的结构对于复合隔膜的热收缩比率、电化学性能均有明显的影响.在沉淀剂中水含量40%、60%的条件下,成功地制备出了热收缩显著降低,电导率、循环性能和倍率性能等电化学性能均有所提升的三层复合隔膜.
In order to reduce the thermal shrinkage ratio of the current commercially available polyethylene lithium ion battery separator at the closed cell temperature and improve the electrochemical performance of the composite separator, the polyvinylidene fluoride (PE) separator was coated on both sides with a submerged precipitation method (PVDF-HFP) microporous coating.The effect of the difference of solubility parameter (Δδ) between mixed precipitant and solvent on the microporous coating structure was investigated by changing the ratio of strong precipitant and weak precipitant. With the increment of Δδ, the micro-pore structure produced by the solid-liquid phase separation gradually expanded and the coating changed from the dense surface structure to the microporous structure in which the spherical particles were aggregated.The structure of the microporous coating had no significant effect on the thermal shrinkage ratio of the composite membrane, Performance were significantly affected by the precipitation agent in the water content of 40%, 60% of the conditions, the successful preparation of a significantly reduced thermal contraction, conductivity, cycle performance and rate performance electrochemical properties have improved three Layer composite membrane.