A cascade electrocaloric cooling device for large temperature lift

Cooling technology that is both compact and flexible is increasingly vital for the thermal management of wearable electronics and personal comfort. Electrocaloric (EC) cooling provides a potential solution, but the low adiabatic temperature change of EC materials has been the bottleneck in its progress. We demonstrate a cascade EC cooling device that increases the temperature change, with enhanced cooling power and cooling efficiency at the same time. The device integrates multiple units of EC polymer elements and an electrostatic actuation mechanism, all operating in synergy. Every two adjacent EC elements function in antiphase (in terms of both actuation and EC effect) to allow heat flow to be continuously relayed from the heat source to the heat sink. The antiphase operation also enables internal charge recycling, which enhances the energy efficiency. Operating at the EC electric field at which the adiabatic temperature change of the material is 3.0 K, a four-layer cascade device achieves a maximum temperature lift of 8.7 K under no-load conditions. The coefficient of performance is estimated to be 9.0 at the temperature lift of 2.7 K and 10.4 at zero temperature lift. Solid-state caloric cooling is a promising alternative to vapour-compression refrigeration yet practical devices are not sufficiently efficient for applications. Meng et al. combine cascade device design with charge recovery and improve the cooling efficiency and temperature lift of an electrocaloric device.