Unleashing the Giant Electrocaloric Effect in Fluoropolymers via a High-Polar-Entropy Strategy

Electrocaloric (EC) refrigeration uses dielectric capacitors that are naturally efficient and have no direct carbon emissions. The idea that electrical capacitors can serve as working bodies in a refrigeration cycle implies that electricity can be directly harnessed, potentially enabling the development of miniature and portable refrigerators, and has therefore attracted considerable attention from both academia and industry. Poly(vinylidene fluoride) (PVDF)-based fluoropolymers exhibit strong dipolar responses and have been extensively studied for EC devices. However, despite their exceptional flexibility, straightforward synthesis, self-healing capability, and low breakdown risk, their relatively low polar entropy-changes limit their refrigeration capacities in practical applications. Rationally designing an EC polymer considering its molecular-scale structure, crystalline features, and interfacial effects remains a major, nontrivial challenge. This work systematically reviews recent advances in EC polymers and focuses on two fundamental points pivotal for enhancing the polar entropy change, that is the electrocaloric effect (ECE): increasing zero-field entropy and reducing the energy barrier of dipolar switching to increase electric field responsiveness. Together, they form a high-polar-entropy strategy that shows the potential to approach the lower and upper bounds of polar entropy to maximize the ECE. This strategy is expected to be effective in predicting and designing other potential EC material systems.