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)-HfO2/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 HfO2 nanofiller with high dielectric properties can effectively increase the breakdown strength and maximum polarization value, respectively. The discharge energy density (Ud) and efficiency (η) of the composite reach 12.01 J/cm3 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 Ud and η, both below 1%. The results suggest that the composite has great application potential for stable charging and discharging under high-temperature environments. [Display omitted] •A polymer nanocomposite for dielectric capacitors with high thermal stability•Mechanical clamping enables a rise in the working temperature from 120°C to 150°C•Energy density and efficiency reach 12.01 J/cm3 and 91.05% at 150°C, respectively•Fluctuations of energy density and efficiency are less than 1% in 25°C–150°C Ge et al. report a method for improving the discharge performance and temperature stability of polymer dielectric capacitors. By structure design and chemical doping, the dielectric capacitors can work stably and efficiently at a high temperature and show good anti-fatigue properties after 106 cycles.