Hygroscopic ionogel for enhanced thermoelectric generation performance

Abstract

Improving thermoelectric generators (TEGs) performance remains challenging in the context of energy crisis and thermal-pollution. Here, we present a strategy for thermal management and performance enhancement of TEGs by sustainable evaporative cooling utilizing highly hygroscopic and adhesive ionogels (PIGs). Rational swelling and poly-[2-(Methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (PDMAPS) chains with group interactions prevent lithium chloride (LiCl) and 1-ethyl-3-methylimidazolium acetate ([EMIM][Ac]) leakage, while carbon nanotubes (CNTs) and MIL-101(Cr) optimize the evaporative cooling of PIGs. PIGs possess high sorption (252.72% at 25 °C, 90% RH for 12 h) and steady sorption-desorption kinetics. Meanwhile, PIGs exhibit high adhesion (130.89 N m⁻¹) on TEGs. The evaporative cooling of PIGs enhances the temperature difference of TEGs. The potential of PIG-TEG is increased by three times at heat source temperatures of 50–80 °C, and the output power density stabilizes at ∼706.25 mW m⁻² after heating at 50 °C for 1 h. Moreover, the PIG-TEG maintains stable output enhancement for prolonged time (over 24 h). Additionally, we integrate PIG-TEGs for the durable power supply of devices and design a movable model car, which utilizes waste heat for self-powering. PIGs realize effective thermoelectric output enhancement of TEGs, and provide ideas in clean energy conversion, wearable devices, and mobile power.