Compressible Polymer Composites with Enhanced Dielectric Temperature Stability

High-dielectric-constant polymer composites have broad application prospects in flexible electronics and electrostatic energy storage capacitors. Substantial enhancement in dielectric constants (ε_r) of polymer composites so far can only be obtained at a high loading of nanofillers, resulting in high dielectric loss and high elastic modulus of polymer composites. Addressing the polarization shielding and the consequent polarization discontinuity at polymer/filler interfaces has been a long-standing challenge to achieve flexible polymer composite with high ε_r. Herein, a polymer composite with interconnected BaTiO₃ (BT) ceramic scaffold is proposed and demonstrated, which exhibits a high ε_r of ≈210 at a low BT volume fraction of ≈18 vol%, approaching the upper limit predicted by the parallel model. By incorporating relaxor Ba(Zr_xTi_1−x)O₃ phase in BT scaffold, dielectric temperature stability is further achieved with Δε_r below ±10% within a broad temperature range (25–140 °C). Moreover, the dielectric performances remain stable under a compressive strain of up to 80%. This work provides a facile approach to construct large-scale polymer composites with robust dielectric performance against changes in thermal and mechanical conditions, which are promising for high-temperature applications in flexible electronics.