Effect of Beta Nucleating Agent Supported on Zeolite or Graphene Oxide on Polypropylene Membranes for Battery Separator Production

Isotactic polypropylene (iPP) is a polymer commonly used due to its thermal and mechanical properties and its affordable price. Adding β-nucleating agents, such as calcium pimelate (CaPim) and fillers, can improve the properties of iPP, increase plastic deformation, and promote the formation of pores in the films during controlled stretching. These characteristics are essential to produce microporous membranes used in various applications, including battery separators. This study explored the impact of incorporating CaPim and fillers, zeolite 4A and graphene oxide, into iPP to create microporous membranes. Different methods were used, such as mixing and temperature-controlled pressing, to increase the compatibility of the fillers with iPP. All of the prepared films showed β-phase formation, both with and without fillers. Films that showed the highest percentage of β-phase were stretched at a controlled temperature and showed both good distribution of small pores and low thickness, which are desirable for use in separators.