Asymmetric alicyclic amine-polyether amine molecular chain structure for improved energy storage density of high-temperature crosslinked polymer capacitor

Abstract Crosslinked structure is proved to be efficient to improve breakdown strength (EB), thermal stability and charge-discharge efficiency (η) of polymer film capacitors, which is of great interest for their application in electric power systems and electrical automobile industry. However, highly crosslinked molecular networks usually lead to weak polarization ability of polymer, which greatly restrict their energy storage density (Ud). To improve polymers’ high-field polarization ability while guaranteeing their EB and thermal stability, we propose the asymmetric molecular chain structure in crosslinked network of epoxy resin by attaching ringlike alicyclic amine (ACA) and linear polyether amine (PEA) on phenol via Mannich reaction. The film exhibits high Ud up to 9.12 Jcm-3 at 550MVm-1 and ambient temperature with 90% efficiency, which is a record high value for Ud among single-layer polymer under the same condition. At 200 MVm-1 and 120°C, a future operating condition towards electric-vehicle applications, prepared film still exhibits Ud of 1 Jcm-3 with 90% efficiency, which is twice of the state-of-the-art BOPP. The results prove that the asymmetric ACA-PEA structure can greatly improve Ud of crosslinked polymer film while maintaining superior energy storage efficiency at high temperature. This work paves a new way for the material design of high-performance polymer film capacitor.