Electrocaloric Cooling‐Driven Self‐Cooling Dielectrics: Integrated Energy Storage and Refrigeration for High‐Power Capacitors

Abstract The thermal failure bottleneck in high‐power polymer capacitors severely limits their energy storage performance breakthroughs. Composite materials combining excellent thermal management capabilities with high energy storage density represent an effective solution to this problem. This study proposes an integrated energy storage‐thermal management design strategy: using a relaxor ferroelectric polymer P(VDF‐TrFE‐CFE) as the matrix and incorporating Ba _0.6 Sr _0.4 TiO ₃ (BST) nanoparticles with varying weight fractions (0–23.08 wt.%) to construct high‐performance polymer‐based nanocomposites. By synergistically regulating the interfacial polarization effect and polarization entropy change, dual breakthroughs in electrocaloric (EC) cooling and energy storage performance are achieved. This study employs infrared thermal imaging technology to directly measure the EC response of composite films. Experimental results show that when the BST weight fraction is 16.67 wt.%, the composite achieves optimal overall performance: under an electric field of 110 MV m ⁻¹ , the recoverable energy density W _rec reaches 4.26 J cm ⁻³ , which is a 20.34% improvement over the pure polymer, with the η of 70.17%; under an electric field of 100 MV m ⁻¹ , the EC temperature change reaches 5 °C, representing a 32.63% enhancement compared to the pure polymer. Therefore, this work achieves a synergistic enhancement of dielectric energy storage and EC cooling performance within a single material system.