Thermally activated dynamic bonding network for enhancing high-temperature energy storage performance of PEI-based dielectrics

To address the paradox of mutually exclusive confusions between the breakdown strength and polarization of the polymer-based composites at high-temperature, a dynamic multisite bonding network is constructed by connecting the -NH₂ groups of polyetherimide (PEI) and Zn²⁺ in metal-organic frameworks (MOFs). Owing to the multisite bonding network being dynamically stable at high-temperature, the composites possess a high breakdown strength of 588.1 MV m^-1 at 150 °C, which is 85.2% higher than that of PEI. Importantly, the multisite bonding network could be thermally activated at high-temperature to generate extra polarization, which is because the Zn-N coordination bonds are evenly stretched. At similar electric fields, the composites show higher energy storage density at high-temperature compared with that at room temperature, and present excellent cycling stability even with increased electrode size. Finally, the reversible stretching of the multisite bonding network against temperature variation is confirmed by the in situ X-ray absorption fine structure (XAFS) and theoretical calculations. This work presents a pioneering example of the construction of self-adaptive polymer dielectrics in extreme environments, which might be a potential method for designing recyclable polymer-based capacitive dielectrics.