Lithium-ion batteries are still the system of choice for energy storage in mobile applications. The development of bipolar batteries is a concept for the realization of large-scale devices for high power densities and capacities. In this research project, electrically conductive polymer-based foils were developed to replace the aluminum foil commonly used. The aim was to obtain flat die extrusion films with thicknesses of less than 100 micrometer and conductivities of approx. 1 S/cm in both in-plane directions and 0.1 S/cm in the trough-plane direction. With the matrix polymer of poly (vinylidene fluoride) (PVDF), this target was achieved by using hybrid nanocarbon filler systems consisting of carbon nanotubes (CNTs) and carbon black (CB). The CB was expected to reduce the strong in-plane and in-flow orientation of the CNTs by bridging the gaps between adjacent CNTs. After the development of suitable formulations and upscaling from small to laboratory scale, the film extrusion was optimized by varying the melt temperature, gap size and take-off velocity. PVDF composite films with 1.0 wt.% MWCNTs and 4.0 wt.% CB were able to meet the requirements. A similar optimization was successfully performed for polypropylene-based films.