The demand for effective cooling and energy storage technologies is growing continuously. The climatic changes, miniaturization, and digitalization have redefined the technological development in the cooling and energy storage industries. The global focus is on the environmental-friendly, efficient, sustainable, and scalable cooling technologies. Owing to all these factors, green alternatives to the traditional air-conditioning and refrigeration are gaining momentum. One of such green alternatives is the electrocaloric effect (ECE). The electrocaloric effect is observed in dielectric materials as they undergo an adiabatic temperature change or an isothermal entropy change under an externally applied/removed electric field. Dielectric materials are capable to store the electrical energy as well. Therefore, they are particularly interesting for the new cooling and energy storage technologies.

In this work, a ferroelectric relaxor polymer, namely, Poly(vinylidene fluoride – trifluoroethylene – chlorofluoroethylene) (P(VDF–TrFE–CFE) is investigated for the electrocaloric effect through the direct and the indirect methods. The electrical energy storage properties of different compositions of P(VDF–TrFE–CFE) and their nanocomposites with inorganic 0D nanofillers are studied.

Initially, the relaxor properties in six different compositions of P(VDF–TrFE–CFE) are studied. Out of these six compositions, the three compositions, 51.3/48.7/6.2, 59.8/40.2/7.3, and 70/30/8.1, are analyzed for the first time. The field induced phase transition results in a double hysteresis loop in a few compositions. Through the direct electrocaloric measurements, it is observed that the electric field induced phase transition results in a higher electrocaloric temperature change. The indirect electrocaloric measurements are conducted with and without compensating the leakage current. It is shown that the indirect method can lead to erroneous results due to the leakage current. The results obtained through the indirect measurements conducted with the leakage current compensation are comparable to the direct measurements. The electrical energy storage properties of the neat terpolymers and their nanocomposites are compared. It is observed that the stored and discharged energy densities of the nanocomposites are superior to the neat terpolymers.