Moisture-gradient-enhanced ionic thermoelectrics

Abstract

Ionic thermoelectrics (i-TEs) demonstrate immense application potential in such fields as wearables and low-grade energy harvesting. Though adequate moisture absorption is required to facilitate ion dissociation in i-TEs, the impact of moisture gradient has been overlooked. Herein, we demonstrate a moisture-gradient-enhanced ionic thermoelectric generator (MGITG) driven by both moisture and temperature gradients. The MGITG exhibits an ionic thermopower of 34.02 mV K-1, a high open-circuit voltage of 644.19 mV, and an ultrahigh 1 h output energy density of 917.54 J m-2. We attribute the enhanced performance to fast and selective ion transport driven by coupled heat and moisture transfer. As a proof of concept, this material enabled the development of wearables capable of monitoring motion and respiration, as well as robotic systems equipped with synchronous environmental and tactile sensing. This work holds promise in the design of high-sensitivity, multifunctional, and high-energy-density i-TEs, facilitating their applications in robotic touch and wearables. Here, the authors develop a moisture-gradient-enhanced ionic thermoelectric generator that achieves high voltage and energy density, demonstrating wearable application for respiration monitoring and robotic systems with environmental and tactile sensing.