干法制备聚合物锂离子电池用PVDF-HFP隔膜的研究

采用相转化法(干法)以PVDF-HFP(聚偏氟乙烯-六氟丙烯共聚物)为本体聚合物制备了聚合物锂离子电池用隔膜.通过扫描电镜对隔膜形貌进行分析,研究了在干法制膜过程中空气湿度对隔膜形貌和性质的影响.采用交流阻抗技术和PC(碳酸丙烯酯)浸入实验分别测定了隔膜的电导率和吸液率.采用吸液率最高,相对湿度50%下制备的隔膜装配电池,测其电化学性质.电池首次充放电效率为88.3%,第五周可达99.4%,表现出良好的电化学性能.

Study on PVDF-HFP membranes prepared by dry process for polymer lithium ion battery

Membranes based on PVDF-HFP as polymer matrix for polymer lithium ion batteries were prepared by phase-inversion method (dry process). Effect of the relative humidity in air on the morphologies and properties of the membranes as prepared were investigated by scanning electronic microscopy (SEM). Ion conductivities and PC uptake rates of membranes were respectively measured in terms of AC impedance technique and immersion test. The sample battery as-sembled with the membrane prepared at 50% relative humidity in air with the highest PC uptake rate exhibits excellent electrochemical performance, namely, the efficiency of the initial and 5~(th) cycle charge-discharge is respectively 88.3% and 99.4%.