Synergistic Thermoelectric‐Piezoionic Ionogel for Multimodal Energy Harvesting

Abstract Harvesting electricity from thermal and mechanical energy sources via thermoelectric and piezoionic effects offers a promising strategy for self‐powered electronics. However, their practical applications are hindered by low and intermittent electricity outputs due to limited thermopower and local ion depletion of the electrolytes under mechanical stress, respectively. Here, a thermoelectric‐piezoionic ionogel (TPIG) is developed that integrates ionic thermoelectric (i‐TE) and piezoionic (PE) functionalities, enabling synergistic energy conversion under thermal gradients and mechanical compression. Owing to the synergistic i‐TE and PE effects, TPIG exhibits a twofold increase in output voltage at a temperature difference of 3 K under 30% compressive strain (39 kPa). This enhancement stems from the chelation of redox ions within the ionic liquid, which induces a transition of the ionic liquid from n‐type to p‐type. This polarity transition effectively couples with piezoionic‐induced selective ion migration under mechanical stress, which amplifies the ionic concentration gradient and significantly enhances the thermopower of TPIG. Scalable thermo‐piezoionic generators composed of 16 TPIG units achieve an open‐circuit voltage of 690 mV and exhibit thermal stability with continuous power generation under large temperature gradients of 80 K. They offer a new paradigm for adaptive energy harvesters operating in dynamic thermo‐mechanical environments.