Electrocaloric Materials for Practical EC Heat Pumps

More than a decade of active electrocaloric (EC) material research has produced several EC materials that exhibit a giant electrocaloric effect (ECE) at high electric fields which is assured by direct measurement. These EC materials have enabled the demonstration of EC cooling devices, which exhibit temperature lifts of more than 10 K at thermal non-loading. These research and development efforts have revealed the critical importance of electrical breakdown, which is common in all electric and dielectric materials and devices under high voltages and electric fields, in developing EC materials and their use in EC devices. This talk will present general considerations in developing EC materials for EC coolers that generate large temperature span with significant cooling powers. Recently reported large ECE at low electric fields (fields much below the electric breakdown) in the P(VDF-TrFE-CFE-FA) tetrapolymers creates opportunities for practical EC coolers. We will present materials studies related to the phase transition behavior in this new class of relaxor polymers. We will also present the associated electromechanical actuations of the materials which may be utilized for heating pumping from the cold load to heat sink.