Polymer-metal layered structures for improved energy storage density

Polymer-based dielectrics with high energy storage density (ESD) are a topic of great interest for several electrical applications involving energy storage such as ultra-capacitors for power delivery, space applications and flexible electronics. The state-of-the-art approach for achieving high ESD is mixing high permittivity ceramic materials in a polymer matrix, which increases the permittivity of the composite. In this paper we propose and experimentally demonstrate a new approach for improving ESD by increasing the breakdown strength of the polymer, or polymer composite, dielectric. Our approach is based on making stacked thin layers of alternating polymer and metal layers, which improves the breakdown strength without affecting the total capacitance. The layered structures have been characterized by impedance spectroscopy, scanning electron microscopy (SEM) and AC breakdown tests. Results show significantly higher breakdown strength for the layered structure compared to single-layer polymer dielectric of the same thickness.