Bilayer-structured nanocomposites with ultrahigh energy density and large discharge efficiency at high temperature via balancing energy storage and thermal conductive layers

Dielectric polymers are good candidates for electrostatic energy storage due to their large breakdown strength (Eb) and high reliability, but they cannot be capable of working efficiently at high temperature. Here, we have designed and developed (Pb0.97La0.02)(Zr0.93Sn0.03Ti0.04)O3 (PLZST) antiferroelectrics (AFEs)@dopamine (DA)/polyetherimide (PEI)-Al2O3/PEI bilayer nanocomposites. Bilayer-structured configurations combine advantages of orthorhombic PLZST AFEs with large maximum electric displacement (Dmax) and low remnant electric displacement (Dr) at elevated temperature, and Al2O3 with high thermal conductivity, which can make nanocomposites possess narrow high-temperature electric displacement-electric field loops. Large dielectric difference of [email protected]/PEI and Al2O3/PEI layers causes the reapportionment of the applied electric field at the interfaces of adjacent layers, which inhibits growth of electrical trees and reduces electrical conduction loss, thus resulting in improved Eb. Consequently, benefited from high Eb of 4570 kV/cm, low Dr of 0.89 μC/cm2, and large Dmax-Dr of 4.75 μC/cm2, the bilayer nanocomposite exhibits not only a large charge–discharge efficiency of 73% but also an ultrahigh discharged energy density of 10.27 J/cm3 at 150 °C, which far better than those of recently reported polymer composites. Finite element simulations on the evolution behavior of electrical trees and dissipation of Joule heat further confirm the rationality of the designed bilayer structure.