Heat Recovery Assisted by Thermo-magnetic-electric Conversion

Converting waste heat into electricity is a promising strategy to address the ever-growing energy crisis. Ferromagnets have potential in heat recovery because of their thermo-induced magnetic transition. However, the conventional thermomagnetic generator based on ferromagnets requires rapid temperature fluctuation, which is difficult to be satisfied in a real-world environment. Here, we report a thermomagnetic-electric energy harvester consisting of a piezoelectric film and a magnetic-phase-transition alloy with low magnetization at low temperature but high magnetization at high temperature. The thermomagnetic-electric conversion in this device is a product effect, that is, the heat is first converted to kinetic energy because of thermo-induced magnetic transition, then to electric energy owing to the piezoelectric effect. The maximum short-circuit current and open-circuit voltage of this thermomagnetic-electric energy harvester approach 1.27 μA and 25 V, respectively. The magnetic-phase-transition alloy-based thermomagnetic-electric energy harvester has the capability to automatically convert the waste heat from a high temperature source into electric energy without rapid temperature fluctuation.