Flexible Active Peltier Coolers Based on Interconnected Magnetic Nanowire Networks

Abstract

Thermoelectric energy conversion based on flexible materials has great potential for applications in the fields of low-power heat harvesting and solid-state cooling. Here, we show that three-dimensional networks of interconnected ferromagnetic metal nanowires embedded in a polymer film are effective flexible materials as active Peltier coolers. Thermocouples based on Co-Fe nanowires exhibit much higher power factors and thermal conductivities near room temperature than other existing flexible thermoelectric systems, with a power factor for Co-Fe nanowire-based thermocouples of about 4.7 mW/K2m at room temperature. The effective thermal conductance of our device can be strongly and rapidly increased by active Peltier-induced heat flow, especially for small temperature differences. Our investigation represents a significant advance in the fabrication of lightweight flexible thermoelectric devices, and it offers great potential for the dynamic thermal management of hot spots on complex surfaces.

Polycrystalline bismuth nanowire networks for flexible longitudinal and transverse thermoelectrics

“…Since the length over which the Nernst voltage occurs in our experiment is more than a factor of 500 greater than the thickness of the NW-based film (28 μm) to which the thermal gradient is applied, large Nernst voltages were demonstrated at room temperature, reaching 300 μV at B = 1 T for Δ T = 1 K. The estimated Nernst signal, | S Nernst | ∼ 2 μV K −1 for B = 1 T is significantly lower than that measured in single crystal Bi at room temperature for the same field strength (∼30 μV K −1 ) due to the low mobilities of the charge carriers in the CNWs. As recently shown with magnetic NWs, 19–23 the template-assisted synthesis of 3D networks of interconnected NWs provides a simple and cost-effective pathway to fabricate flexible thermoelectric films with no sample size limitations and excellent control over geometrical features, morphology and chemical composition. These unique nanoarchitectures based on CNWS show great potential as lightweight, flexible and shapeable thermoelectric devices.…”

“…The recent development of three-dimensional (3D) networks of interconnected NWs has opened up new prospects in the field of flexible thermoelectric materials. 19–23 These networks of crossed nanowires (CNWs), incorporated into 3D porous polymer membranes to form nanocomposite films, meet the essential requirements of electrical, thermal and mechanical stability. The temperature and diameter evolutions of the thermopower of electrodeposited Bi CNWs have been recently reported by applying out-of-plane thermal gradients.…”