Effect of silica nanoparticles and thermoplastics elastomer on the properties of polyethylene separators in lithium batteries

Separator in lithium-ion batteries is naturally a porous membrane that allows electrolyte move between electrodes while prevents their connections. Among the common separators, the polyolefin type has got more attention due to its semi-crystalline structure, good mechanical properties, easy processability and reasonable price. But, its wettability by electrolyte is poor. In this paper, by adding silica nanoparticles to the polyethylene (PE) separator, its wettability by electrolyte was improved. To produce separators, wet method was applied by adding ۴۰% DOP oil to PE and then extracting it with solvent. The porosity obtained in this method was about ۳۰%. Then, to increase the porosity percentage, a thermoplastic elastomer was used instead of DOP oil. It was observed that the porosity content increased up to ۴۰% using this material. Also, the shape and distribution of voids have a better uniformity. The electrolyte uptake was also enhanced by adding nanoparticle and thermoplastic elastomer.