Continuous pyroelectric energy generation with cyclic magnetic phase transition for low-grade thermal energy harvesting

[Display omitted] •Typical thermoelectric devices show low conversion efficiency of thermoelectrics at low temperatures and easy thermal equilibration.•A thermo-magneto-pyroelectric energy generator (TMPyEG), which is a combination of a thermo-magneto-electric generator and a pyroelectric generator, was developed to continuously harvest waste heat and convert it into electric outputs.•The crest factor was migrated by incorporating piezoelectric material by filling the energy gaps between pyroelectric energy output.•TMPyEG outperforms conventional thermoelectric energy harvesting devices, which rely on sole energy conversion mechanisms. Waste heat harvesting is of importance to mitigate global warming so that thermoelectric devices have often been suggested; however, such approaches are challenging because of low conversion efficiency of thermoelectrics at low temperature gradient and easy thermal equilibration. In this study, a novel thermo-magneto-pyroelectric energy generator (TMPyEG) was developed to continuously harvest waste heat and convert it into electric energy without complicated electric bias field, required in typical thermodynamic cycling-based pyroelectric generators. To enable displacement reciprocation without intervention, the second-order magnetic phase transition of the soft magnet on an actuating part was repeated in the presence of a thermal gradient. We further incorporate piezoelectric material to mitigate crest factor by filling the energy gaps between pyroelectric energy outputs. Notably, the generated energy from pyroelectric conversion in TMPyEG is superior to that from the reported thermoelectric generators under the similar thermal conditions.