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

Crosslinked structure is proved to be efficient to improve breakdown strength (E), 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 (U). To improve polymers’ high-field polarization ability while guaranteeing their E and thermal stability, we propose the asymmetric molecular chain structure in crosslinked network of epoxy resin by attaching ring-like alicyclic amine (ACA) and linear polyether amine (PEA) on phenol via Mannich reaction. The film exhibits high U up to 9.12 Jcm at 550 MVm and ambient temperature with 90% efficiency, which is a record high value for U among single-layer polymer under the same condition. At 200 MVm and 120 °C, a future operating condition towards electric-vehicle applications, prepared film still exhibits U of 1 Jcm 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 U 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.