Enhanced Electrocaloric Performance and Temperature-Stable Energy Storage in Nanostructured PVDF-HFP/PMMA Relaxor Blends

Abstract Driven by the global imperative for sustainable energy, this study presents a high-efficiency composite for refrigerant-free solid-state cooling and advanced energy storage. While pure PVDF-HFP suffers from high hysteresis loss and thermal instability, blending it with amorphous PMMA successfully mitigates these issues. Structural analysis confirms that PMMA induces a critical transformation, creating dynamic Polar Nanoregions (PNRs) that are central to achieving high energy efficiency. The optimized P7/PMMA3 composite delivers superior thermal stability, maintaining exceptional energy storage efficiency (>60%) with negligible leakage current even at 95 °C, effectively overcoming the thermal degradation of the pure polymer. Crucially, the material exhibits a giant electrocaloric effect, yielding an adiabatic temperature reduction (ΔTmax) of −20.11 K and a giant entropy change (ΔSmax) of 98 J·kg–1 K–1. This corresponds to an exceptional electrocaloric responsivity (|ΔTmax/E|) of 0.50 K·m/MV, which is 3 to 4 times higher than that of conventional ceramic- or graphene-filled nanocomposites. These findings demonstrate that this tailored PVDF-HFP/PMMA blend is a highly scalable, superior candidate for next-generation refrigeration and high-temperature capacitive energy storage.