A polymer nanocomposite for high-temperature energy storage with thermal stability

Dielectric capacitors’ ability to operate steadily under high-temperature conditions is crucial for contemporary electronic equipment. Here, we report a sandwich-structure polyetherimide (PEI)-boron nitride nanosheet (BNNS)/polyvinylidene fluoride and polymethyl methacrylate (PVDF&PMMA)-HfO 2 /PEI-BNNS composite. On the one hand, the mechanical clamping of PEI film with high-temperature resistance can enable PVDF&PMMA to maintain a high polarization value at 150°C. On the other hand, BNNS with a wide gap and HfO 2 nanofiller with high dielectric properties can effectively increase the breakdown strength and maximum polarization value, respectively. The discharge energy density ( U d ) and efficiency ( η ) of the composite reach 12.01 J/cm 3 and 91.05%, respectively, at 150°C. The composite maintains high thermal stability in a wide temperature range from room temperature to 150°C with fluctuations of U d and η , both below 1%. The results suggest that the composite has great application potential for stable charging and discharging under high-temperature environments.